土壤水分 및 摘果가 '甘平' 만다린 雜種의 裂果發生에 미치는 影響

Abstract

The study was conducted to investigate the effect of soil moisture and flower or fruit thinning on fruit splitting of 'Kanpei' [((C. unshiu × C. sinensis) × C. sinensis)) × ((C. unshiu × C. sinensis) × C. reticulata)] mandarin hybrid cultivated in the plastic film house in Jeju, from 2010 to 2012. The occurrence of accumulative fruit splitting were 5.0%, 9.0%, and 12.9% at the different soil moisture levels with 50∼60%(sufficient), 30∼40%(normal), and below 20∼30%(insufficient) based on volumetric water content (VWC), respectively and fruit splitting decreased with the increase of soil moisture level. As VWC declined, fruit shape index based on the ratio of diameter to length increased, which resulted in higher fruit splitting. There were no significant differences in fruit growth and quality except fruit weight at harvesting time among the soil water treatments. Treatments flower- or fruit-thinned in late May (flower thinning), late June, late July, and late August and not fruit-thinned resulted in 3.2%, 1.1%, 3.0%, 7.5%, and 19.2% of accumulative fruit splitting, respectively and fruit splitting was lower as flower or fruit thinning time earlier. Fruit splitting decreased and peel was thicker as flower or fruit thinning was earlier. The highest rate of fruit growth was obtained from the treatment flower-thinned in late May and fruit growth rate was similar from the treatments fruit-thinned in late June, late July, and late August and was lowest in non-fruit thinning. As flower or fruit thinning time was earlier, fruit diameter, length, and weight was higher, but soluble solids and acidity were similar from the treatments of flower or fruit thinning time except for non-thinning. Lower fruiting load by fruit thinning resulted in lower fruit splitting and peak time and accumulative fruit splitting rate varied depending on the year. Above all, the situation with dryness from late July to early August and heavy rainfall thereafter promoted fruit splitting. To reduce the fruit splitting and alternative bearing, fruiting load with the ratio of leaf to fruit at 120:1 or less was desirable.