Effect of CCC (chlorocholine chloride) on growth and yield of spring wheat in the field

SUMMARY Spring wheat, var. ‘Phoebus’, drilled at 11/2 times the usual rate and grown with three rates of nitrogen was treated with 2.5 or 5 lb. CCC per acre at the sixth‐leaf stage. At maturity, the height of treated plants was only 60% of that of untreated plants, but the percentage shortening was less as nitrogen increased. Although untreated plants did not lodge, CCC increased mean grain yield by 5% by increasing the number of ears and number of grains per ear. Grain weight per ear and thousand‐grain weight were decreased by CCC. The explanation of the increase in shoot number by CCC is not known, but possibly less light was intercepted by the shorter plants, so that later‐formed shoots survived to produce ears. CCC decreased assimilatory area by shortening stems and hence leaf sheath area; lamina area was little affected. It delayed ear emergence by up to 8 days, Leaf‐area index was decreased by CCC and as it increased, net assimilation rate decreased. CCC did not affect nitrogen uptake per unit area of land but it increased nitrogen as percentage of dry matter because it decreased dry‐matter yields.