Changes of Latex Physiological Parameters of Hevea brasiliensis Clones in Different Seasons

In this study, 99 Wickham clones of rubber tree were used as the research material. The average annual latex yield of each tapping from clonal ramet and inorganic phosphorus content, sucrose content, mercaptan content, total solids content in latex were determined, and the correlation between the variation of different clones was analyzed combined with the data of rubber tree DBH in the early of 2018. The results showed that the content of mercaptan and sucrose in July < May < November, and the difference was significant; the content of inorganic phosphorus in May < July < November, with significant difference between different seasons; the dry rubber content and total solids content in May > July > November, and the differences was significant; population latex yield and coefficient of variation in May < July < November. Only the sucrose content was significantly correlation with the annual average latex yield per tapping in May(dry season), the content of inorganic phosphorus, sucrose, dry rubber and total solids was significant or extremely significant correlation with annual average latex yield per tapping in July(rainy season), and the content of mercaptan content, inorganic phosphorus, sucrose, dry rubber and total solids was significant or extremely significant correlation with annual average latex yield per tapping in November(after the rainy season). Among the 3 seasons, the latex physiological parameters in November have the strongest correlation with the rubber tree yield, and in these parameters, content of inorganic phosphorus and sucrose have the strongest correlation with the rubber tree yield. The DBH of the high-yield clones is larger, and the content of inorganic phosphorus was high and the content of sucrose was low in May, July and November. The suitable period for latex physiological determination is November(after the rainy season), and inorganic phosphorus and sucrose contents can be used as important latex physiological parameters to make selection of clones.