i
The response of three drybean cultivars to different
phosphorus fertilizer rates and environmental conditions
B.M. Islam
orcid.org/0000-0002-0942-6249
Dissertation submitted in fulfilment of the requirements
for the degree of Master of Science in Agriculture in Crop
Science at the North West University
Supervisor: Dr E.T. Sebetha
Examination: May 2019
Student number: 22385754
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DECLARATION
I declare that the dissertation hereby submitted to the North West University for the degree of Master of Science in Agriculture in Crop science has not previously been submitted through me for a degree at this or any other institutions; that it's by far my work in design and in execution; and that all materials and results contained herein has been duly stated.
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Acknowledgements
I will like to thank my supervisor, Dr E.T Sebetha, for his supervision and criticism of this research project. I am additionally grateful to the North West University’s Postgraduate Master’s Bursary during my years of study, as well as to the Department of Food Security at the university for their financial support. I am also grateful to Miss Ruth Adebayo who assisted me with the Genstat analysis of all the data. Furthermore, I would like to thank the South African Weather Service for the meteorological data relating to Taung, Ventersdorp, and Mafikeng, as well as the Agricultural Research Council for all the soil and drybean analysis. I am also grateful to Mr Pine for allowing me work on his private farm at Ventersdorp and to the Taung Crop Science Research Station, as well as other workers, who assisted me throughout this research.
Finally, I am thankful to my husband for constantly being there for me and for his endurance with me throughout the process of the study. I would also want to thank my mother and my siblings for their support throughout the duration of this study.
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ABSTRACT
Drybean is a grain legume, which, through biological nitrogen fixation, is important to humans and animals as a valuable nutrient and for the improvement of the soil. Research was conducted to establish the response of three drybean cultivars to varying application rates of phosphorus fertilizer and to varying environmental conditions. The study was conducted during the 2017/2018 planting season at three locations, namely Taung, Mafikeng and Ventersdorp, in the North West province of South Africa that differed in terms of their environmental conditions. The research examined three drybean cultivars (PAN 123, PAN 148 and PAN 9292) at three sites (Taung, Ventersdorp and Mafikeng), and under five application rates of single superphosphate fertilizer, which differed according to each location (Taung = 0, 30, 45, 60 and 75 kg P/ha-1, Ventersdorp = 0, 45, 60, 75 and 90 kg P/ha-1 and Mafikeng = 0, 110, 114, 118
and 120 kg P/ha-1). All the treatment combinations were laid out in a randomized complete
block design (RCBD); with four replications. The assessed growth parameters include plant height, the number of leaves per plant, the chlorophyll content of the leaves, the quantity of nodules and the root length. The results from the research confirmed that PAN 9292 presented with the tallest plants and a larger range of nodules per plant than the other cultivars. PAN 123 produced a larger quantity of leaves per plant, higher chlorophyll content and longer roots length. The results of the research additionally confirmed that the drybean planted at Taung produced stronger growth parameters compared to the other location. The results further revealed that while the grain quality of PAN 123 was higher in ash and crude fibre content, PAN 148 had higher starch content and PAN 9292 had a better fat content. However, none of the cultivars confirmed any significant effect on drybean protein content. The interaction of cultivar × location had a significant effect at the drybean starch content. Chapter 1 presents an introduction and background to the study, focusing on the problem statement, a justification for the study and the aims and objectives of the study. Chapter 2 covers the literature review of the study. Chapter 3 includes the materials used and the methods applied, as well as the effects of phosphorus fertilizer rate, cultivar and location on drybean growth parameters, while Chapter 4 deals with the effects of phosphorus fertilizer rate, cultivar and location on drybean yield. Chapter 5 is about the effects of phosphorus fertilizer rate, cultivar and location on the grain quality of the drybean. Chapter 6 concludes with a discussion on the research findings and recommendations based on the results of the study.
v TABLE OF CONTENTS DECLARATION ... v ACKNOWLEDGEMENTS ... v ABSTRACT ... v LIST OF TABLES ... v LIST OF FIGURES ... v LIST OF APPENDICES ... v CHAPTER 1: INTRODUCTION ... 1 1.1 Problem statement ... 2 1.2 Justification ... 3
1.3 Aims and objectives ... 4
1.4 Hypotheses ... 4
1.5 References ... 5
CHAPTER 2: Literature Review ... 8
2.1 Economic aspects,the production and marketing of the drybean in South Africa ... 8
2.2 Climatic and environmental conditions impacting on drybean production ... 9
2.3 Effects of phosphorus fertilizer rates on drybean production ... 11
2.4 Effects of soil types on drybean production ... 14
2.5 Effects of drybean production on soil fertility improvement ... 15
2.6 Performance of various drybean cultivars ... 16
2.7 Nutritional content and use of the drybean ... 17
References ... 19
CHAPTER 3: Effects of phosphorus fertilizer rate, cultivar and location on drybean growth performance ... 30
3.1 Introduction ... 30
3.2 Materials and methods ... 32
3.2.1 Site description of the study area ... 32
3.2.2 Experimental design... 33
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3.2.4 Pre-planting and soil sampling... 33
3.2.5 Plot size, row number and spacing ... 35
3.2.6 Planting and the source of the planting materials ... 35
3.2.7 Cultural practices ... 35
3.2.8 Fertilizer application ... 36
3.2.9 Data collection ... 37
3.2.9.1 Statistical analysis ... 38
3.3 Results and discussion ... 39
3.3.1 Effects of phosphorus fertilizer rate, cultivar and location on drybean plant height at 48 and 78 days after planting (DAP) ... 39
3.3.3 Effects of phosphorus fertilizer rate, cultivar and location on the number of leaves per drybean plant at 48 DAP and 78 DAP ... 41
3.3.4 Effects of phosphorus fertilizer rate, cultivar and location on the chlorophyll content of the drybean leaf at 48 DAP and 78 DAP ... 42
