Table 1
Entomophily and artificial pollination methods followed for pollinating onion flowers
| Treatments | Procedure of pollination | Treatments |
|---|---|---|
| T1- Indian bee (Apis cerana indica) | One individual bee, actively foraging in onion fields was collected through a test tube and released on to a pre-marked umbel and bagged with plastic mesh of 500 micron diameters to prevent escape. One bee per umbel was released every day from initiation of flowering up to seed set. Duration of release 1 hour |
|
| T2- European bee (Apis mellifera) |
| |
| T3- Himalayan bumble bee (Bombus haemorrhoidalis) |
| |
| T4- Hand gloves (Cloth) | The pollens were collected from un-bagged umbel through the cloth hand gloves and gently rubbed over the bagged umbel and covered with plastic mesh after pollination. Umbels were gently rubbed for 3 minutes |
|
| T5- Hand gloves (Rubber) | The pollens were collected from un-bagged umbel through the rubber hand gloves and gently rubbed over the bagged umbel and covered with plastic mesh after pollination. Umbels were gently rubbed for 3 minutes |
|
| T6- Sponge puff | The pollens were collected from un-bagged umbel through the puff and gently rubbed over the bagged umbel and covered with plastic mesh after pollination. Umbels were gently rubbed for 3 minutes |
|
| T7- Camel Brush | The pollens were collected from un-bagged umbel through the camel brush and gently sprinkled over the bagged umbel and covered with plastic mesh after pollination. Pollens were sprinkled for 3 minutes |
|
| T8- Control (Open) | The umbels were not covered and allowed for free cross pollination by all the pollinating agents |
|
| T9- Control (Close) | The umbels were covered with plastic mesh and only self-pollination was allowed |
|
Table 2
Floral biology of onion composite variety “VL Piaz-3”
| Floral Character | Details |
|---|---|
| Time of flower opening | From 6.20 h to 17.45 h (Throughout the day) |
| Anthesis | Early morning hours from 6.25 to 7.25 h |
| Anther dehisces | Observed from 7.45 h to 16.45 h |
| Stigma receptivity | High between 9.15 h to 15.15 h (Examined through Hydrogen peroxide method proposed by Zeisler (1933)) |
| Number of flowers per umbel | Ranged between 682 to 1211 (842±132.51 average of 25 umbels) |
| Number of umbels per plant | Ranged between 4 to 13 (7.32±2.29 average of 25 plants) |
| Number of umbels per m2 | Ranged between 19–65 (36.66±11.43 average of 12 plots) |
| Days for umbel formation | Ranged between 131–144 days (137.44±3.79 days* average of 100 plants) (19th February to 4th March, 2021) |
| Days for first flowering | Ranged between 143–155 days (149.96±6.54 days* average of 100 plants) (3rd march to 15th March, 2021) |
| Days for last flowering | Ranged between 203–216 days (209.92±3.96 days* average of 100 plants) (2nd May to 15th May, 2021) |
| Total flowering period of crop | Ranged between 60–73 days (67.76±3.83 days* average of 100 plants) (3rd March to 15th May, 2021) |
| Total flowering period of each umbel | Ranged between 13–19 days (15.92±1.98 days average of 25 umbels) |
Table 3
List of insects visiting onion flowers under Himalayan conditions of Uttarakhand, India
| Order of insect flower visitors | List of insects visiting onion flowers |
|---|---|
| Hymenoptera (19 species) | Apis cerana indica, Apis mellifera, Apis dorsata, Apis florea, Bombus haemorrhoidalis, Vespa tropica, Vespula vulgaris, Andrena hilaris, Megachile rotundata, Osmia inermis, Nomia incerta., Halictus sexcinctus, Ceratina smaragdula, Trigona iridipennis, Xylocopa latipes, Sceliphron curvatum, Megascolia azurea, Ceratina sutepensis, Lithurgus atratus |
| Lepidoptera (17 species) | Celastrina argiolus, Chilades pandava, Danaus chrysippus, Pieris brassicae, Parantica aglea, Euploea core, Aglais caschmirensis, Vanessa cardui, Junonia lemonias, Papillio demoleus, Colias ladakensis, Helicoverpa armigera, Lymantria dispar, Acherontia styx, Pieris rapae, Chilades parrhasius, Danaus genetua |
| Diptera (14 species) | Episyrphus balteatus, Metasyrphus corollae, Eupeodes luniger, Eristalis tenax, Macronomia spp., Calliphora vomitoria, Lucilia cuprina, Musca domestica, Eristalinus quinquelineatus, Sarcophaga carnaria, Helophilus trivittatus, Liosarcophaga dux, Eristalis horticola, Eristalinus megacephalus |
| Coleoptera (5 species) | Oxycetonia versicolor, Clinteria kluge, Chiloba acuta, Heterorrhina elegans, Rhomborrhina spp. |

Fig. 1
Diversity of insect pollinators of onion in Himalayas of Uttarakhand, India

