Effect of Tree Spacing on Vegetative Growth and Reproduction in an Early Growth Stage in Two Cultivars of Ficus carica L.

Abstract

The nursery stocks of two fig varieties, ‘Masui dauphine’ and ‘Houraishi’ (Ficus carica L.), were raised by cutting in a nursery, transplanted with changing tree density to an experiment field on July 8, 2004, and cultivated using straight-line training in the Agricultural Food and Environmental Science Research Center of Osaka Prefecture, Japan. The density grades per 1.0-a land area (100 m2) were 200, 66.7, 40, and 6.06. The growth of the aboveground vegetative parts of each tree was monitored at irregular intervals in 2005 by measuring the length and diameter of three organs, i.e. trunk, primary scaffold limb and fruit-bearing shoots. The linear dimensions of the three organs were transformed into dry weight values of woody organs and leaves, giving individual vegetative weight per tree. The fruit were harvested daily during the fruiting season from August to December 2005. The mean values of individual vegetative weight at different densities were approximated well by the reciprocal equation of the C-D effect (hereafter, the SK model), which was proposed by Shinozaki and Kira ca. 50 years ago. Mean annual fruit production per tree at a given density grade was also covered by the SK model, suggesting the clear effect of density on vegetative growth and fruit production in young fig monocultures. The coefficients of the equation conformed to conventional recognition about the poorer vegetative growth and richer fruit harvest in ‘Masui dauphine’ than in ‘Houraishi’. The observed density dependency of the reproductive allocation (RA) represented the decrease of RA with the increase of density in two cultivars although the predicted density dependency of RA was contradictory to that of the observation of the ‘Masui dauphine’.