3.3.7 Effects of phosphorus fertilizer rate, cultivar and location onthe number of nodules per drybean plant before flowering (48 DAP) ... 48
3.3.8 Effects of phosphorus fertilizer rate, cultivar, and location on the root length per drybean plant before flowering (48 DAP) ... 49
References ... 55
CHAPTER 4: Effects of phosphorus fertilizer rate, cultivar and location on the yields and yield components of the drybean ... 68
4.1 Introduction ... 68
4.2. Materials and methods ... 70
4.2.1 Description of the study area ... 70
4.2.2 Experimental design... 71
4.2.3 Plot size, row number and spacing ... 71
4.2.4 Agronomic practices ... 71
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4.3 Results and discussion ... 73
4.3.1 Effects of phosphorus fertilizer rate, cultivar and location on the number of pods per drybean plant ... 73
4.3.3 Effects of phosphorus fertilizer rate, cultivar and location on the pod mass per drybean plant... 75
4.3.5 Effects of phosphorus fertilizer rate, cultivar and location on the pod length per drybean plant... 76
4.3.7 Effects of phosphorus fertilizer rate, cultivar and location on the number of seeds per drybean pod ... 78
4.3.9 Effects of phosphorus fertilizer rate, cultivar and location on the 100 seed mass of the drybean ... 80
4.3.11 Effects of phosphorus fertilizer rate, cultivar and location on the drybean grain yield 82 4.3.12 Effects of phosphorus fertilizer rate, cultivar and location on the aboveground biomass of the drybean ... 82
References ... 84
CHAPTER 5: Effects of phosphorus fertilizer rate, cultivar and location on drybean quality 91 5.1 Introduction ... 91
5.2. Materials and methods ... 93
5.2.1 Description of the study area ... 93
5.2.2 Experimental design... 94
5.2.3 Plot size, row number and spacing ... 94
5.2.4 Agronomic practices ... 94
5.2.5 Data collection and analysis... 95
5.3 Results and discussion ... 96
5.3.1 Effects of treatment factors on the ash content of the drybean ... 96
5.3.2 Effects of treatment factors on the crude fibre content of the drybean ... 98
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5.3.4 Effects of treatment factors on the protein content of the drybean ... 101
5.3.5 Effects of treatment factors on the starch content of the drybean ... 102
References ... 104
CHAPTER 6: Summary, Conclusion and Recommendations…………..………...111
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LIST OF TABLES
Tables Pages
3.1. The results of the chemical and physical properties of the soil collected during the 2017/18 planting season from depths of 0 to15 cm before the planting process at the three locations . 34 3.2. A summary of the respective mean temperature and precipitation values for Taung, Mafikeng and Ventersdorp during the 2017/18 planting season. ... 35 3.3. The respective phosphorus rates applied at Taung, Mafikeng and Ventersdorp during the 2017/18 planting season. ... 37 3.4. The effects of phosphorus fertilizer rate, cultivar and location on drybean plant height (in cm) at 48 and 78 DAP. ... 40 3.5. The interaction effects of cultivar × location on the drybean plant height (in cm) at 78 DAP... 41 3.6. The effects of phosphorus fertilizer rate, cultivar and location on the number of leaves per drybean plant and the chlorophyll content of the drybean leaf at 48 and 78 DAP. ... 44 3.7. The interaction effects of cultivar × location on the number of drybean leaves at 48 DAP. ... 45 3.8. The interaction effects of cultivar × location on the number of drybean leaves at 78 DAP. ... 46 3.9. The interaction effects of phosphorus fertilizer rate × location on the number of drybean leaves at 78 DAP. ... 47 3.10. The interaction effects of cultivar × location on the chlorophyll content of the drybean leaf at 48 DAP. ... 48 3.11. The effects of phosphorus fertilizer rate, cultivar, and location on the root length and number of nodules per drybean plant before flowering. ... 50 3.12. The interaction effects of phosphorus fertilizer rate × cultivar on the number of nodules per drybean plant before flowering ... 51 3.13. The interaction effects of phosphorus fertilizer rate × location on the number of nodules per drybean plant before flowering ... 52 3.14. The interaction effects of cultivar × location on the number of nodules per drybean plant before flowering. ... 53 3.15. The interaction effects of cultivar × location on the root length (in cm) of the drybean plant before flowering. ... 54 4.1. The effects of cultivar x location on the number of pods per drybean plant, pod mass (g) and pod length (cm). ... 74
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4.2. The interaction effects of cultivar × location on the number of pods per drybean plant. . 75 4.3. The interaction effects ofcultivar × location on the pod mass (g) of the drybean plant. .. 76 4.4. The interaction effects of cultivar × location on the pod length (cm) of the drybean plant ... 77 4.5. The effects of cultivar x location on the number of seeds per drybean pod ... 79 4.6. The interaction effects of cultivar × location on the number of seeds per drybean pod. .. 80 4.7. The interaction effects of cultivar × location on the drybean 100 seed mass (g) ... 81 4.8. The effects of location on the drybean field biomass (kg/ha) ... 83 5.1. The effects of cultivar × location on the starch content of the drybean ... 104
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List of figures
Figures Pages
Figure 5.1: The effect of cultivar on the ash content of the drybean ... 97
Figure 5.2: The effect of location on the ash content of the drybean ... 98
Figure 5.3: The effect of cultivar on the crude fibre content of the drybean ... 99
Figure 5.4: The effect of cultivar on the fat content of the drybean ... 100
Figure 5.5: The effect of location on the fat content of the drybean ... 100
Figure 5.6: The effect of location on the protein content of the drybean ... 101
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LIST OF APENDICES Page
Appendix 7.1: Analysis of Variance (ANOVA) for drybean chlorophyll content at 48 DAP
... 115
Appendix 7.2: Analysis of Variance (ANOVA) for drybean chlorophyll content at 78 DAP ... 116
Appendix 7.3: Analysis of Variance (ANOVA) for number of leaves per drybean plant at 48 DAP... 117
Appendix 7.4: Analysis of Variance (ANOVA) for number of leaves per drybean plant at 78 DAP... 118
Appendix 7.5: Analysis of Variance (ANOVA) for number of nodules per drybean plant before flowering ... 119
Appendix 7.6: Analysis of Variance (ANOVA) for drybean plant height at 48 DAP ... 120
Appendix 7.7: Analysis of Variance (ANOVA) for drybean plant height at 78 DAP ... 121
Appendix 7.8: Analysis of Variance (ANOVA) for drybean root length at 48 DAP ... 122
