Effects of Photoperiod on Alternative Respiration Pathway in Nectarine Flower Buds During Dormancy Induction

Characteristics of dormancy induction and alternative respiration pathway （also known as cyanide-resistant respiration） of nectarine flower buds in different photoperiods were studied to determine the function of photoperiod and alternative respiration pathway in dormancy induction. Oxygen-electrode system and respiratory inhibitors were used to measure total respiratory rates and rates of alternative respiration pathway. The results showed that total respiration rate （Vt） in flower buds showed to be double hump-shaped curves. Short day raised, brought the first-hump of Vt forward and delayed the second-hump, while long day delayed the whole curve. The capacity （Vast） and activity （pValt） of SD and LD changed synchronously and both showed to be double hump-shaped curves. Short day made the first climax of Vast and pValt existed much earlier, while long day increased their rates significantly. The length of day had little effects on the later period climax. Long day also increased the contributions of altemative respiration pathway in total respiration rate （pValt/Vt）. The changes in alternative respiration pathway were correlated with the induction of dormancy and adjusted by photoperiod. Short day promoted dormancy induction of nectarine trees, while long day delayed it.

Glucosylated caffeoylquinic acid derivatives from the flower buds of Lonicera japonica

Three new glucosylated caffeoylquinic acid isomers(1–3),along with six known compounds,have been isolated from an aqueous extract of the flower buds of Lonicera japonica.Structures of the new compounds were determined by spectroscopic and chemical methods as()-4-O-(4-O-β-D-glucopyranosylcaffeoyl)quinic acid(1),()-3-O-(4-O-β-D-glucopyranosylcaffeoyl)quinic acid(2),and()-5-O-(4-O-β-D-glucopyranosylcaffeoyl)quinic acid(3),respectively.In the preliminary in vitro assays,two known compounds methyl caffeate and 2?-O-methyladenosine showed inhibitory activity against Coxsackie virus B3 with IC50 values of 3.70 μmol/L and 6.41 μmol/L and SI values of 7.8 and 12.1,respectively.

Effect of Shoot Control on Flower Bud Differentiation,Flowering,and Fruit Setting in Zanthoxylum armatum DC.

In this study,newly sprouted shoots of Zanthoxylum armatum(Z.armatum),which were collected after the harvesting period,were used as the primary experimental specimens.A randomized block design and paraffin sectioning method were used to investigate the flower bud differentiation process and the quantity and vitality of buds.Furthermore,the study examined the response of flowering and fruiting to cultivation methods for shoot growth,including layering and plant growth regulator application.The results showed that(a)layering and application of plant growth regulators for Z.armatum accelerated the process of flower bud differentiation by approximately 20 days compared to the control group.Additionally,both shoot control methods generated more and larger bud primordia and perianth primordia during the same differentiation phase.(b)The application of plant growth regulators resulted in well-developed buds,exhibiting higher levels of flower bud differentiation than the layering method.The quality of flower bud formation for both shoot control methods was superior to that of the control group.(c)The flowering phenological period was relatively consistent between the two cultivation methods,but the fruit maturity phase for shoot-controlled trees occurred 20 days earlier than the control group.(d)Both layering and the application of plant growth regulators significantly decreased the rates of unfertilized flower shedding and fruit shedding.However,no significant difference was noted in fruit setting per inflorescence and per flower between the two methods and the control.The effect of altitude for both methods on the fruit setting was not significant.Under both shoot control methods,the Z.armatum exhibited earlier morphological differentiation of flower buds,faster differentiation process,improved flower bud quality,and significantly decreased rates of flower and fruit shedding.Thus,these cultivation methods demonstrated the potential to promote flowering,improve fruit setting,and reduce fruit shedding in Z.armatum.

Research Progress of Flower Bud Differentiation of Apple

Flowering is a prerequisite for apple fruiting,and apple flower buds are mixed buds,that is,the vegetative organs and flower structure exist in the same terminal bud simultaneously,which are formed in the year before flowering and fruiting,mainly including spur terminal buds and axillary buds.The infrequent formation of flower buds during its growth and biennial bearing are closely related to flower bud differentiation.Therefore,this paper reviews the research progress of flower bud differentiation of apple from the morphological differentiation,plant hormones and flowering-related genes,in order to provide a theoretical reference for efficient cultivation and stable yield of apple.

