Crop cycle length and cane and sugar yields

Two series of trials were initiated to compare different lengths of crop cy cles for sugarcane harvested every 12 months under the local conditions ove r a six-year period. The first series involved harvesting cane every 24 mon ths and in the second series cane was harvested after 16 or 20 months alter nately. All trials included four cane varieties except one in the second se ries where only three varieties Were planted. Cumulative results for both s eries of trials showed a difference in favour of the 12-month cane crop. In the first series after six years, cane and sugar yields were reduced by 19 -48% and 22-60% respectively in the 24-month-old canes compared with 12-mon th-old crops. The level of reduction varied with cane variety. In the secon d series, the declines in cane and sugar yields were smaller, 5-44% and 7-4 9% respectively. Cane lodging, which increased with length of crop cycle, l ed to greater weed infestation, increased damage by rats and rendered manua l harvest more difficult.