ISHS Acta Horticulturae 465: IV International Peach Symposium
THE LEAF GROWTH AND ITS PHOTOSYNTHETIC POTENTIAL IN PEACH GROWN UNDER RAIN SEPARATED CULTIVATION SYSTEM |
| Authors: | C. Chen, C.C. Huang, Y.D. Kang |
| Keywords: | Prunus persica, protective cultivation |
| Abstract:
Peach trees [Prunus persica (L.) Batsch] grown under protection with one side opened and a 3.5m high rain-shelter developed their leaf earlier, showed larger but thinner leaf blades with shorter palisade cells, slightly lower total N content, and comparable specific leaf weight (SLW) as compared to open field trees. Leaves growing under shelter grew strongly and persisted longer. Maximum net Photosynthesis (Pn) rate rose rapidly during the expansion of young leaves. The peak rate occurred within 30 days after the leaves were fully expanded, and lasted until October. The Pn rates were considerably affected by light-thermo effect which always occurred under rain-shelter in sunny days. As in summer in Taiwanese highland, the temperature under Polyethylene (PE) shelter could rise from 25 to or above 30°C, as incident light was increased from 1,000 to 2,000 μEm-2s-1, while in the open field, the amplitude was only 22 to 25°C. As temperature rose beyond 30°C, the stomatal conductance and therefore the Pn rates of peach leaves would drastically and rapidly decline from an average optimum level of 0.45 molm-2s-1 and 13–14 μmolCO2m-2s-1 to 0.2 molm-2s-1 and 6 μmolCO2m-2s-1, respectively. In the open field, the light saturation point of peach leaf photosynthesis occurred at 1,600–2,000 μEm-2s-1 with a maximum Pn rate of 15 μmolCO2m-2s-1, while under rain-shelter, the maximum Pn rate ranged between 13–14 μmolCO2m-2s-1 with a light saturation point of 800–1,200 μEm-2s-1. | |
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