Effects Of Boron Deficiency And Arbuscular Mycorrhizal Fungi Infection On The Growth And Physiological Of Camellia Oleifera Seedlings

Boron is an essential trace element in the process growth and development of plant.It plays an important role in plant physiological process.Boron deficiency results in necrosis of plant growth points,false flowers and other boron deficiency symptoms.Arbuscular mycorrhizal fungi that coexist with plants can improve plant uptake of nutrients and water,promote plant growth,and help plants better cope with stresses in biotic or abiotic environments.Camellia oleifera Abel.is an important local economic forest tree species in China.Boron deficiency in C.oleifera cultivation area is common,which seriously affects the production and quality of C.oleifera.C.oleifera is a mycorrhizal tree species,and AMF infection has carried out more studies on promoting the absorption of phosphorus,nitrogen and other nutrients,but the relationship between AMF and boron action has been less studied in plants,and its mechanism is not clear.This study using potted test,with the biennial C.oleifera seedling(’Changlin 40’)as the test object,with Funneliformis mosseae(Fm)as the AMF inoculum were used to study the effects of boron deficiency treatment and AMF treatment on the growth and development and resistance physiological indexes of C.oleifera seedlings.This study is divided into two parts.Experiment 1: the un-mycorrhizized C.oleifera seedlings were vaccinated with AMF and different boron supply treatment simultaneously to study the effect of boron deficiency on the growth and physiology of C.oleifera seedlings.Experiment 2: the mycorrhizal seedlings seeded for a period of time and the un-inoculated seedlings were boron deficient and normal boron supply to study the effect of AMF infection on the growth and physiology of C.oleifera seedlings under different boron supply conditions.Through the comparative analysis of two experiments,the effects of AMF inoculation under boron deficiency and boron-deficient treated after inoculated with AMF on the physiology of C.oleifera seedlings.The main results were as follows:(1)The AMF can form a good symbiotic relationship with the C.oleifera seedlings in either boron-deficient or normal boron treatment,but the boron deficiency treatment significantly reduced the mycorrhizal infection rate of C.oleifera.The AMF infection rate was related to the matrix boron levels at the time of inoculation.After 90 d of treatment,the mycorrhizal infection rate of C.oleifera seedlings in the under boron deficiency treatment were significantly lower than that under normal boron treatment.(2)Boron deficiency treatment limited the growth of C.oleifera seedlings,but inoculation with AMF can significantly increase the growth of C.oleifera seedlings.After90 d of treatment,the above-ground dry weight,below-ground dry weight and total dry weight,root length,root surface area and root volume were significantly reduced compared with the normal boron treatment.Whether with boron deficiency treatment or normal boron treatment,the above-ground dry weight,below-ground dry weight and total dry weight,root length,root surface area and root volume of C.oleifera seedlings inoculated with AMF were significantly increased compared with the inoculated without AMF.(3)Boron deficiency treatment will affect the absorption of nutrient elements in C.oleifera seedlings,but inoculation with AMF can significantly increase the content of nutrient elements in C.oleifera seedlings.After 90 d of treatment,the content of boron,nitrogen,phosphorus and carbon of C.oleifera seedlings with boron deficiency treatment were significantly reduced compared with the normal boron treatment.Whether with boron deficiency treatment or normal boron treatment,the content of boron,nitrogen,phosphorus and carbon of C.oleifera seedlings of inoculated with AMF were significantly higher compared with those inoculated without AMF.(4)Boron deficiency treatment will lead to the imbalance of intracellular osmotic balance in C.oleifera seedlings.Inoculation with AMF can improve the osmoregulatory ability and antioxidant enzyme activity of C.oleifera seedlings under different boron supply conditions to enhance the plant stress resistance.After 90 d of treatment,The carbohydrate content and activity of 3 antioxidant enzymes of C.oleifera seedlings under boron deficiency treatment were significantly increased compared with the normal boron treatment.Whether with boron deficiency treatment or normal boron treatment,the carbohydrate content and 3 antioxidant enzymes in the C.oleifera seedlings inoculated with AMF treatment were significantly higher compared with those inoculated without AMF.(5)Based on the principal component analysis of the growth and physiological indexes of C.oleifera seedling in experiment 1 and 2.In experiment 1,the normal boron treatment group scored higher than the boron deficiency treatment group;in experiment 2,the AMF inoculation treatment scored higher than the non-AMF inoculation treatment for both boron deficiency and normal boron treatment;comprehensive score for boron-deficient treated after inoculated with AMF treatment(+AM-B)in experiment 2was higher than that of boron deficiency treatment(-B)in experiment 1.Therefore,in the planting process of C.oleifera seedlings,the mycorrhizization treatment is conducted in advance,and the soil boron level is regulated,so as to maximize the promoting effect of AMF,improve the symptoms of boron deficiency in C.oleifera.The results of the above studies indicate,boron deficiency can directly affect the growth of C.oleifera seedlings.Moreover,the boron deficiency affects the infection rate of C.oleifera mycorrhizal and further restricts the growth of C.oleifera seedlings.AMF-Root symbionts can improving the growth environment of C.oleifera seedlings,increase the absorption of boron and other mineral nutrient elements in plants,promote the accumulation of osmoregulatory substances,improve the activity of antioxidant enzymes to reduce the stress of boron deficiency,and effectively alleviate the inhibitory effect of boron deficiency on the growth of C.oleifera seedlings,it is also conducive to promoting the growth and physiology of C.oleifera seedlings under normal boron supply.Therefore,in the low-boron cultivation area of C.oleifera,not only can boron supplementation relieve the symptoms of boron deficiency,but also improve the growth environment of C.oleifera seedlings by inoculation with AMF,promote the infection of AMF and improve the tolerance in boron deficiency environments.