The sugarcane grower faces several constraints which come in the way of boosting sugarcane production and in attaining desired level of sugar in the cane at the field level. These constraints are social, administrative, climatic, managerial or agronomic and technical. In this bulletin, an attempt has been made to briefly discuss the climatic, agronomic and technical constraints.
The sugar production depends mainly on cane yield and percent sugar recovery, hence this objective requires combined attention on cane yield and its sugar contents. Sucrose yields in sugarcane could be improved by increasing the efficiency of biomass production and by increasing the fraction of total biomass partitioned to stalk sucrose or both. This could be achieved by optimally matching the physiology of genotypes to the driving environmental conditions.
A careful study of climatic parameters like mean temperatures, relative humidity and rainfall pattern over the last two decades in relation to the growth period of sugarcane, indicate that the cane in Goa is subjected to heavy evapo-transpiration losses. Moisture stress during the early part of the cane growth mostly during March to June is an important and critical problem.
Similarly, if one takes into consideration the influence of these parameters during the maturity period of cane from mid November to March end, it is seen that the mean minimum temperature ranges between l8.1°C to 20.8°C but hardly reaches a congenial low temperature of 15°C, which is ideal for sugar accumulation. In addition to this, Goa does not enjoy a greater difference between maximum and minimum temperatures due to its proximity to the sea. All these factors come in the way of getting desired productivity and recovery.
The crop requires fairly high temperature, low relative humidity, sunny weather with no rainfall during germination and tillering stage, moderate temperature and high relative humidity and well distributed rainfall for fast growth and cool weather, moderately dry and sunny period for ripening. Early and continuous rains from May to July also influence the development of sugarcane growth, tillering, millable canes and thickness of canes.
Further, this also has to bear on intercultural operations and fertilizer application in time (Narendra Singh et aI., 2008). Heavy rainfall and waterlogging during July- August period delays the growth and development of sugarcane crop and thereby, the sugar accumulation. Further, heavy rainfall and water logging during sugar accumulation period in cane reduce the rate of dry matter production per plant. Re-growth in crop instead of sugar accumulation during the period may also be the possible reason for lower sugar recovery (Tiwari, 2005).
Sucrose accumulation begins in leaves and subsequently translocated into stalks. The ripening of cane occurs because stalk elongation is more sensitive to low temperature, restricted soil moisture and low nutrition. Consequently, the photosynthates which normally support the growth of the plant and stalk elongation get redirected into sugar storage.
Relative temperature disparity is an important factor which helps in cane maturity. Dry conditions or low relative humidity 21- 30 days prior to harvest has direct positive impact on sucrose accumulation in cane. The cool and dry climate during ripening period is conducive to higher accumulation of sucrose. For the process of physiological maturity to occur, where a seasonal reduction of air temperature does not occur, the crop must be subjected to a moderate drought, inducing sugar accumulation in plant tissues.
Sugarcane productivity can be improved by adopting an improved package of practices like planting and harvesting schedule for cane cultivation with sound management techniques. Earlier and delayed harvesting might influence the cane productivity and sugar recovery. Thus, there is a need for proper planting and harvesting schedule so
as to overcome the losses in cane yield and sugar recovery.
These are the primary causes which result in low productivity of cane and poor quality cane for crushing.
I. Quality of seed setts:
With and With and exception of a few progressive growers, the majority have no option but to use whatever planting material that is readily available for planting. The seed sets are often selected from immature or diseased crop, inadequately manured crop or from any source. Not much attention is bestowed upon the very important aspect of sett treatment, which results in a poor crop.
Sugarcane in Goa is irrigated mostly from well, lift irrigation schemes or canal. The growth of cane is maximum during February to May. If during this critical period the crop is subjected to drought, heavy losses in terms of yield and recovery occur in the field. Therefore, it is desirous to provide adequate irrigation during these critical months.
Sugarcane is a heavy feeder and responds to adequate doses of fertilizers. Ignorance of farmers regarding fertility status of soil, soil health and lack of knowledge regarding fertilizers, make the farmer resort to inadequate fertilizer application. The right time of its application and correct method of application are to be thoroughly understood in relation to the soil test reports in order to meet the nutritional requirements of this crop.
January-February is an ideal time for planting sugarcane under Goa conditions. This is not only due to climatic considerations but also to facilitate adequate fertilization before the onset of monsoon. But due to various reasons, sugarcane in Goa is planted as late as May. Such crop neither can be adequately manured nor receive the congenial climate for initial growth. This results in a poor crop.
5.Lesser application of organic manures:
The soil is the storehouse of nutrients. Its physical and chemical characteristics have to be understood. Continuous use of chemical fertilizers alone slowly deteriorates the soils. The soils of Goa are lateritic in nature with poor water holding capacity. Hardly 20-25 percent farmers use organic manures. The water holding capacity of soil have to be restored by use of organic manures. Soils poor in organic content cannot withstand water stress and results in poor growth of cane and the yield. Advanced composting techniques will augment the supply of organic manures.
About 60-65 percent area of sugarcane in Goa will be under ratoon crop at any given time. Though it is a fact that ratoon has many advantages and yields comparable with the plant crop under good management, neglected ratoons have resulted in poor yields and low-quality cane, which has a direct bearing on the overall production and recovery. Good ratoon management practices will resolve this issue.
This is a very important agronomic operation to be done in between the interspaces of cane which includes hoeing, weeding, earthing-up and finally mulching. Due to unavailability of bullock drawn intercultural implements locally, lack of manpower and herbicide usage, etc., no farmer generally does adequate intercultural. Due to this, the roots do not draw sufficient nutrients and weeds cause 60-70 percent losses both in quality as well as the quantity of cane produced. Low-cost tools and implements may facilitate timely intercultural.
Not much attention is paid to the various insect pests and diseases that infest sugarcane crop in Goa. Spraying of the crop is seldom undertaken due to practical difficulties. This has also attributed to the losses in yield and cane quality.
- Central Coastal Agricultural Research Institute, Ela, Old Goa, Goa