| Low temperature cold damage as a natural disaster has gradually become one of the main factors restricting the stable yield of rice in Heilongjiang Province.Rice is a thermophilic crop,and its growth and development are extremely sensitive to temperature.If it is affected by a strong low temperature at the booting stage,it will cause a decrease in physiological activity,spikelet sterility,a decrease in seed setting rate,a serious decline in yield,and even a complete harvest.Salicylic acid?SA?,proline?Pro?and gamma aminobutyric acid?GABA?play an important role in the stress resistance of rice.In this experiment,the cold-tolerant variety Dongnong 428 and the cold-sensitive variety Songjing 10 were used as materials.It was planned to use cold water irrigation to simulate natural cold damage for low-temperature stress treatment.The leaves were sprayed with different concentrations of SA,Pro and GABA at the booting stage of rice.Optimum application concentration of SA,Pro and GABA;according to the screening results,a single dose and compound test?SP,SG,PG and SPG?were conducted on SA,Pro and GABA to study the three foreign substances on rice physiology under cold water stress at booting stage Characteristics,root vitality,dry matter accumulation and distribution,yield,and yield components,revealing the formation of three exogenous substances on rice yield under cold water stress at booting stage,and clarifying the three exogenous substances on rice under cold water stress at booting stage The regulation effect of yield formation,and then determine the best combination combination.This experiment aims to enrich the physiological basis of cold-tolerance research on japonica rice in cold areas,and to provide a theoretical basis for the cultivation of cold-resistant japonica rice in cold areas.The main results are as follows:?1?Different concentrations of SA,Pro and GABA can promote the accumulation of soluble sugar,soluble protein and proline in functional leaves of rice under cold water stress at booting stage,increase the activities of superoxide dismutase,peroxidase and catalase,and The content of osmotic adjustment substance and antioxidant enzyme activity of Nong 428 were higher than that of Songjing 10,indicating that Dongnong 428 had stronger effect on inhibiting membrane lipid peroxidation.Under cold water stress,with the increase of SA,Pro and GABA concentrations,the osmotic adjustment substance accumulation and antioxidant enzyme activity of the two varieties showed a single peak curve change,respectively 0.50 mmol·L-1,40 mmol·L-1 and 4 mmol·L-1Optimally,the content of osmoregulatory substance and antioxidant enzyme activity of SA treatment were higher than those of Pro and GABA treatment,and the effects of Pro treatment and GABA treatment were similar.?2?Different concentrations of SA,Pro and GABA can affect rice spikelet development under cold water stress at booting stage.Under cold water stress,the fertility of rice pollen grains increased first and then decreased with the increase of SA,Pro and GABA concentrations?the difference between Songjing 10 S4 treatment and cold water treatment was not significant?,respectively 0.50mmol·L-1 and 40 mmol·L-1 and 4 mmol·L-1 are the best.Under cold water stress,the spikelet differentiation number of the two varieties showed a single peak curve change with the increase of SA,Pro and GABA concentration?the difference between Songjing 10 P50 treatment and cold water treatment was not significant?,respectively 0.50 mmol·L-1,40 mmol·L-1 and 4 mmol·L-1 had the best effect,in which SA promoted secondary spikelet differentiation in rice,and Pro and GABA promoted primary spikelet differentiation in rice.?3?Different concentrations of SA,Pro and GABA can promote dry matter accumulation of rice grains under cold water stress at booting stage.Under cold water stress,with the increase of SA concentration,the dry matter accumulation of the two varieties increased first and then decreased,with 0.50 mmol·L-1 being the best effect;with the increase of Pro and GABA concentrations,the dry matter accumulation of the two varieties gradually increased At 4 mmol·L-1,the accumulation was the largest,and then showed a downward trend?the difference between Songjing 10 G2treatment and cold water treatment was not significant?.In addition,SA treatment can accelerate the growth rate of Songjing 10 in the mid-phase.?4?Different concentrations of SA,Pro and GABA can significantly increase the yield of rice under cold water stress at booting stage,and the regulation of Songjing 10 is greater than that of Dongnong 428.Under cold water stress,with the increase of SA,Pro and GABA concentrations,the yields of the two varieties increased first and then decreased,respectively,the best effect was0.50 mmol·L-1,40 mmol·L-1 and 4 mmol·L-1,Dongnong 428 The yield of Songjing 10 reached85.26%,77.28%,80.90%and 86.00%,80.34%and 80.86%of normal irrigation level,respectively,indicating that the three foreign substances promoted rice yield under cold water stress at booting stage:SA>GABA>Pro.?5?The optimal concentration of SA(0.50 mmol·L-1),Pro(40 mmol·L-1)and GABA(4mmol·L-1)single-agent and multiple-pair have significant effects on rice internode length and leaf area index under cold water stress at booting stage.Under cold water stress,the single agent of SA,Pro and GABA can significantly increase the internode