Evaluation of Cowpea (Vigna Unguiculata L. Walp) Genotypes for Adaptation to Low Soil-phosphorus Conditions and to Rock Phosphate Application PDF Download
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Author: Sabiou Mahamane Publisher: ISBN: Category : Languages : en Pages :
Book Description
Cowpea (Vigna ungiculata L. Walp) is a major food and fodder legume in poor countries, particularly Sub-Saharan Africa countries. It is generally produced in sandy, acid soils, deficient in phosphorus (P) which severely limits its production. Because processed phosphate fertilizers are expensive and poorly available to farmers, rock phosphate is viewed as a cheap alternative phosphate source. The present study evaluated 696 U.S Core Collection and IITA cowpea accessions for adaptation to low soil P environments and for response to rock phosphate application. Subsequently, organic acid exudation by selected cowpea genotypes as a mechanism for P acquisition from Fe-oxide and Ca bound P was investigated. A low P soil from Nacogdoches pine forest was used to grow plants. There were two P treatments: 0 and 300 mg P/kg of soil as Tahoua (Niger) rock phosphate. At harvest, plant height, shoot and root dry weights were determined and total biomass and shoot-to-root ratios were computed. Shoot P contents of 100 selected accessions were measured. Sixteen accessions reflecting the wide array of responses observed were selected for the organic acid study. Plants were grown in a growth chamber hydroponically with no P and +P nutrient solutions for 3 weeks. Organic acids were collected in a CaCl2-KCl solution. The nature and quantity of the collected organic acids was determined. Cowpea accessions were significantly different in their ability to adapt to Pdeficiency stress and to acquire P from rock phosphate. The parameters most effective in separating the accessions were shoot mass and total biomass. This data will be potentially useful in the selection of cowpea germplasm for (1) adaptation to West African soils of low P fertility, and (2) ability to utilize P from poorly soluble rock phosphate. The predominant organic acid exuded by cowpea roots was a tricarboxylic acid not yet identified. There was surprisingly more exudation of this acid under +P than under -P conditions. Exudation was more highly correlated to roots than to shoots.
Author: Sabiou Mahamane Publisher: ISBN: Category : Languages : en Pages :
Book Description
Cowpea (Vigna ungiculata L. Walp) is a major food and fodder legume in poor countries, particularly Sub-Saharan Africa countries. It is generally produced in sandy, acid soils, deficient in phosphorus (P) which severely limits its production. Because processed phosphate fertilizers are expensive and poorly available to farmers, rock phosphate is viewed as a cheap alternative phosphate source. The present study evaluated 696 U.S Core Collection and IITA cowpea accessions for adaptation to low soil P environments and for response to rock phosphate application. Subsequently, organic acid exudation by selected cowpea genotypes as a mechanism for P acquisition from Fe-oxide and Ca bound P was investigated. A low P soil from Nacogdoches pine forest was used to grow plants. There were two P treatments: 0 and 300 mg P/kg of soil as Tahoua (Niger) rock phosphate. At harvest, plant height, shoot and root dry weights were determined and total biomass and shoot-to-root ratios were computed. Shoot P contents of 100 selected accessions were measured. Sixteen accessions reflecting the wide array of responses observed were selected for the organic acid study. Plants were grown in a growth chamber hydroponically with no P and +P nutrient solutions for 3 weeks. Organic acids were collected in a CaCl2-KCl solution. The nature and quantity of the collected organic acids was determined. Cowpea accessions were significantly different in their ability to adapt to Pdeficiency stress and to acquire P from rock phosphate. The parameters most effective in separating the accessions were shoot mass and total biomass. This data will be potentially useful in the selection of cowpea germplasm for (1) adaptation to West African soils of low P fertility, and (2) ability to utilize P from poorly soluble rock phosphate. The predominant organic acid exuded by cowpea roots was a tricarboxylic acid not yet identified. There was surprisingly more exudation of this acid under +P than under -P conditions. Exudation was more highly correlated to roots than to shoots.
Author: Tulle Wayne Alexander Publisher: ISBN: Category : Languages : en Pages :
Book Description
As a result of rising fertilizer prices and environmental concerns, efforts are being made to develop crop varieties with better nutrient acquisition and use efficiencies to ensure higher yields and sustainability, especially in the semi-arid tropics and sub-tropics where soils are inherently low in nitrogen and phosphorus. Cowpea does not require additional nitrogen fertilizer because of its ability to biologically fix nitrogen, but it needs phosphate application. However, preliminary studies have shown that some cowpea genotypes have the ability to extract bound phosphorus from low-P soils and from rock phosphate. Therefore, a project was initiated at Texas A&M University to develop high yielding cowpea varieties with enhanced acquisition and efficient utilization of phosphorus from low-P soils and rock-P. This study was conducted to screen 12 selected cowpea varieties under low-P soil, with rock- phosphate application. One-kg pots were filled with 1000 g of low-P soil (
Author: Julie Christine Rothe Publisher: ISBN: Category : Languages : en Pages :
Book Description
Cowpea (Vigna unguiculata (L.) Walp.) is a major food legume across Sub-Saharan West Africa where its leaves, pods and seeds are consumed as food and its residues are fed to livestock as protein rich fodder. However, soils of West Africa are poor in phosphorus (P), a soil macronutrient all crops need for growth. Fertilizer with P is not readily available and is too expensive for West African farmers. This research was therefore, undertaken to identify cowpea lines that inherently grow well in P-deficient soils and use them to breed improved cowpea varieties that require less phosphorus fertilization. A hydroponic phenotypic screening method with silica sand was used to identify cowpea varieties that have tolerance to low soil P as measured by shoot dry biomass production. Both tolerant and susceptible varieties from the screen were further analyzed for root biomass, internal shoot P content, and internal root P content. Seed P, particularly the effect of cotyledon P, and total root production were investigated as physiological sources of tolerance. Tolerant cowpea varieties were crossed with susceptible varieties, and the resulting F1, F2 and BC1 seeds were screened to determine the inheritance and genetic control of tolerance. A Recombinant Inbred Line (RIL) population of a tolerant by susceptible cross was mapped using SSR markers to identify linkage groups or QTL for tolerance to low soil P. Phenotypic screening results identified four cowpea varieties to have P-deficiency tolerance (Big John, IT97K-1069-6, IT98K-476-8, and TX2028-1-3-1) and three cowpea varieties (Big John, CB-46, and Golden Eye Cream) to have partial P-deficiency tolerance via high seed P content. All varieties experienced increases in root production under low P treatments relative to normal P treatments. Phenotyping of F1, F2, and BC1 populations showed that low P tolerance is a heritable trait in cowpea with significant additive effects and narrow-sense heritability. Estimates of gene number suggested the tolerance to be a single-gene trait. Mapping linkage groups or QTL for low P tolerance identified QTL in which three SSR markers - CLM0269, 221/222, and CLM0298 - were significantly associated with tolerance and are potential candidates for marker-assisted selection (MAS). The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/152599
Author: Sabiou Mahamane
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