Effects Of Temperature And GA₃+BR On The Sprout,Growth And Setting Characteristics Of Potato 'Heimeiren'?Solanum Tuberosum L.?

‘Heimeiren'is a purple potato variety with fewer stems per plant which result in insufficiency of stems per hectare.The yield is limited without increasing the density which will greatly increase the cost for the expensive seed potato price.In order to find out whether the yield of seed potato can be increased by raising the number of stems per plant,and to explore the relationship between the physiological age of seed potato,tuber vigor,main stems per plant and the yield,this experiment treated tubers with different temperature,gibberellin and brassinolide,and studied their effects on germination,plant growth and tuber set.The main results are as follows:Increasing temperature and GA₃+BR soaking treatment can promote physiological aging of seed potato to raise the number of stem per tuber.It could increase tubers per plant and the yield per hectare within a certain range.In winter cropping,the yields of 10-15??256 DD?and 20??362 DD?treatments were 15.2%and 15.4%higher than the 1.5??122DD?,respectively.Under 256 DD conditions,GA₃+BR₁₀₀ had the highest yield increasing by 3.1%compared with the control,and GA₃ had a 9.3%reduction compared with the control,but there was no significant difference among all the treatments.In autumn cropping,the yields of 336 DD and 504 DD treatments increased by 7.5%and 9.2%compared with 168 DD.The yields of GA₃+BR₁₀₀ treatments were the highest under 504DD conditions,17.2%?single factor test in Chapter III?and 13.2%?three-factor test in chapter IV?higher than the control.GA₃ increased yield by 15.2%?single factor test in Chapter III?and 9.6%?three-factor test in chapter IV?.Temperature,gibberellin and brassinolide had significant interaction on tuber germination,bud growth,tubers per plant and weight per tuber.BR only promoted germination and growth at low temperature for a certain period of time.Temperature and Brassinolide antagonize in affecting potato germination and early growth.Under 168 DD condition,brassinolide had significant effects on seed potato germination and plant growth with 100 nmol/L concentration.While under 336 DD and 504 DD condition,it showed depressing effect.In autumn three-factor test,yield showed a significant quadratic function relationship with stems per plant and stems per hectare increasing first and then down.The theoretical optimum number of stems per plant was 2.35,and the optimum population density was170719 stems/hm².The tubers and the yield per stem decreased linearly with the increasing of stems per plant.Path analysis showed that the main reason for the increase of yield was the increase of tubers per plant.Rapid emergence,the increase of stem number and plant height could promote the tubers per plant.We established the relationship model of physiological age,tuber vigor,stems per plant and yield preliminarily.Tuber vigor increases first and then decreases with physiological age.Yield and tuber vigor is consistent increasing first and then decreasing too.The stems per plant increases with tuber aging in a S-shaped curve.Promoting tuber age to increase stems per plant can increase yield before reaching the optimal tuber vigor,and decrease yield when exceed the optimal tuber vigor.