length of Dongnong 428 2 and 4 and the internode length of Songjing 10 2;the SP,SG,PG and SPG treatments of Dongnong 428 2 and 4The adjustment of the internode length of the inverted 4 showed a synergistic effect,and the internode length of Songjing 10 increased.Under cold water stress,SA,Pro and GABA single-agent treatment of Dongnong 428 significantly increased leaf area index at booting-milk maturity,Songjing 10 at booting stage-wax maturity leaf area index;SP,SG,PG and SPG treatments The increase in leaf area index of Dongnong 428 at booting stage and wax maturity stage was greater than that of single agent treatment,and the increase of leaf area index of Songjing 10 at booting stage and maturity stage was greater than that of single agent treatment,and there was no significant difference between the treatments.?6?The optimal concentration of SA,Pro and GABA single agent and its combination can significantly increase the chlorophyll content and root activity of rice functional leaves under cold water stress at booting stage.Under cold water stress,the chlorophyll content of two varieties of SA,Pro and GABA single treatment increased and the difference between the treatments was not significant;SP,SG,PG and SPG treatment showed a synergistic effect on the regulation of chlorophyll content of the two varieties,and in After the end of cold water stress,it can still maintain a high level of chlorophyll content.Under cold water stress,the chlorophyll a/b value showed the highest in SPG treatment,followed by SP,SG and PG treatment,and the lowest in SA,Pro and GABA single-agent treatment.Under cold water stress,the single agent treatment of SA,Pro and GABA can increase the root vitality of two varieties under cold water stress at booting stage;SP,SG,PG and SPG treatments showed a synergistic effect on the regulation of root vitality of the two varieties?SPG treatment 25d root system?The vitality is not significantly different from the normal control).Dongnong 428 and Songjing 10 had higher chlorophyll content,chlorophyll a/b value and root activity under SPG treatment.?7?The optimal concentration of SA,Pro and GABA single agent and compound pair have effects on dry matter accumulation and transport of rice under cold water stress at booting stage.Under cold water stress,the dry matter output of the stem sheath and leaf of the two varieties of SA,Pro and GABA single agent and the random combination treatment of both increased significantly,and the treatment effect of SP,SG and PG was better than that of the single agent,which contained SA treated stems The dry matter output of the sheath and leaves was higher;the dry matter output of the stem sheath and leaves of the two varieties treated with SPG was the highest,but still had a gap with the normal control.Under cold water stress,the dry matter transport rate of stem sheaths and leaves and the dry matter contribution of stem and leaves of two varieties treated with SA,Pro and GABA were significantly reduced;the dry matter transport rate of stem sheaths and leaves of two varieties treated with SP,SG,PG and SPG The stem and leaf dry matter contribution rate decreased more than single-dose treatment and the difference between the treatments was not significant.?8?The optimal concentration of SA,Pro and GABA single agent and compound pair had significant effects on rice spikelet development under cold water stress at booting stage.Under cold water stress,the fertility of pollen grains of two varieties of SA,Pro and GABA treatments increased significantly and the difference between the treatments was not significant;The pollen fertility of Nong428 is higher than Songjing 10.Under cold water stress,the number of spikelet differentiation increased in two varieties of SA,Pro and GABA single treatment,the number of spikelet degradation and the rate of spikelet degradation decreased,and the effect on secondary spikelets>primary spikelets;SP,SG and PG treatment The spikelet differentiation number of variety increased more than single agent treatment,the spikelet degradation number and degradation rate decreased;SPG treatment Songjing 10 had the most spikelet differentiation number,the spikelet degradation number and the lowest degradation rate,Dongnong 428 spikelet differentiation number,The degradation number and degradation rate are not significantly different from any of the two complex processing.?9?The optimal concentration of SA,Pro and GABA single agent and compound pair had significant effects on rice yield and yield components under cold water stress at booting stage,and the regulating effect on Dongnong 428 yield was greater than that of Songjing 10.Under cold water stress,the yield of two varieties of SA,Pro and GABA single agent treatments increased significantly,and the single agent's promotion effect on rice yield under cold water stress was SA>GABA>Pro;SP,SG and PG treatments on rice yield under cold water stress The regulation effect showed a synergistic effect,and the increase in yield was greater than that of single-dose treatment,and the treatment with SA contained higher yield;the two varieties of SPG treatment had the highest yield but still had a gap with the normal control.The normal control level was 86.32%and 85.85%,and the compounding agent promoted rice yield under cold water stress:SPG>SP>SG>PG. |
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