HEAT Tolerance in Sugarcane (Saccharum officinarum) Genotypes.

In southern Tamaulipas Mexico, heat are major abiotic factors which affect productivity of sugarcane. Identification of plant tolerance to heat, requires novel strategies for measuring plant responses to this stress. Leaf electrolyte leakage is an indirect method that can be utilized as selection criteria for heat tolerance in plants, but it has to be adapted to each species. Thus, it is important to understand how commercial varieties of sugarcane respond to this stress in order to maximize productivity. The objective of this study were to measure heat-induced leaf electrolyte leakage in sugarcane to determine heat tolerant genotypes. In this research, we studied the response of three varieties of sugarcane to heat tolerance by measuring membrane thermal stability (MTS). The research was carried out during the summer of 2014 using three commercial varieties of sugarcane (Mex 68-P-23, CP 72-2086, and Mex 79-431) that are commonly grown under rain-fed conditions. Heat treatment included 60°C applied to ten leaf discs during 60 minutes. Asexually propagated plants were planted in polyethylene bags containing 10 kg of soil in a greenhouse and maintained well-watered during their growth. Electrolyte leakage, estimated as the relative percentage of damage to the cell membrane, was used as criteria for cellular membrane thermo-stability. Results showed that the greatest amount of membrane electrolyte leakage occurred during vegetative stage for the three varieties. The temperature used induced greatest electrolyte leakage depended on the varieties, 73 % for Mex 68-P-23, 85 % for CP 72-2086, and 59 % for Mex 79-431. Based on these studies, the variety Mex 79-431 was the most tolerant to heat stress of the three varieties tested with highest water relative content (90 %), water potential (-0.95 MPa), and osmotic potential (-1.07 MPa); suggesting that this variety could be used under rain-fed conditions in southern of Tamaulipas or in breeding programs for the genotypes development of sugarcane more resistant to heat stress.