The Effect of Potassium Chloride on the Diurnal Changes of the Carbohydrates of the Potato Leaf

Abstract

Samples were taken at 3-hourly intervals from 5 plots which had received different amts. of KCl at planting. Fresh and dry weights, reducing sugar, sucrose and starch were detd. and the data examined statistically. The only significant effect of KCl on the carbohydrates was a marked reduction of sucrose during the middle of the day, at the time of maximum illumination and low water content. There was evidence that the change from light to darkness induced rapid accumulation of sucrose derived from starch, and vice versa. The rate of transloca-tion of carbohydrate during darkness was unaffected by KCl but that of "dry matter" was increased. Assuming that the rate of translocation of carbohydrate was also unaffected at other times, the rate of photosynthesis was increased during the afternoon, but decreased in the early morning. Water content per cent of dry matter was increased by KCl but did not show diurnal variation, water content and dry matter varying together. Significant diurnal changes in "residual dry matter" were found, so that to have expressed the carbohydrate changes on this basis would have given inaccurate results.