Xylem vessels are the main conduits for long-distance water and nutrient transport in most extant angiosperm plants. Vessel length is a highly variable interspecies and intraspecies trait that is affected by environmental conditions, ontogeny, and phylogeny. Methods for determining vessel length have been of interest to wood anatomists and plant physiologists for several decades.
Air injection and silicone injection (BLUESIL RTV141A and B mixtures) are two widely used methods for maximum vessel length determination. However, the validity of both methods needs to be carefully tested for species with different vessel lengths.
In a recent issue of journal Tree Physiology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) recommended the injection of RTV141A only (not mixed with the hardener RTV141B) for determining the maximum vessel length.
The researchers tested the validity of the air-injection and silicone-injection methods using eight tropical species with different vessel-length ranges: short (<0.5 m), medium (0.5–1 m), and long (>1 m).
The results showed that the conventional silicone-mixture injection method tended to underestimate the maximum vessel length substantially, and the ratio of underestimation increased with the vessel length.
In contrast, the simple and widely used air- injection method overestimated the maximum vessel length, but the degree of overestimation was independent of the vessel length.
According to the findings, the researchers recommended the injection of RTV141A only (not mixed with the hardener RTV141B) for determining the maximum vessel length.
“The results should be carefully examined when air injection or silicone-mixture injection is used to determine the maximum vessel length or vessel-length frequency, particularly for long- vesselled species”, said Prof. ZHANG Jiaolin, principal investigator of the study.
ZHANG Jiaolin Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China