Paraffin section observation of flower bud differentiation of Chimonanthus praecox in Kunming and comparison of the differentiation processes in different regions,China

Chimonanthus praecox is an important ornamental plant and cut flower material in China.It blooms in the freezing winter and its flower emits charming fragrance.However,in different region the flowering time is variable.In order to understand the flowering mechanism of Ch.praecox in the winter,we studied the flower bud differentiation in Spring City-Kunming using paraffin sectioning method in the present study.Meanwhile we compared the differentiation process difference from different regions.It was found that the temperature is the key factor for its flower bud differentiation and blossom of Ch.praecox.In the process of bud differentiation,the temperature 20℃was the optimum for inducing changes from vegetative axillary buds to reproductive buds and subsequent morphological differentiation in Ch.praecox.Furthermore in the first three differentiation periods—tepal primordial stage,staminal primordial stage and pistil primordial stage,Kunming took the shortest time to finish the process due to very rapid temperature rise to 20℃,whereas,in Zhengzhou the time for these differentiations was the longest,which may be caused by the slow temperature rise.After May,the high temperature stress forced the flower buds into the first long dormant period in all regions except Kunming.In Kunming,the average temperature was only 20–25℃,so the flower bud continued to differentiate.In all regions,Kunming is the first to complete whole flower bud differentiation even on the early August,and started the second dormancy very early but very long.In the other regions,the plants went through a shorter dormancy and the low temperature broke the dormancy rapidly.Contrarily the plants of Kunming spent a longer period for the low temperature.Thus,the low temperature less than 10℃is a key factor to breaking the second dormancy.Surely the regular effects of temperature on flower bud differentiation and blossom is very helpful for florescence regulation of Ch.praecox.

Changes in Nutritive Materials in Off-season Mango in Flower Bud Differentiation Stage

Under off-season production mode, change laws of nutritive materials in leaves of fruiting mother branches of mango in flowering process induced by dif- ferent agents were investigated. The results showed that the flowering time of manga trees in the potassium nitrate treatment was earlier than the ethephon treatment by 7 d, and changes trends of materials in leaves of the potassium nitrate and ethephon treatments were substantially the same. The nutritive materials in leaves showed trends of increasing at first and decreasing then. In early flower bud differentiation stage, soluble sugar and starch in leaves increased rapidly, and content of soluble protein also increased rapidly and showed its their peak values, thereby providing energy substances and structural substances demanded by flower bud formation. With flower bud differentiation going on, soluble sugar, starch and soluble protein decreased gradually. It was indicated that the accumulation of soluble sugar, starch and soluble protein is beneficial to flower bud differentiation.

Expression of AP1 Gene During Off-season Flower Bud Differentiation of Mango

This study was conducted to investigate changes in the expression of AP1 gene in flowering process. Potassium nitrate and ethephon were sprayed on 7- year-old Guifei trees out of season. The results showed that AP1 gene had a higher expression level in terminal buds, and especially, the expression level increased significantly in late stage of flower bud differentiation. Potassium nitrate and ethephon promoted flower bud differentiation, and the expression level of AP1 gene in- creased in flowering process remarkably. Expression ofAP1 gene of the potassium nitrate treatment was significantly greater than that of the ethephon treatment and the CK.

Observation on Flower Bud Differentiation of Crape Myrtle in Red Soil Environment

Flower bud differentiation is a key component of plant blooming biology and understanding how it works is vital for flowering regulation and plant genetic breeding,increasing the number and quality of flowering.Red soil is the most widely covered soil type in the world,and it is also the most suitable soil type for crape myrtle planting.The flower buds of crape myrtle(Lagerstroemia indica)planted in red soil were employed as experimental materials in this study,and the distinct periods of differentiation were identified using stereomicroscopy and paraffin sectioning.We optimized the steps of dehydration,transparency,embedding,sectioning and staining when employing paraffin sections.When seen under a microscope,this optimization can make the cell structure of paraffin sections obvious,the tissue structure complete,and the staining clear and natural.The flower bud differentiation process is divided into 7 periods based on anatomical observations of the external morphology and internal structure during flower bud differentiation:undifferentiated period,start of differentiation period,inflorescence differentiation period,calyx differentiation period,petal differentiation period,stamen differentiation period,and pistil differentiation period.The differentiation time is concentrated from the end of May to mid-June.Crape myrtle flower bud differentiation is a complicated process,and the specific regulatory mechanism and affecting elements need to be investigated further.

