| With limited arable land and ever-increasing population in China, the food security is becoming a very important issue. Increasing nitrogen input to promote crop productivity has caused many problems, such as lowered nitrogen utilization efficiency, decreased rice grain quality, environment pollution, plant diseases and insect pests incidences of rice field increased, even human’s health compromised, rice field ecological environment deterioration worsen and so on. It is suggested that breeding higher nitrogen use efficient (NUE) rice is the most economic and efficient way to improve the utilization rate of nitrogen and promote high yield persistently. Previous reports have confirmed that large differences of NUE exist among different rice varieties, and multiple factors affecting nitrogen absorption and utilization. Whereas there are too many indicators to evaluate nitrogen absorption and utilization, but some studies don’t research the rice itself. We consider that the indicators to evaluate nitrogen absorption and utilization can be divided between amount of nitrogen absorption (ANA) and nitrogen use efficiency for grain production (NUEg). The study of nitrogen efficient rice should combine high efficiency and high yield to highlight the value of efficiency. So the nitrogen efficiency rice can be divided between nitrogen efficient absorption and high yield, nitrogen efficient use and high yield. The results of study on nitrogen efficient absorption and high yield had been reported nowadays. But some studies chose several varieties which were under-representation. And because of the complex genetic background, the height, growth duration and dry matter weight of per spike of the material of some studies have much difference. So these reason make the evaluation of nitrogen absorption and utilization much harder. For this purpose, we use the Chromosome single substitution segment line (CSSSL) as material, and research it in field and hydroponics cultivation from 2011 to 2013. We analyze the difference of source and library, dry matter accumulation and distribution, yield and its component factors, the absorption and utilization of N, P, K, root system character and so on of different nitrogen efficiency types. We aim to find the fundamental feature of nitrogen efficient absorption and high yield rice and its influencing factors, in order to provide reference for the improvement and high-yield cultivation of nitrogen efficient rice. The main research conclusions are as follows:1. The features of plant height, growth duration, and dry matter weight of per spike of the genetic group:The percentage of plant height in 120-140 cm rang is 83.33%; The percentage of growth duration in 140-150 d range is 90.35%; The percentage of dry matter weight of per spike in 4.00-5.00 g range is 87.72%. Plant height, growth duration and dry matter weight of per spike are main influence factors on nitrogen absorption. In spite of the above three indicators of this study selected materials are variant, but they distribute concentrated.2.In the aspect of nitrogen absorption, nitrogen utilization, yield and its component factors: The feature of ANA and yield of the genetic group is very large. The amplitude of ANA of variation in filed cultivation is 11.53-27.66 g·m-2, in hydroponics cultivation is 19.13-54.52 g·m-2, the maximum is 2.40(in field)-2.85(in hydroponics) times of the minimum. The amplitude of yield of variation in filed cultivation is 311-74-763.35 kg*666.7m", in hydroponics cultivation is 358.18-800.16 kg*666.7m-2, the maximum is 2.45(in field)-2.35(in hydroponics) times of the minimum. With the increase of ANA, the yield is on the rise as a whole. But the relationship of ANA and yield is not always a straight line. The yield is also affected by many factors, such as NUEg. ANA and NUEg both are the factors to affect the yield of the genetic groups. Improving both of them can improve the yield. But the contribution of ANA is larger than NUEg. The panicle number per area and the spikelet number per panicle of the nitrogen efficient absorption and high yield type is large, also to the grain filling rate. As a matter of course, its yield is high.3. In the aspect of source-sink:the source of the nitrogen efficient absorption and high yield type is sufficient, and its quality is high. For specific performance:LAI at heading stage(including efficient and high efficient LAI), LAI at ripening stage, rate of decreased of LAI at grain filling stage, leaf area per panicle, net assimilation rate at grain filling stage are higher than other types obviously. And these characters have different effects on ANA and yield; the sink potential of the nitrogen efficient absorption and high yield type is large, and its quality is high. For specific performance:Formation rate of sink potential is high, the ability to produce the sink potential of sink potential per dry matter weight, sink potential per leaf area, sink potential per nitrogen absorption is high. The sink potential per area and sink potential per panicle are both very high. And these characters have different effects on ANA and yield; Number of spikelet per leaf area and grain weight per leaf area are also high, so the flux of the