ผลกระทบของสภาพอากาศเย็นต่อการผลิตข้าวลูกผสม

Abstract

Rice irrigated area is about 20 % of total country’s paddy field. Rice plantation in this area can be done through out the year but yield in dry season is rather low because the effect of cold temperature during booting state which was longer than usual . Resulting in unfertile seed and low yield. Therefore, research entitled “ The effect of cold temperature on growth and yield of hybrid rices” was conducted at Pathum Thani Rice Research Center in dry season 2009. Hybrid rices : PTT 06001 H and PTT 06008 H had been planted at 4 planting dates. They were 1. early september 2. mid September 3. early December 4. mid December . It was tound that the yield of both hybrid rices planted at early December ware 656 and 723 kg./rai respectively which were lower than that planted at early September. In addition, The yield of both hybrid rices planted at mid December having yield Component, number of seed per panicle healthy seed and harvesting index lower than other planting dates due to the effect of cold temperature during seedling state to tillering state. The temperature during these stages was about 20.5-24.7˚C and during booting state to flowering state was about 20.5-20.8 ˚C. It can be concluded that hybrid rices planted at early December gave lower yield about 35-44 kg./rai or 5-6 % compared to other planting dates.