Effect of Tiller Removal and Shading on Spikelet Development and Yield Components of the Main Shoot of Wheat and on the Sugar Concentration of the Ear and Flag Leaf

Abstract

Continuous removal of tillers from wheat plants (cv. Gamenya) in an irrigated field crop resulted in an 86% increase in grain yield of the ear on the main shoot due, principally, to more kernels per fertile spikelet. On detillered plants 99% of spikelets were fertile with an average of 3.8 kernels per fertile spikelet compared with 91% and 2.4 for the control. Tiller removal increased spikelet numbers by 1 to a mean of 21.4 but did not affect the rate of production of spikelet primordia. The concentration of sugars (glucose, fructose, sucrose) in leaf bases at terminal spikelet formation and in leaf bases and ears just before ear emergence were the same in control and detillered plants. It was considered unlikely that tillers compete with the main shoot for carbohydrates thus limiting ear development and grain yields of the main shoot; instead, competition for reduced nitrogen may be involved. Shading plants to 20% of full sunlight, especially during floret development, reduced grain yields per ear by 50% due to fewer kernels per fertile spikelet (2.2) plus a 32% decline in kernel weight. Tiller numbers and shoot size were reduced by shading while spikelet numbers were reduced by two compared with controls due to a reduced rate of production of spikelet primordia. Shading also reduced sugar concentrations relative to controls in leaf bases at terminal spikelet formation and in ears just prior to emergence. The supply of carbohydrates under shading was limited, affecting growth and grain yields.

Productivity and nutrient uptake of newly released wheat varieties at different sowing times under poplar plantation in north-western India

“…Mcmaster et al (1987) observed that shading (50% of ambient light) from booting to 1 week after anthesis caused greater tiller mortality resulting in fewer spikes per plant. Similar findings were observed by Kemp and Whingwiri (1980) who reported that shading (20% of full sunlight) before anthesis resulted in reduced tiller number. Apart from reduced light intensity (Table 1), production of more leaf litter with increase in age of trees also hampers the crop germination & subsequent growth parameters.…”

Initiation and Development of Spikelets and Florets in Wheat as Influenced by Shading and Nitrogen Supply at the Spikelet Phase

“…At maturity, the grain weight per spike was significantly decreased by shading due to fewer grains per spike and lower mean grain weight (Table 4) . Thus, the compensating mechanism suggested by Kemp and Whingwiri (1980) was not evident in the present study. The different responses to shading may be attributed to the difference in intensity of shading (20% in Kemp and Whingwiri (1980), and 51% in this study).…”

“…However, the effect of shading on the initiation and development of spikelets and florets at the spikelet phase has scarcely been studied. Kemp and Whingwiri {1980) found that shading from the DR toTS stage decreased tiller and spikelet numbers and grain weight, but increased kernel number per ear due to increased number of kernels per fertile spikelet, especially on the basal spikelet. They assumed that after removal of shading, spikelet fertility and kernel number per ear increased to compensate for inferior growth under shading, because they had fewer tillers and spikelets due to the early shading.…”

Inhibition of tillering in cereals by substituted 2-phenoxypropionic acids

“…These studies indicate that the higher yields of modern varieties are associated with increases in the proportion of tillers surviving to bear ears at harvest . Pot experiments with wheat and barley have shown increases in main stem ear weight when tillers are removed [14,15,21] . Donald described a cereal ideotype in which an uniculm habit was an important requisite for high yields [8] .…”