Effects Of Cotyledon Loss On Reserves Nutrient Translocation And Seedling Quality Of Quercus Variables

Cotyledon loss in the autumn and the following spring after emergence of Quercus variabilis are common phenomenon in the nature.This study aims to simulate the interaction between the cotyledon loss intensity in autumn and the cotyledon loss time in the following in a greenhouse environment,and explore the effect of additive effects on nutrient translocation and seedling growth status of Quercus variabilis.The main conclusions are:(1)Cotyledon loss in the autumn can promote emergence time and rate in the following spring.(2)The complete seed seedlings without loss cotyledons in the autumn had their nitrogen transfer to the nursery stocks after 25 days of emergence,while the seedlings with lost cotyledons in the spring had significantly shorter time for the nitrogen transfer to the nursery stocks(8 days).(3)The main effects indicated that cotyledon loss 2/3 make height and diameter decrease 30%?18%respectively,The side effects indicated that cotyledon loss before emergence 20 days could depress seedling growth at the following spring.(4)The interaction effects indicated that intact seeds cotyledon loss in 4days after emergence,survival rate was only 36.3%,biomass decreased 78.2%,cotyledon loss before emergence 25 days could depress the nutrient and carbohydrate.For cotyledon loss 1/3 seeds in the autumn,following spring cotyledon loss in 4days after emergence,survival rate was decrease 65.2%,cotyledon loss in 25 days after emergence almost no effect on seedling growth and accumulation of nutrients.For cotyledon loss 2/3 seeds in the autumn,can significantly inhibit the growth of seedling.Therefore,the additive effects between cotyledon loss intensity and time should be considered well,it has great significance to reveal the regeneration mechanism of Quercus variabilis.Under field environment,the mechanism of the effect of cotyledon loss on seedling survival and growth and acorn reserves tanslocation are not clear.Aims to explore the effect of cotyledon loss time on seedling survival and growth and the kinetics of acorn nutrient and carbohydrate translocation from Quercus variabilis acorns,reveal the mechanism of animal predation on Quercus variabilis seedlings regeneration.The main conclusions are:(1)Under the field environment,seedlings began to emergence after 25 days of sowing.The seedling emergence rate reached a maximum of 10.42%at 35 days,and the final emergence rate was 67.22%.(2)The loss of cotyledons after 20 days of emergence(45 days of sowing)had no effect on the survival and growth of the seedlings.At this time,more than half of the nutrient translocation was occurred.(3)Seed nitrogen and potassium were basically transferred after 50 days of emergence;seed phosphorus,soluble sugar and starch were basically transferred after 60 days of emergence;After 70 days,the total translocation ratio of seed nutrients to seedlings was:starch>potassium>phosphorus>soluble sugar>nitrogen.Therefore,seed and seedling protection should be strengthened within 20 days from sowing to emergence(45 days from sowing)to prevent rodents and birds from feeding so as not to affect the regeneration of the Quercus variabilis.In summary,seed nutrients are very important in the early growth of seedlings.Early cotyledon loss will severely inhibit the growth of seedlings and the translocation of reserves.Therefore,the protection of seeds and seedlings should be strengthened in the early to promote the regeneration of Quercus.