Effect of rootstock on growth, yield and fruit quality of late Valencia sweet orange

Abstract

The citrus rootstock determines several characteristics of the commercial planting material such as tree size, fruit yield, juice quality, maturity date and tolerance to disease like tristeza. The performance of late Valencia budded into four rootstocks; rough lemon, (C. jambhiri); volkameriana (C. volkameriana); Cleopatra mandarin (C. reticulate, Blanco), and Swingle citumelo (C. paradise macf. X P. trifoliate) was evaluated under the tropical himid forest conditions. Parameters such as tree size, yield, juice content, total soluble solids (TSS), titratable acidity (TA), TSS: TA ratio were evaluated after seven years. Results showed that the mean canopy volume of late velencia was significantly influenced by the rootstocks as follows: Rough lemon (Rl) 83.4m1, Cleopatra mandarian (Cleo) 54.5m3, Volkameriana (Volk) 53.5 m3, and Swingle citromelo (Swin) 51.2m1, Fruit size of trees grown on Swin was smallest (195g), while those on Volk recorded the biggest (247)g). RL induced the highest yield (7.21 tonnes/ha) while those on Swin recorded the lowest 5.51 tonnes/ha. The juice content (ww) of fruits ranged between 32% in Volk and 40% in Swin. RL induced the lowest TSS (brix) (10%), while Swin induced the highest (11.8%) among the rootstocks examined. Fruit juice of Late Valencia on RL recorded the highest TA (0.94%) while the TA of juice of trees on Swin, recorded the lowest (0.8%). Fruits of trees budded on Cleo and Swin attained nearly maturity as expressed by (TSS: TA) than those on rough lemon or Volk. The TSS value of fruits grown on RL was consistently lower than trees grown on Swin. Volk induced the highest peel thickness and lowest juice content than fruits grown on the other rootstocks. By planting Late Valencia budded onto these rootstocks, the harvesting period can be spread over a longer period, since the minimum TSS: TA for the different rootstocks is attained at different times during the harvesting season. Based on the difference is the mean canopy sizes, the pant spacing of Late Valencia budded onto Swin or Volk should be closer than that on RL and Cleo to achieve higher yield.