Varietal Differences in Tree Growth, Net CO₂ Assimilation and Endodormancy of Japanese Persimmon Cultivars Grown in a Warm Climate

Abstract

Tree growth, net CO₂ assimilation rates and endodormancy were investigated in four cultivars of 8-year-old Japanese persimmon (Diospyros kaki Thumb.), when grown in a warm climate. The net CO₂ assimilation rates of ‘Hiratanenashi’ and ‘Tone wase’ during the summer were consistently higher than that of ‘Fuyu.’ In late August, that of ‘Nishimura wase’ increased, whereas it remained low in ‘Fuyu.’ The bud break from endodormancy was first observed in ‘Hiratanenashi’ and ‘Tone wase’ in late November. For ‘Nishimura wase’ and ‘Fuyu, ’ those occurred in December. The percentage of buds broken in early January was lower in ‘Fuyu’ than in the other three cultivars. Tree vigor was assessed by an increment of trunk circumference during the growing season. Vigor was greater in early-maturing cultivars than in relatively late-maturing cultivars. It was concluded that cultivars which had higher chilling requirements and lower net CO₂ assimilation rate during the summer were less adaptable to commercial cultivation in a warm climates.