ผลของปุ๋ยไนโตรเจนต่อความหอมและการแสดงออกของยีนในข้าวหอมพื้นเมืองไทย

Abstract

Fragrant rice landraces are highly genetic diverse, have a high ability to adapt to the local environments and some varieties are fragrant rice. The aroma is one of the characteristics of rice grain quality. The major aromatic compound found in rice is 2-acety1-1-pyrroline (2AP), the essential compounds derived from proline. The factors such as environments, cultivation practices, and post- harvest managements have been reported that affect the aroma of fragrant rice. Therefore, the objective of this research was to evaluate the effects of nitrogen application rate on proline contents in leaves at three growth stages (tillering, booting, and flowering stage), yield, yield components, seed qualities and the expression of hadh2 and TPI genes at flowering stage in Thai fragrant rice landraces. The experiment was conducted at Mae Hia Agricultural Research, Demonstration and Training center, Faculty of Agriculture, Chiang Mai University. The experiments were conducted in a complete randomized design (CRD) with 3 replications. The first factor was nitrogen fertilizer rate (N), including 30, 60, 90, 120, 150, and 180 kg of nitrogen per hectare (kgN/ha). The second factor was rice varieties (V), namely Buer Ner Moo 4 (BNM4) (fragrant rice), Khao Dawk Mali 105 (KDML105) (fragrant rice), and Suphan Buri 1 (SPR1) (non-fragrant rice).

The results showed that there are an, effects of nitrogen fertilizer sates on proline content in the rice leaves. The three varieties of rice illustrated high proline content at booting stage compared to the otber two growth stages. At a rate of 180 kgN/ha, BNM4 bad the highest proline content (2.41 µmol/g fresh weight), while KDML105 had high proline content at rates of 150 and 180 kgN/ha (4.05 µmol/g fresh weight) and SPR1 had tbe higbest proline content at 120 and 180 kgN/ha (2.28 µmol/g fresh weight). Furtbermore, the increasing rate of nitrogen fertilizers increased tbe plant beight, panicles per plant, spikelets per panicle, percent filled grain, 100 grain weight, straw dry weight, and grain yield of rice. Sensory evalution for grain aroma revealed that BNM4 and KDML 105 grown at the rate of 60 kgN/ha bad the highest aroma (score 2). The softness of three varieties rice was determined by the alkali test. The sesults illustrated that the increasing of nitrogen rates did not affect the softness of rice grain. The study of the expression badh? and TPI genes of aromatic in three rice varieties at different nitrogen fertilizer sates were conducted at the flowering stage (5 days after the anthesis). BNM4 had the highest expression of badh2 and TPI gene at the rate of 30 (2.14) and 120 (2.67) kgN/ha, respectively, while KDML105 rice bad the highest hadh2 and TPI gene expression at the rate of 90 (2.30) and 180 (2.34) kgN/ha, respectively, and SPR1 rice bad the highest expression of badh2 and TPI gene at the rate of 150 (1.39) and 180 (2.08) kgN/ha, respectively. This data could be useful for cultivation management for enhancing the aroma and productivity of the fragrant rice landraces in the future.