Appendix 7.9: Analysis of Variance (ANOVA) for drybean grain yield ... 123
Appendix 7.10: Analysis of Variance (ANOVA) for drybean 100 seed mass ... 124
Appendix 7.11: Analysis of Variance (ANOVA) for number of pods per drybean plant ... 125
Appendix 7.12: Analysis of Variance (ANOVA) for number of seeds per drybean pod ... 126
Appendix 7.13: Analysis of Variance (ANOVA) for drybean pod length ... 127
Appendix 7.14: Analysis of Variance (ANOVA) for total above-ground drybean biomass . 128 Appendix 7.15: Analysis of Variance (ANOVA) for drybean pod mass ... 129
Appendix 7.16: Analysis of Variance (ANOVA) for drybean ash content ... 130
Appendix 7.17: Analysis of Variance (ANOVA) for drybean crude fibre content ... 131
Appendix 7.18: Analysis of Variance (ANOVA) for drybean fat content ... 132
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1
CHAPTER 1
1 General introduction
The drybean belongs to the family Fabaceae and owing to its high protein content and dietary benefits; it is regarded as one of the most important field crops in South Africa (Agricultural Research Council -Grain Crop Institute, 2002). It is an annual leguminous food crop farmers harvest for its dry seeds. Drybean is presumed to have originated in United States of America (Blair et al., 2006). It is a grain legume, which is important in feeding humans and animals. Furthermore, the fertility of the soil is also improved through the associated process of biological nitrogen fixation and green manuring. Drybean may be fed on as a harvested fresh vegetable, whilst the dry grains can either be cooked and eaten with tender maize or be processed into soups and canned merchandise which include baked beans (DAFF, 2010). Increased drybean production rates could serve as a source for generating income to improve the livelihoods of rural people. The high-yielding varieties of the drybean will continue to contribute to the food security of the rural population in particular and are expected to boost their income generation in the quest to alleviate poverty (Katungi et al., 2009).
Drybean seeds should be cultivated in warm soils (preferably above 13°C) after the danger of frost has passed (DAFF, 2010). Sandy loam, sandy clay loam, or clay loam with clay content material of 15% and 35%, are all suitable for regular drybean growth. Drybean plants prefer a soil pH of 5.8 to 6.5 and extremely susceptible to lower pH soils (Du Plessis et al., 2002). Drybean growth is restricted in unsuitable soil conditions that are too compacted and contains high soil pH. However, drybean plants grow well in soils with a depth of at least 90 cm, which have no deficiencies and which are welldrained (ARC, 2013).
Temperatures between 18°C and 24°C are considered ideal for drybean plants to grow optimally. Extremely warm weather above 30°C during flowering results in flower abscission and lower pod set, as a result decreasing the yield. Daily temperatures lower than 20°C will hinder maturity and bring about empty seed pods (Fageria et al., 2010). Drybean plants require at the least 400 mm to 500 mm of rain at some stage in the growing season, however an annual overall of 600 to 650 mm is considered ideal for regular plant growth (Liebenberg et al., 2002).
Three types of drybeans are mainly produced in South Africa namely, the red speckled bean, the small white canning bean, and the large white kidney bean (Statistics and Economic Analysis, 2013). The red speckled bean dominates the largest market share and is sold for
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preparation at home in retail quantities in supermarkets (ARC, 2013). Drybeans are categorized according to their colour (red speckled and white kidney beans), seed size (small white canning beans, large white kidney beans), growth habit (determinate or indeterminate), and growing season. Among the cultivars that are produced mainly in South Africa is PAN 123 (determinate), which generally performs well in the national drybean statistical trials. It has been approved for commercial scale canning and has the potential for producing good yields (ARC, 2013). PAN 148 (indeterminate) has been proven valued as an excellent and constant performer and is well adapted to all production regions. PAN 9292 is well suited to the production regions of the North West province because of its adaptability over a wide area and its high rate of yield stability (Fourie, 2016).
Applications of phosphorus in terms of the soil analysis results are critical for normal growth, good yields and the quality of the grain (Maiti et al., 2004). Legumes such as drybean require incredibly large amounts of phosphorus for growth, and this fertilizer has been suggested to promote a larger leaf area, greater biomass, better yields, a larger number of nodules and greater nodule mass (Sixbert, 2012). Moreover, phosphorus has crucial effects at the photosynthesis process, root development, fruit formation and improvements in the quality of the drybean crop (Sara et al., 2013).
The drybean grain yield is not drastically affected by phosphorus application under commercial production hence; phosphorus is not a yield-restrictive element. However, phosphorus can be a yield-limiting element in subsistence production in which small portions of phosphorus fertilizer are carried out (Liebenberg, 2014).
1.1 Problem statement
In terms of the essential plant nutrients, many of the soils in South Africa are often deficient in nitrogen and phosphorus. Most, even the fertile soils, are phosphorus-deficient because of the generally low rates of phosphorus content in the soil (Gyaneshwar et al., 2002). Because of the insufficient supply of phosphorus, the demand for this valuable fertilizer cannot be met, and as such, the quality, growth and yields of the drybean are negatively affected.
Low application rates of phosphorus to the soil might in fact impair the growth process of the drybean. Continuous cropping without the application of inorganic fertilizers to improve drybean growth, especially in smallholder farming sector (Mabapa et al., 2010), causes a
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decline in soil fertility. Soil phosphorus is the maximum frequently poor nutrient in Eastern and Southern Africa respectively with the supply of 65% and 80% restricting drybean production (Kimani et al., 2007). The other problem that South African farmers encounter is their choice of the wrong cultivar that results in reduced yields and an inferior quality of seed in that the cultivars are generally not able to perform well in the unsuitable environmental conditions.
