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.