| A comparative experiment was carried out with mechancial seeding method of different seeding and transplanting date during year 2014-2015 in Sichuan Chengdu plain.The experiment was selected suitable variety growth stage types for local and its main popularizing representative varieties(Fyou 498 and Yixiangyou 2115)according to the heat conditions in Chengdu plain and possible safety growth days of mechanical seeding rice in the rape(wheat)-rice cropping system,with setting up 5 seeding datesincluding March 21th(S1),March 31 th(S2),April 10th(S3),April 20th(S4),April 30th(S5),and the seeding age 30d,.and 5 transplanting dates including April 21th,May 1th,May 11th,May 21th,May 31th.Systematic comparatice studies on development progress and utilization of dry matter production,nitrogen accumulation and distribution,tillering characteristics,differentiation and retrogression of spikelets,yield and its components and rice quality of mechanical planting rice under different seeding and transplanting date and varieties in Chengdu plain was comparative evaluated,in order to provide a scientific basis for selecting suitable seeding and transplanting date of mechanical indica hybrid rice in Chengdu plain.The results showed as follows:1.The development progress of mechanical hybrid rice was clearly influenced by different seeding and transplanting date.Along with the delayed seeding date,the date of jointing,heading and maturity of varieties were corresponding delayed,the stages from transplanting to jointing and the stages from jointing to heading significantly reducing,while the stages from heading to maturity increasing,leading to the growth stages clearly reducing at last.2.There was a difference in the characterization of nitrogen accumulation amount and utilization in hybrid rice under different mechanical seeding and transplanting dates.Along with the delayed sowing date,the dry matter productivity,the nitrogen productivity and harvest index showed a trend of decreasing holisticly,while nitrogen content of plant increased at the stages of jointing,heading and maturity.The nitrogen accumulationg amount of stem-sheath at S4 sowing date was less than other treatments at the stage of jointing;and the nitrogen accumulation amount of stem-sheath at the stage of maturity increased at first and then decreased afterwards with the delayed sowing and transplanting date.The apparent nitrogen translocation rate and the contribution to N in spikelet of rice stem-sheath decreased at first and then increased afterwards with the delayed sowing date,while the nitrogen translocation efficiency decreased at first,and then increased afterwards,decreased at last.The nitrogen uptake of 100 kg grain showed a trend of increasing with the delayed seeding and transplanting date.3.The number of tillering and earbearing positions increased with planting early,while decreased with delaying seeding date.The primary tillers of Fyou 498 mainly emerged from 3/0 to 7/0 when seeding from S1 to S2,while emerging from 3/0 to 6/0 when seeding from S3 to S5;the primary tillers of Yixiangyou 2115 mainly emerged from 3/0 to 7/0 when seeding at the stage of S1,while emerging from 3/0 to 6/0 when seeding from S2 to S5.Primary tillers earbeared mainly from 3/0 to 6/0 in the seeding date of S1,while earbearing mainly from 3/0 to 5/0 in the seeding date from S2 to S5.Secondary tillers emerged and earbeared mainly from leaf 3 to leaf 4 on main stem.The main stem contribution to yield was S5>(S2～S4)>S1.The primary tillers and secondary tillers group contribution to yield was(S1～S4)>S5.Leaf 3 to leaf 6 seeding in S1,leaf 3 to 5 in the seeding date from S2 to S5 were the superior leaf positions.Primary and secondary tillers emerging rate was significantly negatively associated with average relative humidity,while significantly positively with average diurnal temperature range,accumulated temperature and sunshine hours of tillering stage;Primary tillers earbearing rate was significantly negatively associated with average relative humidity and average temperature of tillering stage,while significantly positively with average diurnal temperature range of tillering stage,while significantly negatively associated with average relative humidity of inflorescence differentiation and flowering stage,while significantly positively with sunshine hours.4.The numbers of survived,differentiated and retrograded primary,secondary and third branches and spikelets were significantly influenced by different sowing and transplanting dates,varieties,and the interactions of different seeding and transplanting dates with varieties.Along with the delayed seeding and transplanting date,the number of secondary survived branches increased at first,decreased afterwards,then increased at last;the number of secondary survived and differentiated spikelets showed a trend of increasing;while the number of secongdary retrograded spikelets decreased.The total branches,primary,secondary and third survived,retrograded and differentiated branches and spikelets of Fyou 498 were significantly higher than Yixiangyou 2115,while survived primary spikelets were significantly lower than Yixiangyou 2115.The survived and differentiated secondary spikelets were significantly negatively correlated with the dry matter per stem of jointing stage.The numbers of differentiated primary branches and spikelets were significantly positivel correlated with the nitrogen content of jointing stage.The numbers of differentiated third branches and retrograded secondary spikelets were significantly positively correlated with the nitrogen accumulation of jointing and heading stages.5.The productive panicle number,spikelets of unit area were significantly positive associated with grain yield,and seed-setting rate was positively associated with yield,significantly.The grain yield was positively correlated with sunshine hours of mechanical hybrid rice,and the productive panicle number was positively correlated with total accumulation temperature,sunshine hours,significantly;population spikelets and number of grains per panicle showed a significantly negative relation with total temperature,while seed-setting rate was positively correlated with total sunshine hours,significantly.The contribution of spikelets group to yield was the largest,and the setting rate was the second largest.Different sowing and transplanting dates influenced the grains yield through changing total spikelets,seed-setting rate.We should select mechanical hybrid varieties of large panicles first,and increase grain number of panicle on the basis of ensuring enough spikelets,and increase seed setting rate by seeding and transplanting early,so as to achieving high yield in Chendu plain.Comprehensive view,planting before May 11 will be more beneficial to higher yield,planting before May 21 will be in favour of stable yield,while planting after 21 will decrease yield of rice in Chengdu plain. |
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