Comparison Of Agronomic And Nutritional Traits Of Different Forage Oat Strains And Effects Of NaCl Stress On Oat Photosystem

Oat(Avena sativa L.)is a gramineous oat plant with soft stem and leaf quality,good palatability,cold resistance,strong adaptability and good yield stability.It is the main feed for livestock in winter and spring.It is also an important forage,feed and food crop in China.However,owing to the limitation of climate and regional farming system,oats have not been widely popularized in southern China.In recent years,with the development of animal husbandry and dairy industry in China,oat as a high-quality feed has been more and more popular,and the introduction of oat has attracted more and more attention in southern China.Oats have good stress resistance,and planting oats is one of the effective measures to improve saline-alkali soil.In this paper,18 oat strains were selected to compare their biological characteristics and nutrient components of different organs,in order to screen out good oat varieties suitable for cultivation in southern China.In order to provide theoretical support for the cultivation and management of oats in saline-alkali land,the photosynthetic characteristics of two oats under salt stress and the mechanism of calcium on salt stress were studied.The main results are as follows:(1)In this experiment,18 oat varieties were selected to study the biological characteristics of plant height and stem diameter of different oat varieties and the comparison of nutrient components in different parts,so as to provide reference for the study of oat.The results showed that among the 18 oats,the oat HY02 plant height was 200 cm and the stem diameter was 1.2 cm,the leaf length and leaf width,which were superior to other materials.Although the growth period was longer,the comprehensive traits were excellent.HY02 and HY10 have good nutritional quality,the crude protein content of leaves is 43%and 28%higher than the average value,and the crude protein content of HY02 leaves is about twice that of HY11 with the lowest crude protein content.The crude protein content of the stems was 43%and 70%higher than the average value,the NDF content of the stems was 4.8%and 10.6%lower than the average value,and the ADF content of the leaves was 8.0%and 7.5%lower than the average value.In summary,HY02 has more production potential and was most suitable for planting..(2)On the basis of the salt tolerance experiment,the salt-tolerant HY15 and the weak salt-tolerant HY16 were selected as materials.The photosynthesis mechanism of the oat leaf was studied by measuring the fast chlorophyll fluorescence and 820 nm light reflection.The damage mechanism of photosystem I(PSI),photosystem II(PSII)and the entire photosynthetic electron transport chain was compared to the photosynthetic reaction of different oat lines under salt stress.The results showed that the whole photosynthetic electron transport chain of oat leaves was affected by NaCl stress,which resulted in increased Na+ content and increased leaf stress.NaCl stress caused photosynthetic mechanism damage,resulting in slow degradation of PSII and PSI antenna pigments to the reaction center,and reduced PSII effect.Salt stress reduces photochemical activity by disrupting the structure and electron transport of the photosystem,thereby affecting the electron transport capacity of the PSII receptor side(including PSI),which resists stress by increasing absorption and capture of light energy.Compared with HY15,the relationship between PSII of HY16 was looser and more unstable.The resistance of HY16 to NaCl stress and its self-protection ability under photosynthesis under salt stress were weaker than that of HY15.(3)The photosynthetic characteristics of oat leaves under NaCl stress were used to investigate the alleviation mechanism of exogenous calcium ions on NaCl stress.The oats were salt treated by sand culture,and the fluorescence kinetic curves and fluorescence parameters were measured and analyzed by JIP test at 0,10,20,30,40 and 50 days,respectively.The results showed that with the increase of NaCl stress,the PSII reaction center in the oat leaves was inactivated,the energy distribution was uneven,the electron transport was blocked,the PSII oxygen release complex was inactivated,and the stability of PSII was decreased,which destroyed the photosynthetic function of PSII.After 40 days of treatment,under the NaCl stress,the initial fluorescence Fo of HY16 increased gradually,and the maximum fluorescence Fm decreased gradually.The activity parameters of unit reaction center ABS/RC and DIo/RC increased gradually.With the prolongation of stress time,the parameter DIo/CSo The parameters Fv/Fm and PIabs,which represent the photosynthesis efficiency of PSII,decreased gradually,while the change of HY16 was not obvious under NaCl+CaCl2 treatment.It is indicated that by increasing exogenous Ca2+,the accumulation of Na+ in oat leaves can be reduced,and oats can maintain a good growth state in salt stress.With the addition of Ca2+,the resistance of leaf photosynthetic apparatus to NaCl stress increased,and the salt tolerance of PSII donor side and acceptor side was improved.The stability of PSII reaction center was enhanced,and the damage of NaCl stress on leaves was alleviated.Photosynthesis tends to be normal.Planting oats in saline soil and applying exogenous Ca2+ can improve the salt tolerance of oats.