Effects Of Paclobutrazol On Yield And Lodging Resistance In Direct-seeded Hybrid Rice

In recent years, along with the decreasing of rural labor force and poor cultivation benefits, the planting method of direct-seeded rice has been accepted by more and more farmers, cultivation area of direct-seeded rice has been expanding rapidly year by year. But lodging is one of the challenges which the direct-seeded rice has to face,therefor, it is significant to carry out related studies on lodging resistant of direct-seeded rice. The experiment was conducted in experimental farmland of Huazhong Agriculture University in 2014 with Yueyou 9113 and in 2015 with Guangliangyou 558(the first year is late rice, the second year is middle rice). Test sets as follows: Transplanting rice control. Direct-seeded rice control. Spraying PP333 with300mg/L at 1.1 leaf age. Spraying PP333 with 300mg/L before enlongation stage.Spraying PP333 with 300mg/L in both periods. Using A1、B1、C1、D1 and E1 represent each treatment in 2014, and A2、B2、C2、D2 and E2 represent each treatment in 2015.Through different treatment of spraying PP333, the growth and development, yield traits and lodging-related indicators of the direct-seeded rice were been researched,which were expected to provide a theoretical basis for the production of direct-seeded rice cultivation. The main results are as follows:1.Two years experiments showed that the yield of direct-seeded rice was lower than transplanting rice. After spraying PP333 in the experiment of 2014, except D1 treatment, the others yield were all reduced, but there is no significant difference with the control. In 2015, the yield of the three sprayed PP333 treatments were reduced,especially the E2 treatment, and the difference was significant. Lower production was mainly related to the reduction of per panicle. Spraying PP333 could increase the effective ear, grain weight, especially the E treatment.2.C1、E1 treatments could increase the leaf age in 2014, but the effect was not obvious in 2015. The tiller speed, highest seedings of direct-seeded rice were higher than the transplanting rice. Spraying PP333 can further promote tillering in two years,results were as follows: E> C> D, but the spike rate of each treatment was not greatly improved, spike rate of D treatment relatively well in two years.3.In 2014, the total dry matter of direct-seeded was lower than the transplanting rice. Except D1 treatment, the total dry matter of C1 and E1 treatment was slight increased, but there was no significant difference with the control. In 2015, the total dry matter of the three sprayed PP333 treatments was reduced, especially the D2 treatment. Spraying PP333 could decrease the CGR of the enlongation stage-heading stage, which was mainly related to the NAR reduction. In 2014, the CGR of different treatment after heading stage was: A1>C1>D1>E1>B1. In 2015, except E2 treatment was significantly higher than the control, the other treatments have not significant different. For D treatment in two years, the SPAD and the percentage of dry matter in grain have no significant difference with the control in two years, the effect of E treatment was poor.4.The LI of direct-seeded rice was higher than the transplanting rice. Spraying PP333 can reduce lodging index, which was mainly related to the reduction of its bending moment. The effect of D and E treatment was better than others. Spraying PP333 would reduce the internode length, panicle length, plant height and height of center of gravity, but there was little influence on the base of the stem diameter, wall thickness of N3.The effect of E treatment on wall thickness of N4 was inconsistent in two years, which need further verification. E treatment could increase units of dry weight of N3, and N4, while other treatments have little effect. Spraying PP333 can improve the content of starch and soluble sugar of base internode in 2015, results are as follows: A2> E2> D2> C2> B2.5.Yield with effective ear showed negatively correlated, with per panicle showed significant positive correlation. LI with LN3, PH showed significant positive correlation. LI and unit dry weight was significantly negatively correlated in 2015.