Study Of Plant Growth Regulator On The Effects Of The Growth And Flowering Of Bougainvillea

In this study,Bougainvillea spectabilis 'Crimsonlake' was used to research the microstructure of morphological differentiation of flower bud during different stages and the effects of 5 plant growth regulators on its growth,flowering and other related physiological index.This article revealed the mechanism of how does plant growth regulator regulate the growth and flowering.In addition,it can screen out good ones in proper concentration to promote differentiation,prolong the period of flowering and improve the quality of flowers which has some guiding significance for rational cultivation.The main research results are as follows:1.Flower bud morphological differentiation process can be divided into 7 stages as follows:undifferentiated stage,early stage of differentiation,bract primordial differentiation stage,flower primordium differentiation stage,petal primordial differentiation stage,stamen primordium differentiation stage,gynoecia primordium differentiation stage.2.The effects of plant growth regulator on the growth and flowering of Bougainvillea were shown as follows.The effects of exogenous 6-BA on growth of Bougainvillea was not obvious,and three concentrations of exogenous 6-BA all could promote the flowering earlier,and the synergism were more obvious at higher concentrations.At the same time,there was a decreasing trend in bracts,and the number of flowers and ornamental quality were decreased.The 500 and 1000 mg�L-1 exogenous 6-BA treatment could moderately extend the flowering period and the 1000 mg�L-1 treatment was much better.However comparing to the control group,the difference was not so obvious.Low concentration of PP333(50?100 mg�L-1)and exogenous ethylene(25?50 mg�L-1)may moderately inhibit vegetative growth and make it become short,but could prolong flowering period,make it earlier,increase the number of flowers and improve the ornamental quality.Conversely,high concentration of PP333(200?500 mg�L-1)and exogenous ethylene(75 mg�L-1)had inhibition on the vegetative growth and reproduction.All treatments of SNA could excessively inhibit the vegetative and reproductive growth.Low concentration of exogenous GA3(100?200 mg�L-1)could promote vegetative growth while high concentration of it(400 mg�L-1)could get the opposite effect.All treatments of exogenous GA3 could excessively inhibit the vegetative and reproductive growth.3.Before the formation of flower buds,there was no significant difference in the daily average of Ci,Pn,Tr and Gs of all treatments of Bougainvillea.Comparing with the formation of flower buds,the daily average of Pn,Tr and Gs of the control,all treatments of exogenous 6-BA,50,100 mg�L-1 treatment of PP333 and 25,50 mg�L-1 treatment of exogenous ethylene had improved,while Ci had reduced.The daily average of Pn,Tr and Gs of 200,500 mg�L-1 treatment of exogenous 6-BA,50,100 mg�L-1 treatment of PP333 and 25,50 mg�L-1 treatment of exogenous ethylene was higher than the control in the early period of flowering,while Ci was lower than the control,and the effects of 200,500 mg�L-1 treatment of PP333 were opposite.The effects of 500 mg�L-1 treatment of exogenous 6-BA,100 mg�L-1 treatment of PP333 and 50 mg�L-1 treatment of exogenous ethylene were significant different comparing with the control which means that it was helpful for the accumulation of nutrients at early blossom stage and promote the process of flower formation.4.The content of chlorophyll in leaves gradually increased and reached up to the peak in the early flowering period.It could increase the intensity of photosynthesis and provide adequate nutrients for the later flowering.The content of soluble sugar,starch and soluble protein in leaves gradually increased in the early flowering period and early full-blossom period,and it started to decrease when reached up to the peak.It could provide energy and material basis for further differentiation and development through accumulation of nutrients at the stage before blossom.This process was helpful to the construction of flower organs and the maintenance of normal metabolic activities to accelerate the transformation of plants to the direction of reproductive growth.The change of content of MDA was small and also leaf physiological metabolism was stable which revealed strong resistance and adaptability.The activity of POD generally was in bimodal-wave variation,the peaks appeared in the early flowering period and full-blossom period.The physiological metabolism and aging process of the leaves were reflected indirectly.5.We studied on the physiological effects of plant growth regulator on Bougainvillea and the result showed that the 500 mg�L-1 treatment of exogenous 6-BA,100 mg�L-1 treatment of PP333 and 50 mg�L-1 treatment of exogenous ethylene significantly improved the content of chlorophyll in leaves,the content of soluble sugar,starch,and soluble protein and the activity of POD in leaves and inflorescence in the full-blossom period,while the content of MDA just decreased,which was beneficial to keep the physiological activity of leaves and flowers and slow down the aging process.The 200 mg-L-1 treatment of exogenous GA3 significantly increased the content of chlorophyll,soluble sugar,starch and soluble protein while the MDA and POD was not significant.In groups of 1000 mg�L-1 treatment of exogenous 6-BA,500 mg�L-1 treatment of PP333,150 mg�L-1 treatment of SNA,75 mg�L-1 treatment of exogenous ethylene and 400 mg�L-1 treatment of exogenous GA3,no significant difference was found in the level of physiological indexes with the control or lower than the control level.