| Recently, the study of physical agriculture involving multi-disciplinary knowledge, such as biology, physics, has become the issue of common concern for scientists and farmers. At home and abroad, it is focused on the study of light, magnetism, electricity, sound waves on the impact of growth and output in crop. However, the study based on alternative stress, including ultrasound and sound, on the impact of disease resistance in crop is reported seldom. The thesis is to use ultrasound to stimulate rice seeds and sound to stimulate rice seedlings to induce disease resistance in rice. Then the combination of ultrasound stimulation frequency and ultrasound loading time is optimized by germination capacity and disease index in rice. As well as the plant morphology, physiological and biochemical indexes in rice induced by ultrasound and sound were measured and analyzed. It is to provide the basis of theory and application to explore new method for prevention of rice sheath blight. The results of this study were as follows:①In Oryza sativa L. cv. Tetep, Oryza sativa L. cv. Wanhui 88, Oryza sativa L. cv. Yangfujing 7, the results obtained by germination capacity and disease index were as follows: ultrasound (output power: 280W; frequency: 25kHz; loading time: 10min) stimulation significantly increased the germination capacity in rice. The germination capacity increased 5.17% and the relative effect enhanced 13.85% in Tetep. The germination capacity increased 8.34% and the relative effect enhanced 10.78% in Wanhui 88. The germination capacity increased 5.34% and the relative effect enhanced 7.00% in Yangfujing 7. The disease index through ultrasound stimulation has been decreased significantly. The disease index decreased 2.86% and the relative effect reduced 16.00% in Tetep. The disease index decreased 4.30% and the relative effect reduced 13.43% in Wanhui 88. The disease index decreased 1.26% and the relative effect reduced 4.44% in Yangfujing 7. It is showed that ultrasound significantly enhanced the resistance to rice sheath blight.②The germination capacity and disease index are as to be the test indexes in Tetep, Wanhui 88, Yangfujing 7. The combination of ultrasound stimulation frequency (25kHz, 45kHz) and ultrasound loading time (0min, 3min, 5min, 8min, 10min, 12min, 15min, 20min) is optimized by the experiment of two-factor randomized block. The results showed that ultrasound stimulation (frequency: 25kHz; loading time: 8min) is the best to the combined effect of growth, development and resistance in rice.③Ultrasound and sound, as alternative stress, significantly reduced the hazard of rice sheath blight in rice through observing plant morphology and leaf tissue. The disease index induced by ultrasound (output power: 280W; frequency: 25kHz; loading time: 8min) decreased 2.85% and the relative effect reduced 15.16% in Tetep. The disease index induced by sound (intensity: 100dB; frequency: 1000Hz; loading time: one time a day, 5h/one time, 20 days) decreased 3.82 % and the relative effect reduced 21.35% in Tetep. It is concluded that the effect of sound-induced disease resistance is superior to ultrasound-induced effect.④In rice, the ultrasonic and acoustic stimulation can accelerate superoxide radical (O2·-)production rate change, and enhance superoxide dismutase (SOD) and peroxidase (POD) activities, and increase phenylalanine ammonia-lyase (PAL) on the response speed of Rhizoctonia solani. The results showed that the rice treated by alternative stress perceive the signal infected is faster than non-treated, and the defence-related enzymes are induced to express quickly. Thus, the O2·- is declined rapidly in rice treated by alternative stress because of the enhancement of enzyme activities.⑤According to plant phenotypic plasticity, cross-adaptation, memory function, experimental results and analysis, as well as references, the conclusion is as follows: the properly physical stimulation, such as sound, light, electricity, magnetism, treat plant seeds or seedlings. Plant is response to external physical stimulation through the changes of reactive oxygen species and enzyme activities after perceiving physical signals. As the enhancement of enzyme activities, the excessive reactive oxygen species has been removed, phytoalexin has been synthesized, cell wall has been thicken, and plant bring about systemic acquired resistance (SAR). In the future, the plant may always have the physical stimulation signal because of the memory function. After bacteria infection, the plant cell membrane receptor perceive the signals of bacteria infection and plant system would collect the SAR information induced by physical stimulation. Because of cross-adaptation, the gene of disease resistance is expressed by the activation of SAR information induced by physical stimulation. Thus, the physiological and biochemical indexes, such as reactive oxygen species and defence-enzyme, and plant phenotype is changed so as to achieve the suppression role of disease.In this paper, the optimization of ultrasound parameters and the assumed physical stimulation role to plant disease resistance provided theoretical basis for pathology and potential application to improve disease-resistant in crop.
|
PDF Full Text Request