SRA-LGAREC U P D A T E S

Published by the SRA-La Granja Agricultural Research and Extension Center La Granja, La Carlota City

Negros Occidental, Philippines ? 0973-222-810

Vol. 2 No. 8 October 1998

DETERMINING MATURITY OF CANES

The sugarcane plant manufactures sugar through the process of photosynthesis. When the cane plant is still young most of the sugar is used for vegetative development. However, when past the boom stage of growth and conditions are less favorable for growth, more sugar is translocated into the storage tissues in the form of sucrose. When growth rate declines and much sugar have been stored, the sugarcane plant is considered to be matured and ripened and ready for harvest. The following conditions will limit vegetative growth and hasten ripening: ? ? Low temperature with

high temperature range markedly restricts the uptake of nitrogen and thus limiting synthesis of new cells (growth) and improving juice quality.

? ? Mild nitrogen starvation. Excessive nitrogen as well as late application tends to delay maturity of the crop. In

practice, all the required fertilizers are applied within the four months after planting in order not to delay maturity of the crop.

? ? Moderately dry, sunny and relatively cool days retard growth and favor storage of sugar in the cane stalk. Rainfall occurring during the ripening stage triggers vegetative growth and lowers brix and sugar content since the stored sugar is used for tissue development. For irrigated fields, moisture control is done by not irrigating the field four to six weeks before harvest in order to hasten ripening.

Guides in determining maturity of canes ? ? Age of crop (10-12

months). Maturity is often determined by the chronological age of the crop. However, the influence of climate and cultural factors, such as the adverse effect of El Niño that delays optimum growth, makes age an unreliable index of cane maturity.

Yellowing of leaves in the whole field is uniform.

? ? The stalks become yellowish.

? ? There is shortening of internodes in the upper portion of the stalk.

? ? There is more or less a uniform brix reading in the entire stalk. Juice samples are taken from the top, middle and base of the stalk. A brix reading test using a handheld refractometer is made for each portion. An immature stalk has a high brix reading at the base and low at the middle and top. The overmature registers high brix at the top and low at the bottom.

Sugar yield is low when the sugarcane plant is harvested before or after maturity. Thus before deciding when to harvest a sugarcane field, the tell -tale signs of a fully matured and ripened cane should manifest./glr SOURCES: SRA, 1991. Handbook on

Sugarcane Growing.

SRA, 1997. OPSI Farm Management Training Manual.