RESUMO
Aim: The present investigation was carried out to study root anatomy of sugarcane cultivars (CoLk 94184 and CoJ64) planted under waterlogged condition through Scanning Electron Microscopy (SEM). Methodology: Two sugarcane (Saccharum spp. hybrid) cultivars, CoLk 94184 and CoJ 64 were evaluated for changes in root anatomy in response to waterlogging during 2017-2018. For waterlogging treatment, crop was grown in deep plot which was waterlogged upto a depth of 1 m during active grand growth stage (monsoon season) along with untreated control plot. After three months of waterlogging, the plants were uprooted to study the root morphology and anatomy through SEM. Results: Waterlogged plants showed aerial root formation in both the cultivars but number and mass were higher in CoJ64. Aerenchyma was formed in the cortical region of both control and waterlogging roots but the size was relatively increased in waterlogged. Irregular and damaged surface cells with longer root hairs were observed in waterlogging treatment. Waterlogged roots exhibited cell distortion, loss of uniformity in endodermis and pericycle regions and higher number of metaxylem vessels. Interpretation: The study concluded that waterlogging treatment caused structural anomalies and induced anatomical and surface ultra-structural changes in both the cultivars, but the level of deformation was relatively higher in genotype CoJ 64, indicating sensitivity towards waterlogging as compared to cultivar CoLk 94184.
RESUMO
Aim: The aim of the present investigation was to study the effect of waterlogging on growth and physiological behaviour of sugarcane varieties, and to evaluate these in relation to waterlogging tolerance to identify reliable physiological parameters for screening sugarcane genotypes for waterlogging tolerance.. Methodology: Ten sugarcane varieties including four tolerant and one sensitive were planted under waterlogged and non waterlogged (control) conditions. Waterlogging was imposed for 70 days at the crop age of 120 days, thereafter water was completely drained. Based on relative cane weight (% waterlogged/control), the ranking of varieties was done for waterlogging tolerance. Changes in cane weight, stalk growth rate, internode length, chlorophyll stability index and antioxidant enzyme activity were measured at the end of waterlogging. Leaf samples were analysed for nitrogen, phosphorus and potassium content. Correlation between waterlogging tolerance and different traits was assessed. Results: Based on relative cane weight (% waterlogged/control), CoLk 94184 was found to be the most waterlogging tolerant variety while CoJ 64 the most sensitive. Waterlogging remarkably reduced stalk growth rate and a significant positive correlation was found between waterlogging tolerance and stalk growth rate during waterlogging. The average internode length of sugarcane varieties increased by 11% in waterlogging as compared to control. Tolerant varieties had high chlorophyll stability index than sensitive one showing that tolerant varieties had less chlorosis in waterlogging. Waterlogging caused a significant increase in antioxidant enzyme activity of catalase, peroxidase and superoxide dismutase, however these increase were higher in tolerant varieties. Waterlogging induced severe deficiencies of N, P and K in sugarcane; the leaf N and K concentration were below critical deficiency level. A strong positive correlation was found between leaf K content and waterlogging tolerance. Interpretation: Stalk growth rate, chlorophyll stability index and leaf potassium concentration during waterlogging were identified as efficient physiological traits for screening the sugarcane varieties for waterlogging tolerance.