Sandy soils, low erratic rainfall and high temperatures lead to limited production yields (Ayisi et al., 2004) that characterize most parts of South Africa. Planting drybean in an environment that experiences high temperatures can delay the flowering stage of the plant (ARC-GCI, 2013). Extreme high temperatures during the growth period reduce drybean yields. In contrast, delayed maturity and empty seed pods are caused by daylight temperature below 20°C. Drybean requires a neutral and moderately acid soil pH for everyday crop increase. However, nodulation troubles are expected to arise whilst the pH falls below 5.5 (Mabapa et al., 2010). Aluminium and manganese become other stressors that could kill rhizobia in soils with a pH below 5.0 (Drew et al., 2012). Drybean is susceptible to acidic soil and its growth is restricted on soils that are compact, too alkaline or poorly drained. Since limited fertility or nematode damage will result in such conditions, drybean does not grow well in sandy soil (Liebenberg, 2014). Furthermore, clay soils, that are often poorly drained, could also limit drybean yields.
1.2 Justification
Because drybean production in North West province is limited commercially, this research is aimed at subsistence farmers and small-scale farmers. These farmers produce only for consumption at home and because of their lack of knowledge about the effect of phosphorus fertilization on drybean production; they rely on the use of organic manure to fertilize the soil. As such, this research was aimed at increasing the production rates of both the subsistence and small-scale farmers in order to raise the crop production rates since the demand for drybean in the market place is high.
Towards the conclusion of this research, the identification of and recommendations for appropriate application rates for phosphorus fertilization in respect of drybean cultivars will be a helpful aid in promoting effective phosphorus management programmes for the soils in South Africa with such deficiencies. The correct application rates of phosphorus could sustain production and improve drybean yields on phosphorus-deficient soils.
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1.3 Aims and objectives Aim
To investigate the effects of phosphorus fertilizer rates, cultivar and location on growth, yield and grain quality of drybean.
The objectives of the study are:
To determine the effects of specific application rates of phosphorus fertilizer on the performance of the drybean;
To determine the effects of cultivars on the performance of the drybean;
To determine the effects of different environmental conditions on drybean production.
1.4 Hypotheses
The null hypotheses of the study are to establish the following:
Different application rates of phosphorus fertilizer have no effect on the performance of the drybean;
Different cultivars have no effect on the production of the drybean;
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References
Agricultural Research Council - Grain Crop Institute (ARC-GCI). 2013. Drybean production manual. Agricultural Research Council: Annual Report: Pretoria, South Africa: ARC, 2013.
Ayisi KK, Whitbread AM, Mpangane PZN. 2004. Growth and symbiotic activities of cowpea cultivars in sole and binary cultures with maize. Tropical legumes for sustainable farming systems in Southern Africa and Australia, edited by Whitbread AM and Pengelly BC. Australian Centre for International Agricultural Research. p. 115.
Blair MW, Giraldo MC, Buendia HF, Tovar E, Duque MC, Beebe SE. 2006. Microsatellite marker diversity in the common bean (Phaseolus vulgaris L.) Theoretical and Applied Genetics. 113: 100 – 109.
Buruchara R. 2007. Background information on common beans (Phaseolus vulgaris L.) in biotechnology, breeding and seed systems for African crops.
DAFF (Department of Agriculture, Forestry and Fisheries).2010. Drybean Production Guide. Government Printer: Pretoria.
DAFF (Department of Agriculture, Forestry and Fisheries). 2011. Production guideline for Bambara groundnuts. Directorate of Agriculture: Information Services. Pretoria, South Africa.
Drew E, Err DED, Ballard R, O’ara, Deaker R, Denton M, Yates R, Gemell G, Hartley AE, Phillips L, Seymour N, Howieson J, Ballard J. 2012. Inoculating Legumes: a Practical Guide. Grains Research and Development Corporation: Kingston.
Du plessis J. 2002. Maize production. Department of Agriculture, Republic of South Africa. Directorate: Agricultural Information Services, ARC-Grain Crops Institute, Potchefstroom. Production Guide. Government Printer: Pretoria.
Fageria NK, Baligar VC, Clark RB. 2006. Physiology of crop production. New York: The Haworth Press 345.
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Fageria NK, Baligar VC, Moreira A, Portes TA. 2010. Drybean genotypes evaluation for growth, yield components and phosphorus use efficiency. Journal of Plant Nutrition. 33:2167 - 2181.
Fourie D. 2016. Drybean cultivar recommendations. ARC – Grain Crop Institute, Potchefstroom.
Gomez O. 2004. Evaluation of the Nicaraguan common bean (Phaseolus vulgaris L.) 49 landraces. Doctoral Thesis, Department of Ecology and Crop Production Sciences. Uppsala, Swedish University of Agricultural Sciences.
Gyaneshwar P, Kumar GN, Parekh LJ, Poole PS. 2002. Role of soil microorganisms in improving 390 phosphorus nutrition of plants. Plant and Soil Science Journal. 245: 83 - 93.
Katungi E, Farrow A, Chianu J, Sperling L, Beebe S. 2009. Common bean in Eastern and Southern Africa: a situation and an outlook analysis. International Centre for Tropical Agriculture publication.
Kimani JM, Kimani PM, Girithi SM, Kimenju JW. 2007. Mode of inheritance of common bean (Phaseolus vulgaris L.) traits for tolerance to low soil phosphorus (P). Euphytica. 155: 225 - 234.
Liebenberg AJ. 2002. Drybean Production. Department of Agriculture in cooperation with the Agricultural Resources Council: -Grain Crops Institute. Government Printer: Pretoria.
Liebenberg AJ. 2014. Drybean Production. Department of Agriculture in cooperation with the Agricultural Research Council -Grain Crops Institute. Government Printer: Pretoria.
