Abstract:
Moisture stress is a challenge to cowpea production in the drought prone
areas of eastern and north eastern Uganda, with yield losses of up to 50% reported.
Genotypes grown by farmers are not drought tolerant. This study was
therefore, undertaken at Makerere University Agricultural Research Institute
Kabanyolo to identify cowpea genotypes tolerant to drought. Thirty cowpea
accessions comprising of Ugandan landraces and released varieties, Brazilian
lines, Makerere University breeding lines, elite IITA germplasm and seven
IITA drought tolerant lines as checks were screened for drought tolerance at
vegetative and reproductive stages. The experiment was designed as a 2 × 37
factorial and laid out in a split-plot arrangement, 37 genotypes of cowpea at
two soil moisture stress levels (T1, no stress and T2, severe stress) with all
factorial combinations replicated two times in a screen house. The genotypes
showed considerable variability in tolerance to drought. Genotypes were significantly
different for chlorophyll content (P ≤ 0.01), efficiency of photosystem
II (P ≤ 0.05), non-photochemical quenching (P ≤ 0.05), recovery (P ≤
0.01), delayed leaf senescence (P ≤ 0.01), grain yield (P ≤ 0.01), 100 seed
weight (P ≤ 0.05), number of pods per plant and number of seeds per pod (P
≤ 0.001). There was a high significant positive correlation between chlorophyll
content and efficiency of photosystem II (r = 0.75, P ≤ 0.001) implying that
chlorophyll content and efficiency of photosystem II could be used as efficient
reference indicators in the selection of drought tolerant genotypes. Genotypes
SECOW 5T, SECOW 3B, SECOW 4W, WC 30 and MU 24 C gave relatively
high yields under stress and no stress conditions, maintained above mean chlorophyll
content, efficiency of photosystem II and had good recovery scores
from stress and thus were tolerant to drought stress induced at both vegetative and reproductive stages.
