Some effects of artificial variation in light interception, number of grains and husk constriction on the development of grain weight in normal and high-lysine barley

Abstract

The grain weights of normal and high-lysine cultivars were compared in field and pot experiments in which the supply of assimilate per grain was adjusted by a variety of treatments involving application of fertilizer, thinning, degraining or defoliation. The results of these experiments indicated that in normal cultivars, grain weight was affected both by the supply of assimilate from the green tissues and by internal factors in the grain which limited the accumulation of this assimilate. Some evidence suggested that physical constriction of the expanding endosperm by the surrounding husk could be one of these factors; the effects of the husk on growth of the caryopsis was not clear.The development of grain weight in the high lysine cv. Riso 1508 was initially similar to that of normal cultivars, but the cessation of growth as maturity approached was more abrupt. Increased assimilate availability resulting from the application of fertilizer, thinning or degraining treatments effectively increased grain weight in this cultivar, but to a lesser extent than in low-lysine cultivars. Conversely, decreased assimilate supply as a result of defoliation produced less marked reductions in grain weight in the high-lysine type, suggesting that the reduced starch accumulation associated with the high lysine characteristic rendered superfluous some of the photosynthetic capacity in these types.

Determinants of spring barley yield in a high-yield potential environment

“…Various source:sink manipulation experiments across a range of environments on barley (Willey & Holliday 1971;Habgood & Uddin 1983;Grashoff & dAntuono 1997;Arisnabarreta & Miralles 2008b), wheat (Fischer 1985;Abbate et al 1997) and triticale (Estrada-Campuzano et al 2008) have highlighted the importance of the stem extension period for grain number determination through its influence on grain number survival. The above authors highlight the influence of grain number/ear rather than ear number/ m 2 on grain number formation during this period, and other theoretical discussions on yield improvement in wheat concur with this (Reynolds et al 2000;Miralles & Slafer 2007).…”

“…The rapid ear growth period during stem extension is crucial for grain number determination in wheat through its influence on grain number/ear (Fischer 1985;Abbate et al 1997;Reynolds et al 2000;Miralles & Slafer 2007). In barley, grain number/ear is similarly influenced by growth during the stem extension period (Willey & Holliday 1971;Habgood & Uddin 1983;Grashoff & dAntuono 1997), where some of the spikelets or florets initiated pre-stem extension will die at a young age (Kirby 1973(Kirby , 1977Gallagher et al 1975;Waddington & Cartwright 1983;Kirby & Appleyard 1984). Stem extension is a phase where there is a large increase in total crop growth rate (Kirby 1977) and significant spikelet mortality can occur due to a shortage of photosynthate (Richards 2000;Arisnabarreta & Miralles 2008a) and nitrogen (N) (Baethgen et al 1995) or in response to changes in environmental conditions, namely interception of photosynthetically active radiation (PAR) (Fischer 1985;Reynolds et al 2009) and photoperiod (Gambín & Borrás 2010).…”

“…Grain number in barley is highly correlated with yield across a range of environments (Gallagher et al 1975; Baethgen et al 1995; Abeledo et al 2003; del Moral et al 2003; Blake et al 2006; Bingham et al 2007 a ; Peltonen-Sainio et al 2007; Serrago et al 2013). Barley has the capability to produce a surplus of assimilate for grain filling from post-anthesis photosynthesis and pre-anthesis storage reserves (Gallagher et al 1975; Habgood & Uddin 1983; Wade & Froment 2003; Bingham et al 2007 a ). This has led to the conclusion that grain number largely determines, and as such limits, yield in barley and that further yield increases may be achieved through an increase in grain number.…”

Husk to caryopsis adhesion in barley is influenced by pre- and post-anthesis temperatures through changes in a cuticular cementing layer on the caryopsis

“…Equally, the size of the husk organs would contribute to the capacity for contact between the husk and caryopsis. Indeed, grain size has been postulated to be determined by the physical limitation of the size of the husk [ 12 , 13 ], potentially due to effects of pre-anthesis temperature on floret growth [ 14 ].…”

Carbohydrate metabolism enzymes in CO2‐enriched developing rice grains of cultivars varying in grain size

“…In CO2-enriched rice plants, we were unable to detect significant increa.ses in starch synthesis and subsequent grain growth resulting from high CO2-induced sucrose accumulation, suggesting that the grain growth was not limited by sucrose supply from maternal tissue. The irresponsiveness of grain growth to high CO2 treatment might be related to the rigid glumes (husk) which might form a severe constriction limiting further expansion of developing grains (Matstisbima 1957, Habgood andUddin 1983). Thus, the potential dry matter accumulation in developing rice grain is likely regulated by the glume size predetermined at anthesis, rather than the photosynthate supply from maternal tissue at grain filling.…”