TITLE:
Response of Cowpea Genotypes to Drought Stress in Uganda
AUTHORS:
Saul Eric Mwale, Mildred Ochwo-Ssemakula, Kassim Sadik, Esther Achola, Valentor Okul, Paul Gibson, Richard Edema, Wales Singini, Patrick Rubaihayo
KEYWORDS:
Drought Tolerance, Moisture Stress, Non-Photochemical Quenching, Split Plot
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.8 No.4,
March
20,
2017
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 IITAdrought
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 highly 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.