Physiology of Sucrose Productivity and Implications of Ripeners in Sugarcane

Sugarcane is grown in India in about 4.7 million hectares with a production of 348 million tonnes and sugar output of 32.34 million tonnes during the year 2017–2018. Although cane yield has doubled over the years, it is not so in the case of sugar recovery. Genetic and environmental factors influence sugarcane growth, sucrose accumulation as well as maturity processes. Sucrose in storage compartment of cane stalk is the ultimate balance between synthesis and internal consumption in simple terms; nevertheless, it is stored against a number of complex processes such as respiration loss, demand from growing shoot and root tissues and also the dormant lateral buds apart from pests, diseases and abiotic stress factors. Maturity or ripening in sugarcane is the culmination of diphasic physiological processes occurring in individual internodes. In the first stage of maturation, only about 50% of sucrose is accumulated. Additional sucrose accumulation occurs in the second phase of maturity and is so closely related to ripening. The response of sugarcane to proven ripeners varies with variety, rate of application, physiological stage of the crop and environmental factors before and after ripener application. Decline in recovery is primarily due to crushing of pre-mature canes and delayed harvest of over-mature canes. Sugar recovery is dependent on the juice quality and influenced by factors, viz. moisture stress, light, temperature and nutrient availability. There is wide scope for the use of chemical ripening agents, viz. Ethrel, Glyphosate, Fusilade Super and Gallant Super, which show differential varietal response across locations to either induce ripening or to synchronize ripening with the harvest schedule.