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

ANDRES ALBERTO RODRIGUEZ; MARIANA CHECOVICH

Simposio; Simposio Fronteras en biociencias 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 variates (ARS-USDA). Seedlingsof each varieties were grown under conditions of optimal temperature (28/24°C day/night).when the third leaf emerged half of the seedlings were transferred to a STcondition (21/13°C day/night). The growth of the third leaf of each plant wasdetermined until ceased. We evaluate different parameters as the time and the rateof elongation, the final length of the leaf, the size cell, the PSII performance,the net photosynthesis rate and the stomatal conductance. The main effect ofthe ST stress was the reduction of the final length (13 and 69% according tothe variety). This effect was attributed to the fall registered in elongationrate under ST and not to the size cell because did not shown difference betweentreatments. A PCA was performed to determine the relationship between theparameters described above. Also, the accessions were characterized respect ofits tolerance to ST in highly susceptible, moderately susceptible or tolerantbased on the PCA results. The results of this work will help to design futurestrategies the obtaining of cultivars that perform better under this stress