Effect Of Plant Growth Retardants On Shoots Growth And New Bamboo’s Photosynthetic Characteristics Of Phyllostachys Nigra

In this paper, shoots of Phyllostachys nigra from experimental base of International Centre for Bamboo and Rattan in AnHui province, which the height was between15～30cm, was closed to discuss the effect of2types of plants growth retardants on biological characteristics of Phyllostachys nigra under foliar spraying by different concentration of CCC and PP333, including survival rate, plant height,base diameter,under-branch height, internode length, the average daily growth and the height growth. We studied relevant net Photosynthetic rate (Pn), Transpiration rate (Tr), Stomatal conductance (Gs), Intercellular CO2concentration (Ci) and the content change of internal chlorophyll a and chlorophyll b under dwarf treatment in Summer. Autumn, and Spring. The research was going to find out the best concentrations of plant growth retardants for Phyllostachves nigra dwarfing, aiming to provide guidance for improving ornamental value and applied range of Phyllostachves nigra.CCC and PP333both significantly inhibited plant height, base diameter.under-branch height, internode length, daily average height, increased the base diameter, achieved good effect on dwarf.the dwarfing effects of the two chemicals were not significant at very low or high concentrations. The optimal concentration of2500mg/L CCC and800mg/L PP333. Compared with CK, treating by2500mg/L CCC and800mg/LPP333, showed the plant height, under branch height, leaf area, internode length, and the average daily growth rate were apparently reduced by48.90%,36.13%,31.99%,48.67%,48.80%and43.44%,41.55%,28.40%,43.17%,43.13%, respectively. Moreover, the base diameter treated by two concentrations were increased14.88%and12.40%.Compared with CK, The survival rate of Phyllostachys nigra shoots were separately decreased23.75%and26.25%. Significant differences were found in the high growth processes, but still followed the slow-fast-slow growth trend.With the increasing concentration of the growth regulators, leaf Pn. Tr, Gs change trend firstly increased and then decreased. but Ci change trend was just the opposite, these indies achieved the maximum or minimum value in2500mg/L CCC and800mg/L PP333. Treating by2500mg/L CCC and800mg/L PP333. Leaf Pn, Gs and Tr were significantly higher than control and other treatment. Compared with CK, with2500mg/L CCC treatment, Pn, Tr, Ci increased by48.25%,49.75%.48.54%in summer,34.75%.38.72%.41.01%in autumn and35.02%.35.90%,57.02%in spring, respectively; Gs was significantly lower than control and other treatment, three seasons respectively reduced by21.02%,18.82%and22.76%compared with control. Compared with CK,800mg/L PP333treatment increased by40.70%,38.92%,38.60%in summer,31.27%,43.70%,38.85%in autumn and34.63%,33.33%,42.98%in spring, respectively; Gs was significantly lower than control and other treatment, three seasons respectively reduced by18.92%,19.53%and20.53%compared with control.With the increasing concentration of the growth regulators, the content of internal leaf chlorophyll a, chlorophyll b were firstly increased and then decreased. and achieve the maximum value in2500mg/L CCC and800mg/L PP333. All the treatments in varying degrees were higher than the control. Compared with CK, with2500mg/L CCC treatment, chlorophyll a, chlorophyll b increased by16.20%,8.13%in summer,19.59%,16.47%in autumn and23.53%,14.75%in spring, respectively; With800mg/L PP333treatment, chlorophyll a, chlorophyll b increased by14.93%,6.51%in summer,18.07%,14.70%in autumn and21.91%,14.74%in spring, respectively.