Sheet-mulching Cultivation Promotes the Number of Floral Buds via Upregulation of Citrus Flowering Locus T Expression in Two Citrus Cultivars,‘Haraguchi-wase’ and ‘Harehime’
Sheet-mulching cultivation during the fruit developmental stage is often carried out to produce high-quality Satsuma mandarin (Citrus unshiu Marc.) and ‘Harehime’ ((‘Kiyomi’ × ‘Osceola’) × ‘Miyagawa-wase’) fruits because they show high Brix% by exposure to drought stress conditions. In this study, we investigated the effect of drought stress on the number of floral buds in ‘Haraguchi-wase’ Satsuma mandarins and ‘Harehime’. To clarify the relationship between drought stress and the number of floral buds, we applied four different drying treatments to the fruit trees, (i) first-half drying (drying treatment during the first-half of the fruit development stage), (ii) second-half drying (drying treatment during the second-half of the fruit development stage), (iii) all-drying (drying during the full fruit development stage), and (iv) well-watered (non-drought stress during the fruit development stage). The drying treatment was applied to the fruits at ψ max −0.7 to −1.2 MPa at an intensity comparable to proper drought stress for high-quality fruit production according to our previous studies.
