Time-Space Flowering and Podding Characterization in Erect-growing Summer Mung Bean Vigna radiate L. CURRENT STATUS: POSTED

The flowering and podding sequences and patterns in different Mung bean varieties were studied by examining the flowering and podding of Xilv 1 and Anlv 7, in order to provide a basis for Mung bean hybridization and high efficiency production. It was shown that the flower period of Mung bean could be divided into initial, full bloom, final stages, and secondary full bloom and final stages. Flowers mainly distributed at nodes 6-8 at the initial flowering stage; distributed at all plant nodes, especially at the nodes on lower branches at the full bloom stage; and sporadically distributed at the final flowering stage. The flowering sequence of Mung bean was that they began to flower on the first inflorescences developed from axillary buds and then flowered first at proximal nodes on lower branches, then at nodes on relatively upper branches, and finally at nodes on top branches. There were the highest numbers of open flowers and fructifying pods on lower branches, followed first by those on relatively upper branches and finally by those on top branches.


Background
The flower number and podding rate of Mung bean (Vigna radiate L.) are the determinant factors to its yield (Mondal 2007). Although Mung bean is capable of flowering in great quantities, it sheds off great numbers of its flowers and pots, which limits its yield increase (Saitoh 2004;Islam et al. 2010).
High yield varieties of Mung bean set greater numbers of flowers than low yield varieties and the yields of the formers are extremely significantly positively correlated with their pod and flower numbers and extremely significantly negatively correlated with their propagation efficiencies (Mondal 2013;Ashrafuzzaman 2013;Singh 2014). Leguminous crops are characterized by a highly varying flowering period, which determines their pod maturities to some extent . The flower and pod distributions over time determine use efficiencies of assimilates by kernels, which lays down a basis for yield increasing (Erkut 2007). Bruening and Egli(2000) held that in leguminous crops, limited yields were because early rapid pod and kernel growths consumed a major part of assimilates, thus forming a heavier weight than pods and kernels set late in the growing season (Begum et al. 2007;Fakir 1997). In soybean, the earlier flowering starts, the slower pods and kernels develop, which is conducive to a consistent pod maturity (Ltd 2004). The greater numbers of flowers does Mung 4 bean form over 14-21 days after flowering, the more pods it will keeps and then the higher its kernel yield will be when it reaches its maturity (Mondal et al. 2009). In varieties with a long flowering period, pods tend to mature over a relatively long time, which is not favorable for harvesting. In order to make Mung bean mature over as short a time as possible, it is better to adopt such varieties that have less shoots and flower in great quantities over 10-15days after flowering Iqbal et al. 2015).
Pods at same nodes are easy to affect one another (Egli 2005), and pods at different nodes are relatively independent (Heitholt et al. 1986). At same nodes, the flower shedding rates at the base of the primary raceme, which occurs earlier, are lower than those of the secondary and tertiary racemes, which occurs later (Brun and Betts 1984;Heitholt et al. 1986). At same nodes of a plant, the abortion rates of early flowers and pods are much lower than those of the late ones (Huff and Dybing 1980;Brun and Betts 1984;Tambal 2000). These results indicate that the flowering and podding pattern of Mung bean is of great significance to increasing possibilities of successful hybridization, developing varieties that set pods over a short time and yield increasing. However, there have been fewer researches on the flowering and podding pattern of time and space of Mung bean. Accordingly, the study presented in the paper researched on the flowering and podding pattern of time and space of Mung bean with two erect growing varieties of Mung bean in order to characterize flowering and pod setting of Mung bean in the field.

Materials And Method
Materials Currently, newly-developed varieties as well as promoted and adopted varieties in Mung bean production all grow erect (Bain et al., 2007), so that the study chose Xilv 1 and Anlv 7, two erectgrowing varieties of Mung bean, as its trial materials.

Experiment Design
The study carried out its experiment on Experiment Depending on their daily numbers of newly-opened flowers, the flowering periods of the two varieties were divided into five stages, initial, full-bloom and final stages, and secondary full-bloom and final stages. It can be seen from Table 1 that the initial flowering stage was short, lasting 2-4 days and at this stage the daily number of newly opened flowers numbered less than two; the full bloom stage lasted more than ten days and at this stage the daily number of newly opened flowers per plant increased day by day to more than 3; the final flowering stage lasted 9-12 days, and at this stage, the daily number of newly opened flowers numbered less than two on average ; then there and Xilv 1 had a full bloom stage of 25 days but did not saw its secondary full bloom and final flowering stages.  the upper stem nodes, which probably resulted from insufficient nutrient supplies to pods on branches at the upper stem nodes. In Xilv 1, there was the highest pod fructifying rates on branches at stem node 1, followed first by those at relatively upper nodes and then by those at flowering onset stem nodes and upper stem nodes. And the pod fructifying rates varied less in Anlv 7 than in Xilv1 and peaked on the branches at stem node 4, reaching 77.58%.

Flowering and podding characterization by plant
Pods develop from ovaries and thus the flower number per plant is the major contributor to bigger differences in fructified pod number. It can be seen from Table 2 that the flower and pod numbers of Xilv 1 and Anlv 7 differed greatly, standing at 63.9% and 67.2%, respectively. Anlv 7 had higher numbers of opened flowers and fructified pods and higher poding rates per plant than Xilv 1.

Discussion
In Leguminous crops, flowering and podding are dynamic processes and whether pods can be formed and kept until their maturity or not is dependent on when and where they develop   number-a small daily flower number. In Mung bean, the vegetative growth, flowering and kernel filling durations were in a negative proportion to the temperature as an important environmental factor that determine the reproductive growth (Begum et al. 1998;Roknuzzaman et al. 2007). However, Zhang Zhang (1992)revealed that in Mung bean, the lowest nodes at which there were open flowers were nodes 2-5 and the flower and pod shedding percentage were more than 30%, believing that nutrient transports were the major factor to affect flower and pod shedding off and environmental conditions obviously affected the flower numbers at different nodes (Jiang and Egli 1993;Egli 2010). This study found that there were more flowers and pods, and higher fructifying pods on lower branches. Flowers during the late growth make a very small contribution to the final yield (Ojehomon 1970;Subhadrabandhu et al. 1978); and lower pod numbers at upper nodes probably result from an insufficient nutrients transports to upper flowers and pods of plants, but the details of this cause needed to be further studied.

Conclusion 11
In Mung bean, the flowering period could be divided into initial stage, full bloom stage, final stage,

Ethics approval and consent to participate
Not applicable.

Consent for publication
Not applicable.

Availability of data and materials
All data generated or analysed during this study are included in this published article.

Competing interests
The authors declare that they have no competing interests.

Funding
Shaanxi provincial key research and development plan project "research integration and demonstration of efficient and simplified key cultivation technologies for small grain"(2018tscxl-ny-03-01); Shaanxi provincial agricultural science and technology innovation and transformation project "research and integration demonstration of key technologies for green and efficient production of small grain" (nykj-2018-yl19). These funds enabled fields to be properly managed and data to be collected in an orderly manner These fund have provided financial support for the conduct of the experiment and ensure the smooth conduct of the experiment.
Authors contributions: N W, J Z, Xl G designed this work and prepared the first draft of the manuscript. Md H, Y F, Yn Z and HQ W collected field data. P Y, Jf G and Xl G revised and approved the submitted version of the manuscript. All authors read and approved the final manuscript.