The Effects Of Sowing Date On Leaf Age And Spike Differentiation Process Of Hybrid Rice

In order to study the effects of sowing date on the leaf age and spike differentiation of hybrid rice in the rape/wheat-rice double-cropping system rice region in northeast Sichuan,four representative varieties with significant differences in growth period were used as materials,stage sowing experiments was conducted in local field conditions to observe and compare the total leaves of main stem,the leafing duration,the leaf emergence rate,the days of spike differentiation,and panicle quality of hybrid rice varieties in the different sowing dates,further analyzed the relationship between leaf process,spike differentiation and effective accumulated temperature in the corresponding stage.Provide a theoretical basis for formulating reasonable cultivation measures.The results of the study are as follows:1.The sowing date had a significant effect on the total leaves of main stem,the leafing duration of the main stem,and the leaf emergence rate of the hybrid rice.The total leaves of the main stem of the phase III significantly reduced by 6.1%.With the sowing date delayed,the leafing duration shortened by 8-15 days.The time required for leaves to reach different leaf positions increased with the increase of leaf position,and the segmented leaf position decreased with the sowing date delayed;The leaf emergence rate of Phase II and Phase III increased by 10.4% and 14.6%,respectively.2.With the delay of the sowing date,the effective accumulated temperature of the main stem leafing duration gradually decreased,while the daily average temperature gradually increased.The effective accumulated temperature of the main stem leaves duration in different hybrid rice varieties showed obvious differences in response to the sowing date.3.The effective accumulated temperature required for leaf emergence from different leaf positions rises exponentially with increasing leaf position.As the sowing date is delayed,the effective accumulated temperature required for leaf emergence at the low leaf position gradually decreases;The effective accumulated temperature required for leaf emergence at high leaf position gradually increases.The effective accumulated temperature required for leaf emergence at different leaf positions of different hybrid rice varieties at phase I and phase II was increased with the two-discontinuous exponential curve,and the effective accumulated temperaturerequired for leaf emergence at different leaf positions in phase III was increased with a continuous exponential curve.4.With the delay of sowing date,the total time of spike differentiation first increased and then decreased,over Phase I,phase II increased 4.5%,phase III decreased2.8%,while the daily average temperature increased first and then remained unchanged,and the effective accumulated temperature increased first and then decreased.It indicates that the spike differentiation was the slowest at phase II,relatively fast at phase III in three sowing dates.The delay of sowing date did not promote the spike differentiation of stage 1-2 and stage 2-3,on the contrary,the process of spike differentiation was delayed to a certain extent.However,it promoted other stages of the spike differentiation.5.Sowing date has a great influence on the quality of spike.With the delay of sowing date,the effective panicles per plant significantly decreased,phase II and phase III decreased by 2.1% and 3.2%,respectively.Total grains per spike,filled grains per spike,and panicle weight all showed significant increases in phase II,which were increased by 21.2%,23.1%,and 19.2%,respectively.There was no significant difference in seed setting rate;the 1000-grain weight decreased slightly and then rose slightly.Phases II and III decreased by 4.5% and 3.0%,respectively;production was significantly reduced by 31.0% in phase ?.