Stress indices based on cane and sugar yields: Implications in selection of sugarcane varieties for drought tolerance

Abstract

Drought is a major cause of yield loss for many important crops including sugarcane. Due to increasing demand for sugar by a growing world population, it is needed to accelerate the selection of sugarcane clones/varieties that are resistant/tolerant and productive under water stress conditions. This study was conducted to assess the relative drought tolerance of diverse sugarcane clones/varieties evaluated under water stress (E2) and normal (E2) conditions for sugar and cane yields. Analysis of variance revealed significant differences among tested clones/varieties under both the water regimes. Per cent cane and sugar yield reduction in comparison to normal (E1) situation was assessed that ranged from 16.66–47.89 and 25.54–62.54 per cent, respectively under stressed (E2) conditions. Since, water deficit is the single largest abiotic stress affecting sugarcane productivity and the development of water use efficient and drought tolerant cultivars is an imperative, eleven stress indices were worked out from cane and sugar yields recorded under normal and stress conditions as reported earlier to see their effectiveness in sugarcane crop. Study is suggestive that lower score values for seven stress and stability indices viz. stress susceptibility index (SSI), stress tolerance index (STI), yield stability index (YSI), yield index (YI), drought resistance index (DI), relative drought index (RDI) and modified stress tolerance index (K1STI and K2STI) higher score for stress tolerance (TOL), mean productivity and geometric mean productivity (MP and GMP) and stress susceptibility percentage index (SSPI) categorized the clones/varieties as tolerant ones and vice versa. Further association studies showed that all the indices exhibited significant positive interaction with cane and sugar yields (CY and SY) under stress conditions except SSI and SSPI. Also inter association with different level of magnitude and significance among/between different indices were observed indicating their importance for selection of clones under drought stress situations. YI and DI had a positive correlation with RDI, GM, MP, K1 & K2 and between themselves for both cane and sugar yields indicating that they are a better predictor of potential cane and sugar yields under a stress conditions and can be useful for sugarcane researchers. Besides, clones and varieties reported in study with lowest score for SSI, STI, YSI, YI, DI, RDI and (K1STI and K2STI) and highest score for TOL, MP, GMP and SSPI be categorized for enhanced tolerance to water stress in present global warming situation in terms of their resilience to stress and production capacity to have better cane and sugar yields.