Creation of new plants. Selection of plants

you are: Creation of new plants

High present crops of agricultural crops became possible appreciably thanks to art of selectors to which managed to create many productive disease-resistant grades. One of outstanding successes has been reached with corn. The modern corn is the hybrid which has united genes from several inbrednyh of lines.

Genetikam was known for a long time that long inbriding lowers capacity and efficiency of the majority of agricultural crops and pets. Crossing of some vysokoinbrednyh lines quite often causes the phenomenon named geterozisom, or hybrid force. Descendants from such crossings much more largely also differ from parental grades bolshej capacity and efficiency, obviously, owing to presence in their cages of special combinations of genes. Despite the newest data received in the field of molecular biology, we cannot offer an exact biochemical explanation to this strengthened growth of hybrids.

For creation of modern hybrid corn four separate lines have been used. At first these lines crossed in pairs, and then two hybrids received thus have crossed among themselves and as a result it ' double crossing ' have received hybrid corn.

Certainly, the seeds made by such plants at self-pollination, not ' breed in cleanliness ', and differ high variability. Therefore farmers should buy annually the new seeds made on special seed farms. Despite such additional expenses, the American farmers go on it as at sufficient application of fertilizers of an expense for seeds pay off productivity increase. The profits received as a result of increase of productivity at the expense of cultivation of only one hybrid corn, could cover all sum spent for studying of plants in the USA for all time of existence of the country. Initial increase of crops of corn in the thirties and has been caused later by introduction of these genetic hybrids, and their further increase is connected with increasing application of chemical fertilizers, and then and pesticides. Hybrid grades are deduced now and for many other vegetative cultures, and, despite high cost of manufacture of hybrid seeds, these seeds provide almost on all globe rich crops and good incomes.

By means of selection and crossing also it is possible to raise productivity of cultures, creating the grades adapted for special local conditions. Many old local grades which long since are grown up in the field though are low-yield, at entering into soil of small amounts of fertilizers appear more productive, than the high-yielding grades created for intensive agriculture; besides they are steadier against diseases. Similar grades contain the valuable genofund expecting that it have started to use for areas with extreme conditions.

Now selectors give especially a lot of attention to searches soleustojchivyh plants for their cultivation in the areas which soils became salted. Some wild-growing kinds of tomatoes, for example, grow in seaside areas where salty splashes of ocean reach. The genes which are available for these kinds, could raise soleustojchivost cultivars of tomatoes. Tests on soleustojchivost grain cereals stored in seed banks are conducted also; thus already it was possible to reveal at them considerable distinctions which can form a basis for deducing soleustojchivyh grades. It shows, what important role is played by seed banks even if in them are stored ' become outdated ' grades. Similar programs spend in searches holodo - or drought-resistant grades.