Further Observations of the Incidence of Blotchy Ripening of the Tomato

Summary The annual fluctuation in percentage o‐f fruit affected with “blotchy ripening” on potassium‐deficient and nitrogendeficient plots at the Cheshunt Experimental Station is significantly negatively correlated with the mean daily number of hours of bright sunshine between 1 April and 31 August. The weight of fruit of potassium‐deficient plants is raised and the percentage of blotchy fruit reduced, either by increase of potassium supply or by increase of light. This beneficial effect of increase of light on the crop of potassium‐deficient plants is of much greater magnitude than any corresponding effect on the crop of nitrogen‐deficient or completely manured plants. The juice of the blotchy areas of potassium‐starved fruits has diminished capacity for starch hydrolysis. Increasing severity of potassium starvation is associated with progressive increase in level of dry weight per unit area of the leaves. The influence of potassium on the production of blotchy fruit is briefly discussed.