Physiological traits imparting drought stress tolerance to promising sugarcane (Saccharum spp.) clones

Drought is one of the most important environmental constraints limiting sugarcane (Saccharum spp.) production worldwide. It is estimated that nearly 60% of the total sugarcane area suffers from water stress. Using the important physiological markers, drought tolerance potential of elite sugarcane clones is evaluated every year at ICAR-Sugarcane Breeding Institute, Coimbatore to identify those suitable for cultivation in drought prone areas of India. The present study is the field evaluation of six sugarcane clones in the advanced varietal trial conducted during the year 2018–2019, wherein the relevance of physiological traits conferring adaptive tolerance to drought is reinstated. In the formative phase, drought stress resulted in an average reduction of 20.5, 36.5, 22.1, 5.9 and 4.7 per cent in shoot population, plant height, leaf area index, SPAD chlorophyll index and photochemical efficiency (Fv/Fm) respectively. However, the clones Co 12009 and Co 12012 showed relatively better growth attributes both under control and drought stress which were on par with the resistant standards Co 86032 and Co 99004. Drought induced 12.6, 15.7, 23.5 and 32.9% reduction in internodal length, cane height, single cane weight and cane yield, however the clones Co 12009 and Co 12012 recorded comparatively higher cane yield of 86.6 and 94.1 tonnes/ha under drought condition, respectively. The clones Co 12009 and Co 12012 were rated as tolerant due to their ability to sustain cane yield and juice quality potential under drought stress, which might be attributed to retaining superior morphological and physiological traits.