Sugarcane Cultivation Techniques: Key Points and Methods Explained
Sugarcane has high nutritional value. It contains a relatively large amount of water, which accounts for 84% of the sugarcane. Sugarcane is richest in sugar, with sucrose, glucose and fructose content reaching 12%. In addition, scientific analysis shows that sugarcane also contains other substances needed by the human body, such as 0.2 g of protein, 0.5 g of fat, 8 mg of calcium, 4 mg of phosphorus and 1.3 mg of iron. Furthermore, sugarcane also contains 16 amino acids beneficial to the human body, including aspartic acid, glutamic acid, serine and alanine, as well as vitamin B1, vitamin B2, vitamin B6 and vitamin C.
Biological Characteristics of Sugarcane
Sugarcane is an annual or perennial ratoon tropical and subtropical herbaceous plant, belonging to C4 crops. Sugarcane is a plant with high photosynthetic efficiency, a high light saturation point, a low carbon dioxide compensation point, a low photorespiration rate and great photosynthetic intensity; therefore sugarcane has a high biological yield and large returns. The sugarcane stalk is upright, thick and juicy, and its surface is often covered with a white powder. The leaves are alternate, with small sharp teeth along the edges, and the flower spike is a compound raceme. Sugarcane is a temperature-loving and light-loving crop. It requires an annual accumulated temperature of 5500degC-8500degC, a frost-free period of more than 330 d, an average annual air humidity of 60%, annual rainfall of 800-1200 mm, and more than 1195 hours of sunshine. Sugarcane has a relatively wide adaptability to soil, with clay loam, loam and sandy loam being better. Sugarcane can grow in soil with a pH value of 4.5-8.0, but a soil pH value of 6.5-7.5 is suitable.
Climatic Conditions for Sugarcane Cultivation
From the planting of seed cane to the maturity and harvest of cane stalks, the whole life of sugarcane can be divided into five stages: germination, seedling establishment, tillering, stem elongation and technological maturity. The speed of sugarcane growth, the level of yield and the amount of sugar content are closely related to climatic conditions, with the effects of temperature and moisture conditions being the greatest.
1. Germination
The minimum temperature required for sugarcane buds to germinate is an average daily temperature above 13degC; germination accelerates above 20degC, and 30-32degC is most suitable for germination. Sugarcane germination requires a soil temperature (0-10 cm) above 18degC. Below this temperature, germination is slow, the germination rate is low, and missing plants are likely. In production, to promote rapid germination, measures such as seed soaking and sprout promotion, raising seedlings for transplanting, and timely planting with plastic film mulching are usually adopted. The temperature for sugarcane rooting is lower than that for germination; generally, rooting begins to sprout at an average daily temperature of 10degC, and 20-27degC is most suitable. During the germination process of seed cane, vigorous respiration is needed to produce energy to supply the needs of germination. If the soil humidity is too high, there is too much water, planting is too deep, or the soil covering is too thick, the growth of the roots and buds of the seed cane will be affected.
2. Seedling Establishment Stage
The seedling establishment stage requires an average daily temperature above 15degC, with about 75% of the maximum field water-holding capacity being suitable, mainly to meet ecological water use. Too much or too little soil moisture hinders root growth and is unfavorable to the growth and development of seedlings.
3. Tillering Stage
Both air temperature and soil temperature have obvious effects on tillering. Generally, the tillering stage requires an average daily temperature above 20degC, with 25-30degC being most suitable; within this range, the higher the temperature, the more tillers. With appropriate moisture, there are more tillers and tillering is faster, but too much water leads to poor soil aeration and also affects tillering. Light intensity is the main factor affecting tillering. Under weak light, auxin is less damaged by photo-oxidation, which can promote main stem elongation. With sufficient sunlight, there are many and strong tillers; otherwise, there are few tillers, tillering is delayed, and growth is weak. With less than 5 hours of light per day, sugarcane plants generally do not tiller. With sufficient nutrients, there are more tillers, especially with nitrogen and phosphorus fertilizers having the greatest effect on tillering. In addition, shallow hilling, frequent intertillage and sufficient soil oxygen can all promote tillering.
4. Stem Elongation Stage
This stage is the fastest-growing period in the whole life of sugarcane, and it is also the key period determining cane stalk yield. The sugarcane stem elongation stage requires high temperature and sufficient sunlight, water and nutrients, as well as environmental conditions without tropical cyclones. An average daily temperature of about 30degC is most suitable; at as high as 40degC it still elongates slightly; below 20degC, elongation slows as the temperature decreases; below 15degC, elongation stops. Under general conditions, sugarcane can enter the elongation stage only when the average temperature is above 20degC, and can enter the grand elongation stage only when the ten-day average temperature is 27degC. Therefore, in areas with high temperatures and long warm periods, sugarcane grows quickly and has high yield and sugar content.
The sugarcane stem elongation stage is the period with the greatest water demand in the whole life of sugarcane, accounting for about 50-60% of the total water demand in the whole life of sugarcane, with an average daily water consumption of 3-4 cm. During this period, the soil must preferably maintain 80-90% of the maximum field water-holding capacity. If rainfall is insufficient, timely irrigation is necessary; otherwise, if water is lacking at this time, growth stagnation, short internodes and reduced sugar content will occur, thereby affecting both cane yield and sugar yield. A gentle breeze makes field ventilation good and is beneficial to sugarcane growth. However, strong winds and typhoons are very harmful after the peak elongation period, often tearing and breaking sugarcane leaves and causing cane stalks to break and lodge, so the yield on the windward side is often lower than that on the leeward side. The sugarcane elongation stage is also the period with the greatest fertilizer demand, among which nitrogen absorption accounts for about 50% of the whole growth period, and phosphorus and potassium account for more than 70%, so heavy fertilization should be applied in the early elongation period.
5. Technological Maturity Stage
This is the period when the sucrose content of sugarcane gradually accumulates to its peak and the quality of cane juice reaches its best. The technological maturity stage requires cool, dry, clear weather without frost, which is favorable to sugarcane sugar accumulation. High temperature and humidity are favorable to sugarcane growth but unfavorable to sugarcane sugar accumulation. According to research: strong light during the day, high humidity, low temperature and coolness at night (average night temperature 12-14degC), low relative humidity, and a cool, dry climate with a daily temperature difference of about 10degC are most favorable to sucrose accumulation, and the cane juice quality is also the best. Therefore, climatic conditions such as high temperature, high humidity, small temperature difference and insufficient light during the sugarcane maturity period are all unfavorable to sucrose accumulation. The timing of the maturity period is related to the variety; early-maturing varieties accumulate sugar faster than late-maturing varieties.