temperature Influence. Germination of seeds

you are: temperature Influence

Temperature requirements for germination of seeds considerably vary depending on a kind. For example, for annual Delphinium the temperature 15°С, and for a melon - from 30 to 40 °s is optimum. However many seeds remain at rest even at humidifying and temperature approaching for germination. Sometimes it is possible to interrupt such rest with light (gl. 11), a way preinkubatsii at certain temperature, increases in quantity О2, washing away ingibitorov, physical destruction of covers of a seed or a fruit. Seeds of plants of a moderate zone often demand nizkotemperaturnoj stratification before inkubatsiej at more heats; it detains germination till the spring, preventing possible damage of gentle sprouts by frosts. On the other hand, seeds of some plants, for example a white oak, sprout right after falling on the earth and quickly form deeply going root system.

Dry seeds do not react to stratification, and before influence in low temperature it usually allow to bulk up completely. Assume that at processing there are any metabolic transformations which are shown in change of intensity of breath, ways of a translocation, the maintenance of enzymes and even speed of division and a stretching of cages. One very important complex of changes concerns balance of hormones: levels ABK usually decrease, while the maintenance gibberellinov () or tsitokininov (in others) increases in one seeds. ABK, as a rule, it is connected with rest, and gibberelliny and tsitokininy - with synthesis and growth processes. Stratification, thus, leads ' posleuborochnomu to ripening ' and by that biohimicheski prepares for the subsequent germination at more heat.

Some plants, mainly deserted, before germination stratification is necessary for Simeons at heats. In other cases there is an interrelation between temperature and illumination conditions. For example, seeds shchiritsy Amaranthus retroflexus sprout in the dark if to hold them some days at 20 °s, and then to transfer on 35 °s. But if to exclude low temperatures light is necessary for germination. It, apparently, specifies in requirement for Fdk. Recollect that the considerable part of phytochrome in seeds is in the form of Fdk which after humidifying of seeds can turn again in Fk. As the reference of Fdk at Amaranthus at 20 °s goes very slowly, and at 25 °s - four times faster, demanding Fdk processes which conduct to germination, can occur in cooling. thus, for germination we can put some specific requirements for temperature and light in communication with FdK, and others - with hormones. Whatever was reguljatornyj the mechanism, it should influence finally activity of genes and itself should be under its influence.