Flower and fruit development of a low-chill peach, ‘KU-PP2’ in plastic houses with and without heating

Abstract: Although ‘KU-PP2’, a low-chill peach cultivar, was released for high-quality peach production under forcing culture, the performance of ‘KU-PP2’ trees under forcing conditions has yet to be determined. In this study, we investigated the spring phenology, fruit development, and fruit quality of ‘KU-PP2’ in a heated plastic house compared with the same traits in an unheated plastic house and open field conditions. We found that the forcing conditions accelerated the spring phenology and harvest period of ‘KU-PP2’. Heated conditions shortened the number of days from dormancy release to blooming and the length of the fruit development period, resulting in the blooming of flowers in late February, with fruit begin harvested as early as mid-May, which was notably earlier than blooming and fruit harvest under natural conditions by 4 and 6 weeks, respectively. Similarly, the unheated conditions accelerated the time to blooming and harvest by up to 3 and 4 weeks, respectively compared with the open field conditions. However, although the fruit produced by trees raised in the heated plastic house could be harvested at an earlier date, the amount of fuel used for the heating system was 50 L per tree, which could be prohibitively expensive for commercial production. Although the fruit growth pattern did not differ significantly between the forcing and natural conditions, the rate of fruit growth at stages S1 and S2 was higher in the heated plastic house than that under the other assessed conditions. Furthermore, the size and quality of fruit obtained under forcing conditions were slightly larger and superior, respectively, than those of fruit produced under natural conditions. Moreover, we found no evidence of split-pits under the forcing conditions. The findings of this study accordingly indicate that cultivation of the low-chill peach ‘KU-PP2’ under forcing conditions is conducive to a notably earlier harvest of fresh peaches. These observations advance our current understanding of the flowering, fruit development, and fruit production of low-chill peaches under forcing conditions.