EVALUATION OF THE PRODUCTIVITY OF TWO SUGARCANE (Saccharum officinarum L.) VARIETIES AS INFLUENCED BY MULCHING, K-FERTILIZATION AND IRRIGATION INTERVAL
Four experiments comprising three field trials were conducted at the upland sugarcane experimental field of the National Cereals Research Institute Farm, Badeggi (90 451 N; 60 071 E) in the Southern Guinea savanna ecological zone of Nigeria from 2010 to 2012 wet and dry seasons. The fourth experiment was conducted at the screen house of the Research Institute. Two varieties of sugarcane used for the experiments were chewing sugarcane (Bida Local) and industrial sugarcane i.e. National Cereals Sugar 008 (NCS 008). The first experiment was to determine the effect of different mulching materials on the growth and yield of sugarcane was a 2 x 3 x 2 factorial in a randomized complete block design (RCBD) with three replications. The second experiment that evaluated various parts of sugarcane cutting that could be planted by the farmers was a 3 x 3 x 2 factorial laid out in a randomized complete block design (RCBD) with three replications. The third experiment which assessed the effect of harvesting time and three polyethylene colour as mulch on postharvest quality of sugarcane was a 4 x 2 factorial laid out in randomized complete block design (RCBD) with four replications. The fourth experiment determined the growth performance of sugarcane under different watering regime and K-fertilizer rates was a complete randomized design (CRD) with four replications laid out in the screen house. Three setts of sugarcane were planted per row and ratoon for each experiment was assessed for the next cropping season for all the experiments. The following parameters were measured: establishment count, stalk length and girth, number of stalks, tillers produced, nodes and inter-nodes, % brix, stalk yield. Establishment count significantly (p<0.05) differed in both the plant and the ratoon crops in 2010 and 2011. In the ratoon crop, mulching with groundnut shell produced higher establishment count (60%) compared to 52% when rice husk was used. Also, increasing organic matter rate increased the establishment count in the ratoon crops. In all the sampling periods, the stalk length of NCS 008 variety was significantly (p< 0.05) higher compared to that of Bida local in both cropping systems. Mulching at 40 t ha-1 gave the best yield for both the plant and ratoon crops when compared to 0 and 20 t ha-1. Plots mulched with 40 t ha-1 of groundnut shell gave the highest yield. The highest stalk yields of 42.25 and 50.31 t ha-1 were obtained from plant and ratoon crops in 2010 and 2011 respectively for NCS 008; 38.12 and 45.19 t ha-1 in 2010 and 2011 respectively, for Bida local. . Furthermore, the optimum stalk yields obtained from 40 t ha-1 in 2010 and 2011 plant and ratoon crops were higher than the maximum obtained for 0 and 20 t ha-1. The brix content from NCS 008 was significantly (p<0.05) higher than Bida local. The top parts of NCS 008 and Bida local significantly (p<0.05) performed higher than either the middle or the bottom part. NCS 008 grew significantly (p<0.05) taller than Bida local for plant and ratoon crops. The application of 90 kg K ha-1 gave the highest yield of ratoon when compared with the application of either 0 or 60 kg K ha-1. The least yield was obtained from 0 kg K ha-1 for both crops. Coloured polyethylene significantly (p<0.05) increased the vegetative growth of sugarcane when compared with control. Plot harvested at 12 MAP performed better than those harvested at 10 MAP. The yield from black polyethylene mulch proved superior to red and green colour at 12 MAP. Better sugarcane yield (45.40 t ha-1) was obtained by polyethylene mulching compared to no mulch (10.73 t ha-1). Incidence of smut, dead heart, termite attack was not evident with the use of polyethylene mulched plant and ratoon crops in 2010 and 2011. The application of 90 kg K ha-1 decreased the establishment count of Bida local. Six days watering interval and potassium application at 90 kg K ha-1 significantly (p<0.05) increased the stalk length, stem girth, leaf area and dry matter component of Bida local in 2010 and 2011. The application of 60 and 90 kg K ha-1 produced more tillers than 0 kg K ha-1 in 2010 and 2011. 90 kg K ha-1 produced more nodees than 60 and 0 kg K ha-1. Watering interval increased the length of the inter-nodes. The application of 90 kg K ha-1 had the highest K-content. The yield and % brix were highly significant (p<0.05) in ratoon crops than in plant crops in all the experiments. NCS 008 produced more yield than Bida local. Hence, NCS 008 is recommended for estate and sugarcane out growers. Ratooning with the use of organic waste should be employed so that the yield of sugarcane can be increased in successive cropping. The use of agricultural waste such as groundnut shell will considerably reduce the cost of inorganic fertilizer as well as reducing or eliminating the environmental hazards caused by such waste. The use of organic materials at 40 t ha-1 is recommended as mulching material. The top and middle parts should be used by farmers to propagate sugarcane. Incidence of smut, dead heart, termite attack was not seen with the use of polyethylene mulch in plant and ratoon crops of 2010 and 2011. Therefore, the use of colour polyethylene should be encouraged. Watering interval of 6 days and application of 90 kg K ha-1 is recommended to obtain maximum growth and yield of sugarcane.