Mabapa PM, Ogola JBO, Odhiambo JO, Whitbread A, Harreaves J. 2010. Effect of phosphorus fertilizer rates on the growth and yield of three soybean (Glycine max) cultivars in Limpopo Province. African Journal of Agricultural Research. 5: 2653 - 2660.
Maiti R, Jana D, Das UK, Ghosh D. 2004. Anti-diabetic effect of aqueous extract of seed of Tamarindusindica in streptozotocin in induced diabetic rats. Journal of Ethnopharmacology. 92: 85 - 91.
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National Department of Agriculture, ARC-Grain Crops Institute. 2002. In: Liebenberg AJ (Ed), Drybean Production.
Sara S, Morad M, Reza CM. 2013. Effects of seed inoculation by rhizobium strains on chlorophyll content and protein percentage in common bean cultivars (Phaseolus vulgaris L.). International Journal of Biosciences. Vol 3, No. 3: 1 - 8.
Sixbert M, George MT. 2012. Evaluation of common bean (Phaseolus vulgaris L.) genotypes for adaptation to low phosphorus. International Scholarly Research Network. 9: 10.
Statistics and Economic Analysis. 2012. Drybean market value chain profile. Department of Agriculture, Forestry and Fisheries. Government Printer: Pretoria.
Statistics and Economic Analysis. 2013. Millennium Development Goals, Country Report 2013.
Xiaolong Y, Yaoguang L, Jonathan L, Hong MA. 2008. Adaptation of soybean to low phosphorus soils of tropical and subtropical South China: a Radical Approach. McKnight Foundation: Collaborative Crop Research Program (CCRP), Annual Report.
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CHAPTER 2 Literature Review
2.1. Economic aspects, production and marketing of the drybean in South Africa
Based on the report of Statistics and Economic Analysis (2012), South Africa produces only 75% of the drybean consumed in the country. A non-stop attempt is being made to acquire better production costs consistent with unit price with the intention to increase profitability and to satisfy the ever-growing demand for food, especially protein. The restrained local supply and the huge call for drybean in the South African markets generally result in realistic price increases (Statistics and Economic Analysis, 2010). Achieving a good net profit is dependent on choosing an appropriate market class, good varieties to grow, and a good environment (location) in which to grow the crop (ARC-GCI, 2012). Drybean is usually used for human intake, as a livestock feed and for soil fertility improvement (DAFF, 2010).
In South Africa, drybean is either canned or sold in pre-packed quantities, with the latter dominating the market. More than 80% of the small white beans produced in South Africa are used within the canning industry as a canned product in tomato sauce and are offered as baked beans (Fourie et al., 2010). Cultivar differences have an effect on the canning of drybeans required in the canning industries (ARC, 2010). Owing to the variations in the different cultivars and the availability of the approved cultivars for the canning process, it is not always possible to supply beans of a consistent size to the consumer. Management practices from the cultivation to the storage of drybeans have an effect on the canning process of the crop (Fourie, 2012).
According to Statistics and Economic Analysis (2012), all the industries involved in the production of drybean can help to reduce the high unemployment rate. The increase inproduction of the drybean could boost the economy of the country in that there is a large demand for it on the market (Statistics and Economic Analysis, 2013). An increase in the production of the drybean together with its health benefits could improve the food security of the population, more especially in the rural areas. Drybeans are preferred by farmers because of their rapid growing properties that enable households to earn cash income to satisfy their need to purchase food products when other crops have not yet matured (DAFF, 2010).
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Drybean production regions in South Africa are Mpumalanga, Gauteng, Free State, North West, Limpopo, Kwa Zulu Natal and Northern Cape, with Free State having the biggest quantity of farmers, specifically approximately 273, observed by means of Mpumalanga, with 199, and North West Province with 47 (Statistics and Economic Analysis, 2012). The red speckled drybean cultivar is usually cultivated and commands the most important market percentage, accompanied with the aid of the large white kidney bean and the small white canning bean respectively in South Africa (DAFF, 2010).
In South Africa, the amount of drybean produced does no longer meet the local demand, as a result, the country imports drybean to the value of one hundred and twenty million (ZAR) annually with the imports specially from Asia, United States of America and Europe whilst imports from Africa are minimal (Statistics and Economic Analysis, 2012). Drybean is produced in the following districts of North West Province namely, Ngaka Modiri Molema, Dr Kenneth Kaunda and Bojanala district.
Drybeans are cultivated for local consumption by small-scale farmers and mostly at the subsistence level as a component in the canning industry (DAFF, 2010). According to DAFF (2010) smallholder framers produce drybean at subsistence level for local markets, however, a part of the drybean they produce in South Africa contribute to the canning industry. In South Africa, drybeans are either canned or sold in pre-packed quantities, the latter dominating the market. Approximately 85% of the drybean crop is marketed by the pre-packing industry, with the red speckled variety being the most popular (Statistics and Economic Analysis, 2012). There are more than 30 large enterprises in South Africa specialising in the pre-packing of drybeans and about 13 large canners. North West Province, however, has no canners. Pre-packing enterprises are found in most of the provinces, with the largest number located in Kwa Zulu-Natal (Statistics and Economic Analysis, 2012).
2.2. Climatic and environmental conditions affecting drybean production
The drybean is an annual crop that thrives in a warm climate. Drybeans are suited to the tropics, subtropics, and the warm temperate regions (International Centre for Tropical Agriculture, 2000). It grows normally at temperatures between 18°C and 24°C. The crop takes between 85 to 115 days to mature depending on the cultivar and season, while the yield potential in South Africa ranges between 1.5 and 2.5 tonnes per hectare (DAFF, 2011). The maximum
10
temperature during flowering should not exceed 30°C for P. vulgaris (DAFF, 2010). Day temperatures below 20°C will delay maturity and cause empty mature pods to develop. High temperatures during flowering could lead to flower abscission and a low pod set, and, therefore, low yields (Smith, 2006). The rhizobia in the soil and on the seed die when the soil temperature exceeds 35°C (Drew et al., 2012). Nelda et al. (2001) have reported that small seeded cultivars tend to germinate and grow faster than the large seeded ones when grown at rather high temperatures (28°C).
