Grain Yield Increase in Recent Argentine Wheat Cultivars

Abstract

This study analyzes differences in potential yield among six semidwarf awned spring bread wheat (Trilicum aestivum L.) cultivars recently selected in Argentina. Yield was considered as the product of number of grain per square meter (NG) and weight per grain. The NG was analyzed in terms of (i) duration of the inflorescence growth period (excluding grains), (ii) crop growth rate during that period, (iii) partitioning of crop dry matter to spikes during the same period, and (iv) grain/spike weight ratio (i.e., number of grains per gram of spike). The data were obtained from two field experiments in the Province of Buenos Aires. Grain yield (range: 453–689 g m−2) was related more to NG (range: 13.3–21.3 ✕ 103 grain m−2) than to weight per grain. Duration of spike growth period was the same (27 d) for all cultivars. During this period, intercepted photosynthetically active radiation, radiation‐use efficiency (mean: 2.7 ± 0.28 g MJ−1), and crop growth rate (mean: 26 ± 2.5 g m−2 d−1) were similar for all the cultivars examined. Differences among cultivars in partitioning to spikes (ranges: 28–34%) were significant. The NG, however, was not related to partitioning to the spike. There were clear differences among cultivars in the grain/spike weight ratio (range: 61–106 grain g−1); NG was more closely related to this ratio (r = 0.96, P < 0.01) than to dry weight of spikes at the end of their growth period (r = −0.30). Increments in potential yield by means of high grain/spike weight ratio were not previously reported and may be a path to future potential yield improvements.

Wheat physiology: a review of recent developments

“…On the other hand, for a given genotype, Fischer (2007) demonstrated under controlled conditions that F s was quite stable across different total assimilation amounts, and even different potential spike sizes, as caused by early photoperiod effects on spikelet number. Abbate et al (1998) found only small differences in F s (range 0.29-0.34) among modern semi-dwarf Argentine cultivars. Reynolds et al (2001) reported that the GN advantage associated with LR19 from Agropyron was associated with a proportional increase in F s .…”

“…Following Eqn 1, D s did not vary in a tall versus short isogenic comparison (see references in Fischer 2007) nor in the comparison of modern Argentine wheats (Abbate et al 1998), so apart from Serrago et al (2008) above, cultivar effects on D s have yet to be described. However, large Argentine cultivar differences in the duration of the phase (TS/SE to AN) in 8C (at least 2-fold for a given photoperiod) were reported by Whitechurch et al (2007), and these may reflect differences in D s , which falls largely within TS/SE to AN.…”

“…Sayre et al 1997;Abbate et al 1998). However, a positive effect of genetic progress (year of release) on RUE between start of SE and AN, and on SDW a , was seen in UK winter wheats released between 1972 and 1995 (Shearman et al 2005).…”

“…Fischer 1984Fischer , 2007Abbate et al 1998;Slafer et al 1999). The explanation is that shorter stems, growing at the same time as spikes, compete less for limited assimilate, permitting spikes to acquire more, but the real control mechanisms are likely to be much more complex (Fischer and Stockman 1986;Bancal 2008).…”

Fifty years of wheat breeding in Southern Brazil: yield improvement and associated changes

“…This strong association between number of grains per unit area and yield would indicate that the supply of assimilates for grain growth (source capacity), along with the reserves accumulated in the vegetative organs, at pre-anthesis stage, were enough to meet the demand of developing grains (sink capacity). The high number of grains per square meter and a sufficient production of assimilates to produce additional grains could be a result of a longer spike development period at pre-anthesis (Calderini & Reynolds, 2000), higher crop growth rate during that period, greater partitioning to spikes or more grains per weight of spikes (Abbate et al, 1998). However, the ability of changing the morphogenetic pattern within the spike, thus favoring the development of a higher number of grains per spike, that have been attributed to the gene Rht (Waddington et al, 1986), could also have contributed.…”