Physiological responses, yield, and latex-related traits of promising Hevea brasiliensis genotypes across two Amazonian climate zones with seasonal water deficits: implications for germplasm selection

Abstract This study aimed to assess changes in physiological responses, early rubber yield and latex biochemical quality in nine promising rubber tree ( Hevea brasiliensis ) genotypes and the clone IAN 873 (control) during first year tapping in large-scale clonal trials under seasonal water deficits in two climate zones in the Colombian Amazon. Our results showed that, with a larger water deficit (i.e., dry season and semi-humid warm location), all genotypes had a lower photosynthetic rate, lower extrinsic water use efficiency, and lower leaf water potential. On the contrary, a higher yield and a greater metabolic activity related to latex production were evidenced in the semi-humid warm location than in the humid warm location. Thus, the highest yield values and traits related to latex quality were observed in the rainy season and in the semi-humid warm location, where the FX 3899 P1 and FDR 4575 genotypes had a significantly higher productive yield, an intermediate DRC, a higher sucrose consumption, a more active metabolism and a greater capacity to prevent stress with an increase in the content of thiols in the latex. Greater physiological and productive adaptability, with and without the water deficit, were observed in the genotypes FX 3899 P1, FDR 4575 and GU 198 in both climate zones. This better adapted germplasm to water limitations has a high selection potential for H. brasiliensis breeding programmes in the northwestern Colombian Amazon.