Preliminary Study On The Key Technology Of Rice Seedling Raising By Orderly Machine Throwing

In recent years,mechanical orderly seedling throwing cultivation is a new mechanized planting method,which has great development potential.In order to solve the key problems such as the rapid growth of seedlings under high temperature existing in the process of orderly machine throwing seedling raising,the experiments of single hole sowing rate,regulator screening and soaking concentration,parameter optimization and seedling combination were carried out in qianshanhong Town,Datonghu District,Yiyang City in2020.1.The results showed that single hole sowing rate and Paclobutrazol had an effect on seedling growth.The seedling quality of single hole with 2 seeds was better than that of single hole with 1 seed,significantly better than that of single hole with 3 seeds,but the growth rate of seedling height had no significant difference with other sowing rates;Paclobutrazol treatment significantly reduced the seedling height growth rate;The results showed that the treatment of 2 seeds / hole + Paclobutrazol soaking had significant height control effect,and the seedling quality was significantly better than other treatments,mainly for the increase of total root number and single stem base width.2.The height control effect of the combination of seed soaking and spraying with regulators was significantly better than that of single seed soaking or single spraying.Among them,the combination of Paclobutrazol seed soaking,Uniconazole and calcium tetracycline spraying showed the best performance in the tested treatments.The seedling height at 30 d seedling age decreased by 8-10 cm compared with the untreated control,and the leaf age increased by about one leaf compared with the untreated control.3.The orthogonal test of chemical control agent concentration parameters showed that the combination of 15% Paclobutrazol 10 g / kg soaking seeds for 18 h,spraying Uniconazole50 g / 667m2 and calcium tetracycline 20 g / 667m2 at one leaf and one heart stage showed the best concentration.When the seedling age reached 28 d,the leaf age was 4.79 leaves,the seedling height was 10.35 cm,the average number of tillers was 2-3,the leaf length decreased by 0.2-0.7cm,and the total root number and stem base width increased significantly.4.The results showed that the combination of precision sowing + chemical control treatment + dry control seedling had the best seedling height control effect and seedling quality.When the seedling age was 35 days,the height of the seedling still met the requirements of machine throwing,the root of the seedling was less exposed,the stem base was wide and strong,with 1-2 tillers.The rate of seedling leakage was the lowest in the field,and there was no turning green period after seedling throwing in the field,and tillering occurred quickly and tillering rate was high.To sum up,drought control seedling raising and precision sowing are feasible means to enhance the quality of mechanical throwing seedlings.The combination of Paclobutrazol seed soaking combined with Uniconazole and calcium cyclamate spraying can effectively control the height of mechanical throwing seedlings and prolong the suitable throwing age of medium and late rice seedlings.