A Scenario of Abiotic Stress Impact on Production Potential of Sugarcane: A Climate Resilient Crop

Sugarcane is the most endergonic and hardy C₄ crop of tropical and subtropical areas. Drought, water logging, low temperature, mineral deficiency and salt stress depending on duration and intensity of stress depressed cane yield to an extent of 20–40 per cent, 5–20 per cent, 2–5 per cent, 25–50 per cent and 20–30 per cent, respectively. Both low and high temperature stress (<10°C and >40°C) caused damage in subtropical areas. Hence, an average cane yield potential of 80–100 t/ha is realised in tropical India, which was significantly higher than that of 65–75 t/ha in subtropical India. The normal cane yield under optimal conditions had been recorded as 125–250 t/ha which was 49–54 per cent of world record yield as against that of 20–35 per cent achieved yield in other crops like wheat, rice, maize, soybean and others. All these proved sugarcane as most climate-resilient crop suited well for climate resilient agriculture vis-à-vis climate smart agriculture.

The water requirement of sugarcane had been found to be 295 mole of water transpired/mole of CO₂ fixed, the lowest among all C4 plants. It withstood drought because it accumulated prolline and trehlose and possessed EDTA ossmocticum in the cytoplasm. The silicated layer on leaves besides silicated leaf hairs reduced transpiration and conserved moisture in leaves.

Cane and sucrose productivity was reduced significantly under both low (<10°C) and high (>42°C) temperature, but it withstood 10°-15°C and 38°-42°C temperature because it had silicated-potassium/Na layer on the cell wall of leaves which was a bad conductor of heat. Consequently, temperature stress was not transmitted to cytoplasm and plant escaped from injury.

The activity of UDP trans glucosylase, sucrose phosphate synthatase, sucrose synthatase and sucrose phosphtase enzymes in response to abiotic stress had been studied little except, the processes of unloading of sucrose from leaves to sink (stalk), and its split into glucose and fructose by invertase at apoplast, and thereafter, resynthesis to sucrose and final accumulation into vacuole/cytoplasm of parenchymatous tissues. This was the sucrose, which was harvested in cane, and finally extracted at mill to a level of 11 per cent. The Genetic, abiotic and biotic factors and invertase enzymes affected sucrose recovery. At mill level, sucrose was depressed even upto 6–8 per cent due to degree of delay in crushing cane, attack of Leuconostoc bacteria, formation of dextron and sucrose inversion in tissues.

Attempts on molecular interventions using sodERF3 to mitigate salinity and drought, gene encoding peroxidise and osmolyte trehlose/proline against drought and heat shock protein/EST encoding putative xanthium dehydrogenase against low temperature stress were in progress.