Pollination behaviours and Pollinators of Vegetable Crops

Pollination plays important role in genesis and evolution of a plant species. It is the base of any plant diversity. Pollination followed by fertilization and consequently development of fruit and seed not only produces foods but also is one of the important building block of crop improvement.

On the basis of pollination behaviour vegetables are generally classified into 3 distinct groups. They are,

Autogamous (Self-pollinated): In this crops, pollination involves the stigma of the same flower that produces pollens or other flowers at the same plant, which effect natural self-fertilization. Extent of natural cross pollination in these crops are normally less than 10% (<10%). Hermaphroditism is predominant here.

Often Cross-Pollinated: In these crops, self-pollination is predominant but due to morphological nature of the crop natural cross-pollination exceeds 25% (>25%).

Allogamous (Cross-pollinated): In these crops pollens from the flower of one plant is transferred by some agents (insects, wind, humans etc.) to the stigma of flowers of another plants to effect pollination. Generally some morphological barriers which might be controlled genetically or physically favours cross pollination. In cross-pollinated crops natural cross pollination exceeds greater than 60% (>60%).

Modes (Agents):

I. Abiotic: Wind (Anemophily), Water (Hydrophilic)

II. Biotic: Insects (Entomophily), Birds (Ornithophily), Bats (Chiropterophily), Snails (Malacophily), Ants (Myrmecophile)

a.    Entomophily: Pollination through insects

b.    Anemophily: Pollination through wind (Spinach, Beet, Palak, Amaranthus)

c.    Hydrophily: Pollination through water. Eg. Ceratophyllum, Vallisneria, Eichhornia etc

Hydrophily is of two type:

-Hypohydrophily: (Pollination below the surface of water) is observed in Zostera, Ceratophyllum.

-Epihydrophily: (Pollination over the surface of water) is observed in Vallisneria.

d. Ornithophily: Pollination by birds. Eg. Erythrina, Bombax, Grevilloa, Bignonia, Callistemon, Agave etc.

e.  Chiropterophily: Pollination by bats. Eg. Kigellia pinnata, Anthocephalus, Bauhinia etc.

f.  Malacophily: Pollination by snails. Eg. Arisaema.

Some vegetable crops and their pollination habits

Vegetable Crops	NCP (%)	Pollinator	Place of Report
Tomato	0.59-4.90	Bumblebees	California
	0.00-5.00	Honeybees and Solitary bees	San Marzano & California
	1.50-15.00	Native Bees	Mexico
	15.00-26.00	Solitary bees	Peru
	4.2-11.00	-	Italy
Potato	0.00-20.00	Bumblebees	Scotland
Eggplant/Brinjal	0.20-46.80	Insect & Wind	Japan
	0.70-15.00	Insect	India
Chilli	7.00-37.00	Honeybee & Thrips	US
	58.00-68.00	Insects	India
	1.77-54.91	Insects	Mexico
Lettuce	1.33-6.22	Helictus spp
Cowpea	1.00	Bumblebees & Wild Honeybees	US
Cluster Bean	1.00-4.40	Wild insects & Bees	Texas
Winged Bean	0.00-7.67	-	Phillipines & Papua New Guinea
Faba Bean	24.00	Honebees	China
	29.50-69.80	-	Britain
	25.00-50.00	-	Denmark
	0.00-46.00	-	India
French Bean	6.00-10.00	-	Brazil
	0.00-0.007	-	California
Watermelon	0.00-0.53	-	-
Okra	0.34-27.30	-	-
Sweet Potato	2.21-56.41	-	-
Spinach	19.6-96.8	Wind	-
Beet root	-	Wind	-
Carrot	97.6-98.9	Honeybees	US
Radish	Highly Cross-Pollinated	Bumblebees & Honeybees	-
Chinese Cabbage	19.00	Honeybees	-
Pak-Choi	85.00-100.00	Honeybees	-
Cauliflower	40.00-50.00	Honeybees, Bumblebess & Blowflies	-
Kale	83.00	Honeybees, Bumblebess & Blowflies	-
Cabbage	73.00	Honeybees, Bumblebess & Blowflies	-
Knol-Khol	91.00	Honeybees, Bumblebess & Blowflies	-
Brussels Sprout	72.00	Honeybees, Bumblebess & Blowflies	-
Broccoli	95.00	Honeybees, Bumblebess & Blowflies	-
Onion	95.00-100.00	Blowflies	-
Muskmelon	85.00-95.00	Honeybees	California
	5.40-73.20	-	California
Cucumber	65.00-70.00	Honeybees & Solitary Bees	-
	17.00-36.00	-	US

Isolation distance: 0-10%=100-150m; 11-25%=200-300m; 25-50%=300-500m; 50-75%=500-1000m; 75-100%= >1000m