Study On The Key Factors Affecting Of Cerasus Humilis Cuttings In Closed Box Environment

Cerasus humilis is an endemic tree species in China,which can be propagated rapidly by cutting.However,because of the uniqueness of C.humilis cuttings,the environmental conditions for cuttings were strict.In this paper,the cuttings of C.humilis Var.’Nongda 6’ were used as material,cuttings were put into a closed transparent box,and the changes in environmental conditions and photosynthesis were measured;the cutting quality,cutting season,cutting type,cutting position,concentration of rooting agents and pathogens control were studied.The results are as follows:1.Under greenhouse conditions,the water loss rate of the substrate in the transparent box were low whether the lid was open or closed.The water loss rate of the box with open lid was 1.3% per day on average,while that of the box with closed lid was 0.42%.The daily variation of the temperature in the box starts from 0:00pm,and the temperature went through a ‘down-up-down’ pattern on both sunny and cloudy days;The change of relative humidity formed a single valley curve,the lowest point is about 13:00;The diurnal variation of light intensity in the box was consistent with that of the greenhouse and the outside,however,the light intensity in the box was 15% lower than that of the greenhouse.The change of CO₂ concentration in the box was consistent with that of the greenhouse in a day.The concentration of CO₂ decreased at first and then increased,and it was lower inside than outside the box.2.The diurnal variation of net photosynthetic rate（NPR）of the original leaves and the newly bearing leaves on cuttings were both under a bimodal curve when the box was open,and the NPR of the original leaves were higher than the newly bearing leaves;The NPR of the original leaves and the newly bearing leaves were both under an unimodal curve when the box lid and ventilation holes were both closed,however,the NPR of the new leaves were higher than the original leaves;When the ventilation holes were open in the closed box,the NPR of both leaves were also under an unimodal pattern and the NPR of original leaves were higher than that of new leaves before 15:00.3.Spraying 20 ppm NAA 7 days before cuttings collection had the best rooting effect,and the rooting rate could reach 82.86%.During the rooting period of cuttings,spraying 1500 times of amino acid + 0.1% urea+ 0.2% potassium dihydrogen phosphate had the highest rooting rate（82.57%）;The best rooting effect was obtained when 500 times of thiamides copper solution was used for disinfecting,and the rooting rate reached 61.69%。4.With the treatment of P2 rooting agent,the rooting rate of the nodal incision was higher than that of the internode incision no matter the concentration of P2 was high or low.When using P2 as the rooting agent,the dilution ratio varied in different cutting season.In April,the highest rooting rate（88.57%）was obtained by using 10-fold dilution;The highest rooting rate（82.85%）was obtained by using 15-fold dilution in May,and the highest rooting rate（71.9%）was obtained by using 20-fold dilution in June,while in July and August,the highest rooting rate was 71.41% and 78.57% respectively,both of which were under the treatment of 4 times dilution of P2 rooting agent.5.The rooting rate of upper shoot in C.humilis was better than that of second shoot and first shoot（half leaf or whole leaf）.The highest rooting rate（71.9%）was obtained when the root agent was diluted 20 times;The concentration range of rooting agent for top cuttings of C.humilis was 6 to 8 times diluted P2,and 4 to8 times and 4 to 6 times diluted P2 for middle cuttings and lower cuttings repectively.The rooting rate of underground stem cuttings from C.humilis was the highest when the concentration of rooting agent was diluted 2 times and dipped for 30 seconds.6.Variations were found in rooting abilities for different varieties.The best rooting rate for each variety can be obtained by using suitable rooting agent.The rooting rate of ’Nongda 7’ cuttings was the highest（85.33%）when using 15 times diluted P2,while the rooting rates of ’Jinou 1’ and ’Nongda 5’ was the highest（about 70%）when they were treated with 10 times diluted P2.In conclusion,the cutting propagation of C.humilis could be realized by controlling the key influencing factors with transparent box.