Search

Salt stress is one of the major environmental problems in agricultural production, severely limiting crops’ germination, growth and yield. Silicon (Si) is a widely recognized beneficial element in plants, which can promote plant growth especially under stressful conditions. With the emergence of nanotechnology in agriculture, silicon nanoparticles (SiNPs) have been shown to be a promising tool in nano-enabled agricultural production. However, the comparative effects of Si and SiNPs in alleviating salt stress in plants remain unclear, which would limit the application of SiNPs in agricultural practice. In this study, the effects of SiNPs and conventional Si (silicate) on tomato (a typical low-Si accumulator) seed germination, reactive oxygen species (ROS) content, antioxidant enzyme activity, and the expression of genes related to hormone metabolism were investigated. The results showed that SiNPs more effectively promoted seed germination percentage, fresh weight, and Si content than conventional Si. Simultaneously, SiNPs more significantly modulated the activities of antioxidant enzymes and alleviated salt stress-induced oxidative damage in tomato seeds. Moreover, exogenous SiNPs addition promoted the expression of genes responsible for gibberellin (GA) synthesis and abscisic acid (ABA) catabolism, while downregulating the expression of genes related to GA deactivation and ABA synthesis in tomato seeds under salt stress. Overall, our results indicate that SiNPs are more effective than conventional Si in promoting tomato seed germination under salt stress via modulating antioxidant enzyme activity and key endogenous hormone metabolism, which could be based on the higher accumulation of SiNPs in tomato seeds than conventional Si.

Aiming at the problem that the ground plant protection machine is difficult to enter for plant protection in the middle and late stages of maize field, this paper designs a UAV centrifugal spraying system for maize plant protection based on centrifugal nozzle and plant protection UAV. A single nozzle parameter test was carried out, and the results showed that the droplet size is related to the liquid supply flow rate and the nozzle speed. According to the optimal biological particle size theory, the nozzle parameters with the liquid supply flow rate of 1000 mL/min and the rotation speed of 14000 r/min are selected to test the droplet distribution characteristics under actual operation conditions, and the droplet size, droplet density, coverage and other important indicators of aviation spraying operations are analyzed. The experimental results show that the flight speed of the UAV significantly affects the droplet distribution in the bottom layer of maize. The droplet coverage and droplet deposition of each sampling layer decrease with the increase of flight speed. When the flight speed is 1.5 m/s, the coefficient of variation of the centrifugal spraying system is the smallest, and the droplet deposition effect is the most uniform. This study can provide a reference for the parameter optimization and correct use of centrifugal plant protection UAV in the middle and late plant protection operations of high-stalk crops such as maize. [ABSTRACT FROM AUTHOR]