Drybean is a warm season crop and are normally no longer stricken by excessive temperatures so long as the moisture inside the soil is adequate. The crop requires uniformly moist soil conditions for normal growth. The ideal conditions for drybean cultivation are to be grown in soils that are warm with lowest temperatures higher than 13°C, after all of the dangers of frost has exceeded. Chandhla (2001) has reported that drybean planted in areas with a minimum temperature below 8°C will not germinate. It has been reported that drybean does not germinate in cold soils and is tremendously susceptible to frost. For this reason, this crop should be planted in warm soils, ideally soils warmer than 18°C after all hazard of frost has exceeded. Nodule formation and existence of rhizobium bacteria in the soil have been reported to be affected by temperature (Kabahuma, 2013). Fageria et al. (2006) have reported that owing to their genotypical properties, the various drybean cultivars respond differently to different environmental conditions.
Drybean grown under rain-fed conditions requires no less than 400 to 500 mm of rain all through the growing season, however annually a total of 600 to 650 mm is considered best to increase yield (ARC, 2010). According to Fageria et al. (2002), drybean production in many areas occurs under rain-fed conditions; consequently, water deficit limits yield and causes instability in production rates. However, although there are reports that the common bean is susceptible to drought stress, the production of this crop in many areas of the world is in fact carried out under drought-stress conditions where there is an inadequate supply of water as a result of limited rainfall or irrigation (Souza et al., 2003; Zlatev and Stoyanov, 2005; Machado Neto and Dura˜ es, 2006).
The water requirements for the production of drybean depend on the nature of the soil and environmental factors, but the drybean is considered virtually intolerant to water stress (Fageria et al., 2010). Several studies have reported reductions in drybean yields as a result of increasing
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water deficits (Dapaah et al., 2000; Boutraa and Sanders, 2001; Wakrim et al., 2005; Bourgault et al., 2010). Efetha et al. (2011) noticed significant increases in average drybean seed yields on frequently irrigated field as opposed to treatments on less frequently irrigated soils.
Drought stress on account of low rainfall and extremely high temperatures is reported to diminish the growth parameters and yield components of many of the positive attributes of faba beans, except in respect to the number of days to flowering and moisture retention in the leaf (Emam et al., 2010). Genotypes with indeterminate reproductive maturity may be advantageous in regions with low precipitation and long growing seasons (Nleya et al., 2001). Such genotypes may be able to get better and bring higher yields as opposed to the genotypes with determinate reproductive growth. Following drought stress, reports have been made on the accelerated maturity of the crop, along with reduced grain yield and a lower mean 100 seed mass (Molina et al., 2001).
Drybean plants can tolerate some degree of moisture stress during the growing season without a major impact on the final yield. However, numerous repeated days of water stress will typically negatively affect the yield (Mabapa et al., 2010). Furthermore, owing to pod drop and a high incidence of disease, the crop does not tolerate humid environments (FAO, 2015). Too much rain can result in plants that are deformed or diseased with a fungal growth. A dry growing season can be remedied by supplementation with water applications using a sprinkler irrigation system, which are considered suitable for drybean production (Fourie, 2010). Excessive drying of the soil can cause the plants to be stunted and would thus cause a reduction in the number of pods and leaves.
2.3. Effects of phosphorus fertilizer rates on drybean production
Phosphorus fertilizer is one of the best extensive determinants of plant increase (Wang et al., 2012) and plays a substantial function in organic nitrogen fixation. For the symbiotic nitrogen fixation to arise the roots must engage with compatible rhizobia in the soil and factors that might generally have an impact on root growth, or the activity of the host plant could affect nodulation. Phosphorus is the basis for the formation of useful energy that is vital for sugar formation and translocation. Dependent on nitrogen fixation, the common bean crop requires more inorganic phosphorus than would be the case with the similar crop provided with inputs of mineral nitrogen (Robinson et al., 2001).
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Soil phosphorus is regarded as a lacking nutrient and its supply is restrained in 65% and 80% of the drybean production regions of Africa continent (Kimani et al., 2007). Phosphorus is needed in quite huge quantities by legumes such as drybean for growth and has been mentioned to promote larger leaf area, higher biomass and nodule mass, higher yields, and large numbers of nodules (Sixbert and George, 2012). Moreover, phosphorus offers critical effective consequences for photosynthesis, root improvement, fruiting and crop quality (Sara et al., 2013).
Yadav (2017) reported poor growth in broadbean plants in treatments where no phosphorus was applied before flowering. The application of the correct amount of phosphorus enhances plant growth, nodule development and nitrogen fixation (Graham and Rosas, 2014). To overcome the phosphorus deficiency in soils, phosphorus fertilizer should be applied within or close to the seed-row at planting time to facilitate an early seasonal uptake of phosphate ions by the crop roots. Li et al. (2011) reported that the good response of leguminous crops to phosphorus fertilizer is mainly determined by the amount of soil phosphorus available.
Along with a deficiency of nitrogen, a deficiency of soil phosphorus is one of the maximum critical abiotic factors restricting crop production. In general, it has been pronounced that 40% of crop production on the world’s arable land is determined by means of the accessibility of phosphorus and sub-superior rates of phosphorus can bring about yield losses to the order of 5 to 15% (George et al., 2011).
Owing to the symbiotic process between the roots of the legume and the surrounding bacteria, phosphorus has received great attention owing to the dramatic effects observed in low-phosphorus soils when low-phosphorus fertilizer is applied to legumes, including Phaseolus vulgaris L. (Zaman et al., 2006; Fageria et al., 2010). Phosphorus enhances root improvement, which improves the delivery of other nutrients and water to the growing parts of the plant, resulting in an extended photosynthetic area and thereby more dry matter accumulation. Robinson et al. (2001) pronounced the effect of phosphorus in stimulating root and plant growth, in the initiation of nodule formation, as well as in influencing the overall efficiency of the rhizobium bacteria.
