**2.1 Selection of land**

To avoid harbouring of root rot or wilt pathogen, the selection of healthy edaphic conditions is the first priority for a normal luxuriantly growing plant. Neutral pH with loam clay loam soil was selected for the experiment at the Village-Belu, P.O. Madhappur, Amdanga, North 24 Parganas (Latitude 22°11′6″ N to 23°15′2″ N and Longitude 88°20′ to 89°5′ E) West Bengal, India.

*Pollination Biology and Environmental Water Pollution Indicator of Onion (*Allium cepa *L.) DOI: http://dx.doi.org/10.5772/intechopen.111475*


#### **Table 1.**

*Heavy metal, Chloride and pH analysis of three Experimental locations water samples (Preonagar, Mathpara and Harishnagar).*

#### **2.2 Bulb selection and environmental condition**

Onion bulbs around 5–6 cm in diameter were selected for sowing of the above field. The good flowerings were obtained by cool weather after bulb planting. It was also noticed that the good sunshine at the time of full blooming stages helped in attracting the beneficial pollinators for the higher rate of hybrid vigour seeds through cross-pollination. One more important parameter was kept in mind that relative humidity (RH) would be in the lower range during the time of seed development. As for the farmer's concern, the experiment was started in the month of the middle of October for sowing the bulb in the field of the above area.

#### **2.3 Experiential laying out**

The buds were planted in beds of size 1×3 m with 20–25 cm spacing during October. The experiments were conducted in Randomised Complete Block Design (RCBD) with 3 replications.

#### **2.4 Floral biology**

Morphology, physiology and phenology of plant flowering play a vital role in the reproductive capability of individual plant species. A flower's attractiveness to the visiting fauna and efficiency of pollen transfer to those visitors depend on the morphological characters, i. e. shape, colour and flower architecture [11]. The crosspollinated onion plants are completely dependent on the different types of insects for their pollination [12]. Complete field observation was conducted to invent the onion floral characteristics, flower (bud) initiation and duration, number of days for maximum flowering, number of peduncles per bulb. The number of florets per

inflorescence, life of single floret, colour of the florets and odour were observed in the field materials.

*Phenology*

Plant phenology is concerned with the timing of recurring events such as



#### **Table 2.**

*Different morphological characters of the Allium cepa L.*

*Pollination Biology and Environmental Water Pollution Indicator of Onion (*Allium cepa *L.) DOI: http://dx.doi.org/10.5772/intechopen.111475*

### *Volume of nectar*


## *Pollinators*

