Screening Of Rice Varieties With Different Water Use Efficiency And Their Photosynthetic Characteristics

Rice is one of the three major food crops in the world?wheat,maize and rice?.China is the largest country in which rice is grown.At the same time,the rice also consume huge fresh water which account for 70 % of agriculture and 40 % of the human society.The cultivated area and total yield of Japonica rice account for 32 % and 35 % of total sown area rice in China in 2005,respectively.The rice planting area was more than 4 x 107 ha and total yield exceeded 2.5 x 1011 kg at Heilongjiang in 2016,respectively.However,the fresh water resource is a limiting factor for rice sustainable development.On the basement of engineering and agronomic water-savings,improving water use efficiency of rice would reduce the water requirement for a specific yield potential and thus can help save considerable amount of irrigation water.In our study,we analyzied the genetic diversity of 102 major rice materials in resources nursery,and a survey of?¹³C was undertaken in 102 diverse germplasm accessions in the field experiment.After these,we conducted pot experiment for studying the response of different WUE rice materials to the limited irrigation in water consumption,growing development,matter partitioning,stomatal adaptation,photosynthetic physiology.The main results of the study are as follows:?1?Analyses of genetic structure of the 102 rice materials indicated that: when K equals to 3,?K has a maximum,showing that the 102 rice materials are classified into three subgroups,and the first,second,third subgroups included 25,35,42 materials,respectively.?2?The leaf carbon isotope discrimination(?¹³C)of 102 materials ranged between-28.238 ‰ and-26.322 ‰,and a 1.916 ‰ total range of ?¹³C values among 102 accessions,which average value is-27.526 ‰.The shennong 265 and ji96-104 has maximum and minimum value,respectively.?¹³Cshowed an positive relationship with plant height,tiller number,harvest index,the correlation index was0.228 ? 0.207 ? 0.343,respectively.?¹³C showed an inverse relationship with plant dry matter,thecorrelation index was 0.321.?3?Longdao 10 had much lower transpiration rate,transpiration water consumption,and the smaller stomata length under the water limited conditions.The transpiration water consumption of longdao 10 is much lower than binxu.The leaf net photosynthetic rate of longdao 10 decreased smaller than longdao5 and binxu under the water limited conditions.?4?At the grain-filling stage,the dry matter of leaf and sheath of longdao 10 was maximum,which provided a sufficient source-sink for grain-filling under the water limited conditions.This is the main strategy for longdao 10 adapting to the situation of lack water.?5?Rice yield is decided by three factors of ears per mu,grains per spike and grains weight,and theses factors are affected by the water condition.Under water limited condition,longdao 5 had themost filled grain number per panicle,there was significant difference between longdao10 and binxu.1000-grain weight in primary spikelets for longdao10 was significantly larger than longdao5,and1000-grain weight in secondary spikelets for longdao10 was significantly larger than longdao5 and binxu.