The importance of manual pollination in protected agriculture

Sat, 26 Jan 2019 11:35:00 +0530

In today's blog, we will attempt to explain the science behind pollination, its impact, and reasons for failure. Understanding this will provide a better insight into the causes of why fruiting and flowering may not be occurring as expected.

What is Pollination?

Before we explain the process of pollination, it is vital to understand the different parts of plants that are involved in the process.

Anther - it is the male reproductive part of flowers that produces pollen grains.
Pollen grains - these consist of one or more vegetative cells and a reproductive cell (think of these as sperm cells).
Stigma - it is the female reproductive organ of a plant that acts as a receptor for pollens.

Pollination is the process of transfer of pollen grains from the anther of a male flower to the stigma of the female flower.

The Significance of Pollination

To continue the circle of life, a living organism must produce its progenies. Plants are no exceptions to this natural cycle. Plants develop their progenies by creating seeds for the next generation. The process of pollination aids the circle of life in the case of plants. Proper pollination increases the percentage of fruit set in flower. Later, the fruit will produce the seed, thus completing the circle of life.

Kinds of Pollination

Self-pollination

Self-pollination is the process of transfer of pollen grain from the anther of one flower to the stigma of the same flower or the stigma of another flower on the same plant. Tomato is an example fo a self-pollinating plant.

Cross-pollination

Cross-pollination is the process of transfer of pollen grain from the anther of one flower to the stigma of a flower on another plant that belongs to the same species. Cucumber is an example of a cross-pollinating plant.

Self-pollination, as the name suggests, does not need any external vector. The anther and stigma are positioned such that the transfer of pollen grain happens naturally. Cross-pollination, however, requires external stimuli, often a vector, like an insect, to transfer pollen from one flower to the other.

Challenges of cross-pollination in a controlled environment

Cross-pollination is normally aided through insects. Insects collect pollen and nectar from the flowers as food. As they forage, they spread the pollen from one flower to another flower, one plant to another plant. In an open environment, this process works well, and environmental factors like wind, water, rain, etc. further aid the process of pollination. A protected environment restricts the movement of natural pollinators. This limitation leads to a reduced rate of, or improper pollination, which results in no fruit set or deformed fruits and seeds. Due to this, yield reduces in the plants grown in a protected environment. In such cases, a farmer can aid the process of pollination by carrying out manual/hand pollination.

How to carry out Manual Pollination

First, check for the male and female flowers.
Using a small plant brush collect the pollen grains from anthers of the male flower
Smear them on the stamen of the female flower. Or take the male flower and give a gentle tap over the stigma of the female flower.

While carrying out the process of manual pollination, One should be careful so as not to damage the stigma. A damaged stigma would lead to unfruitfulness. We did experience this first-hand and have shared the same in an earlier blog .

Happy Growing!

Find out what causes a deformed cucumber

Thu, 17 Jan 2019 09:37:11 +0530

At the CG garden, when we grew cucumbers for the first time, we did not get any fruit due to pest infestations and lack of pollination. On our second attempt, we are happy to share that the results were sweet. Most of the cucumber fruits were very tasty, but we did notice some funny-shaped cucumbers also.

We noticed some cucumbers that looked different. We had a few curled cucumbers and a few with a bulge towards the far end. When we investigated the reasons for these funny-shaped cucumbers, we realized that we were not doing the pollination in the right way. To know how to do hand pollination, refer to this blog. In our case, the reason was improper pollination. In your case, it may be something else too. Read on to find out the main reasons that lead to the formation of misshapen cucumbers.

Reasons for deformed cucumbers

Improper Pollination

Generally, pollination in cucumber will be facilitated by insects, especially honey bees. When there is a lack of insects in the garden, especially in protected farms, like ours, no or incomplete pollination will occur. In the case of no pollination, you will not get any fruit at all. In the case of incomplete pollination, however, enough pollens do not reach the stigma of the female flower. In this case, the part of the fruit that gets enough pollen gets developed fully, whereas the part that does not get a good number of pollens fails to grow to its full potential. Often this part is the blossom end. The incomplete pollination leads to the deformed cucumber.

Hot Weather

High temperatures can impact pollination adversely in multiple ways. During warm weather, the pest activity decreases. The reduced activity can lead to a lesser number of pollens getting transferred to the stigma. Even if a sufficient number of pollens do get transferred, many of those may be sterile. The reason for this is because the sterility of pollens decreases with an increase in temperature. Apart from this, due to high heat, the stigma receptivity of the flower reduces; anthers may die too, thus leading to improper pollination and causing deformed fruits in the plants.

Excessive Nitrogen

Cucumber needs a lot of nutrition during the vegetative stage. However, once the plant matures, the nutritional requirements change. At this stage, the plant needs a relatively lesser amount of Nitrogen. If the nutrient solution is not adjusted appropriately, it may also lead to misshapen fruits.

Irregular Water Suppply

Cucumber needs a lot of water. During the warm season, this requirement increases further. In case the farmer does not provide a sufficient amount of water to the plants, the plant may come under water stress and form deformed fruits.

Lastly, there are a couple of more things that one should take care of if doing hand pollination.

One should take care to ensure that stigma does not get damaged during pollination.
Also, one has to be aware and informed regarding the perfect time for pollination. The stigma receptivity varies for different time crop combinations. For cucumbers, the best time to pollinate is usually between 6:00 AM and 8:00 AM.

Taking care of the above-listed aspects, the grower can increase her chances of getting proper shaped good cucumber fruit.