GENETIC VARIABILITY, HERITABILITY AND RELATIONSHIPS AMONG DROUGHT TOLERANT-TRAITS IN COWPEA (VIGNAUNGUICULATA[L.]WALP.)MAGIC - RILS POPULATION
GENETIC VARIABILITY, HERITABILITY AND RELATIONSHIPS AMONG DROUGHT TOLERANT-TRAITS IN COWPEA (VIGNAUNGUICULATA[L.]WALP.)MAGIC - RILS POPULATION
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Date
2019-11
Authors
ABIOLA, AbdurRazaaq
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Abstract
Erratic rainfall pattern exposes cowpea to drought at critical stages of growth of the crop. This is inspite of the inherent capacity of cowpea to withstand drought. There is no information on drought adaptability of cowpea MAGIC-RILs germplasm. This research was therefore, conducted to evaluate genetic variability, heritability and relationships among seedling stage and post-flowering stage drought tolerant-traits in Cowpea MAGIC - RILs population and select parents for further breeding activities. Screenhouse evaluation was carried out using a simple Wooden Box technique to investigate the responses of the lines to drought stress at the seedling stage. Field trial was conducted to screen the lines for their responses to post flowering stage drought stress. Results obtained from the Wooden Box Experiment showed high genetic variability among the lines fordrought tolerance at the seedling stage. New drought tolerant genotypes were identified, for instance MAGIC 162 and MAGIC 012 which both had a recovery rate of 100% and both maintained low leaf senescence scores of 2 were found to be highly tolerant to drought stress at the seedling stage. They also had a Type 1 Drought Tolerant Type which was the same as DanIla which was the drought-tolerant check. Field trials results demonstrated that cowpea MAGIC-RILs is a promising genetic resource to address drought stress in sub-Saharan Africa. The quantitative indices of drought tolerance STI and GMP were used to classify the genotypes. MAGIC 061, MAGIC 063, MAGIC 144 and MAGIC 032 were found to be tolerant to drought at post-flowering stage and classified as Class A due to their uniform superiority in both water-stressed and well-watered environments. Genotypic variability for drought tolerance existed amongst the tested genotypes. There exist relationships among drought-tolerant traits at both the seedling and the terminal stages. Leaf senescence is the most important predictor of recovery at the seedling stage and it is negatively correlated with recovery rate. The negative correlation between leaf senescence and recovery rate could serve as an early indicator of the ability of cowpea MAGIC RILs to recovery from drought stress after rehydration. For terminal drought tolerance, stress tolerance index (STI) and geometric mean productivity (GMP) were highly positively correlated at p < 0.001. The seven (7)MAGIC RILs (MAGIC 162, MAGIC 012, MAGIC 336, MAGIC 301, MAGIC 213, MAGIC 204, MAGIC 129) selected at the seedling stage are recommended for use as parents for the development of new germplasms for further breeding pipelines. Ten (10)MAGIC RILs (MAGIC 061, MAGIC 063, MAGIC 144, MAGIC 032, MAGIC 115, MAGIC 305, MAGIC 004, MAGIC 005, MAGIC 015, MAGIC 257) selected as terminal drought tolerant lines are recommended for preliminary and multi-locational trials.
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A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES,AHMADU BELLO UNIVERSITY ZARIA, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF MASTER OF SCIENCE IN BOTANY DEPARTMENT OF BOTANY FACULTY OF LIFE SCIENCES AHMADU BELLO UNIVERSITY, ZARIA
Keywords
GENETIC VARIABILITY,, HERITABILITY,, DROUGHT TOLERANT-TRAITS,, COWPEA,, VIGNAUNGUICULATA. L, MAGIC - RILS,