Light Intensity and Fruiting Effects on Carbohydrate Contents, Spur Development, and Return Bloom of ‘Hartley’ Walnut1

Abstract

Abstract Leaf number, area and chlorophyll content, and specific leaf weight were greater in light-exposed spurs of ‘Hartley’ walnut ( Juglans regia L.) than those grown in the shade. Starch content increased early in the season in shaded spurs, but the accumulation ceased while the nuts stored dry matter. In exposed spurs, starch increased steadily until harvest. After harvest, starch level decreased in exposed and shaded spurs. Light intensity did not affect percentage composition of spurs and fruit with respect to carbohydrates or oil content in kernels. Increased exposure to light resulted in higher percentage of return bloom, greater spur growth, and more pistillate flowers per spur the following season.