Plant Reproduction and Germination

According to Farmer and Moore, four daughter cells are formed from single cell in meiosis. As a result ofmicrosporogenesis (meiotic division) in four microspore mother cells, 16 pollen grains will be produced.

In orthotropous (atropous) ovule, the micropyle, funicle and chalaza lie in a straight line.

The movement of pollen tube towards embryo sac is chemotropism as it occurs in responce to certainchemical substances like auxin and carbohydrates.

Double fertilisation is the unique feature of flowering plants, whereby from a single pollen grain, the two sperm nuclei within the pollen tube fuse with different nuclei within the embryo sac of the ovule. Fusion of one sperm with egg cell nucleus forms zygote and the fusion of other sperm with diploid secondary nucleus forms triploid primary endosperm nucleus.

Unisexuality of flowers prevents autogamy (self pollination) but not geitonogamy (pollination betweenseparate male and female flowers on the same plant).

In angiosperms, one male gamete fuses with the egg to form the diploid zygote. The process is called syngamy. The other male gamete fuses with the two polar nuclei to form triploid primary endosperm nucleus. The process is called triple fusion. These two acts of fertilization constitute the process of double fertilization.

In porogamy, pollen tube enters the ovule through the micropyle. It is the most common way of the entry of pollen tube inside ovule.

In embryo sac of angiosperm, egg apparatus occurs towards micropylar pole and generally organises by two synergids and one egg cell. Egg cell has a large vacuole at its upper end and a prominent nucleus near its lower end. Synergids show a filiform apparatus attached to their upper wall. It is known to attract and guide the pollen tube. Each of the synergids has a vacuole at its lower end and the nucleus at its upper end.  

Dry seeds of moong are kept in water for a day and wrapped in wet cloth the next day. This way they develop small white structures growing out of them. The seeds are then said to be sprouted or germinated. 

Generally, it is the seeds of the plants which are used to extract oils. For example: seeds of mustard, linseed etc. 

Recalcitrant seeds are seeds which cannot be stored for longer period of time like some horticultural plants, e.g. mango.

 Lodoicea maldivica is the botanical name of  double coconut or Seychelles nut and has the largest seed.

The pericarp in caryopsis is fused with the seed coat and the grains of rice and wheat which are examples of caryopsis are considered both seed and fruit since there is no different layer of seperation. 

Phanerogams (Gymnosperm and Angiosperm) are the plants that reproduce by means of seeds and not by spores. They are the plants that produce seeds. 

 Better the seed, better would be the crop yield. Seeds should be of good quality, give high yield and should be clean and healthy. Hollow and lighter seeds mean the seeds are eaten/ attacked by and are not good to be used.