Study On Breeding New Super-high Yield Wheat Varieties Which Can Be Sowed And Harvested Earlier To Adapt To The Rotation Of Winter Wheat (Triticum Aestivum L.) And Rice (Oryza Sativa) In The Sichuan Basin

Food security is the one of several important issues facing the modern world. Particularly in China,maintaining large population growth rate,and the plantation is decreasing,so that enhancing yield per unit is a very important mission.Wheat is the secondly largest food crop only to rice.Sichuan Basin is one main growing region for grain.Wheat plays an irreplaceable role in total grain production of Sichuan. Therefore,it is of great significance to enhance the production breeding research on wheat in the Sichuan Basin and to continue to improve its potential wheat yield per unit.Potential wheat yield in the Sichuan Basin has been a standstill for many years,and following results were found according to analysis:inadequate illumination is a main weather factor limiting the wheat production in Sichuan Basin,and the rice-wheat growing system makes plantation in a spare in the annual September and October, waste of light and heat resources is serious;Under the eco-climatic conditions in the Sichuan Basin,the temperature at wheat later growth stage raises fast,and easy to cause heat-forced maturity,these bring about instability in wheat yield.With regards to this,and many of the previous research results,we believe that: earlyplanting-earlymaturity wheat cultivars may be more suitable to eco-climatic conditions and rice-wheat growing system in Sichuan Basin and is conducive to raising potential wheat yield.However,it is not in keeping with cultivation habit and techniques in nearly 50 years.Therefore,it is worthy to make in-depth study on techniques and theory.In order to verify the feasibility of achieve the super-high-yielding of earlyplanting-earlymaturity wheat in Sichuan Basin,and provide the theoretical basis for new super-high-yield wheat breeding,election and accumulate breeds resources. We analyzed the meteorological data recorded for nearly 11 years come from Meteorology Bureau of Qionglai City in Sichuan.And during 2005-2007 when trial being carried out,adopted new wheat lines in the regional trial in Sichuan province and the new varieties(lines)by our team,we studied the wheat development,yield components,grain grouting characteristics and grain quality at different sowing phase. The results are as follows:1.According to analysis on meteorological data from Meteorology Bureau of Qionglai City in Sichuan where the trial was carried out,we found that an important climate characteristic of the Sichuan Basin is in the annual mid-November,the temperature drop rapidly,rainfall decrease significantly,sunshine hours number reduce.Therefore,advancing the sowing of wheat is be able to secure more temperature accumulation,better soil moisture,effective rainfall after sowing,and better emergence of wheat seedlings and growth.In addition,during 2005-2006 when the trial carried out,the ten-day average temperature of wheat on growing date was basically consistent with the average value of the multi-year,rainfall maintained the same value to average value of the multi-year,those years were normal years,while, during 2006-2007,ten-day average temperatures were most higher,rainfall was less, it was more typical warm drought winter,therefore,the results are more representative.2.In 2005-2006,using all materials(60 lines)tested in regional trial in Sichuan Province,and MY11 as the control,we studied the adaptability of wheat in Sichuan Basin sown advanced 10 days(24st,Oct)to early sowing,those were found:all the lines grew and developed normally,average seed setting rate were up to 97.99%,it indicated that in normal years,the sowing date can be advanced on vast scale. Meanwhile,there is a big difference on the leaf numbers,leaves emerge rate,spike differentiation process,jointing stage,heading stage,flowering stage,and mature stage.The gap between the earliest and the lasts one of heading stage,flowering stage, and mature stage was 12 d,6d and 6d,respectively.And the MY11 grew fastest, headed and flowered first.This showed that Spring Wheat lines are weaker than MY11,and there is a big difference between thermal-photo response and certain differences on adaptability to early sowing.Those provide a favorable breeds base for screening new super-high-yielding earlyplanting-earlymaturity wheat varieties.3.In 2006-2007,compared the advanced sowing(October 20)and normal sowing (October 30)using all the lines(66)attended in the regional trial,we found that:in the same sowing date,growth and development process correspondingly advanced, such as the average seedlings stage,the average