Effects of Restricted Rooting Volume on Vine Growth and Berry Development of Kyoho Grapevines

Effects of restricted rooting volume on vine growth and berry development were evaluated on Kyoho grapevines. The grapevines were planted in three buried beds with volumes of 0.05 m³, 0.1 m³, 0.15 m³ and in the field (unrestricted). Vines grown under restricted rooting volume had thinner and longer primary roots and more secondary and lateral roots. Smaller rooting volume tended to result in a more rapid reduction of soil moisture and led to a smaller trunk, shorter shoot, smaller leaf area, and lower photosynthetic rate. As a result, berry set was up 15 to 20% and almost all berries were seeded. For vines grown in the field, berry set was less than 10% and half were seedless fruitlets. Vines grown under restriction of rooting zone also showed improvement in accumulation of skin color and juice total soluble solids. Favorable vine growth and berry characteristics were achieved when rooting-zone depth was 20 cm and rooting-zone volume was adjusted to about 0.025 m³ per square meter of leaf area in buried bed.