Field performance of heat tolerant mutant rice lines generated from Oryza sativa and Oryza glaberrima

This study evaluated mutant lines developed from two cultivated species of upland rice, Oryza sativa, and Oryza glaberrima, in field experiments conducted during the hot and dry seasons of 2014/2015 in Morogoro, Tanzania. The growth yield and yield components of 34 and 14 Gamma induced mutant upland rice lines developed from O. sativa (Kihogo red) and O. glaberrima were evaluated, respectively. The mutant lines were selected based on variable expression of heat shock protein genes (HSPs) in previously conducted heat tolerance studies. The minimum and maximum temperatures and rainfall during the field performance experiment were measured between 20 oC and 35 oC, and 32.7 mm and 155.5 mm, respectively. The data for 12 yield and yield component parameters such as days to early and 50% flowering, days to physical maturity, plant height, number of tillers, number of panicles, spikelets, filled grains, unfilled grains and 1,000 grain weights were collected and analysed using ANOVA and Principal Component Analysis. Significant differences (P≤0.05) were obtained among the mutant lines in terms of grain yield, spikelet sterility and other variables, which were further used as criteria for selection of heat and drought tolerant rice lines. Eight heat and drought tolerant mutant rice lines with high yields (over 3.5 ton/ha) and low spikelet sterility were selected for further advancement in breeding programmes