The Response of Three Varieties of Sugarcane to Water and Heat Stress In Southern Tamaulipas Mexico.

In southern Tamaulipas Mexico, drought and heat are major abiotic factors which affect productivity of sugar cane. Thus, it is important to understand how commercial varieties of this crop respond to these stresses in order to maximize productivity. Several physiological selection criteria have been suggested for use in determining sensitivity of sugarcane to these stresses, but these have not been used extensively, in part due to a lack of understanding of how this plant responds mainly to a lack of water. In this research, we studied the response of three varieties of sugarcane to drought by measuring leaf temperature (LT), total water potential (TWP), and membrane thermal stability (MTS). The research was carried out during the summer of 2009 using three commercial varieties of sugarcane (MEX 681345, MEX 79431, and CP-722086) that are commonly grown in the region under rain-fed conditions. Asexually propagated plants were planted in polyethylene bags containing 10 kg of soil in a greenhouse and maintained well-watered during their growth. Two months after planting, irrigated plants were maintained at above 80% of field capacity while drought treatment consisted of withholding water until the soil reached the permanent wilting point, followed by two irrigations and determination of LT, TWP at 8:00, 14:00, and 20:00h every other day, and also measurement of MTS (electrical conductivity of solution method). Compared to control plants, by the end of the experiment, drought resulted in a significant increased LT (averaging 2.22 °C higher), significant reduced TWP (averaging 0.41 MPa lower), and significant increased MTS (averaging 35% higher). Based on these studies, the variety CP-722086 was the most resistant to drought and heat stress of the three varieties tested suggesting that this variety could be used under conditions of southern Tamaulipas, México or in breeding programs for the development of genotypes of sugarcane more resistant to drought and heat stress.