Crop - sugarcane

 Sugarcane

Sugarcane or sugar cane refer to several species and hybrids of tall perennial grasses in the genus Saccharum, tribe Andropogoneae, that are used for sugar production. The plants are two to six metres (six to twenty feet) tall with stout, jointed, fibrous stalks that are rich in sucrose, which accumulates in the stalk internodes. Sugarcanes belong to the grass family Poaceae, an economically important flowering plant family that includes maize, wheat, rice, and sorghum, and many forage crops. It is native to the warm temperate to tropical regions of Southeast Asia and New Guinea.

Sugarcane is the world's largest crop by production quantity, with 1.8 billion tonnes produced in 2017, with Brazil accounting for 40% of the world total. In 2012, the Food and Agriculture Organization estimated it was cultivated on about 26 million hectares (64 million acres), in more than 90 countries.

About 70% of the sugar produced globally comes from a species of sugarcane called Saccharum officinarum and hybrids of this species. All sugarcane species can interbreed, and the major commercial cultivars are complex hybrids.

Sugarcane accounts for 79% of sugar produced; most of the rest is made from sugar beets. While sugarcane predominantly grows in tropical and subtropical regions, sugar beets typically grow in colder temperate regions.

Sucrose (table sugar), extracted from sugarcane in specialized mill factories, is either used as raw material in the food industry or fermented to produce ethanol. Products derived from sugarcane include falernum, molasses, rum, cachaça, and bagasse. In some regions, people use sugarcane reeds to make pens, mats, screens, and thatch. The young, unexpanded flower head of Saccharum edule (duruka) is eaten raw, steamed, or toasted, and prepared in various ways in Southeast Asia, including Fiji and certain island communities of Indonesia.

Sugarcane was an ancient crop of the Austronesian and Papuan people. It was introduced to Polynesia, Island Melanesia, and Madagascar in prehistoric times via Austronesian sailors. It was also introduced to southern China and India by Austronesian traders at around 1200 to 1000 BC. The Persians and Greeks encountered the famous "reeds that produce honey without bees" in India between the 6th and 4th centuries BC. They adopted and then spread sugarcane agriculture. Merchants began to trade in sugar, which was considered a luxurious and expensive spice, from India. In the 18th century AD, sugarcane plantations began in Caribbean, South American, Indian Ocean and Pacific island nations and the need for laborers became a major driver of large migrations of people, some voluntarily accepting indentured servitude and others forcibly exported as slaves.

Growth Stages of sugarcane

Sugarcane, a C₄ plant, is considered as one of the most efficient convertors of solar energy. It has five growth phases-  

Germination Phase

                                        

• When cultivated commercially, sugarcane is propagated only vegetatively by stem parts (Cuttings) or by whole stems.
• Seed propagation is employed only in selection.
• Planting cuttings should have at least three buds.
• The sprouting phase (the beginning is marked by 10% and the complete stage by 75% pf sprouts) is thought to commerce when two leaves appear on the stem.

Tillering Phase

                       

• Tillering of sugarcane in the tropics begins soon (in about 15-20 days) after the first sprouts appear.
• The secondary sprouts are formed from underground buds.
• In early ripening varieties of sugarcane, tillering lasts for 4-6 months, and finishes after the row contact.
• In the late-ripening varieties of sugarcane, tillering lasts long as 6-8 months.
• Every new sprout appears in 2 to 4 days.
• Under field cultivation each plant develops :

            (a) In the strong-bushy varieties 20 to 40 sprouts

            (b) In medium-bushy 15 to 25 sprouts

            (c) And in weakly-bushy 8 to 12 sprouts.

                                                   

Grand Growth Phase

This stage lasts for 5 to 8 months. Sugarcane plants normally vegetate at this stage, if properly supplied with heat and moisture. 

• Grand growth phase starts from 120 days after planting and lasts up to 270 days in a 12-month crop. During the early period of this phase tiller stabilization takes place. Out of the total tillers produced only 40-50% survives by 150 days to form millable cane.
• Most important phase of the crop wherein the actual cane formation and elongation and thus yield build up takes place.
• Leaf production is frequent and rapid during this phase with LAI reaching around 6-7.
• Under favourable conditions stalks grow rapidly almost 4-5 internodes per month.

                                  

                                                 Fig: Grand growth phase

Maturation and Ripening

• This phase lasts for about three months.
• Its maturation is determined by a definite sucrose level in the stems (up to 14-16% stem mass) and a low level of reducing sugars.
• The commercial ripening of stems can be identified quite reliably by the ratio of refractometry indices of juice taken from the seventh-eighth internodes and lower (0.95-0.98). In tropics, by harvesting time the sugarcane stems accumulate on the average up to 14-16% sugar; in subtropics 8-12% sugar.