tillering stage,average jointing stage, the average heading,the average flowering stage and average maturity stage were respectively ahead 11 d,16d,27d,8d,9d,7d and 4 d;as for the yield components changes,when advance sown,there is an increase in the average spikes number and the average number of grains per spike,1000-grain weight decreased slightly,and ultimate yield increased 4.13%,while as for the output from descending order,the ones dealed with early sowing occupied the top three,and a maximum output was respectively 8204.1 kg/hm²,7887.275 kg/hm² and 7820.575 kg/hm².This showed that early sowing could obtain higher potential yield by changing wheat reproductive process.4.During 2005-2007,more studies were carried out using wheat varieties Chuannong 23,Chuannong19 and J210.During 2005-2006,set two sowing date: October 24(early sowing)than November 3(control sowing),the varieties(lines) Chuannong 23,Chuannong19 and J210.The results were:contrasting to early sowing, ear of grain and grain per spike number of the three genotypes did not change significantly,and there has been an increase grain weight,and therefore the output have increased considerably:the yield of Chuannong 23,Chuannong 19 and J210 respectively increased 3.97%,8.80%and 12.64%,and J210 to the highest potential yield,and output reached 8396.85 kg/hm² by early sowing,increased 13.34%and 23.48%respectively than Chuannong 23 and Chuannong 19 sown in the same date.It showed that J210 had the greatest potential yield among the three genetype,and yield increasing character was most obvious in the early sowing way.During 2006-2007, J210 had the highest yield up to 7112.8 kg/hm² when sown on October 18^th,increased 29.92%than the ones sown on November 5^thyield.This further proved that early sowing did increase potential yield.5.During 2006-2007,we studied on the grain grouting characteristics of the J210 on 10 sowing date.The results showed that:grain-grouting process on different sowing date can be better fitted using y=c/(1+ae^-bx),the coefficient of determination reached above 0.99.The equation parameter indicates wheat-grouting process.By equation parameters we found that the wheat grouting incremental period shortened along with sowing date delaying.The grouting rate in incremental period appeared increasing trend,the fast growing date extended along with sowing time delayed, grouting rate in the fast growing period appeared reducing trend.Thus the difference of kernel weight was not obvious by the end of fast increasing period.According to standard growth curve,wheat grain grouting process should exist a longer ease increasing period,but the actual ease increasing period was very short,only for 2.75 to 4.45 days,was largely different with the theoretical value;this stage the growth of grains was small,but it decided different grains weight among the ones in different sowing date.This may be due to the late heat-forced maturity resulting wheat grain grouting process be not successfully completed,and grain grouting process initiated earlier and more fully when sown early,resulting in the higher grain weight.It also demonstrated the necessity of the earlyplanting-earlymaturity in Sichuan Basin.6.During 2006-2007,we studied on the grain quality of the J210 on 10 sowing date. The results showed that:there was no significant difference on nutritional and processing quality of J210 among the treatments on different sowing date.It just increased slightly along with sowing time advanced.This showed that wheat quality would not be reduced as early sowing.7.Through two years of testing,we acquired a set of breeds resources and their descendants better suited to early sowing,as breeding materials and research materials for earlyplanting-earlymaturity wheat.To sum up,the temperature and light response type of wheat in Sichuan Basin ex(?)'s variations,and suitable sowing according to genotypes can achieve the super-high-yielding of wheat through earlyplanting-earlymaturity in Sichuan Basin, We should make use of existing breeds resources in Sichuan Basin,strengthen study on super-high-yielding breeding using earlyplanting-earlymaturity wheat varieties. The breeding of new earlyplanting-earlymaturity super-high-yielding wheat varieties should focus on weak spring wheat or semi winter wheat,the suitable sowing date is about October 20,and suitable heading time is about March 15 under normal circumstances.As for the yield component,1000-seed weight should be improved on the basis of maintaining the existing number of ear of grain and grain per spike,and the target production in a normal year should reach more than 7500 kg/hm²,at the same time,it is need to strengthen screen and culture the cold-resistant wheat cultivars.