The structures of floral organs and reproductive characteristics of an ornamental bamboo species,Pleioblastus pygmaeus

As a woody grass,bamboo has special reproductive habits with an extremely long vegetative phase.Pleioblastus pygmaeus is a kind of ornamental dwarf bamboo species with high ecological and economic value in China.There was no documentary record of the flowering of P.pygmaeus until 2015,which bloomed in the Bamboo Garden of Nanjing Forestry University.Generally,bamboo plants rarely bear fruit or have a low seed setting rate,but this species has a high seed production.This study explores developmental reasons using anatomical methods.The process of flower bud differentiation and a series of important reproductive development processes including anther wall development,microsporogenesis,megasporogenesis,male and female gametophyte development,and embryonic development were investigated sequentially.Each stamen contained three tetrasporangiate anthers and the development of anther wall was of Monocotyledonous type.The microspores finally matured into 3-celled pollen grains by two successive mitoses.The pistil was composed of three carpels,with an anatropous,tenuinucellate and bitegmic ovule in a single ovary.The formation of embryo sac belonged to Polygonum type.With three mitoses,functional megaspore developed into the embryo sac with eight nuclei within seven cells.The development of stamen and pistil was synchronous in the same floret.The development of embryo followed Grass type and the development of endosperm belonged to Nuclear type.The development of endosperm was earlier than that of embryo.The study enriches basic knowledge of reproductive biology of bamboo plants and is of great fundamental significance to furtherly explore flowering mechanism of P.pygmaeus and to cultivate bamboo plants sustainably.

Study on Reproductive Growth Characteristics and Seed Germination of Eucalyptus dunnii in Sichuan Province

Studying the flowering development and seed germination of Eucalyptu dunnii and mastering the reproductive growth law can provide a theoretical basis for seed garden construction. In this study,a blooming plant growing in Zitong County was selected as the experiment subject. The results were as follows： florescence date of Eucalyptus dunnii was Mid-late February to mid to late October. Depending on morphologic change,flowering can be divided into 6 phases： Flower bud differentiation stage,inflorescence formation stage,opercle color change stage,capsule enlargement and shedding ring formation stage,flowering period,seed development stage. The development process of the buds on the same inflorescence was basically the same,the growth of buds near the base of the same branch was faster than that of the top buds,and the development of flower buds in different positions was random. There were 3-4 ovary cavities in a capsule. The number of shriveled seeds was far more than the number of effective seeds,and the average of each capsule contained five normal seeds which could develop into seedlings.

Sorbitol induces flower bud formation via the MADS-box transcription factor EjCAL in loquat

Sorbitol is an important signaling molecule in fruit trees. Here, we observed that sorbitol increased during flower bud differentiation(FBD) in loquat(Eriobotrya japonica Lindl.). Transcriptomic analysis suggested that bud formation was associated with the expression of the MADS-box transcription factor(TF) family gene, EjCAL. RNA fluorescence in situ hybridization showed that EjCAL was enriched in flower primordia but hardly detected in the shoot apical meristem. Heterologous expression of EjCAL in Nicotiana benthamiana plants resulted in early FBD. Yeast-one-hybrid analysis identified the ERF12 TF as a binding partner of the EjCAL promoter. Chromatin immunoprecipitation-PCR confirmed that EjERF12 binds to the EjCAL promoter, and β-glucuronidase activity assays indicated that EjERF12 regulates EjCAL expression.Spraying loquat trees with sorbitol promoted flower bud formation and was associated with increased expression of EjERF12 and EjCAL. Furthermore, we identified EjUF3GaT1 as a target gene of EjCAL and its expression was activated by EjCAL. Function characterization via overexpression and RNAi reveals that EjUF3GaT1 is a biosynthetic gene of flavonoid hyperoside. The concentration of the flavonoid hyperoside mirrored that of sorbitol during FBD and exogenous hyperoside treatment also promoted loquat bud formation. We identified a mechanism whereby EjCAL might regulate hyperoside biosynthesis and confirmed the involvement of EjCAL in flower bud formation in planta. Together,these results provide insight into bud formation in loquat and may be used in efforts to increase yield.

Key Techniques of Stereoscopic and Efficient Cultivation of Strawberry in Southern Xinjiang

Strawberry is rich in nutrition,which is the only fresh fruit in winter in southern Xinjiang,with good prospect of stereoscopic cultivation.In this paper,the key techniques such as stereoscopic cultivation pattern,the combination of different modes,the substrate of strawberry cultivation,the drip irrigation system,the formula of nutrient solution,the selection of varieties,the propagation of seed and seedling,the induction of flower buds,the planting and management of plants,and the green control of diseases and insect pests are introduced,and greenhouse space and solar energy are fully used to maximize the economic and social benefits of strawberry farming combined with tourism.The results will further promote the quality and efficiency of strawberry industry in southern Xinjiang,and provide a reference for strawberry growers.