Phosphorus fertilizer application drastically influences the number of pods and the pod length in drybean cultivation (Fageria, 2006). An increase in the amount of phosphorus applied
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increases the number of pods per plant. Similarly, Shubhashree (2007) and Veeresh (2003) have also reported that different rates of phosphorus fertilization would influence the number of pods per drybean plant. According to Meseret (2014), the application of phosphorus fertilizers increases the quantity of pods per plant over the control plants. The study conducted by Zafar et al. (2011) on incorporated phosphorus supply and plant growth promoting rhizobacteria on growth, nodulation, yield and nutrient uptake in Phaseolus vulgaris revealed that two mineral phosphorus fertilizers applied at 60 kg P/ha-1 improved plant height, quantity
of nodules and nodule fresh and dry weight.
Low rates of performance, limited dry matter production and reduced leaf area are associated with an inadequate supply of phosphorus to the drybean plant (Sixbert and George, 2012). Other studies show that a limited availability of native soil phosphorus, coupled with a poor utilization efficiency of added phosphorus is a major constraint limiting the productivity of the drybean. Drybean is therefore susceptible to low soil phosphorus rates when accompanied by conditions of low soil fertility.
However, the use of phosphorus fertilizer is limited by its high cost. Furthermore, organic inputs do not generally provide sufficient phosphorus for optimum crop growth because of their low concentrations of phosphorus (Aulakh et al., 2003). Satisfactory amounts of phosphorus fertilizer result in increased growth, earlier maturity and increased root growth, the last mentioned meaning that plants can explore the soil for nutrients and moisture. As such, adeficiency of phosphorus would generally slow down overall plant growth (Sixbert and George, 2012).
The higher quantity of pods per plant, longest pod length, largest pod circumference on French bean with treatments involving applications of 60 kg of phosphorus/ha-1 as compared to those
of 0 kg phosphate/ha-1 and 40 kg phosphate/ha-1 was reported by (Rahman et al., 2007). On the
other hand, in the case of the Faba bean (Vaciafaba), El-Gizawy and Mehasen (2009) recorded the highest plants with the largest number of branches, the greatest 100 seed mass and the largest seed yield per plant with applications of 30 kg phosphorus/ha-1.
According to DAFF (2010), the yield response to phosphorous fertilization is not dramatic in commercial production of drybean. However, under subsistence production, where little fertilizer is applied, phosphorus can be a factor to limit yields. The availability of phosphorus in the soil is a major determinant of the volume of drybean production since the beans are
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susceptible to soils that are low in phosphorus content. The deficiency of phosphorus might also additionally restrict nitrogen fixation through its effects on growth and the endurance of the rhizobia, nodule formation and functioning and host plant growth (Tang et al., 2001). Where the phosphorus content of the soil is lower, it is to be recommended that superphosphate be broadcasted and ploughed into the soil to a depth of 15 to 20 cm before planting. Phosphorus can also be band-placed with the seed at the time of planting and in soils with a low pH (DAFF, 2010). According to Shubhashree (2007), applications of phosphorus fertilizer result in higher leaf area and number of branches per drybean plant. In biological nitrogen fixation, phosphorus is critical for nodule formation and functioning as well as for specific nitrogenase activity (Kouas et al., 2005). Unlike other legumes, common bean is a poor nitrogen fixer; this is attributable to some genetic factors and its sensitivity to physical and environmental stresses (Yadegari et al., 2010).
2.4. Effects of soil types on drybean production
Drybean is susceptible to saline soils and yield reduction can occur on soils with higher salinity content. It is thus wise to examine the soil for soluble salts to determine whether salinity is a problem inside the discipline because salinity causes leaf scorching. Saline soils affect germination, emergence and subsequently plant growth. Thus, plants that grow in saline soils may become yellowish and be stunted in their growth (Grafton, 2002).
Drybean grows well in soils that are at least 90 cm deep without mineral deficiencies. They do well in soil that is well drained for the proper development of the root system so that the crop is able to absorb the available nutrients and water for normal growth (DAFF, 2010). Sandy loam, sandy clay loam or clay loam with clay content of between 15% and 35% is suitable for normal drybean production. It is not recommended for drybean to be planted on sandy soils because of their low fertility. According to DAFF (2010), the drybean prefers an optimum soil pH of 5.8 to 6.5 and is highly sensitive to acidic soils.
The drybean requires well-drained and well-aerated soil for normal growth. It is not well adapted to heavy clay soils, and is not tolerant to water logging. Drybean will not grow well in soil that is compact, lacks nutrients, particularly phosphorus, or that is too alkaline or poorly drained (DAFF, 2012). Brevedan et al. (2003) stated that a lower soil pH of 4.0 to 4.5 consequently results in appreciably reduced quantity of nodules and nodule dry and fresh mass. However, Sulieman and Hago (2009) found out that failure in nodulation of the common bean
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changed because of a substitute of calcareous soils at pH rates of 8.1 and 8.5, which prevail in the topsoil and subsoil respectively. Low soil fertility is another crucial element restricting yields in most drybean-production areas, with phosphorus deficiency serving as a main nutrient factor (Fageria et al., 2002).
2.5. Effects of the drybean on soil improvement
Legumes play a significant role in agriculture through their ability to enhance soil fertility and the physical condition of the soil through their ability to fix nitrogen. The cultivation of the drybean could be an alternative source for providing nutrients to the soil, especially in the form of nitrogen (Mitran et al., 2018). However, there are biotic and abiotic factors that have a negative effect on the symbiotic relationship between legumes and bacteria and which would thus reduce their ability to fix nitrogen in the soil. They include prolonged drought conditions, highly acidic or alkaline rates, as well as extreme temperatures (Dimkpa et al., 2009; Xie et al., 2009; Meena et al., 2015). Nitrogen fixation is limited in heavy clay soils or compacted soils due to poor soil aeration (Liebenberg et al., 2010). Drybeans are regarded a poor nitrogen fixer and thus, approximately 56. 04 kg/ha of nitrogen is fixed in the soil (Drew et al., 2012). The residual effects of nitrogen fixation by drybean is that nitrogen forms a major component of chlorophyll, which is crucial for photosynthesis. In this process, sunlight is used to convert water and carbon dioxide into food sugars such as glucose, which are vital to the growth and development of the plant. Nitrogen also forms a major component of amino acids which is the building blocks of proteins (ARC, 2010). During biological nitrogen fixation, the bacterium, Rhizobium, invades the roots and thus after weeks the nodules are formed.
