Studies On The Photosynthetic Characteristics Under Stresses In Chaling Wild Rice (Oryza Rufipogon Griff.)

To explore the photosynthetic charateristics under stresses in wild rice so as to give support for its utilization in rice breeding the photosynthetic physiological indexes such as net photosynthesis rate (Pn), chlorophyll fluorescence parameters, etc. in Chaling wild rice (Oryza rufipogon Griff.) leaves under chilly, high temperature,and drought stresses or no stresses were measured using rice cultivars as control. The results are as follows:Under chilly stress (average daily temperature 10-12℃), the photosynthesis rates in Chaling wild rice leaves at tillering stage were high than those of tested rice varieties including japonica cultivar Nipponbare, indica cultivar 93-11, and super high grain yield hybrid Liangyoupeijiu, and the the values of chlorophyll fluorescence parameters Fv/Fm, Fv'/Fm', and NPQ were a lit higher than those of rice cultivars control, which showed the good ability of photosynthesis of Chaling wild rice under low tempreture.At the condition of high tempreture (the maxmum air temperature is 39℃,and the temperature on leaves surface is 44-45℃), the Pn of Chaling wild rice was significantly higher than those of cultivars at tillering stage, and the value of chlorophyll fluorescence parameter NPQ was a little larger than those of controls, which shows the great capacity of photosynthesis of Chaling wild rice under high tempreture.Under the drought stress, the Pn of Chaling wild rice was much higher than those of cultivars at tillering stage, and its Pn fell more slowly than those of rice cultivars as the water decreased in pot soil. After watering again, Chaling wild rice got significantly higher Pn than rice cultivars. These results indicate that the Chaling wild rice has better photosynthesis capacity either at drought condition.Under the normal condition, the activity of RuBP carboxylase, the values of chlorophyll fluorescence parameters Fv'/Fm', qP (can show light harvesting ability), and the chlorophyll content in leaves of Chaling wild rice were higher than those of cultivars control. Additionally, the stomata density on its leaf surface is higher than those of controls, but its stomata size is smaller than those of two cultivars, i.e. 93-11 and Liangyoupeijiu, as well as the same as that of another cultivar Nipponbare.Based on above results, it is thought that Chaling wild rice has a good photosynthesis capacity under low temperature, high temperature, and drought stresses, and has some excellent photosynthesis characters in the normal condition, which can be used as an source for improvement of cultivar rice photosynthesis.