Resource use, energetics and sensory quality of lowland rice genotypes given various nutrient sources, quantum enhancers and water management

Two studies were conducted for two rice croppings in Brgy. [village] Pangasugan, Baybay, Leyte [Philippines] from January 27 - November 13, 2009 to assess production practices aimed at improving yield, resource use, energetic and sensory quality of lowland rice genotypes grown under various nutrient sources, quantum enhancers and water management. Study 1 evaluated the effects of full dose (70-60-30) of inorganic fertilizer using area, solophos and muriate of potash, fresh (5 t/ha) or composted cow manure (5 t/ha), quantum enhancers BD 500 (25 g/ha) or Agnihotra ash (30 g/ha) applied alone or combined with half rate inorganic fertilizers or with composted cow manure (CCM) on genotype PSB RC18. Study 2 assessed conventionally flooded and alternate wet and dry water management on four rice genotypes namely: SL-8H, Pinili-l, Masipag and PSB RC18. Parameters measured included agronomic characters, yield and yield components, soil quality, resource use productivity and efficiency, economics and grain sensory quality. The full dose of inorganic fertilizer and half dose treatments + quantum enhancers or composted cow manure yielded better by 27% and 15-30%, respectively than control. CCM + quantum enhancers increased yield by 12-23% while lone quantum enhancers by 3-4% over the control. Application of fresh cow manure yielded 38% higher than control and 15% higher than full dose inorganic treatment due to more productive tillers/hill, longer panicles with more grains and higher grain filling rate. It also produced plants which were markedly taller with bigger LAI [leaf area index] and heavier straw. This superior response was however comparable with those treated with inorganic fertilizer at full and half rates combined with either CCM or quantum enhancers soil in plots applied with fresh cow manure had relatively higher OM [organic matter] and nutrient contents, microbial activity and lower bulk density. N and P concentration and uptake were also higher as compared to the control. Fresh cow manure also gave higher water and energy productivity and efficiency relative to inorganic fertilizers at full or at half rates + CCM or quantum enhancers. It was the most resource use efficient (33%-37% compared to control or 18%-73% compared to full dose of inorganic fertilizer) and computed most profitable. Rice given quantum enhancers alone or combined with other treatments was more preferred by consumers in terms of aroma, taste, tenderness and cohesiveness. Hence at this time of energy crisis and climate change, the use of quantum enhancers, which are also known to alter the environment, would be valuable addition to organic farming. With a tbsp/ha applied, benefits also extend up to improving sensory or food quality. Follow up studies in combination with organic supplements but lesser than 5 tons/ha would help push the movement towards better production, productivity, energetic and quality of produce. Water management did not significantly affect yield and yield components of genotypes affirming that rice can be grown in reduced water regime. Alternate wet and dry (AWD) water management had earlier heading and maturity time and shorter grain filling duration. Due to inherent characteristics, genotypes differed significantly in growth, yield and yield components. Alternate wet and dry method was the most productive and efficient in terms of water and energy use relative to the conventional practice. Genotype PSB RC18 grown in AWD was the most water and energy efficient and gave higher net returns. Water management also affected grain sensory quality. AWD enhanced aroma, taste, tenderness and cohesiveness of freshly-cooked rice. However, genotype ranking depended also on water management. Grains of PSB RC18 was in sensory terms more preferred when grown under AWD while Pinili-l was most preferred when conventionally grown. Among genotypes, Pinili-l and PSB RC18 were most acceptable.