Research On Water Use Efficiency Of Rice Based On Far-red Light Irradiation

The situation of agricultural water-saving in China is severe.It is particularly important to study the biological water-saving measures to improve the water demand of crops themselves.This study starts with the demand for agricultural water conservation.A multi factor combination experiment on rice seedling growth under light control environment was conducted.The molecular regulatory mechanism of changes in water demand characteristics of rice seedlings induced by light signals has been clarified.The stomatal response mechanism of light signaling regulating water use efficiency（WUE）in rice has been explored.The pore conductivity model for far-red light irradiation environment has been modified.The optimal far red light intermittent irradiation mode for WUE has been proposed.The response mechanism between stomatal gas exchange parameters and water use under light controlled environments was identified.1.The molecular regulatory mechanism of changes in water demand characteristics of rice seedlings induced by light signals has been identified.The experimental rice seedlings were cultured in a far-red light environment for 25 days.Seedling samples from the best growing experimental group were selected for detection of differentially expressed genes in the transcriptome and endogenous hormones in plants targeted to the metabolic group.The analysis of differentially expressed genes in transcriptome showed that farred light intermittent irradiation enhanced the expression of genes in plant hormone metabolism pathway.The detection results of endogenous plant hormones in the targeted metabolic group showed that the contents of abscisic acid,salicylic acid,cytokinin,and jasmonic acid hormones in rice seedlings increased after irradiation with far red light,while the contents of auxin,gibberellin,and ethylene plant hormones decreased.The comprehensive manifestation is that the far-red light signal improves crop WUE by regulating stomatal opening and development.2.The effect of far red light irradiation on WUE of rice seedlings was analyzed based on changes in stomatal characteristics.The mild salt drought stress environment was set up in this study.By observing the parameters of gas exchange,leaf stomatal density and stomatal area of rice seedlings,the effect of far red light irradiation on WUE of rice seedlings under salt and drought stress was explored.Research has found that after being irradiated with far-red light,the stomatal density of rice seedlings increased by 48.5%-68.6%,the stomatal area decreased by 35.7%-74%.The stomata were small and densely distributed.The change of stomatal characteristics led to the enhancement of leaf photosynthesis and the weakening of transpiration.Under far red light irradiation,the WUE of rice seedlings increased by 129.3%.3.The stomatal conductance model reflecting crop WUE under far red light environment has been revised.Based on the calculation results of gas exchange parameters in Study 2,the adaptability of Ball Berry linear porosity conductivity model（BB model）and optimal porosity behavior theoretical model（USO model）was compared and analyzed.In the absence of far red light,the USO model has a better fit than the BB model.For the stomatal conductance model under far red light environment,the A_nxphotosynthetic rate correction parameter was introduced to modify the BB model and USO model under far red light environment.The modified model has improved the fitting accuracy by 8%and15.3%,respectively,significantly improving the estimation accuracy of rice WUE in far-red light environments4.The optimal far red light irradiation mode for crop WUE has been clarified.There are many factors that affect the growth and development of rice under intermittent far red light irradiation.In order to explore the optimal far red light intermittent irradiation mode for crop water use efficiency（WUE）,a single factor experiment was first set up.The optimal factors for seedling growth potential and WUE were selected from 5 rice varieties and 4different peak wavelength far red LEDs.The results showed that the GGO model with a peak wavelength of 755nm had higher WUE in rice seedlings under far red LED.The optimal intermittent irradiation mode is:single irradiation for 19 minutes,intermittent for19 minutes,and daytime white light irradiation after the end of far red light irradiation.Under this condition,the WUE of rice seedlings significantly increased by 208%compared to the control group.With the goal of saving water for crops themselves,this study achieves the following results based on light control methods.The optimal far red light intermittent irradiation mode for rice seedling WUE was proposed;The molecular regulatory mechanism of the effects of far red light signals on water use and stomatal development in rice seedlings has been elucidated;Corrected the pore conductivity model for predicting WUE under far red light irradiation.This study provides a reference for the development of modern water-saving agriculture and crop water-saving work in light-controlled agriculture from micro-mechanism research to macro-model construction.