Thermotolerance and Physiological Traits as Fast Tools to Heat Tolerance Selection in Experimental Sugarcane Genotypes

Heat stress limits the growth, development, and yield of crop plants when it occurs during short or long periods of time. An experiment was conducted with the objectives of ( i ) evaluating the cell membrane thermostability (CMT) as an indicator of heat tolerance in sugarcane and to determine its relationship with physiological parameters under heat-stressed conditions, and ( ii ) evaluating the utility of CMT for selecting heat-tolerant genotypes in a breeding program. A total of nine elite experimental, and four commercial sugarcane genotypes were evaluated for CMT, and the results are expressed as relative cell injury (RCI). Six genotypes were classified as highly tolerant and seven as highly sensitive. We concluded that the use of RCI, as an indicator of CMT in sugarcane genotypes, is a suitable useful parameter for selecting the genotypes tolerant to heat stress in a breeding program. This procedure, combined with other characters, helps to identify sugarcane plants with the ability to maintain a high yield photosynthetic rate under stressful field conditions. Furthermore, it offers an opportunity to improve selection efficiency over that of field testing, since high temperature stresses do not occur consistently under field conditions.