An attempt to increase yield by controlling leaf‐area index

Abstract

SUMMARY Previous work showed that the leaf‐area index ( L ) of kale crops in their later stages of growth can be much above the optimum for dry‐matter production, which was between 3 and 3.5. When L was held close to 3.5 during July‐September 1955, by repeated thinning of plants, the total yield of dry matter including thinnings was increased by about 6%. When thinning was more severe yield was not increased. In a similar period in 1956, thinning that held L between 3.5 and 4 or between 3 and 3.5 did not increase total yield of dry matter, because in this year optimal L was much higher than before. The explanation of the seasonal variation in optimal L is not known.