FRUITING EFFECTS ON LEAF CHARACTERISTICS, PHOTOSYNTHESIS, AND ROOT-GROWTH IN PEACH-TREES

Effects of fruiting on leaf characteristics, photosynthesis, and root growth were assessed trees (Prunus persica (L.) Batsch. cv, Hakuto) after adjusting the number of fruits per tree. 1. Compared to leaves on non-bearing trees, those on fruiting trees were thinner, less wide, and darker green. The more intense green pigmentation indicates that the chlorophyll was more concentrated in leaves of bearing than in those from non-bearing trees. During the fruit maturation stage, former accumulated more starch in the chloroplasts than leaves of the latter as determined by the I-KI staining method, transmission electron microscopy, and starch analysis. The photosynthetic rate per unit leaf area (Pn) was faster in leaves of fruiting limbs during the fruit maturation stage; no significant difference in Pn between leaves of fruiting and defruited branches was detected during Stage II of fruit development. 2. The elongation of new roots in fruiting trees was reduced proportionately to increasing fruit number during the fruit growth period, whereas the new roots on non-bearing trees continued to elongate throughout the vegetative period. At fruit harvest, the total root volume of non-bearing trees was larger and the starch content per root dry weight was higher. On fruiting trees, renewed root growth was observed several days after harvest while the starch in the roots continued to accumulate until the leaves senesced.