Gains from Selection for High Grain Yield under Contrasting N Environments in F2 Populations of Wheat Diallel Crosses
1Department of Agronomy, Faculty of Agriculture, Cairo University, Giza, Egypt.
2Wheat Research Department, FCRI, Agricultural Research Centre (ARC), Giza, Egypt
2Wheat Research Department, FCRI, Agricultural Research Centre (ARC), Giza, Egypt
Abstract
Breeding of low-N tolerant cultivars of wheat is one approach to reduce N fertilizer input, while
maintaining acceptable yields. The objective of this investigation was to develop new bread wheat genotypes
(transgressive segregants) of high grain yield under low-N stress conditions. Seventy fiveF3 families were selected
for high grain yield fromF2populations of diallel crosses among 6 parents under low-N and high-N and evaluated
for grain yield and nitrogen use efficiency (NUE) traits in their F3progenies compared with their parents under
both high and low N conditions, using a split plot design in lattice (9 x 9) arrangement with three replications.
The best F3 families (4) that exhibited the highest grain yield and NUE under low-N as well as under high-N and
exceeded significantly their better parents in the respective crosses were identified. They were all selected under
low-N conditions and were significantly superior over their respective better parents. Actual significant
superiority over the better parent in grain yield/plant ranged from 21.5% for SF11 to 33.7% for SF13 under low
N stress and from 14.2% for SF14 to 25.3% for SF11 under high-N conditions. Actual gain from selection for
high yield in the best F3 selected families is higher than corresponding expected genetic gains under both low-N
and high-N.Superiority in grain yield over better parent were attributed to their high superiority in number of
spikes/plant reaching to 80.1%, number of grains/ spike reaching to 31.2% and 100-grain weight reaching to
50.9% under low-N target environment. Selection in F2 populations under low-N for high grain yield caused
simultaneously a superiority in NUE, which reached to 30.4% under low-N and 22.7% under high-N
environment. Moreover, superiority of the best selectants in grain yield and NUE traits was associated with
superiority in grain protein concentration in most cases, which reached to 45.9 and 47% superiority for SF13
under low-N and high-N, respectively over the better parent.
