The responses of spatial situation, surface structure characteristics of leaves and sensitivity of two local rice cultivars to enhanced UV-B radiation under terraced agricultural ecosystem

Abstract

Under the situ terraced field experiments, effects of artificial UV-B radiation enhancement (0, 2.5, 5.0, 7.5 kJ m−2) on spatial situation and surface structure of leaves and responses index of two local cultivars rice (Oryza sativa L.)—Yuelianggu and Baijiaolaojin in Yuanyang County, China in shooting stage were studied. The results showed that: (1) due to the enhanced UV-B radiation, leaf apex–base distance, leaf pedestal height, leaf rolling degree and wax content in leaves increased, while leaf apex–stem distance, distance between leaves and leaf angle decreased. The response index of growth was positive when UV-B levels were 2.5 and 5.0 kJ m−2, which showed some adaptation. (2) The enhanced UV-B radiation resulted in smaller stomata with higher density and more papilla for both rice cultivars. (3) The enhanced UV-B radiation also leaded to larger silica cells and significantly increases the amount of papilla, spike and epidermal hair for both rice cultivars. (4) Yuelianggu cultivar showed an excellent adaptation on the aspect of spatial situation with UV-B radiation of 2.5 and 5.0 kJ m−2, while Baijiaolaojin exhibited better adaptation respecting the surface structure of leaves when UV-B was 2.5 kJ m−2. By changing spatial situation of leaves, structure and density of stomata, and non-stomatal structures (wax layer, silica cell, cork cell, papilla, spike and epidermal hair), two self-retention rice cultivars could adapt to the increased UV-B radiation. On the aspect of the response index, Baijiaolaojin showed better adaptation than Yuelianggu did when the UV-B was 2.5 kJ m−2.