Evaluation and differential expression of genes conferring drought tolerance in selected maize genotypes in the Morogoro Region of Tanzania

摘要

Experiments were conducted at Sokoine University of Agriculture in Morogoro, Tanzania to assess the growth performance and grain yield of ten maize cultivars under well-watered and water stressed conditions. The ten cultivars (CML 444, CML395, CML539, WE 4107, WE 2112, WE 3102, WE 4112 and WE 4116) obtained from Water Efficiency Maize for Africa (WEMA) project and two local market cultivars (‘STAHA’ and ‘TMV1’) were grown in a Randomized Complete Block design with a 10×3 factorial treatment arrangement and three replications. The three drought stress treatments were 50, 75 or 100% of field capacity with 10 kpa (equivalent to field capacity) and 30 kpa (drought) using tensiometers. Drought stress was initiated at vegetative stage (three weeks after emergence) for thirty days and flowering stage (one week before to two weeks after flowering). Plant height, stem diameter, leaf length, leaf width and chlorophyll content were measured at weekly intervals from two weeks after planting to maturity. Days to anthesis and silking were used to calculate Anthesis-Silking Interval (ASI) and kernel dry mass were recorded at harvest. Vegetative growth responses were not affected by water stress, but plant height and leaf chlorophyll content tended to decrease, while ASI ranging from 5.2 to 11.1 days and kernel dry mass decreased with increased drought stress. Dry kernel weight was significantly greater among five of the cultivars designated drought tolerant and the lowest in the two drought susceptible cultivars. Drought tolerant genes were expressed at different levels and only a few cultivars expressed all three genes at the vegetative and flowering stages. Thus, vegetative response of maize to drought stress varied based on cultivars. However, it appears that drought stress exerted more impacts on reproductive processes compared to vegetative.