Effects of Spraying Prohexadione Calcium on Mechanical Harvesting Agronomic Characters,Yield and Quality of Sesame under Different Densities

LÜ Shuli; DING Fang; TIAN Zhuangbo

doi:10.15933/j.cnki.1004-3268.2025.02.007

Abstract：In order to explore the effects of spraying prohexadione calcium under different planting densities on the agronomic traits,photosynthetic characteristics,quality and yield of sesame,and to integrate the effective cultivation measures for the mechanical harvesting of sesame through factorial experiments,with Shangzhi 196 as the test material,a two-factor split-plot experimental design was adopted.Different densities were set as the main plots(D1:180 000 plants/ha;D2:210 000 plants/ha;D3:240 000 plants/ha),and different application amounts of prohexadione calcium were set as the sub-plots(CK:0 g/ha,spraying clear water;T1:425 g/ha;T2:500 g/ha),with a total of 9 treatments.The results showed that with the increase of planting density,the stem diameter of sesame showed a gradually decreasing trend,with a decrease range of 2.01%—4.56%.The SPAD value of leaves showed a trend of first increasing and then decreasing,and the D2 treatment was the highest,which was 0.82%and 6.65%higher than those of D1 and D3 treatments respectively.The leaf area index(LAI)and chlorophyll content had similar performance patterns.The average value of the D2 treatment was 4.72%and 5.17%significantly higher than the average values of D1 and D3 treatments respectively.The net photosynthetic rate(Pn)and stomatal conductance(Gs)were significantly decreased,and the intercellular CO2 concentration increased significantly.The number of capsules per plant and the thousand-grain weight decreased obviously,with the reduction ranges being 1.28%—8.45%and 1.39%—5.92%respectively,but there was no significant effect on the quality of sesame.After spraying prohexadione calcium,with the increase of the application amount,the plant height,the height of the first capsule,and the length of the main stem fruit axis of sesame decreased significantly,with the reduction ranges being 7.89%—10.64%,11.91%—14.01%,and 5.29%—9.01%respectively.The photosynthesis was effectively enhanced.Meanwhile,the number of capsules per plant,the thousand-grain weight,and the yield were significantly increased,with the increasing ranges being 5.72%—11.14%,2.57%—6.25%,and 3.34%—6.42%respectively.The content of crude fat decreased to some extent,while the contents of linoleic acid and crude protein were effectively increased,with the increasing ranges being 2.25%—6.08%and 3.80%—8.84%respectively.Among all treatments,D1T2 treatment had the highest Pn and 1 000-grain weight,followed by D2T2 treatment,with no significant difference between the two treatments,and D2T2 treatment had the highest SPAD value,LAI,pod number per plant and yield,which significantly increased by 7.01%compared with D2CK.Comprehensive analysis shows that when the planting density is 210 000 plants/ha,spraying prohexadione calcium at a rate of 500 g/ha once at the seedling stage and once at the early flowering stage is relatively ideal for optimizing the plant type of sesame,improving the agronomic traits for mechanical harvesting,and enhancing the yield and quality.