Effects of awns on the photosynthesis and yield of wheat, Triticum aestivum

Abstract

Two pairs of awned and awnless near-isogenic lines of winter wheat were used in a field study in which canopy enclosure apparatus and carbon-14 dosing were employed to assess the contribution of the awns to photosynthesis and grain yield. Awns contributed an average of 12'2% to canopy gross photosynthesis but did not increase the net photosynthesis of the complete canopy. The presence of awns decreased photosynthesis in the remaining ear structures and in the flag and penultimate leaf laminae. Seven days after dosing during the phase of rapid grain filling, 80% of the carbon recovered was located in the grains. The awns intercepted 9% of the incident visible radiation when fully green, and senesced at similar rates as the ears and flag leaves.In a second experiment the effect of awns on grain yield and its components was investigated in crosses segregating for height and presence of awns. Awns did not increase grain yields in either experiment. It appears that for British conditions in the absence of severe drought there is little advantage to be gained at present by breeding awned varieties of wheat.

Natural variations in the promoter of Awn Length Inhibitor 1 (ALI‐1) are associated with awn elongation and grain length in common wheat

“…ALI‐1 was the first wheat awn‐controlling locus observed to reduce GL and TGW, especially under drought conditions. The contribution of awn to grain yield has been extensively investigated, and the photosynthesis of awn is widely accepted to be responsible for the improvement of grain weight (Grundbacher, ; Evans et al , ; Olugbemi et al , ; Li et al , ; Li et al , ). This work illustrates that ali‐1 removes sink limitations with larger grain size, providing a reacquaint of the effects of wheat awn on grain production.…”

Effects of Removal of Some Photosynthetic Structures on Some Yield Components in Wheat

“…These reductions were reported 20.8 % by Saghir et al (1968) and 16.8 % by Mahmood and Chowdhry (1997). It is pointed out that the yield and the grain size in the awned wheat variety are higher than the awnedless one and this increasing is more determinative in the dwarf genotypes and under conditions of drought (Atkins and Norris 1955, Olugbemi et al 1976b, Ledent and Moss 1979, Chhabra and Sethi 1989. At the heading; while the flag leaf, the second upper leaf blade and awneds removal reduces 1000-grains weight at the proportion of 1.9-24 %, it increases the proportion of grain protein.…”

Crop characteristics and the potential yield of wheat

“…The daily total of solar radiation in the photosynthetically active waveband (400-700 nm) was taken as close to the long-term average for June and July for three stations in central and eastern England, at 8-4 MJ/m a /day. Of this, 33% was taken as being intercepted by the ears, the remainder being incident on the crop, and the ears were assumed to contribute 15% to the gross photosynthesis of the canopy (Olugbemi, Austin & Bingham, 1976;Austin et al 1976). This procedure was used because of the difficulty of estimating the leaf area equivalent of the ears and because their light-intercepting properties were likely to have been considerably different from those of the leaves.…”