Fig. 2
Insect pollinator density obtained through in-situ method of sampling in onion crop at three time frames of the day during peak flowering period (*F-values calculated at 5% level of significance)
Table 4
Foraging rate of pollen and nectar foragers of A. c. indica at three time intervals in a day during three flowering periods
| Pre peak flowering (<25%) | Peak flowering (>50%) | Post peak flowering (<25%) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Bee foragers | 10.00 h | 13.00 h | 16.00 h | F-value | p-value | 10.00 h | 13.00 h | 16.00 h | F-value | p-value | 10.00 h | 13.00 h | 16.00 h | F-value | p-value |
| No. of flowers visited by pollen foragers | 24.52±1.91 a | 23.52±1.44 b | 19.71±1.63 c | 1.79* | 0.018 | 31.86±2.72 a | 29.86±1.79 a | 30.57±2.92 a | 0.41 | 0.863 | 27.48±6.49 b | 28.95±5.53a | 25.71±5.82 c | 0.14 | 0.0098 |
| No. of flowers visited by nectar foragers | 23.42±2.13 b | 26.41±1.57 a | 23.54±1.95 b | 0.64* | 0.0069 | 16.33±1.98 b | 17.69±2.01 b | 19.11±1.38 a | 1.65* | 0.021 | 26.14±1.63 ab | 27.18±1.25a | 24.69±1.87 c | 0.36* | 0.0089 |
| No. of umbels visited by pollen foragers | 4.95±1.28a | 4.19±0.94c | 4.57±1.10b | 3.68* | 0.0261 | 3.24±0.74a | 3.60±1.01a | 3.45±1.03a | 1.31* | 0.32 | 4.14±0.79b | 4.71±1.31a | 4.19±1.03b | 5.06* | 0.0083 |
| No. of visited by nectar foragers | 3.98±1.01b | 3.87±0.69c | 4.23±0.98a | 0.42* | 0.0085 | 2.13±0.47c | 3.01±0.57a | 2.94±0.73b | 0.67* | 0.0099 | 4.23±1.03b | 3.99±1.07c | 4.57±0.87a | 0.89 | 0.0053 |
Table 5
Time spent in seconds by individual pollen and nectar forager bee of A. c. indica on onion flowers during three time frames and three flowering periods
| Pre peak flowering (<25%) | Peak flowering (>50%) | Post peak flowering (<25%) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Bee foragers | 10.00 h | 13.00 h | 16.00 h | F-value | p-value | 10.00 h | 13.00 h | 16.00 h | F-value | p-value | 10.00 h | 13.00 h | 16.00 h | F-value | p-value |
| Pollen foragers | 1.76±0.26 a | 1.82±0.51 a | 1.80±0.36a | 1.91* | 0.16 | 1.47±0.28a | 1.34±0.31b | 1.44±0.50a | 0.80* | 0.0058 | 1.79±0.4a 3 | 1.78±0.42a | 1.77±0.45a | 1.30* | 0.32 |
| Nectar foragers | 3.04±0.61c | 3.12±0.70b | 3.30±0.62a | 11.75* | 0.0002 | 3.46±0.60b | 3.28±0.62c | 3.92±0.54a | 2.57* | 0.0077 | 2.96±0.63b | 2.87±0.62c | 3.08±0.62a | 1.53* | 0.0025 |
Table 6
Pollen and nectar foragers of A. c. indica visiting onion flowers at three time intervals in 1 m2 area in a span of one minute during three flowering periods (averages from 3 flowering days)
| Pre peak flowering (<25%) | Peak flowering (>50%) | Post peak flowering (<25%) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Bee foragers | 10.00 h | 13.00 h | 16.00 h | F-value | p-value | 10.00 h | 13.00 h | 16.00 h | F-value | p-value | 10.00 h | 13.00 h | 16.00 h | F-value | p-value |
| Number of pollen foragers | 21.29±3.99 c | 27.00±5.29b | 30.71±5.99a | 0.27* | 0.0094 | 19.29±2.81c | 39.00±7.90b | 42.57±6.55a | 1.72* | 0.002 | 26.00±3.65c | 43.43±4.79b | 46.43±4.12a | 1.96* | 0.0014 |
| Number of nectar foragers | 78.71±3.99a | 73.00±5.29b | 67.86±3.34 c | 0.69* | 0.0006 | 80.71±2.81a | 61.43±6.97b | 57.43±6.55c | 1.77* | 0.0018 | 74.00±3.65a | 56.57±4.79b | 53.57±4.12c | 0.87* | 0.0048 |
Table 7
Quantitative seed yield data of onion obtained through entomophily and artificial pollination methods
| Treatments | Fruit set (in %) | Average number of seeds per umbel | Seed weight per Umbel (in grams) | Test weight of seeds (in grams) | Yield per ha (in kg) |
|---|---|---|---|---|---|
| A. c. indica | 46.79 | 394±6.35b | 1.38±0.18b | 4.2±0.01b | 503.70 |
| A. mellifera | 36.46 | 307±9.02c | 1.05±0.22c | 3.9±0.02c | 383.25 |
| B. haemorrhodalis | 21.26 | 179±4.36d | 0.82±0.11d | 2.8±0.02d | 299.30 |
| Hand gloves (cloth) | 11.40 | 96±3.00f | 0.38±0.11g | 3.3±0.02e | 138.70 |
| Hand gloves (rubber) | 8.79 | 74±3.61g | 0.34±0.09h | 2.9±0.03g | 124.10 |
| Sponge puff | 17.34 | 146±4.73e | 0.66±0.19e | 3.1±0.02f | 240.90 |
| Camel brush | 17.10 | 144±4.58e | 0.59±0.15f | 2.6±0.01h | 215.35 |
| Control (open) | 85.99 | 724±7.00a | 3.90±0.47a | 4.7±0.01a | 1423.50 |
| Control (close) | 7.84 | 66±4.04h | 0.31±0.04i | 2.2±0.01i | 113.15 |
| SE(m) | 12.98 | 0.215 | 0.013 | ||
| C.V. | 3.141 | 64.95 | 6.913 | ||
| F-values | 2461.78* | 27.41* | 38.67* | ||
| p-values | 0.00014 | 0.00007 | 0.000011 |
[i] Note: F- values calculated at 5% level of significance,
[ii] DMRT- Duncan's multiple range test (DMRT) was carried out for comparing the significant differences in the mean values of various treatments

Fig. 3
Assessment of per cent fruit set with respect to total number of flowers per umbel under different pollination treatments.