Observational experiments on flowering and pollination processes
Source: Experiments in Botany
Operation method
basic program
Principle
Sexual mating determines the transmission of genes at the population level and thus has had a profound effect on plant evolution, and there is a wide variety of mating patterns in angiosperms. Pollination within the same flower is usually called autogamy, and pollination between different flowers is called heterogamy. Intra- and inter-flower pollination on the same plant do not have different genetic effects, and are essentially "autogamy", but only pollination and fertilization between plants of the same species are "heterogamy". Only pollination and fertilization between small homozygous plants are "heterozygous". The structural characteristics of the flower and the pattern of flowering are adapted to different modes of pollination, and pollinators such as insect winds, water currents, etc., contribute to the realization of specific mating processes.
Materials and Instruments
Flowering Plants Move 1 Determination of mating mode (1) Observation of floral characteristics and blooming style: firstly, it should be distinguished whether the flower under observation is bisexual or unisexual, and if it is unisexual, it should be noted whether it is monoecious or dioecious. Secondly, attention should be paid to observe the maturation order of pistil and stamen, female flower and androgynization. Unisexual flowers can avoid autoflowering, if it is a hermaphrodite flower, androgynous maturation is also a mechanism to avoid autoflowering, it is strictly heterogamous when it is dioecious, and monoecious can not avoid homozygous heterogamous pollination unless mechanisms such as androgynous maturation are present at the same time. Once again, the color, odor, and presence of nectar-secreting structures can be used to make preliminary judgments about the mode of pollination. Insect-pollinated flowers usually have brightly colored perianths, are fragrant or have other special odors, and mostly produce nectar; wind-pollinated flowers are usually smaller, have no brightly colored perianths or have degraded perianths, and are usually unscented and do not produce nectar. (2) Artificially controlled pollination test; With the method of artificially controlled pollination, the affinity of different plants in hybridization and crossbreeding can be probed according to the fruiting situation. Generally, the following treatments can be designed ② bagging: bagging complete hermaphroditic flowers to determine whether there is a possibility of self-fertilization in the natural state. ③ de-masculinization: remove the stamens from bisexual flowers without bagging to determine whether there is a possibility of cross-pollination and fruiting in the natural state; ④ de-masculinization and bagging - removing the stamens from bisexual flowers and then bagging them, or bagging the female flowers to determine if there is a possibility of non-fertilized seed setting; ⑤ Artificial selfing: pollinating pistils with pollen from the same plant and bagging them to determine selfing affinity; ⑥ Artificial heterosis: the pistil was pollinated with pollen from other plants and bagged to observe heterosis fruiting. The fruiting rate after various treatments was counted and the untreated chemistry was used as a control. When performing operations such as desexing, bagging and hand pollination, pollen contamination should be completely avoided. 2 Observation of wind pollination In order to study whether wind pollination works on the flowers of a certain plant, the method of netting can be used, so as not to allow insects to have the opportunity to visit the flowers, and if it can bear fruit normally, then it indicates that wind pollination is effective. Nylon netting can be used when netting, and the larger flowers such as trees or shrubs should be individually netted, while small herbaceous plants can be used to cover the whole plant or even a small group of the entire netting. The distance pollen grains are dispersed with the wind can be detected using the gravity slide method. After determining the pollen source, petroleum jelly can be spread evenly on the slide, and the slide can be placed at different distances from the pollen source with different forces (depending on the height of the plant and the size of the pollen source, different strategies should be used, e.g., for herbaceous plants, slides can be placed at distances of 0.2m, 04m, 0.6m, ---, 2.0m, and 2.0m, respectively). For example, for herbaceous plants, the slides can be laid at a distance of 0.2m,04m,0.6m,---,2.0m, and for trees, the slides can be laid at a distance of 5m, 10m, 15m,---,50m.) The petroleum jelly-coated side of the slides should be faced upwards, and after a period of time (usually 12h or 24h), the slides should be retrieved sequentially. The pollen grains on the slides were counted under the microscope. In order to correctly identify the pollen grains of the research object, the pollen grains of the plant can be scattered on a piece of slide coated with petroleum jelly under the microscope for comparison to calculate the number of pollen grains per unit of area per unit of time of a single plant stock dispersed to different distances, so as to measure the distance and intensity of pollen flow. 3 Observation of insect pollination (1) Statistics on the frequency of insect flower visit: Insect flower visit may help plant pollination, but the flower visitor is not equivalent to the pollinator. In the field study. Can only make statistics on the frequency of flower visitors to the flowers of a particular plant to observe the research object of a few open flowers, statistics if ten 15mm or 20mm time period of the number of times insects visit each flower, if there are different groups of insects to visit. Records should be kept for wasps, flies, butterflies, beetles, etc., and the number of times each flower is visited by (each type of) insect per hour should be counted. In order to determine the species of flower-visiting insects and whether they are pollinators, specimens of each type of flower visitor should be collected and brought back to the laboratory for further identification, and a scanning electron microscope can be used to confirm whether the body surface of each insect carries pollen grains of the object of study. (2) Statistics on the flight distance of flower-visiting insects: In order to assess the distance of pollen flow formed by insect activities, it is usually necessary to make statistics on the flight distance of insects when visiting flowers. In the actual observation, according to the different density of the studied plant population, several distance levels (such as 0m, 0-5m, 5-10m, 10-15m, 15-20m, >20m, etc.) can be decided, and the proportion of different flight distances can be counted, and generally the flights that landed on the same plant are regarded as the flight distance of 0 m. Since pollinators will not unload all collected pollen into their offspring after visiting a flower, it is necessary for the insect to make the statistics of flight distances when visiting flowers. Since pollinators do not unload all the pollen they collect on the next flower they visit, the actual distance of the insect-borne pollen flow is greater than the observed and counted flight distances of the flower-visiting insects. Therefore, some pollen labeling methods should be used to get a more accurate picture of insect-borne pollen grains. For more product details, please visit Aladdin Scientific website.
netting