Effect Of Mechanized Transplanting Density On The Growth And Development Characteristics Of The Female Parent Population In Hybrid Rice Seed Production

To explore the suitable density for the mechanized transplanting of female parent population in hybrid rice seed production,6 rice female parents(Xiang-ling628 S,FengyuanA,Guan-zhan63 S,Shen95A,Y58 S and H638S),which owning different growth period and tiller characteristics were selected.Four mechanized transplanting densities(18 cm × 14 cm,20 cm ×14 ?,24 cm ×14 ?,30 cm × 12 ?)and a control density of 20 cm×16.7 cm were selected to study the tillering characteristics,duration from seeding to heading,heading characteristics and the composition of spike and grain of female parent population,which influenced by different mechanized transplanting densities,and the tillering characteristics,duration from seeding to heading,heading characteristics,the composition of spike and grain of single holes female parents,which transplanted by using transplanter were investigated,the results showed as following:1.The duration from seeding to heading of 6 female parents that transplanted by transplanter under 4 different densities prolonged 0 to 3 days than those transplanted by manual,and the extended days of different female parents were diverse.With the increase of the mechanized transplanting density,the duration from seeding to heading,heading period and middle heading time of the female parents showed a prolonged trend,no significant difference in heading period and middle heading time under 4 different densities were detected,but the difference of the duration from seeding to heading 4 different densities was significant.Therefore,under the condition of mechanized transplanting,due to the influence of mechanized transplanting density on the duration from seeding to heading of different female parents,the sowing gap stage of the female parent should be adjusted to ensure the flower synchronization of parents.2.With the decrease of the mechanized transplanting density,the number of spikelet per panicle of each female parent was increasing,and the spike rate was decreasing.The highest seedling,effective spike and spikelet numbers of unit area were different in the different female parents,these traits increased in Xiang-ling628 S,Feng-yuanA,Guang-zhan63 S and Shen95 A following the increase of mechanized transplanted density,when the density was 18cm×14cm,these traits achieved the maximum value,while,under the density of 18cm×14cm and 30cm×12cm,these traits achieved the maximum and minimum value in H638 S,respectively.Under the density of 20cm×14cm and 30cm×12cm,these traits achieved the maximum and minimum value in Y58 S,respectively.3.In order to get optimum value of heading characteristics and spike grain composition,the mechanized transplanting density of 20cm×14cm was adopted in Y58 S,and the density of 14cm×18cm was adopted in other five female parents(Xiang-ling628 S,Feng-yuanA,Guang-zhan63 S,Shen95A and H638S).Otherwise,under the mechanized transplanting density of 30cm×12cm,Y58 S,H638S can also get a higher female parent spike grain population.4.Under the 4 mechanized transplanting densities of 6 female parents,the number of single holes mechanized transplanting seedling was range from 0 to 7,and the leakage point rate was 7.7%~16.5%,1~4 seedlings accounted for more than 75% percent of single holes mechanized transplanting seedling,the average seedling number of single holes was 2.4 seedlings.5.With the increasing of the number of mechanized transplanting seedlings,the duration from seeding to heading of single holes female parents shortened 1-4 days and the heading period of single holes shortened 1-2 days,the duration from seeding to heading and heading period shortened,following the increasing of mechanized transplanting seedlings.This indicated that the difference of single holes mechanized transplanting seedlings can lead to irregular heading of the female parent population.6.With the increase of the number of mechanized transplanting seedlings,the number of single holes effective panicles in the female parent first increased and then stabilized,meanwhile the number of spikelet per panicle showed the decrease trend.The number of spikelet of single holes was first increasing and then decreasing with the increase of mechanical transplanting seedlings,and the mechanical transplanting seedling every hole 3 to 5 seedlings is appropriate.