Design and Development of Artificial Pollinizer for Pollinating Tropical Vegetables under Protected Cultivation

Abstract

Artificial pollination is a process that is highly require in vegetable crops grown under protected cultivation since, protected environment offers barriers to natural agents for pollination such as insects, wind or water. A study was undertaken to design and develop an artificial pollinizer for pollinating tropical vegetable crops under protected cultivation. To obtain preliminary data required for the design, floral and physical characteristics of flower, anther and pollen of selected tropical vegetable crops were studied in laboratory conditions. Accordingly a conceptual design was evolved and two models of artificial pollinizers were developed. Suitability of the developed pollinizer was evaluated in laboratory as well as field conditions. Results of the evaluation have been presented and analyzed. Six tropical vegetable crops were selected for the preliminary studies like floral characteristics, physical and dimensional measurements of flowers, anther and pollen grains were conducted in the laboratory. Sizes of pollen grains were measured by using Olympus Bx43 light microscope and the measurements were taken using the software Ultrascope version 9.1. Shape was determined from standard shape charts suggested by UPOV, 2007. The shape of pollen grains of tomato, pumpkin and ash guard are found to be „circular‟ with a Length/Width ratio ranging from 1: 1 to 1: 1.1. Pollen grain of chilli is „broad deltate‟ with L/W ratio of 1: 1.2. Pollen grains of water melon and cucumber are „narrow oblate‟ with a L/W ratio of 1: 1.13 to 1:1.15. Based on the preliminary studies, functional requirements and conceptual designs two models of the artificial pollinizers were designed and developed. Artificial pollinizer Model – I uses air as the medium for collection of pollen from flowers. Suction pressure developed by a vacuum pump suck the pollen grains from the male flower to a pollen collection chamber. The pollen collection unit is provided with a brush tip which detach the pollen grains from the flower and suckedby a vacuum pump are deposited in a pollen collection chamber. A screen mesh filter of 15 μm aperture is used in the chamber to prevent the pollen grains from carry away. Components of artificial pollinizer model – I includes pollen collection unit, pollen collection tube, adaptor for pollen collection chamber, pollen collection chamber, air tube, air tube adaptor, a connector and a vacuum pump. An electric powered air blower of 220 V, 50 Hz and 0.55kW is used as vacuum pump. The blower produces a suction velocity of 20-22 ms -1 at 13,000 rpm. Artificial pollinizer Model – II uses water as the medium for collection of pollen from male flowers. Water is sprayed from a nozzle to the male flower kept carefully in a pollen collection chamber. Water spray produced by a pneumatic hand pump from the nozzle wash out the pollen grains from the flower and is collected in the water tight container. Components of artificial pollinizer Model – II includes a spray nozzle, pneumatic hand sprayer, water container and pollen collecting chamber. Collected pollen can be sucked by a syringe for spraying to the female flower for artificial pollination. Dry pollen collected by Model – I is also mixed with water and used for artificial pollination using a syringe. Evaluation of artificial pollinizer was done by accessing pollen viability and fruit set efficiency. Viability of pollen was observed under laboratory condition and fruit set efficiency was observed under field conditions. From the studies it is observed that, pollen viability is decreasing with increase in storage period for both the crops. Maximum pollen viability is observed when artificial pollination was done with fresh pollen grains. Also, the viability is found higher for pollen stored in 1 % sucrose solution than pollens stored in plain water in both crops. Study on fruit set efficiency is also seems to be decreasing with increase in storage period for both the crops. Maximum fruit set efficiency is observed when artificial pollination was done with fresh pollen grains. Fruit set efficiency is higherfor pollen stored in 1 % sucrose solution than pollens stored in plain water in both crops. Also the fruit set efficiency values are on par with manual pollination. Stages of fruit development in cucumber and watermelon crops are also observed on the 3 rd , 7 th and 15 th days after artificial pollination and found that the artificial pollination done using the artificial pollinizer was successful.