The wild type of Rhododendron simsii is mainly distributed in eastern Asia. In Vietnam, this species grows along streamsides or riversides in northern and central parts at above 800-1400 m altitude. In contrast, Japanese R. simsii species is distributed in sunny and grassy slopes on the islands of Kyushu and Ryukyu Archipelago. Plants grow in different environmental conditions may perform different morphological or physiological characteristics. In this study, the heat stress tolerance of Vietnamese and Japanese R. simsii was evaluated by electrolyte leakage technique to measure the cell membrane thermostability (CMT) using fresh leaf discs. In addition, R. eriocarpum, which is considered as one of the most heat resistance evergreen azaleas species in Japan, and the F1 hybrids with Vietnamese R. simsii were also used as materials. In the results, the relationship between the relative injury (RI) value in the leaf discs and the water bath temperature treatments was sigmoidal in all samples. A single temperature treatment of 50°C for 30min resulted in 38.9% and 31.7% RI value in Vietnamese and Japanese R. simsii, respectively, but only 14.5% in R. eriocarpum. Interestingly, the hybrids showed the moderate value from their parents (24.8%). In greenhouse condition, there was no significant difference in shoot dry weight between samples collected in June (27/20°C) and that in August (34/26°C) of R. eriocarpum while two R. simsii accessions and F1 hybrids showed significant differences. It suggests that R. eriocarpum seemed to be a heat resistant species. Regressing the shoot dry weight ratio versus their RI values at 50°C of all species was linear relationship. The negative correlation existed between two values indicated that the electrolyte leakage technique is appropriate for evaluating the heat stress tolerance among evergreen azalea species. Heat stress tolerance of R. eriocarpum (seed parents) seems to be inherited to its F1offspring.
|ジャーナル||Journal of the Faculty of Agriculture, Kyushu University|
|出版ステータス||出版済み - 2018|
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