Study of rice tolerance at suboptimal temperatures in a panel with broad genetic diversity

RODRIGUEZ ANDRÉS; CHECOVICH MARIANA LEONELA

Simposio; FRONTIERS IN BIOSCIENCE 3; 2018

Rice (Oryzasativa L.) is regarded as the most important crop in terms of humannutrition. For rice at the seedling growth stage, the critical range of lowaverage daily temperatures is 12-13°C while the optimum range is 25-30°C. In thesouth-central rice region of Argentina, the average daily temperature is 16ºC(21/13ºC maximum/minimum) is a stressful condition of suboptimal temperatures(ST) for rice growth. In this sense, the aim of the present work was detectrice cultivars with contrasting performance under ST. For this purpose it wasevaluated the physiological response of 407 rice varieties(ARS-USDA). Seedlings of each varieties were grown under conditions of optimaltemperature (28/24°C day/night). when the third leaf emerged half of theseedlings were transferred to a ST condition (21/13°C day/night). The growth ofthe third leaf of each plant was determined until ceased. We evaluate differentparameters as the time and the rate of elongation, the final length of the leaf,the size cell, the PSII performance, the net photosynthesis rate and thestomatal conductance. The main effect of the ST stress was the reduction of thefinal length (13 and 69% according to the variety). This effect was attributedto the fall registered in elongation rate under ST and not to the size cellbecause did not shown difference between treatments. A PCA was performed todetermine the relationship between the parameters described above. Also, theaccessions were characterized respect of its tolerance to ST in highlysusceptible, moderately susceptible or tolerant based on the PCA results. Theresults of this work will help to design future strategies the obtaining ofcultivars that perform better under this stress.