| Dendrocalamopsis oldhami(Keng)f.is an excellent bamboo specie for shoot with the characteristics of long shoot period,good quality and high yield in China.The introduction of D.oldhami from Wenzhou,Zhejiang Province and Youxi,Fujian Province to Beijing in solar greenhouse has good economic prospect,but it is restricted by two main factors:(1)The maximum height of conventional solar greenhouse is 3.5 m while the height of D.oldhami is generally above 4.0 m.so it is necessary for operation and managemen to obtain dwarfing trait(2)D.oldhami can not adapt to outdoor low temperature condition of Beijing at overwintering period,there are differences in cold tolerance adaptability of D.oldhami from different provenances This paper focuses on these two problems which need to be solved urgently in production practice.In this paper,the best dwarfing methods were selected from three dwarfing treatments:spraying plant growth regulator(Mepiquat),cutting of new bamboo stalk and,bamboo shoot truncation then applied in facility dwarfing cultivation The effects of dwarfing treatment on growth and photosynthetic characteristics as well as the cold resistance related indexes physiological indexes and chlorophyll fluorescence of two provenances in Beijing facility dwarfing cultivation were studied.The main results are as follows:1.In Youxi,Fujian Province,the effects on D.oldhami morphological indexes by spraying DPC,new bamboo stalk and bamboo shoot truncation were compared,and the dwarfing method which could effectively control the growth of plant height was screened out.Spraying DPC with 9 different concentrations had no significant inhibition effect on plant height(P>0.05).After cutting of new bamboo stalk,top incision to the next node dried,the dwarfing rate of treatment G4 was 61.45%Bamboo shoot truncation treatment changed significantly morphological characteristics,there was a significant negative correlation between plant height and bamboo shoot height before truncation(R~2=0.90,P<0.01).Plant height of H5 treatment reduced from 539.40 cm to 234.70 cm,it reduced by 56.49%compared with the control group.Bamboo shoot truncation treatment reduced significantly the under branch height,internode number and branch rate while it promoted the main branch length.Survival rate of D.oldhami ranged from 82.14%to 85.71%,and no significant difference on survival rate was observed among different treatments(P>0.05)2.Effects of the bamboo shoot truncation on chlorophyll contents and chlorophyll fluorescence characteristics of D.oldhamiThe chlorophyll a,chlorophyll b and chlorophyll total content of D.oldhami enhanced and chlorophyll a/b decreased.The initial fluorescence(F0)of different bamboo shoot truncation treatments did not differ significantly from the control group,and the PS?maximal photochemical efficiency(Fv/Fm)and photochemical quenching coefficient(q P)enhanced,while the nonphotochemical quenching coefficient(NPQ)reduced.With the plant height reducing,the maximum values of electron transport rate(ETR)and PS?actual photochemical efficiency(Yield)were achieved under H5 treatment and increased by 48.63%and 42.17%respectively compared with the control group.Pearson correlation analysis showed that plant height negatively correlated with total chlorophyll total content and Fv/Fm,Yield and ETR and positively correlated with chlorophyll a/b and NPQ.3.The bamboo shoot truncation was selected from the origin of D.oldhami and applied to Beijing facility cultivation to explore the effects on morphology and aboveground biomassIn Beijing facility cultivation,the dwarfing law of bamboo shoot truncation is basically consistent with the southern origin.The plant height of bamboo shoots and the control group reached a very significant difference(P<0.01).with the WH3 treatment,the plant height of the D.oldhami was 223.80cm,and the dwarfing rate reached 50.88%.The fresh and dry biomass of the organs on the ground was highest with bamboo stalks,followed by bamboo branches and bamboo leaves.The percentage of stem,branch and leaf biomass of WG3 bamboo shoots after shoot cutting was 50.57%,26.00%and 23.43%,respectively.There was no significant difference in biomass allocation among different shoot cutting treatments(P>0.05).4.Comparing the changes of cold resistance indexes physiological and chlorophyll fluorescence parameters at overwintering stage from two provenances in Beijing dwarfing cultivationWith the decrease of temperature,the relative conductivity,MDA,free proline,soluble sugar and chlorophyll a/b of D.oldhami in Youxi,Fujian and Wenzhou Zhejiang provenance increased significantly,while the chlorophyll content of leaves decreased(P<0.05).During low temperature stressprocess,F0,Yield and NPQ of D.oldhami in Wenzhou,Zhejiang maintained normal level,while Youxi Fujian showed trend of increasing first and then decreasing.We concluded that the low temperature stress of two provenances was the most serious in February.With the increase of temperature in March,the low temperature stress of two provenances were alleviated to some extent.Considered with production practice,It could be concluded that H5=180 cm was the optimal bamboo shoot truncation treatment,not only it gained ideal plant height,but also improved light use efficiency.Treatment H5 was able to reach plant height requirement of facility cultivation.Thus it voided the waste of bamboo wood as well as removed DPC residual risk.Wenzhou Zhejiang had a wider range of resistance strategies for the low temperature stress than Youxi Fujian... |
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