Effects Of Paclobutrazol Application Methods On Lodging Resistance And Yield Of Rice

Rice is one of the most important food crops in the world.at present,the yield reduction caused by lodging is still common all over the world.Paclobutrazol plays an important role in improving crop agronomic characters and enhancing lodging resistance.At present,the research on the resistance of paclobutrazol to crop lodging is mainly focused on the spraying concentration and single application mode of paclobutrazol,so this study was carried out in the teaching and research base of Jilin Agricultural University in Changchun City,Jilin Province in 2021.Using rice varieties "Wuyoudao 4" and "Jijing 525" as experimental materials,the split plot design was adopted,with paclobutrazol soaking(S1)and non-soaking(S0)as the main area.the period of paclobutrazol spraying(no spraying(F0),inverted fifth leaf(F3),inverted fourth leaf(F2)spraying,inverted clover(F1)spraying)was used as the secondary area.To explore the effects of different application methods of paclobutrazol on physical characters,lodging resistance,Internode assimilation,dry matter accumulation and yield of rice,in order to provide theoretical basis and technical reference for lodging resistance and high yield cultivation techniques of rice.The main results are as follows:(1)Compared with the non-soaking treatment,paclobutrazol decreased plant height,center of gravity,Internode length and Internode length,and increased Internode thickness and wall thickness.Regardless of whether seed soaking or not,the regulation effect of paclobutrazol spraying at different leaf ages on stem physical properties decreased with the delay of spraying period,and inverted five-leaf spraying(F3)was the best,and the regulatory effect of inverted fiveleaf spraying(S1F3)was better than that of inverted five-leaf spraying(S0F3)under seed soaking condition.(2)Compared with the non-soaking treatment,the seed soaking treatment with paclobutrazol increased the bending resistance and bending moment of the second Internode of rice base,and decreased the lodging index.No matter whether soaking seeds or not,spraying paclobutrazol at different leaf ages showed a decreasing trend with the delay of spraying period,and the regulation effect of inverted five-leaf spraying(F3)was the best,and the regulation effect of inverted five-leaf spraying(S1F3)on lodging resistance of basal second Internode under seed soaking condition(S1F3)was better than that of inverted five-leaf spraying(S0F3).(3)Compared with the non-soaking treatment,paclobutrazol increased the contents of soluble sugar,starch,cellulose and lignin in the second Internode of rice.No matter whether the seeds were soaked or not,spraying paclobutrazol in F3 could significantly increase the contents of soluble sugar,starch,cellulose and lignin compared with other spraying periods,and the promoting effect of spraying on the synthesis of assimilates in the second Internode under the condition of seed soaking(S1F3)was better than that of spraying without soaking(S0F3).(4)Compared with the non-soaking treatment,paclobutrazol decreased the dry matter accumulation at full heading stage and 30 days after heading,and increased the dry matter accumulation at mature stage.No matter whether the seeds were soaked or not,the dry matter accumulation of rice sprayed with paclobutrazol at different leaf ages decreased with the delay of spraying period.Spraying paclobutrazol on F3 could increase the dry matter accumulation at mature stage,and the dry matter accumulation of S1F3 was better than that of S0F3 without soaking seeds.(5)Compared with the non-soaking treatment,the soaking treatment increased the rice yield.Wuyoudao 4 and Jijing 525 increased an average yield of 2.79% and 0.72%,respectively.No matter whether the seeds were soaked or not,the yield of paclobutrazol in different leaf ages decreased with the delay of spraying period,and the yield of the treatment of spraying paclobutrazol in F3 was the highest,and the yield of spraying in the condition of seed soaking(S1F3)was higher than that of spraying without soaking(S0F3).To sum up,seed soaking with paclobutrazol(100mg/L)and spraying on the top five leaves(300mg/L)could significantly regulate the physical characters,lodging characteristics,dry matter accumulation,Internode assimilates and yield traits of rice.