Effect of different drying methods on grains losses, milling, seed, seedling and eating qualities of different rice varieties

The study was conducted to determine the effect of different drying methods usually practice by farmers in Northern Luzon, Philippines in drying their rice (palay) after harvest. Three varieties used as test crop for drying were: IR-64(A1), PSB Rc-10 (A2), and PSB Rc-82 (A3) and the different drying methods used were T1 (Drying in the highway), T2 (Undisturbed pavement), T3 (Drying over a netted plastic fabric on concrete pavement), T4 (Drying in a netted plastic fabric over soil surface, T5 (Flash dryer) and T6 (Mechanical Flatbed Dryer). The treatments were arranged in a modified split-plot designed designating variety as the main plot and drying methods as the subplot. It was conducted during the dry season harvest of April 2003. The sub drying studies, flash and mechanical drying studies were conducted at Isabela State University, Echague, Isabela and the drying on highways were conducted in San Isidro, Isabela and at Alicia-San Mateo Road, Alicia, Isabela. Results showed that no varietals difference were noted in the physical losses of grain during drying as well as on milling quality, except in eating quality where IR-64 and PSB Rc-82 had exhibited superiority in sensory traits with the PSB Rc-10. On the other hand, drying rice on the highways significantly increased the physical losses during drying by as much as nine percent. Inversely, minimal grain losses with no significant differences were incurred in drying rice using the other methods such as drying on a netted plastic fiber over pavement, and over soil surface as well those dried in mechanical flatbed and flash dryer. Moisture reduction and drying rates were significantly faster in highway drying than those grains dried in other methods of drying. Highway drying produced a significantly greater number of cracked kernels as a consequence of rapid moisture reduction and impact of the vehicles passing over the grains during drying with poor milling recovery. Minimal or lesser cracked kernels or broken rice in rice dried in plastic fabric over concrete, soil surface, mechanical flatbed and flash dryer with excellent milling and brown rice recovery, greater head rice and higher milling degree. Germination is very low in rice dried in the highways while rice dried in the other methods exhibited greater percentage germination, faster germination rate and faster seedling establishment. Seedling root-shoot ration was reduced by highway drying but not in the rice dried in netted plastic fabric over the soil, mechanical flatbed and flash dryer. Higher seedling survival rate was shown by the rice dried on netted plastic fabric, mechanical flatbed dryer and flash dryer and the amylose-amylopectin ration reduced in rice dried in mechanical flash and netted plastic fabric. Hence, it is recommended to use netted plastic fabric over the soil, mechanical flatbed and flash dryer to maintain if not to improved the milling, seed, seedling and eating quality of rice.