Abstract
Abstract Spike fertility index (a.k.a. fruiting efficiency) at maturity (FE m ) has been proposed as a promising selection criterion for improving grain yield (GY) in bread wheat. However, its usefulness as an early-generation selection criterion aiming at increasing GY in advanced generations remains to be established. On the other hand, there is no information about the feasibility of using spike harvest index (SHI) as an indirect selection criterion for increasing GY. In this study, a biparental population derived from a cross between 'Baguette 10' and 'Klein Chaja'', Argentinian spring bread wheat cultivars with contrasting FE m , was evaluated from early generations (F2 and F3) to recombinant inbred lines (RILs, tested in seven experiments). Associations of FE m and SHI measurements between early generations and RILs were established. Also, responses in grain number/m 2 (GN) and GY in the RILs after simulated selection for high FE m or high SHI in early generations under four selection strategies comprising combinations of different selection intensities (50%, 25% and 10%) were assessed. Significant and positive correlation was found between FE m measured in early generations and in the RILs (r=0.32, P<0.05) and SHI measured in the F 3 and in the RILs (r=0.26, P<0.05). After selection for high FE m in early generations, responses in GN were positive in all the experiments under all four simulated selection strategies: GN increased by 5.1 to 22.1% as compared with the population mean, depending on the selection strategy. Responses in GY were positive in three out of four selection strategies, averaging -1.3 to 2.1% depending on the selection strategy. Contrarily, responses to selection in GN and GY in the RILs using SHI as a selection criterion in early generations were negative or neutral. In this way, our results validate the use of FE m as a selection criterion in early generations for increasing GN and GY in advanced generations of bread wheat breeding programs.
Highlights
Bread wheat (Triticum aestivum L.) is one of the most important crops that supply the world demand for food
Plant material A recombinant inbred line (RIL) population was developed from the cross between two Argentinian cultivars with contrasting FEm: Baguette 10 (B10; high FEm) and Klein Chajá (KCJ; low FEm)
Significant, positive associations were found between FEm in early generations and FEm best linear unbiased predictors (BLUP) in the RILs (r=0.32, P
Summary
Bread wheat (Triticum aestivum L.) is one of the most important crops that supply the world demand for food. Under a current and future scenario of increased global demand for grains and limited possibilities of expanding cropping areas, breeding efforts must concentrate on further improving grain yield (GY) (CIMMYT, 2019). One manner to achieve this faster is through the identification of yield-related traits which are amenable to high-throughput phenotyping, and their utilization as selection criteria in breeding programs. Grain yield in bread wheat can be considered as the product between the number of grains per unit area (GN) and individual grain weight (GW); of these components, the former is the one which best explains GY variations (Fischer, 1985; Abbate et al, 1995; Calderini et al, 1999; González et al, 2014). One of the difficulties with using variables quantified as per unit area is obtaining reliable data in early generations of breeding programs, in which not enough seed is available
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