Effect Of Seeding Date On Growth Characters And Yield Formation Of Intercropping Wheat In The Hilly Regions In Sichuan Province

In order to find the suitable sowing date with intercropping wheat in the hilly regions in Sichuan province, we measured growth stage, climate factors, dry matter production, tiller formation pattern, ear differentiation, floret flowering, grain filling and yield in field experiment with different wheat varieties(Chuanmai 104, Mianmai 367, Chuanmai 55 and Shumai 51) in 2012-2014,and the seeding date was 10/18, 10/23,10/28,11/2,11/7,11/12 in 2012/2013, which were labeled as S1,S2,S3,S4,S5,S6, and the seeding date was 10/14,10/21,10/28,11/4,11/11 in 2013/2014, which were flagged as D1,D2,D3,D4,D5.The main results were as follows:1.The phonological period delay with the delay of seeding date, the time from sowing to jointing was elongated, but the date from jointing to anthesis and anthesis to harvest shorten, and the whole growth stage was shortened too. As the sowing date delayed 5 to 7 days, harvest time delayed 1 to 5 days, and early seeding made 7 to 12 days to harvest comparing with late sowing. With the delaying of sowing date, accumulation temperature and sunshine hours of whole growth stage were decreased, and the climate conditions from seeding to jointing, and jointing to anthesis had the great difference with different sowing date, and early sowing had the better one.2. The dry matter accumulation of single stem and population was clearly influenced by seeding date. The dry matter of single stem produced quickly with early seeding in anthesis and maturity, so the dry matter accumulation of single stem decrease with the delay of sowing date. Late sowing had the less accumulation of group in jointing, in the end, the dry matter accumulation of each seeding date was S1>S2>S3>S4>S5>S6. The plant height and ear length was decrease with the delay of sowing date too.3. The trend of stem and tillers were clearly influenced by cultivar and seeding date. The tiller development dynamic graph was a unimodal curve, and the maximum was found at jointing stage. The Shumai 51 has the better stooling and ratio of tillers survived than Chuanmai 104. Early or late seeding were unfavorable to the tiller development, and the best one was D2 and D3, but the ratio of tillers survived was only 50%. The location and incidence was different from each sowing date. The primary tillers of early seeding date(D1) emerged from leaf lto leaf 5, among which tillers from leaf 2 to 3 had higher emerging rate, but the primary tillers of late seeding date(D5) emerged from leaf 1 to leaf 3, and mainly concentrated in leaf 1 to leaf 2. The secondary tillers had low emerging rate with each sowing date. Only the primary tillers survived in Sichuan, and only the primary tillers of leaf 1 to leaf 4 survived, the primary tillers of leaf 5 and all secondary tillers couldn’t survive. The highest rate of surviving was T1, and the rate was 30%, T4 was the lowest one,and the rate was only 2%.4. Ear development of Chuanmai 104 was fast than Shumai 51, and made 7-20 days in advanced to match tetrad period. Late seeding date made the time delay to each period. Double ridge period, floret primordium differentiating period, and stamen and pistil primordium differentiating period were clearly influence by sowing date. As delaying of seeding date, total number of spikelets and fructification of spikelets were decrease, and early or late made the degeneration rate increase. Differentiation florets and fertility florets decreased with the delay of seeding date, and more than 50% of florets were abortive. The grain number of different spikelets was a unimodal curve, in which from 5 to 14 spikelets had the higher grain number, and from 1 to 2 spikelets almost had no florets can seed. The grain number of 5 to 14 spikelets was the decisive factor to grain number per spike, and the average of grain number per spikelet was 3.4. Early seeding made the time of maximal filling rate and active grain-filling period increase, and the rate of grain filling during gradual increase stage decreased, but the grain filling rate of rapid increase stage, the grain filling rate of slight increase stage, the average filling rate and the maximum grain filling rate increased.5. Spike number, grain number per spike and 1000-grain weight were decreased with the delay of seeding date, the same as yield. During the different sowing time, the coefficient of variation on spike number and grain number per spike was larger, 1000-grain weight was the least one. Yield were positively correlated with yield components, and the contribution rate was grain number per spike> spike number> 1000-grain weight. Therefore, winter wheat could be sowed after 18 October in Sichuan province, but a precocious should be sowed before 28 October。Sowing at this time, incidence rate of tiller, and spike number were more, number of spikelet and floret differentiation and grain number per spike were more. At the same time, the occurrence time of maximal filling rate and active grain-filling period were longer, and avoiding the "high temperature force maturity", grain weight is more. Then, the yield components were coordinated, and yield was higher.