Construction and Efficiency of Selection Indices in Wheat (Triticum aestivum L.) under Drought Stress and Well-Irrigated Conditions

Abstract

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Aggregate selection helps making selection decisions for improved profitability and permits to exploit information on correlated traits to improve accuracy. In the present study, the efficiency of trait selection was assessed by the Smith-Hazel (SHI) and the Pesek-Baker (PBI) models in 35 wheat genotypes under drought stress at heading and well-irrigated conditions at the Research Farm of Shiraz University, Iran in 2011 and 2012 years. The analysis of correlated response (CR) revealed that thousand grain weight (TGW) with CR = 24.05 (in 2011) and 9.15 (in 2012) and harvest index (HI) with CR = 18.37 (in 2011) and 9.08 (in 2012) had higher indirect effects on grain yield (GY) increase under drought stress. In both years, biological yield (BY), grain number/spike (GN), TGW, and GY had the highest genetic gain (ΔG) in SHI model. The top ten landraces in PBI for the trials in 2011 were also placed in the top rankings for grain yield under drought stress conditions. These results and estimation of the efficiency of selection (ΔH) revealed that PBI (ΔH = 19.95 and 16.5 in the first and 11.15 and 11.06 in the second year) was more efficient than SHI (ΔH = 9.58 and 8.97 in the first and 9.74 and 8.59 in the second year) in view of identifying superior genotypes based on aggregate trait selection. Overall, repeatability estimates for grain yield (33%-57.8%) was relatively low showing that individual plant selection has low efficiency for wheat improvement whilst aggregate trait selections leads to relatively high genetic gain (1.63-2.75) for grain yield.

Direct and Indirect Selection for Grain Yield and Grain Weight in Late Generations of Bread Wheat under Drought Stress and Normal Irrigation Environments

“…[10,15] noted higher genetic variability under drought than under irrigation. In addition, [16,18] reported that the variation decreased under drought stress because of the influence of the genotype by drought interaction.…”

“…Refs. [17,18] noted a greater reduction in heritability of most complex traits under drought than under irrigation conditions, which may be due to the decrease in genetic variation and the influence of the genotype by drought interaction. Ref.…”

Evaluation of Cowpea Landraces under a Mediterranean Climate

“…All landraces under study did not differ statistically significantly from each other, nor compared to the improved line, regarding their seed yield (kg ha −1 ). This fact is probably due to the unfavorable field conditions, which led to the production of low seed yield and did not allow landraces’ potential to be unfolded in our study [ 78 , 79 , 80 ]. In particular, the seed yield of the VG2 landrace from Atsiki of Lemnos was low (0.56 t ha −1 on average).…”

Construction of some selection procedures for improvement of grain yield in durum wheat

“…The breeder may use such selected families in breeding programs aimed at increasing wheat grain yield. Overall, grain yield estimates were low, indicating that individual plant selection is inefficient for wheat improvement whereas aggregate trait selection results in relatively large genetic gain for grain yield (Ghaed-Rahimi et al, 2017).…”