Shading responses of cherimoya [Annona cherimola] leaf chlorophyll content, leaf morphology, shoot growth, leaf gas exchange and fruit production under plastic house conditions
2001
Higuchi, H. (Kyoto Univ. (Japan)) | Yonemoto, J.Y. | Utsunomiya, N. | Sakuratani, T.
Heat stress damages under plastic house conditions in summer have caused low productivity of cherimoya (Annona cherimola Mill.). Six-year-old 'Big Sister' cherimoya trees were grown at 3 different shading levels under plastic house conditions to examine if the shadings improve cherimoya production. The plastic house was divided into 3 sections : regular plastic house condition as a light shading, middle shading condition which was provided by a combination of the plastic film of the house and shade cloth, and deep shading condition produced by the plastic film with two sheets of the shade cloth. Shoot length, shoot diameter, leaf number, and total leaf area reduced as shade increased, but inter-node length and single-leaf area increased. Leaf chlorophyll content increased at deep shading condition. Leaves at light and middle shading performed higher CO2 assimilation rate (Ac) with higher stomatal conductance. Under high light, high leaf temperature caused high leaf vapor pressure deficit, resulting in a reduction of gas exchange rate. Throughout the daytime, Ac at light shading was maintained at a higher level than the other conditions except during midday, when stomatal conductance and leaf water potential were lowered. Under deeper shading conditions, fruit weight and quality were decreased and the harvest was delayed. Heavy shade using shade cloth under plastic house conditions appeared to detrimental to cherimoya production. A shading of 50-70% sunlight was thought to be adequate to obtain optimal light environment for cherimoya cultivation.
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