| 1.This reserach was conducted to study the effects of different seedling ages(20d,25 d,30d,35d)on seedling quality,mechanical transplanting quality,growth and development and yield with rice of Deyou4727 as material at the Southwestern University farm in 2016.In order to determine the two season rice transplanting suitable seedling age range,provide fundamental basis for realization of hybrid rice with high yield and high efficiency.The main results are as follows:(1)Seedling age has significantly effect on the yield and its components of the rice Deyou4727.It showed the highest yield in 20d(591.94 kg/mu)> 25d(568.32 kg/mu)(not significant),but a extremely significant effect over 30d(519.43 kg/mu)and 35d(479.18 kg/mu)seedling age.The correlation analysis showed that the effective panicle number,the total photosynthetic potential of heading to maturity,and the dry matter accumulation in this stage were significantly correlated with the actual yield,while the number of grains per panicle was not significantly correlated with yield.That 20 d and 25 d seedling age had the highest yield is mainly because the effective panicle number was significantly higher than that of other seedling age treatments.So,short seedling age increase the yield by increasing the effective panicle number,which increases the total number of spikelets and heading to mature photosynthetic potential.Thus,only under the premise of high panicles and increase other yield components can we achieve high yield of transplanting rice.(2)Along with the prolonging of seedling age,the quality of machine-transplanting rice Deyou4727 seedlings and transplanting has obvious changes.The leaf age,false stem height,base stem width,total rooting number,root length and plant dry weight per of mechanized planting rice all increase significantly.For example,the leaf age of the 35 d seedling was more 1.24 than the 20 d seedling,but green leaf number increase slowly only 0.41 and no significant difference.It showed that the overlength of seedling age,higher plantheight,more yellow leaf,less root number,root-shoot ratio decreased,sugar nitrogen ratio drops,seedling quality get worse,all went against the growth and development of mechanized transplanting rice.With the extension of seedling age,seedling miss rate and seedling damage rate increased significantly,and the coefficient of variation of total tiller per hole increased.20 d seedling age seedling miss rate was 4.63%,damage rate was 5.40%,coefficient of variation of tiller number at tillering stage was 7.83%,but 35 d seedling age miss rate reached 22.33%,damage rate was as high as 31.47%,the coefficient of variation was significantly increased to 14.52%.The four seedling age no significant difference in seedling age 20 d and 25 d,30d and 35 d difference is also not significant.It is that the longer the seedling age,seedling miss rate and damage rate increased significantly,25 d is the critical time for the change of the quality of transplanting,and transplanting before 25 d helps to improve the quality of the machine.(3)Along with the prolonging of seedling age of machine transplanting rice Deyou 4727,heading date delay,using the days of transplanting seeding age as x,using days of transplanting heading as y,the regression equation y=0.42x+57.7(R2=0.9692**),explaining that each seedling age prolonged 1 days was postponed for 0.42 days at heading stage.With the seedling age extension,the effective tillering stage and maximum tillering age of Deyou4727 will be advanced,the highest seedling number and effective panicle number decreased obviously,but the spike rate increased.However,the spike rate is affected not only by the influence of seedling age,but also by the number of basic seedlings.Auxiliary test showed that different regularity of tillering seedling per hill of different seedling age indicate that the more seedling per hill transplanting tiller earing rate is much lower than the less transplanting,indicated that 1 seedling>2 seedling>3 seedling>4 seedling>5 seedling.1 and 2 seedlings per hill,the tillering time was earlier,the time of termination of tillering was delayed,and the tillering node was widely distributed.The tillering node mainly concentrated in 3/0,4/0,5/0,6/0,7/0,but 3,4,5 seedlings per hill,the tillering time was delayed,the time of termination of tillering was earlier,so the tillering node of a section focused on 5/0,6/0,delayed seedling age reinforce this trend.With the increase of the number of seedlings,the theoretical yield of each node showed a tendency to decrease with the increase of middle and high nodes but decrease of low nodes.(4)The leaf area index(LAI)of short seedling ages(SSA,20 d and 25d)was significant higher than long seedling ages(LSA,30 d and 35d)in terms of maximum tillering stage,heading stage,elongation stage and mature stage,so did dry weight accumulation.SSA' was also higher than long's on the photosynthetic potential of heading-mature stage,especially.Though the net assimilation rate and dry weight accumulation were higher via LSA' process and it can't compensate the loss of the photosynthetic potential decreased,therefore,the total dry weight accumulation is lower than SSA' treatments.(5)Different treatments in different growth periods of the last piece of the whole exhibition leaf(second leaf counting from the top)chlorophyll(SPAD)increased with age as a whole.At the maximum tillering stage,heading stage and milking stage of LSA' SPAD was significantly higher than that of SSA,SPAD has increased with the prolonging of seedling age at mature period.With the extension of seedling age,the light transmittance ratio of the canopy of mechanized transplanting rice increased significantly.The population leaf area is too small,the population light transmittance is high,and the light interception rate is reduced.It is difficult to obtain a better population structure,and affecting the yield increase.But the group in the lower part of light is good,provideing physiological conditions for improving the LSA of net assimilation rate,which increase LSA of grain number per panicle.In conclusion,the correlation analysis of morphological index,yield and its components in different periods of growth of mechanical transplanting rice Deyou4727 under this experimental proper seedling conditions showed that effective panicle number is the primary factor of high yield formation.Through the combination of higher in a certain range of effective spike and LAI phase,and more dry matter accumulation in the late growth stage,to ensure the machine transplanting rice photosynthetic potential and net assimilation rate of coordinated development,could be the most effective way to eventually obtain high yield.2.By selecting five different Oryza sativa varieties of early-maturing,medium-maturing,late-maturing as materials and using different sowing date,studied the influence of the full panicle to mature the climate of ecological conditions on the comprehensive quality of rice.The results showed as follows:(1)Comparing early sowing with late sowing,the effect of sunshine hours and rainfall were not obviously different,however,the temperature factors were obviously different.comparing the early sowing and late sowing stage,the average temperatures were respectively 22.76-23.82 ? and 21.5-22.13 ? from full panicles to maturity;21 days to mature,the average temperature of early sowing was 22.85-23.4 ?,while late sowing was 19.97-20.27 ?,late sowing was low of 1.41-3.14 ?,having significantly differences.Comparison of rice comprehensive quality,the early sowing treatment was significantly higher than the late one,but it had great differences between different varieties.Early-maturing tianyouhuazhan and medium-maturing chuanyou8377 late sowing is superior to early sowing,suitable for late sowing to improve the comprehensive quality,but the other three varieties are the opposite.(2)It showed that under the normal conditions which ensure the full panicle's and grain filling's safety growth in the lowest temperature,temperature had effect on grain quality from late full panicle 21 days to maturity stages.Delaying sowing,reducing average temperature of the late grain filling period and improving rice quality method,but it should care about moderation. |
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