Amomum villosum and Clerodendranthus spicatus are two kinds of herb species and are regarded as the suitable intercropped species for increasing the additional income of rubber farmers and for remoulding the mid-aged and aged rubber plantations. However, the water-use characteristics of rubber tree in these agroforestry systems (AFSs) were still rarely reported. 

In a study published in Agricultural Water Management, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) investigated the plant water use and the interspecific interactions in rubber - Amomum villosum and rubber- Clerodendranthus spicatus agroforestry systems which were converted from the aged rubber monoculture 

The researchers applied stable isotope techniques to study the plant water competitions (i.e., hydrological niche, which was confirmed through plant water-absorbing patterns by the analysis of the stable hydrogen and oxygen isotopes of the xylem and soil water through Bayesian mixing model; and water use efficiency which was analyzed through the stable carbon isotope of the leaves of rubber trees and their intercropped herbs).   

They also measured the concentrations of leaf carbon (C), nitrogen (N) and phosphorus (P) of the rubber trees and their intercropped herbs in the two agroforestry systems to check the competition effects on plant nutrient status in the rainy and dry seasons in 2016. 

They found that the water-use patterns of the aged rubber tree were still flexible. Intercropping the medicine herbs could help rubber trees take up more deep soil water. However, the weak competition for water in both agroforestry systems could not help improve the water use efficiency of rubber trees. In addition, the decreased leaf N of rubber trees in the agroforestry systems suggested that the N absorption of rubber trees was limited. 

“Therefore, intercropping the medicine herbs with rubber tree still need more consideration on the design of such agroforestry systems, especially in terms of the soil water conservation and management,” said Prof. LIU Wenjie, principal investigator of the study. 

Contact 

LIU Wenjie  Ph.D Principal Investigator      

Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China