nitrogen efficient absorption and high yield type is expedite.4. In the aspect of dry matter production and distribution:The dry matter production per area of nitrogen efficient absorption and high yield type is high, but the harvest index is medium. In the aspect of dry matter production:The dry matter production and its proportion at heading and grain filling stage are higher than other types, especially at grain filling stage. Dry matter production per panicle at ripening stage is the highest. Percentage of biomass distributed in stem-sheath and leaf of the nitrogen efficient absorption and high yield type is high,but the character of leaf is low. But the characters at ripening stage have no advantage. However, the dry matter weight of all organs at ripening stage are much higher than other types.5. In the aspect of nitrogen absorption and utilization:The feature of yield of the genetic group is very large. The amplitude of ANA of variation in filed cultivation is 11.53-27.66 g·m-2, in hydroponics cultivation is 19.13-54.52 g·m-2, the maximum is 2.40(in field)-2.85(in hydroponics) times of the minimum. The nitrogen absorption per area at heading, grain filling and ripening stage are higher than other types, the same as nitrogen absorption per panicle and nitrogen absorption intensity at ripening stage, but the nitrogen content of whole plant is low or lower. The percentage of N distributed in leaf at heading stage, in stem-sheath and green leaf at ripening stage are large, but in yellow leaf and panicle have no advantage. The N use efficiency for grain output, N use efficiency for dry matter production and N harvest index are medium or low. In the aspect of the 5 groups of influence factors of nitrogen absorption:the effect of nitrogen absorption at grain filling stage on ANA is higher than nitrogen absorption at heading stage, panicle nitrogen absorption is higher than stem-sheath and leaf nitrogen absorption, nitrogen absorption is higher than panicle number per area, dry matter production per area is higher than N content of whole plant, nitrogen absorption intensity is higher than the growth duration.6. In the aspect of P absorption and utilization:The P absorption per area at ripening and grain filling stage of the nitrogen efficient absorption and high yield type are large than other types, the same as P absorption per panicle at ripening stage. The percentage of P absorption of stem and sheath at heading and ripening stage, the P absorption intensity per area and per panicle at ripening stage are both very high, the same as P addition in panicle at ripening stage. But the P content of panicle and whole plant at heading stage are medium. The P use efficiency have no advantage. The P absorption per area and per panicle at ripening stage, the P absorption intensity, the ability to transfer P are all very high.7. In the aspect of K absorption and utilization:The K absorption per area at heading, ripening and grain filling stage of the nitrogen efficient absorption and high yield type are large, the same as P absorption per panicle. The percentage of K distributed in stem at heading and ripening stage, the percentage of K distributed in panicle at ripening stage, the P absorption intensity per area and per panicle, the K content of stem-sheath and whole plant at heading stage, the K content of stem-sheath, green leaf, panicle and whole plant, K addition in panicle at grain filling stage and the K harvest index at ripening stage are all very high. The K absorption per area and per panicle are higher than other types, the same as K absorption intensity and K translocation at grain filling stage. These are mainly benefit by the high K concentration in whole plant and stem-sheath.8. In the aspect of root characters:The root characters per plant (number of adventitious roots, total length of adventitious roots, root dry weight of adventitious root), per panicle (total length of adventitious roots) and per strip(number of adventitious roots, root dry weight of adventitious root, adventitious roots diameter) and the ratio of shoot to root at heading and ripening stage are large or larger. But the characters of root activity(total root absorption area, root activity absorption area, proportion of root activity absorption in total root absorption area) are in medium. According to the path analysis and correlation analysis results, we find that root dry weight of adventitious root per plant, the ratio of shoot to root at heading stage, the maximum root length and total length of adventitious roots per plant are the main root characters to influence the ANA of this genetic group.9. In the aspect of filtrating nitrogen efficiency cultivar:Combining the results in field cultivation and hydroponics cultivation, we filtrate different nitrogen efficiency rice which has large differences in nitrogen absorption and utilization, yield, and root characters. The nitrogen efficient absorption and high yield type has 3 varieties, they are L23, L68 and L111; The nitrogen low absorption and low yield type also has 3 varieties, they are L2, L3 and L57. The selected varieties can provide important cropping resources for the follow-up study of nitrogen efficiency rice. |
PDF Full Text Request