Effects of Rootstock Varieties, Leaves and Grafting Conditions on Scion Growth in Eggplant

Abstract

Studies were conducted on the effects of root stock varieties, leaves and size on scion growth and assimilate transport in eggplant. The translocation and distribution of photosynthetic assimilates from root stock and scion leaves on different stock/scion combinations were determined by ¹⁴CO₂ pulse feeding method.
1. Different root stock varieties resulted in a variation of the scion growth response. The scion dry weight and leaf area were extremely higher in rootstock varieties of 'Taibyo VF (Solanum integrifolium Poir. × S. melongena L.) ' and Scarlet eggplant (S. integrifolium Pior. : Hiranasu ('Akanasu': Takii Seed Ltd)) than in 'Senryo No. 2 (S. melongena L.) '. However, the root weight were not changed significantly between root stock varieties.
2. The scion growth was enhanced by increasing the number of root stock leaves from 0 to 3. When three leaves were left on the root stock, the scion grew vigorously, indicating that these leaves significantly affect growth.
3. The percentage distribution of ¹⁴C-assimilates by the stock leaves to the scion ranged from 3540% on 28 days after grafting; about 50% of the assimilates in the root stock came from the scion leaves.
4. The source-sink relationship between the scion leaf and the roots was analyzed by relative sink strength (RSS) and was found to be unrelated; however, a close relationship was found between the root stock leaves and roots. The relationship between growing parts and both scion and stock leaves was strong. The photosynthetic assimilates from both scion and root stock leaves were translocated through the graft union, the amount is depending on the degree of vascular connections established.