Genetic dissection of grain yield and physical grain quality in bread wheat (Triticum aestivum L.) under water-limited environments

Abstract

In the water-limited bread wheat production environment of southern Australia, large advances in grain yield have previously been achieved through the introduction and improved understanding of agronomic traits controlled by major genes, such as the semi-dwarf plant stature and photoperiod insensitivity. However, more recent yield increases have been achieved through incremental genetic advances, of which, breeders and researchers do not fully understand the underlying mechanism(s). A doubled haploid population was utilised, derived from a cross between RAC875, a relatively drought-tolerant breeders' line and Kukri, a locally adapted variety more intolerant of drought. Experiments were performed in 16 environments over four seasons in southern Australia, to physiologically dissect grain yield and to detect quantitative trait loci (QTL) for these traits. Two stage multi-environment trial analysis identified three main clusters of experiments (forming distinctive environments, ENVs), each with a distinctive growing season rainfall patterns. Kernels per square metre were positively correlated with grain yield and influenced by kernels per spikelet, a measure of fertility. QTL analysis detected nine loci for grain yield across these ENVs, individually accounting for between 3 and 18% of genetic variance within their respective ENVs, with the RAC875 allele conferring increased grain yield at seven of these loci. These loci were partially dissected by the detection of co-located QTL for other traits, namely kernels per square metre. While most loci for grain yield have previously been reported, their deployment and effect within local germplasm are now better understood. A number of novel loci can be further exploited to aid breeders' efforts in improving grain yield in the southern Australian environment.

Wheat Yield and Weedness under Different Rate of Nitrogen Fertilization

“…On the same variant of fertilization 3N 2 (120 kg N ha -1 + 100kg P ha -1 ) other investigated wheat cultivar Lazarica achieved the highest yield (3724 kg ha -1 ). Grain per square meter were positively correlated with grain yield and influenced by kernels per spikelet, a measure of fertility (Bennett et al, 2012 Agropyrum repens L. Chenopodium album L. Chenopodium album L. The least grain yield was found on control variant for both of analyzed wheat cultivars Lazarica (1880kg ha -1 ) and Julija Mono (1740kg ha -1 ) tab. 3.…”

Ppd1, Vrn1, ALMT1 and Rht genes and their effects on grain yield in lower rainfall environments in southern Australia

“…In the Trident/Molineux population, the positive allele for grain yield on chromosome 4D came from Trident (Kuchel et al 2007). However, in the RAC875/ Kukri population, the positive allele in southern Australia came from RAC875 (Bennett et al 2012a), but in a heat environment in Mexico it came from Kukri (Bennett et al 2012b). Similarities to these interactions and effects were observed in our study (Tables 6 and 9), but clearly more work is required to determine the contribution of ALMT1 to the QTL effects observed in the Trident/Molineux and RAC875/Kukri populations.…”

“…A rainfall/evaporation parameter was calculated by dividing growing-season rainfall by growing-season evaporation (Nidumolu et al 2012). Bennett et al (2012a) suggested that the proportion of rainfall received during the vegetative stage relative to growing-season rainfall might be important for classifying environments for wheat production in lower rainfall environments in southern Australia, so a rainfall ratio parameter was calculated as the ratio of rainfall between 1 April and 15 September to growingseason rainfall.…”

“…Molineux carried ALMT1-I, cv. Kukri carried ALMT1-V, and the breeding lines RAC875 carried ALMT1-I, so the Trident/Molineux population studied by Kuchel et al (2007) and the RAC875/Kukri population studied by Bennett et al (2012aBennett et al ( , 2012b were both segregating at the ALMT1 locus. ALMT1 is located on chromosome 4D, and in both populations, a QTL was detected on this chromosome.…”

Heat and drought stress on durum wheat: Responses of genotypes, yield, and quality parameters

“…These results on TKW seem to indicate that, under the drought stress conditions of Cd. Obregon (morning-dew environment), the plant tends to produce less numbers of grains per spikelet (and/or less tillers), maintaining grain size and density practically similar to that under the no-stress condition, while, under heat stress (but no water and N limitations), the plant tends to have a shorter grain filling period, reducing grain size and maintaining relatively high TW (Yang and Zhang, 2006; for a review; Bennett et al, 2012). Most cultivars showed practically no change in FP (97e105% of E1) under E2 and variable increases (4e16% higher than in E1) under E3, most likely related to the reduction in TKW observed in E3.…”