Agronomic and morphophysiological behavior of potato genotypes in response to heat

Abstract

With the growth of the world population, it is necessary to increase food production. However, increasing production is becoming increasingly difficult in the face of rising global temperatures, posing a major risk to food security. High temperatures have a strong negative effect on agricultural production, however, heat tolerant cultivars are essential to mitigate the effects of global warming. The objective of this work was to identify morphophysiological characters that contribute to the performance of potato genotypes under heat conditions and that can improve the efficiency of selection of tolerant clones. Two different studies were carried out, the first one carried out in Brazil, at the Universidade Federal de Lavras (UFLA) in the period from 2014 to 2018 and the second one conducted in the United States Department of Agriculture (USDA) in 2017. In the first group of experiments we evaluated the behavior of different tetraploid potato genotypes regarding the beginning of tuberization, duration of the vegetative cycle and agronomic characters in three growth seasons (winter, drought and rainy) with different temperature conditions. In addition, we tried to identify morphophysiological characters that associate the performance of genotypes with heat toler ance. It was observed that high temperatures significantly delayed the onset of tuberization and, consequently, reduced the period of tuber bulking. On average, the increase of 1 °C delayed the beginning of tuberization by 3.8 days taking into account the mild temperature regimes (winter season) and heat stress (drought and rainy seasons). In crops under high temperatures there were a decrease in total tuber yield and also in tuber dry matter content compared to the winter season crop. It was estimated that on average the increment of 1 ºC reduced tuber dry matter content by 0.47%. Genotypes with long vegetative cycle and early tuberization were the most productive in the threegrowth seasons. High temperatures increased the partitioning of photoassimilates to plant canopy in detriment of tubers. The genotypes Markies, CBM 16-16, CBM 09-10, IRF 02-71, IRF 09-44, IRF 07-61 and IRF 10-24 were the most heat tolerant. The most productive genotypes at high temperatures presented higher leaf area index and shoot dry matter content. The analyzes of the antioxidant defense system in this work did not allow the differentiation between the tolerant and heat sensitive genotypes when they were submitted to stress throughout the vegetative cycle. In the second group of experiments we evaluated heat tolerance in diploid wild Solanum species as measured by the ability of these genotypes to form microtubers in tissue culture under high sucrose concentration. Solanum berthaultii, S. sogarandinum, S. kurtzianum and S. candolleanum were the most heat tolerant species evaluated.