Physiological Mechanism Of Trichoderma Harzianum Prolonging The Green Period Of Zoysia Matrella

Zoysia matrella is widely used in various garden areas,because of its good growth,lower maintenance cost,better resistance to pests and good turf quality in summer,however,due to poor cold resistance,it was the earlier yellowing stage because of low temperature in the Yangtze River basin and the north of the China,the ornamental effect was poor.Therefore,it has become a hot topic in the research to explore an ecological,environmental protection,efficient and convenient management method to improve cold resistance and prolong ornamental green period of Zoysia matrella.In this study,with the material of Zoysia matrella,and the Trichoderma harzianum with different irrigation concentrations(0、1、2、3、4g/L)and different irrigation times(1、2 、 3 times)were used as different treatment methods,to analyze the physiological mechanism of Trichoderma harzianum prolonging the green stage of Zoysia matrella.The main research results are presented as follows:1.Effect of Trichoderma harzianum on the re-greening stage of Zoysia matrell(1)Trichoderma harzianum can advance the greening time of Zoysia matrella and be conducive to the accumulation of above-ground biomass.Compared with the control,irrigated three concentrations of 3 g/L(C3-T3),irrigated one,two,three concentrations of 4 g/L(C4)could be green earlier 30 days,C3-T2 treatment was able to be 18 d earlier,other treatments were returned early at 7-12 d.C3-T2,C3-T3 treated leaves were longer and thiner,C4 treated leaves were shorter and wider,it suggested that different concentrations of Trichoderma harzianum could affect the leaf morphological characteristics.The C3-T3 treatment significantly increased the fresh weight by 167.3%,the dry weight was significantly increased by 134%,compared to the control(C0-T1).The effects of C3-T2 and C4-T2 were the second,with fresh weight respectively increasing by 139.3% and 144.3%,and dry weight respectively increasing by 122% and 124%.It indicated that the appropriate irrigation concentration and irrigation times were conducive to the accumulation of aboveground biomass.(2)Trichoderma harzianum increased the chlorophyll content and antioxidant enzyme activity,promoted photosynthesis,and reduced the relative leaf conductivity of Zoysia matrella.Overall,C3-T2 treatment improved the chlorophyll content and net photosynthetic rate,significantly higher than other treatments,compared with the control,respectively increasing by 281.4%,369.6%.The stomatal conductance and antioxidant enzyme activity(CAT,POD,SOD,APX)of the C3-T3 treatment were better than the other treatments and were significantly different from the control treatment,respectively increasing by 241.7%,185.8%,112%,206.2% and 238.2%.The effect of C3-T3 treatment reduced the relative conductivity compared to the other treatments,which was 39.8% lower than the control,alleviating the damage to the cell membrane caused by cold stress.(3)Trichoderma harzianum promoted the uptake of soil quick nutrients(ammonium nitrogen,effective phosphorus,quick potassium),which reduced the content of soil quick nutrients,and increased soil antioxidant enzyme(urease,sucrase)activity.The test results showed that,under C3-T3 treatment,ammonium nitrogen,effective phosphorus,and quick-acting potassium were significantly decreased respectively significantly increasing by 51%、49%、36%,compared with the control,and increased urease and sucrase activity were the highest in C3-T3 treatment,which were 194% and 600% over the control,soil dehydrogenase activity was reduced by90.0% in the C4-T3 treatment.(4)Trichoderma harzianum altered the soil bacterial population size,diversity and richness of community structure.In contrast to the control,the number of bacterial OTU contained in different treatments was ranked as C3(32)> C2(30)> C1(29)> C4(16),suggesting that Trichoderma harzianum altered the soil bacterial population,but too a high concentration can have an inhibitory effect.In Shannon index size showed C0> C4> C3> C2> C1,C0 varied significantly from the other treatments,C3 and C4 treatments were not significant.This indicated that Trichoderma harzianum showed an inhibitory effect on community diversity,lower concentration of which the inhibition was more pronounced.In contrast to the control,in the Zoysia matrella roots of Trichoderma harzianum,the relative abundance of Acidobacteriota,the relative abundance of Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium,Sphingomonas,Pseudomonas were remarkably improved,changed the community structure,promoted the growth and development of turfgrass.2.Effect of Trichoderma harzianum on the Yellowing stage of Zoysia matrella(1)Trichoderma harzianum was able to delay the yellowing time of Zoysia matrella.The delayed yellow time of gully leaf generally increased with concentration.Compared with the control,irrigated three concentrations of 3 g / L(C3)could delay 40 d yellow,irrigated three concentrations of 4 g / L(C4)could delay 35 d yellow.(2)Trichoderma harzianum could increase the chlorophyll content and antioxidant enzyme activity of the grass leaves.The chlorophyll content increased first and then decreased with the concentration,the highest chlorophyll content was found in the 3 g / L(C3),but it was higher than that of the control group.It was inconsistent that the trend of CAT,POD and SOD enzyme activity with increasing concentration.The CAT enzyme activity was first increased and then decreased,the CAT enzyme activity was found in the 3 g / L(C3),significant differences was significant among the treatments.Compared with the control,CAT enzyme activity was significantly increased by 41% in C3 and C4 treatment and 32%,respectively.The POD and SOD enzyme activities were on the rise.Compared with the control,POD enzyme activity by C2,C3,and C4 treatment was increased by 41.4%,42.9%,and 46.8%,respectively,the SOD enzyme activity by C2,C3,and C4 treatment was increased by 50.9%,118.9%,and 124.9%,respectively,less variation between the treatments.(3)Trichoderma harzianum was able to reduce the relative leaf conductance.With increasing concentrations,the relative conductivity of each treatment was on a downward trend,and all were significantly lower than the control.C4 treatment was best,with a significant reduction of 26.6%.C2 and C3 treatments were second,significantly decreased by 18.4% and 23%,respectively.It indicated that Trichoderma harzianum can alleviate the damage of cold stress to grass natich and reduce the relative conductivity of leaves,but the higher the concentration is not the better.