A Preliminary Study on Partial Rootzone-drying Irrigation for Litchi(Litchi chinensis Sonn)

Nandao seedless litchi(Litchi chinensis Sonn) trees were used to study the effect of the partial rootzone-drying(PRD) irrigation method on the growth,fruit-bearing and carbohydrate accumulation in leaves of the trees.The results showed that PRD retarded the shoot growth as compared with the normal irrigation(CK),but did not in comparison with that when the irrigation was done by reducing half of the regular amount of water in the rootzone(HN).The fruit yield under PRD irrigation was significantly the highest,and significantly the lowest under HN,among the treatments and control.On fruit quality,except for juiciness,PRD produced better or similar characteristics in comparison to CK.Other than shape of the fruits,HN yielded considerably inferior fruits to CK or PRD.Overall,PRD was considered the most desirable irrigation method.The contents of chlorophyll a and starches in leaves,net photosynthetic rate of leaves,leaf chlorophyll a/b ratio,and sugar content after 14d were highest among the three methods when PRD was applied.Furthermore,the respiratory rate of the tree leaves when PRD was used appeared lower than HN.It suggested that PRD could enhance the photosynthesis and improve the carbohydrate accumulation in leaves.