Developmental and physiological traits associated with high yield and stay-green phenotype in wheat

Abstract

Water availability is a key limiting factor in wheat production in the northern grain belt of Australia. Varieties with improved adaptation to such conditions are actively sought. The CIMMYT wheat line SeriM82 has shown a significant yield advantage in multi-environment screening trials in this region. The objective of this study was to identify the physiological basis of the adaptive traits underpinning this advantage. Six detailed experiments were conducted to compare the growth, development, and yield of SeriM82 with that of the adapted cultivar, Hartog. The experiments were undertaken in field environments that represented the range of moisture availability conditions commonly encountered by winter crops grown on the deep Vertosol soils of this region. The yield of SeriM82 was 6–28% greater than that of Hartog, and SeriM82 exhibited a stay-green phenotype by maintaining green leaf area longer during the grain-filling period in all environments where yield was significantly greater than Hartog. However, where the availability of deep soil moisture was limited, SeriM82 failed to exhibit significantly greater yield or to express the stay-green phenotype. Thus, the stay-green phenotype was closely associated with the yield advantage of SeriM82. SeriM82 also exhibited higher mean grain mass than Hartog in all environments. It is suggested that small differences in water use before anthesis, or greater water extraction from depth after anthesis, could underlie the stay-green phenotype. The inability of SeriM82 to exhibit stay-green and higher yield where deep soil moisture was depleted indicates that extraction of deep soil moisture is important.

Functional characterization of GPC-1 genes in hexaploid wheat

“…A functional stay-green trait enables the plant to synthesize and store greater levels of assimilates, which can lead to increased crop yields under certain environments (Richards 2000;Christopher et al 2008;Zhou et al 2011;Derkx et al 2012). Our photosynthesis measurements showed that the GPC-1 mutants maintain photosynthetic activity for longer than the control lines; hence we can classify the GPC-1 mutants as functional stay-green mutants.…”

Water: the most important ‘molecular’ component of water stress tolerance research

“…Zaman-Allah and colleagues (2011a) reached the same conclusion with twenty chickpea genotypes contrasting for terminal water stress tolerance. Nevertheless, the benefit of deeper root systems has been shown in other studies (Kirkegaard et al 2007;Christopher et al 2008;Hund et al 2009). For example, a simulation study indicated that maize yields would increase if the root depth increased (Sinclair and Muchow 2001).…”

“…Several authors have argued that the presence of small amounts of water during key crop stages such as the grain filling period would confer a major benefit (Ketring and Reid 1993;Christopher et al 2008;van Oosterom et al 2011). Unfortunately, it is difficult to measure water extraction precisely in the field, especially the small but key amounts that may be extracted during the grain filling period; however, a lysimetric method now exists in which a precise water extraction measurement is possible at all crop stages (e.g.…”

Wheat physiology: a review of recent developments

“…Certainly RUE levels during grain filling have improved (e.g. Miralles and Slafer 1997), and some modern varieties appear to show better 'stay green' (Christopher et al 2008). Finally it appears that grain-filling photosynthetic activity can actually be increased by a larger GN sink (see above).…”