Generation mean analysis of some agronomic traits, blast disease and stem borer resistance in two rice crosses under two N-levels [electronic resource].

Includes references.

Two rice croses (HR2824-B-3-2-3 x Sokha 101) and (GZ 5110-20-1-3 x Sakha 101) and their six population (P1, P2, F1, F2 BC1 and BC2) were evaluated for some agronomic characters, blast reaction and Stem borer under two nitrogen fertilizer levels: 411 and 80 units feddan LI and L~ Highly significant positive values of heterosis were found for grain yield/plant. panicle length andd primary branches in cross I at L, and L: and high negative heterotic effects were detected for blast reaction at both nitrogen levels stem borer % at L1 in cross I. Highly significant negative values for inbreeding depression were obtained for stem borer" and blast reaction in both crosses at L1 and L2 Highlyy significant positive values (Id) werefoundfor grain yield/plant, panicle length and primary branches at the two nitrogen 1evels and both crosses. Overdominance, ov'er the higher parent was found for grain yield/plant, panicle length and primary branches in cross I III both nitrogen levels, spikelets/ panicle and primary branches in cross II at L1, L2 grain yield/plant and panide length in cross /I at L10 and harvest index % for the same cross at L1 overdominance, over the 1ower parent, was recorded for plant height ill cross I at Ll and L10 plant height and dates to heading at L1 in cross II Partial dominance towards the better parent. wasfoundfor spikelets/panicle and panicle length in cross I at LI and L10 harvest index" at L2 in the same cross. Absence of dominance wasfoundfar Stem borer % in cross I at L,. The additive gene effects (a) werefound to be highly significant for all traits in both crosses and both nitrogen levels except for blast reaction and primary branches in the cross I at L,. stem borer % and harvest index % ill cross II at L2 and spikelets/ panicle in the same cross at L,. Dominance gene effects (d) were detected to be highly significant for most of the studied characters except for plant height in cross I at L2 panicle length in cross II at L, and L10 days to heading and grain .yield/plant at L2 in cross /I and spikelets/ panicle in the same cross at L1 Significant additive x additive (aa) epistatic types were exhibited for all studied traits except for spikelets/ panick in cross I at L1 and primary. branches at L1 in the same cross but. blast reaction in cross II at L, and L10 plant height and stem borer % at L1 in the same cross, High heritability estimates in broad sense wae detected for all traits studied in both crosses at LI .-I L~ High estimates of narrow sense hertabilily were found for days to heading III L, and L2 in both crosses. primary branches in cross I at L1 and L1 and panicl length and fertilily % at Ll and L1 in cross II, grain yield/plant, harvest index % "panicl length in cross I at L" blast reaction in crosses I and /I. Genetic advance under selection Ag % was found to be high in magnitude for stem borer % and blast reactioninthetwocrosses at LI and L2spikelests/paniclein cross II at L, and L1.panicle lengthe in crosses : and II at L1 relatively, moderate gendic gain was observea for harvest index % and primary branches in cross I at L1 Low genetic gain was detected for the rest of thestadiecd characters under L, and L1 in both crosses. Grain yield/plant was significant posifively correlated with fertility % panicle length, no. of primary branches. harvest inIlD: % and no.. of spikelets/ panicle in cross I at both nitrogen levels. Stem Drought.

Summary in Arabic.

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