Effects of Nitrogen Fertilizer on Grain Qualities of Khaw Dauk Mali-105 Aromatic Rice

Abstract

Thirteen pot and field experiments were conducted to examine the effects of N fertilizer on cooking and eating qualities of Khaw Dauk Mali-105 aromatic rice. The cooking qualities were measured by sensory methods. The results have led to the following conclusions and recommendations: 1) Aroma, softness, whiteness stickiness and glassiness of cooked milled rice varied inversely with percent N in paddy. 2) Considering in the whole range of paddy yields, aroma and glassiness did not vary with the rate of N fertilizer. However, these qualities did not vary with the rate of N fertilizer in the range of fertilizer rates which produced less than 80% of the maximum paddy yield whereas they varied inversely with the rate of N fertilizer in the range of those that produced 80% to the ones that suppressed the yield. 3) The softness, whiteness and stickiness varied with N-fertilizer rate. Beginning with no nitrogen in the soil, the application of N fertilizer increased these qualities of rice up to the yield level of 16-34%, after which increasing rated of N fertilizer resulted in lower qualities. However, in the range below 80% paddy yield, changed in the qualities due to increases in N fertilizer were small and, therefore, detection of changes in the qualities was difficult. 4) Soils that produce high quality rice are those which are low in nitrogen. 5) In production of rice with N fertilization to increase profit, care must be taken to avoid application of N fertilizer at the rate higher than the level which produce maximum yield. 6) soils containing N at the level higher than the level that begins to produce the maximum yield are not suitable for production of the aromatic rice since too low quality produce will be inevitably obtained.