Before being sown some seeds require some preparation. This treatment may well be scarification, stratification , wet seed or seed wash with cold or warm.
The wet seeds is usually done by soaking the seeds in warm water for 24 to 48 hours. 1 washing the seeds is very common in the case of fruit (as the flesh of the fruit surrounding the seed can be rapidly attacked by insects or pests. 2 3 To clean the seed, usually the seed is rubbed with a piece of cloth or paper, and sometimes are washed from the seed. 4 Usually seed washing is performed soaking the seeds for about 20 minutes in water at a temperature of 50 C. 5 warm to hot water will kill microorganisms that might have survived in the seed surface. The cleaning with water at high temperature is very important in seeds of tropical fruits that can be easily infected such as lychees and rambutans .
In addition to the preparation processes previously noted, the germination is favored if land is used free of disease. Especially if it comes to producing seed germination particularly difficult (such as some tropical fruits), treatment and previous land preparation (along with the use of land with minerals and acidic conditions most suitable, prepared soil or other substrate appropriate) is extremely important. The two processes of preparation of the soil used are pasteurization and sterilization . Is generally more convenient to choose the pasteurization since it does not kill all microorganisms. The sterilization may be used when attempting to plant vegetables particularly difficult. To pasteurize the soil, the soil must be heated for 15 minutes in an oven at a temperature of 120 C.

Among the crops grown stand of oats , the wheat , and rye , grasses and legumes are also planted from seed in both corn and soybeans are planted in a more spaced. When planting, the rows are spaced about 70 cm from each other, and try to space the individual seeds, and for this we use various devices to provide seeds to exact intervals, maximizing the yield and seed saving.

When planting, place very little land and in some cases none of the seeds. Generally speaking, seeds can be planted so that the layer of soil that the cover is 2 to 3 times the size of the seeds.

The sifonogamia is a type of plant fertilization simple (in gymnosperms ) or double (in angiosperms ) which implies the presence of a pollen tube through which passes the pollen to the embryo sac . 1represents a mode of adaptation to the environment terestre as male gametes are never released to the external environment. 2 is given in the angiosperms and most gymnosperms .

The pollen tube carries the male gamete to the egg cell , although gymnosperms older (as Gyngko ) have zoidiogamia . After this the pollen gives rise to two sperm that swim to fertilize the egg cell .Fertilization is simple: the male gamete fertilizes only the female forming a 2n zygote, the rest of the tissue, with the endosperm or nutritive tissue, is n. In angiosperms , however, fertilization is twofold: one male gamete fertilizes the endosperm .




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