Increasing the tolerance of fig tree to drought stress by trunk thinning

Abstract

The fig tree is native to Iran, east of Asia and Syria. Shortage of precipitation and drought is one of the greatest problems in rain-fed fig cultivation areas. A random complete block design with three replications was used to investigate the effect of trunk thinning on drought disorders. Since 'Sabz' fig trees are trained with multiple trunks, 16 intensities of trunk thinning applied during winter pruning were compared. The treatments were obtained pruning five different groups of tree to leave 0, 1, 2, 3, or 4 trunks tree-1, respectively. The pruning intensity of each of the 16 treatments was evaluated calculating the ratio between the total circumference of the remaining trunks and the total trunk circumference before the application of thinning treatment (here after trunk diameter ratio). The results suggested that the different levels of trunk thinning had positive effects on leaf width, leaf number, leaf water potential, leaf temperature, fig fruit color and size. Thinning all the trunks had the best effect on tree vegetative appearance under drought stress conditions. Trunk thinning treatment that pruned trees to leave 2 trunks and provided a trunk diameter ratio of 0.5 was more suitable than other treatments in terms of vegetative growth and fruit quality and quantity. The latter pruning strategy is recommended for increasing tree tolerance to drought, fruit yield and quality. This will increase grower income and allow the protection of rain-fed fig orchards in dry years.