Weather Conditions Suitable for Sugarcane Crop

Sugarcane is able to grow over a prolonged season. Under warm humid conditions, it can continue its growth, unless terminated by flowering. However, its height is strongly influenced by the age of the crop and season. Temperatures above 50⁰ C arrest its growth; those below 20⁰ C slow it down markedly and severe frost proves fatal. The crop does best in the tropical regions receiving a rainfall of 750 to 1,200 mm. It can also be grown in sub-tropical areas, but where the climate is subject to extremes, and the dry season is long, the growth period of the crop is restricted to a bare four months in the year, and the yields tend to be distinctly lower than those in the tropics. In tracts receiving a relatively high rainfall (1,200 to 1,500 mm), e.g. in parts of Uttar Pradesh, Bihar, Orissa, West Bengal and Assam, the crop is grown without irrigation and thrives on the moisture conserved in the soil. For ripening, it needs a cool, dry season; but where rainfall is too heavy and prolonged, the quality of the juice tends to be low, and where the weather remains comparatively warm and moist throughout the year, it does not ripen well. In years of drought, the crop becomes a little fibrous and in the dry areas generally, only the hardier and more fibrous varieties can be grown. The climatic conditions of Maharashtra and parts of Karnataka, and the Telengana area of Andhra Pradesh are ideal for sugarcane; in some of these areas, its yield per hectare has shown a steady increase owing to improved culture. The acreage under sugarcane has also increased.

Sugarcane is a warmth-loving crop, restrictions in growing season can arise due to insufficient soil warmth for germination and checking of growth of the cane stalk by low air temperature. The minimum soil temperature for the germination of sugarcane sets is in the range of 19-21⁰ C. the optimum range is from 27-38⁰ C, while temperatures above 38⁰ C are not conducive. Though temperature upto 43⁰ C are tolerated under high soil moisture status, the weather situation is conducive for borer pest attack and sprouts suffer extensive damage under these conditions. The effects of low root temperatures are operative even with warm air temperatures. Warm air temperatures when root temperatures are low lead to nitrogen starvation of leaves and poor juice quality. Root temperatures exert modifying influence on the effect of air temperatures on the rate of formation of nodes. The minimum threshold temperature for cane growth is 16⁰ C. A check in vegetative growth occurs when the mean daily air temperature drops below 21⁰ C. Thus, low air temperatures are most effective in inducing ripening and lead to better juice quality. For flower development higher night temperatures may be required. The optimum temperature for sucrose synthesis in leaves in 30⁰ C.

Sugarcane is termed as a short-day plant since interruptions of the night period delay flowering. However, its photoperiod requirements for flower initiation are a high length greater than 10 hours and a day length greater than 11 hours. Thus it is an intermediate type though of a rare kind.

Rain is particularly harmful to cane without a protective leaf canopy. Strong wind is a natural for sugarcane. Wind damage results in termination of growth of stalk, metabolic depletion and reduced assimilation till a new canopy is established.

Sub-optimal temperatures for germination often mean a delay in the start of the planting season for sugarcane. Waiting for the natural build up of the soil warmth exposes the crop to unfavorably high temperatures in the tillering phase.

Occurrence of temperatures arresting growth in the winter period restricts the crop growth period in North India. For e.g., in the North Indian region November to February is not conducive for crop growth. Therefore attempts have been made to treat the canes chemically for continuation of growth. Gibberellic acid (GBA) has been used for this purpose. However, initial stimulation soon wears off and the improvement in elongation is at the expense of girth, and cane tonnage is not improved.

When sugarcane flowers, terminal growth is arrested. This reduces the capacity of the cane for sugar accumulation. Maleic hydrazide is known to reduce flowering and arrest growth.

(Sugarcane
Growers)