Legumes are a major component in sustainable incorporated farming structures as they restore atmospheric nitrogen (Korir et al., 2017; Suzaki et al., 2015). Including legumes in cropping systems performs a critical position in improving soil fertility through symbiotic nitrogen fixation (Berg, 2009; Fenchel, 2011; Meena et al., 2017). Common beans can be produced as a single crop or be intercropped with cereals, which includes maize, sorghum or pearl millet, or even planted in rotation with cereal crops. The benefits of intercropping or crop rotations encompass higher soil fertility control, better pest and disease control, crop diversification, as part of hazard control, and superior productiveness at reduced production costs (Broughton et al., 2003). According to the (Agricultural Research Council, 2010), the drybean can be used to improve soils because of its ability to fix nitrogen, and as green manure, thus adding to the organic matter in the soil. According to Kutu (2008), in their efforts to increase crop productivity and conserve soil, smallholder farmers have used intercropping cereals with
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legumes. Apart from fixing atmospheric nitrogen, the legumes also help to increase the organic content of the soil as they produce huge quantities of foliage that contribute as constituents to the composition of the soil. Furthermore, they also enhance the water-holding capacity of the soil (Meena, 2017).
2.6. Performance of different drybean varieties
According to the ARC-Grain Crop Institute (2010), three growth habits are associated with the edible drybean. They are classified as the determinate or bush type (type 1) and the indeterminate vining or trailing growth habits (type 2) and the indeterminate runner type (type 3). According to Werner (2005), early maturing drybean cultivars fix more atmospheric nitrogen than late maturing ones.
The red speckled drybean variety is commonly produced in South Africa and commands the largest part of the market. The large white kidney bean and the small white canning bean respectively (DAFF, 2010) follow it. Depending on the variety, the crop requires between 85 and 120 days from planting to maturity (Buruchara, 2010). The first half of this period involves vegetative development and the latter half-reproductive development.
Among the cultivars that are produced mainly in South Africa, PAN 123 (a determinate type) has performed well in the national drybean statistical trials (Fourie et al., 2010). PAN 123 has been approved for commercial-scale canning and has a good yield potential (ARC, 2012). It has also been considered the first choice in the small white canning bean category in South Africa and is accepted favourably by many of the large canning companies in the country (PANNAR, 2018).
Some of the characteristics that are considered in the canning of the drybean include its mineral composition and nutrient rate, its effective moisture content, its percentage volume increase when cooked, its cooking time after soaking, the dimensions of the seed, its crude protein, crude fibre, and crude fat content, its carbohydrate content and the seed colour (Gathu, 2012). PAN 148 (an indeterminate) has been proven to be a good performer since it maintains a uniformly high rate of excellent performance and it is well adapted to all of the agricultural production regions of South Africa.
PAN 9292 is well suited to the North West production regions because of its wide range of adaptability over area and its stability in maintaining high yield rates (PANNAR, 2016). PAN 9292 also presents with good grain quality and is less prone to mechanical damage during
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harvesting because it is small and round. Its good all-round resistance to disease makes it an excellent choice for both small-scale producers and large-scale commercial farmers (PANNAR, 2016).
2.7. Nutritional content and the use of the drybean
Drybeans contain high starch, protein and dietary fibre and are an excellent source of potassium, selenium, thiamine, vitamin B6, molybdenum and folic acid (Karanja et al., 2011). Drybean is considered to be the most beneficial and important field crop in SA because of its high protein and fibre content (Liebenberg, 2002). The dietary benefits and contribution of beans to a healthy human diet are recognized by means of non-earning companies targeting human ailments, which include most cancers, diabetes and coronary heart disease (Haugen and Bennink, 2003). Drybeans are an essential legume and a most important source of protein throughout the world. Although the nutritional quality of drybean proteins is lower than that of animal proteins, they are an affordable alternative for many people in the country (DAFF, 2012). Drybeans contain starch, which has a more beneficial effect on the blood sugar balance than many other carbohydrate foods. Eating drybeans helps in weight loss. Drybeans also contain a variety of nutrients and fibres with potential anti-cancerous effects and are good in reducing the cholesterol rate (Brian, 2011). Recent research also indicates that the consumption of grain legumes such as the drybean slows the onset of AIDS in HIV-positive people and therefore, an improved bean production would directly address several critical health issues for African communities (Xiaolong et al., 2008).
Drybean plays an important role on vegetarians’ diet as it contributes to their eating and health benefits. Its health benefits include; its low saturated fats content and high vital vitamins content and phytochemicals (George, 2011). However, the drybean additionally carries numerous compounds, which have historically been classified as anti-nutrients, which are compounds that would intrude with the absorption and digestion of nutrients (Marathe, 2011). Drybeans are an imported staple food in most part of the world, especially in Central and South America and in Africa. The common drybean is of global agronomic and dietary importance and its consumption varies intensely by means of geographical areas and among numerous nations (Uebersax, 2006). This crop is usually used for human consumption, for animal feeds and to improve the fertility of the soil (DAFF, 2010). For human consumption drybean is used as ingredients in soups, chilli dishes, in baked bean and casserole recipes, as refried bean paste, and in fresh salads, and can be purchased dry or as previously cooked and canned products
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(ARC, 2010). Drybeans, which do not meet human food-quality standards, can be used as livestock feeds (ARC, 2012).
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