Drought resistance in spring wheat cultivars. III.* Yield associations with morpho-physiological traits

Abstract

This paper describes associations between yield performance under drought and morpho-physiological traits, determined both under drought and non-drought conditions, for a large set of diverse cultivars of bread wheat (Triticum aestivum L.), durum wheat (T. turgidum L.), triticale (X Tritosecale Wittmack) and barley (Hordeum vulgare L). Performance under drought was considered in terms of grain yield and drought susceptibility, the latter being proportional to the decrease in yield relative to yield without drought. Species effects are considered, but greatest attention is paid to associations amongst bread wheat cultivars (n = 34), based on phenotypic and genotypic correlations, multiple linear regression and principal components analysis. Under drought, which reduced yield on average 60%, greater yield was most closely associated with greater total dry weight at maturity. Variation in traits associated with plant water relations had only a minor influence. The best prediction of yield under drought, from traits measured in the absence of drought (non-drought traits), was given by a linear model containing total dry weight, kernel weight and leaf waxiness, all with positive coefficients. Drought susceptibility, as defined, was unrelated to plant water relations under drought, but was related to various non-drought traits. It increased with increased non-drought yield, harvest index, kernels per sq metre, kernels per spike and leaf water potential, and with decreased plant height and waxiness. One part of these associations with drought susceptibility appeared to be related to variation in height, probably arising from the action of the Norin 10 dwarfing genes; part, however, was independent of height. The relationships suggested that direct selection for increased yield in the absence of drought, or selection via most of the non-drought traits, increased drought susceptibility and, depending on drought level, may increase or decrease yield under drought. No trait had clearly desirable effects on yield both in the absence of drought and drought susceptibility; total dry weight appeared to have the least undesirable effect on susceptibility. ______________________ *Part 11, Aust. J. Agric. Res. 30: 801 (1979).

A Metabolic Gene Cluster in the Wheat W1 and the Barley Cer-cqu Loci Determines β-Diketone Biosynthesis and Glaucousness

“…This process is accompanied by the accumulation of b-diketone waxes on surfaces of various glaucous cereal crops. Indeed, glaucousness has been established as an advantage for yield, especially under dry conditions (Fischer and Wood, 1979;Johnson et al, 1983;Febrero et al, 1998;Merah et al, 2000). Glaucousness in wheat is not only governed by the wax production locus W1 but is influenced by the dominant epistatic effect of Iw1 (in hexaploid wheat also W2 and Iw2).…”

Comparative behavior of wheat and barley associated with field release and grain weight determination

“…This could be ascribed to differences in (i) flowering time, (ii) grain-filling duration and/or (iii) the grain-drying period comprised from physiological maturity to the time grains reach the commercial moisture values (14%). Literature showed that flowering time is generally earlier in barley than in wheat (Fischer and Wood, 1979;Miralles and Richards, 2000;Cossani et al, 2009Cossani et al, , 2011. For the grain-filling period, the scenario is less certain: there are studies where barley grain filling was sometimes shorter than (López-Castañeda and Richards, 1994;Ugarte et al, 2007), or similar to (Fischer and Wood, 1979;Lingle and Chevalier, 1985;Ugarte et al, 2007) that of wheat.…”

“…Calviño et al (2003) quantified soybean yield reductions of 56 kg ha −1 per day of sowing delay, highlighting the importance of advancing the winter crop harvest in this double-cropping system. Barley could therefore be better than wheat for this system as there is evidence that it matures earlier (Fischer and Wood, 1979;López-Castañeda and Richards, 1994;Cossani et al, 2009Cossani et al, , 2011. This could be ascribed to differences in (i) flowering time, (ii) grain-filling duration and/or (iii) the grain-drying period comprised from physiological maturity to the time grains reach the commercial moisture values (14%).…”

Dwarfing genes, water-use efficiency and agronomic performance of spring wheat

“…A positive association between Rhtl and Rht2 dwarfing genes and drought susceptibility was found by Fischer and Wood (1979). Duwayri (1984) observed that semidwarf wheats were more susceptible to drought.…”