Assimilation and Distribution of Photosynthate in Winter Wheat Cultivars Differing in Harvest Index

Abstract

Yield differences among New York winter wheat (Triticum aestivum L.) are related to harvest index. This study was conducted to see how four cultivars, which differed in harvest index and plant height, differed in partitioning of photosynthate before and during grain filling. Experiments were conducted in field plots grown at Hamden, CT in 1985 and 1986 in Cheshire fine sandy loam (coarse‐loamy, mixed, mesic Typic Dystrochrept). The assimilation, distribution, and retention of radioactivity from 14CO2‐derived photosynthate was measured. In each year, the canopy was labeled at heading and early and late in grain filling. Harvest index was inversely related to stem height. The fractional distribution of the 14C remaining at maturity varied with labeling date and cultivar. The amount in the spike was 0.35 to 0.5 when labeled at heading, with less than 0.15 in the grain. When labeled during grain filling, a greater fraction of 14C was distributed to the spike in the semidwarf than in the tall cultivars, 0.9 and 0.8, respectively, and most of the 14C in the spike was in the grain. Almost half of the radioactivity initially assimilated was lost from the plants by maturity. Tall semi‐dwarf ‘Purcell’ retained a greater fraction of radioactivity initially assimilated than did tall ‘Honor’, 0.56 and 0.51, respectively. Thus, differences in harvest index were related to differences in distribution of photosynthate and to differences in retention of photosynthate to maturity.

Osmoregulation-mediated differential responses of field-grown fennel genotypes to drought

“…Differences in harvest index are known to be related to differences in distribution of photoassimilates and differences in the pattern of retention and/or remobilization of the photosynthates (Gent and Kiyomoto, 1989). Achievement of greater harvest indices under water stress conditions has been postulated in an array of crop species including wheat (Davidson and Campbell, 1984) and corn (Brown, 1986) and our findings with fennel's harvest index (Table 7) are in accordance with the latter reports.…”

CN-Wheat, a functional–structural model of carbon and nitrogen metabolism in wheat culms after anthesis. II. Model evaluation

“…Simulations also showed a significant contribution of the chaff (20 %) to culm photosynthesis. The predominant contributions of the flag leaf and chaff to photosynthesis during post-anthesis stages is in agreement with several studies (Evans and Rawson, 1970;Gent and Kiyomoto, 1989;Araus et al, 1993). The contribution of chaff varied from 10 to 76 % according to genotype (presence or absence of awns) as well as experimental conditions and procedures, which may be affected by the recycling of respired CO 2 occurring in grains and bracts (Araus et al, 1993).…”

Effects of Nitrogen and Plant Density on Growth, Yield and Chemical Composition of Two Winter Wheat (Triticum aestivum L.) Cultivars

“…This agrees with KRAMER (1979). It is also reported that plant height (GENT and KIYOTO 1989) and N dressing (SPIERTZ and ELLEN 1978) affect HI. However, in this experiment nitrogen did not affect HI ( Table 2).…”