Studies On Biological Characters And Ecological Adaptations Of Upland Rice Native Of Brazil

Upland rice has good resistance to drought and its water consumption only accounts for 20 percent of rice.when the world water shortage becomes more and more serious ,upland rice planting is very important to food security,especially in drought area,hill and mountain areas. In this study, 4 upland rice traditional varieties (Iapar-9, Iapar-6, Tangara, Rioparanaiba) from Brazil and three-line hybrid rice from China were adopted .By 3 experiments-comparison on growth and development characteristics of different varieties,drought resistant agent test and different seeding date test, the growth duration,material production characteristics,drought resistance, rice yield and quality were investigated. The main results were as follows:1. The growth and development characteristics of upland rice(Oryza sativa L.) native of Brazil in Changsha area was analysised and proved.Tangara and Iapar-9 are suitable to be planted in Changsha area with good plant type and moderate growth duration. In order to avoid drought menace during seed filling stage, they should be sown from 10th April to 10th May. Tangara had higher effective spikle,1000-grain weight,dailey output and harvest index.Tangara also showed higher yields than other varieties.Iapar-64 possessed shorter growth duration, which was favorable for avoiding drought stress.2. The photosynthesis" and material production characteristics of different varieties were compared.Tangara and Xinxiangyou 80 had higher LAI with 7.7 and 7.8 respectively at full heading stage,and their LAI descended more slowly during seed filling stage. In addition, they had suitable plant height and good plant type, which was propitious to high yield.3. The effect of different chemical control on drought resistance was compared. Suitable chemical resistants could increase the content of leaf chlorophyll, boost root vigor and improve rice quality.Different resistant agents had different effects on Iapar-9 and Tangara.The effects of fulvicacidHuangfusuanyan and Yunda-120 werebetter.4. Suitable colony establishment and reasonable LAI are necessary to high yield cultivation.During late growth stage, root vigor and leaf photosynthesis must be high and maintain longer duration. Low output ratio of stem and leaf sheath dry matter in upland rice varieties may be one of the limited factors to high yield.