Biomass formation and nutrient partitioning in potted longan trees under partial rootzone drying

Publication Type

Journal contribution (peer reviewed)

Authors

Srikasetsarakul U; Spreer W; Ongprasert S; Wiriya-Alongkorn W; Sringarm K; Sruamsiri P; Müller J

Year of publication

2011

Published in

Acta Horticulturae

Band/Volume

889/

Page (from - to)

587-592

Conference name

ISHS 6th International Symposium on Irrigation of Horticultural Crops

Conference location

Vina del Mar (Chile)

Conference date

2. - 6.11.2009

In Northern Thailand (Dimocarpus longan Lour.) is the most important fruit crop. With fruit development taking place during the dry season, irrigation is needed to ensure high yields. With production irrigation water is becoming scarce. In previous studies it was documented, that under “partial rootzone drying” (PRD) high yield can be obtain with 33% reduced irrigation water use. The reason of this increase in WUE was so far not researched.
Ten split-root longan trees were irrigated on one half of the root system, changing at a two weeks interval, and compared to ten trees which received the double amount of irrigation water on both sides of the root. The new formed leaves were classified in four size classes and counted to compare the canopy development under both irrigation regimes. After three months the trees were cut and separated into roots, trunk and leaves. Fresh and dry weight of the biomass and total leaf area were compared. Five samples of each part were analyzed on the macro-nutrient (N, P, K) composition.
It was show that the biomass formed under PRD was significantly less than under normal irrigation. The leaf size was lower under PRD and especially the root had not well developed. The P and K contents in all organs of the PRD treated trees was less, while the N content was not significantly lower.
This study shows that under PRD less biomass is produced as under full irrigation. In combination with previous results which show no yield reduction it can be concluded that longan tree under stress reduce their vegetative growth but not the generative growth. For Thailand, PRD is an appropriate irrigation method as during the time of fruit growth irrigation water can be saved.