Study On The Effect Of Tree Management And Hormone Treatment On Larch Seed Setting

Larix(Larix)is an important afforestation tree species in Northeast China,It has strong adaptability and excellent material,can grow rapidly in early stage,meanwhile it has fewer pests and diseases.However,larix has problems such as long interval between fruiting years,difficulty of seed collection and low seed yield.In this study,larix clonal seed orchard was the research object.Tree management and hormone stem injection were test methods.To study the effects of trunk cutting,pruning treatment,hormone type,concentration,dosage and treated date on larix fruit setting.In order to provide technical assist for seed orchards to improve yield and management level.The main findings are as follows:The experiment of tree management of trunk cutting and pruning in the second generation Larch Orchard of Qingshan fine seed base proves that tree management can improve the fruiting amount.Cutting treatment increased the total solid amount by 166%?335%,with an average of 226%.Trunk cutting treatment decreased the height of the seed layer.Except 3.5 m level of trunk cutting,other treatments increased the total solid amount by 7%-146%,with an average of 72%.Trunk cutting+pruning treatments resulted to unstable seed amount,and the total solid amount varied from-36%to+43%,Trunk cutting can make the fruiting layer move down:the amount of fruiting in the lower layer of the canopy can be increased by 50%-207%,with an average of 134%,and the amount of fruiting in the middle layer of the canopy can be increased by 28%-240%,with an average of 113%.Cutting treatment can increase the amount of fruit set in each layer of canopy:the amount of fruit setting in the high layer increased by 212%-373%,with an average of 296%;the amount of fruit setting in the middle layer increased by 217%-360%,with an average of 271%;the amount of fruit setting in the low layer increased by 82%-295%,with an average of 160%.The effect of three kinds of treatments om improving the amount of seed set was pruning>trunk cutting>trunk cutting+pruning.Tree management of 13a larch orchard can help to improve the yield and reduce the difficulty of harvesting.In another experiment,L9(34)orthogonal test results showed that GA4+7 had the best effect on improving seed set,the average fruiting amount was 9.6%higher than the average;the fruiting amount at 1000 mg/L and 3 mL was 12.11%and 47.80%higher than the average;the fruiting amount of earliest treatment on June 17 was the largest,15.08%higher than the average.The univariate test with date as the control variable showed that the effect of GA3 500 mg/L 2 mL on larch fruit setting was more regular than that of GA4+7 500 mg/L 2 mL,and the difference of fruit setting amount was obvious in some clones at different treated date.The effect of hormone treatment was better for clones with lower seed set;Hormone treatment can improve the ratio of seed production in the upper and middle layers of the crown,which may cause the seed production layer to move up.