Identification of morpho-physiological parameters for selection of heat tolerant potato genotypes

Abstract

Potato (Solanum tuberosum) is a species with origin and domestication in the Peruvian-Bolivian Andes, and is therefore known as a cold climate crop. With the expansion of the cultivation area to the tropics and climate change forecasts, the effect of heat stress on potato crop is one of the biggest concerns in potato breeding programs. The effectiveness in obtaining heat-tolerant genotypes can be improved through multidisciplinary studies, involving, in addition to genetics, plant physiology, as well as other areas of knowledge. Therefore, the objective of this work was to identify morphophysiological parameters responsible for the greater adaptation of potatoes to high temperature conditions. To this end, two studies were conducted. The objective of the first study was to determine the possibility of selecting heat-tolerant genotypes using non-destructive evaluation methods, based on the two phases of potato photosynthesis. To this end, eight potato genotypes were characterized according to their response to different thermal regimes. Chlorophyll a fluorescence and gas exchange variables were analyzed, in addition to measuring morphoagronomic variables. The second study aimed to identify the best time to carry out germplasm screening to evaluate heat tolerance, as well as the main morphological, biochemical or physiological traits associated with this response. To this end, four potato genotypes were subjected to two temperature regimes, control and stress. Assessments were carried out at three times, in the beginning of the tuberization period, in the beginning of the tuber bulk stage and the end of the tuber bulk phase. Supraoptimal temperature stress caused losses in energy and glucose production due to the closure of stomata, affecting negatively the yield and quality of tubers. Photosynthetic parameters appear to be good indicators of heat tolerance, especially when the evaluation is carried out at the beginning of the tuberization phase, with photosynthetic variables being those that best indicate tolerance.