According to the experiment, this measure increases the yield by more than 20% compared with the early harvest. This method can avoid high temperature. When 70% of seedlings emerge, combined with middle tillage, 15 kg of ammonium sulfate or 1000 ~ 1500 kg of human feces are applied per mu. In production practice, if spring potato seeds are to be sown in autumn in the same year, in order to promote their early emergence and neat emergence, seed potato treatment can be carried out before sowing in addition to improving the storage method of seed potato.
Summer sowing and seed retention is to store the seed potato produced in the spring of the first year under low temperature until the summer of the second year; Make the tuber setting stage in the cold condition of late autumn. 19cm plant pots should be sown and cultivated in time. When mending seedlings, dig out the seed potatoes in the seedling bed, break down the seedlings, first dig a small pit with a depth of about 15 cm in the center of the whole seedling nest, and then spread the roots of the seedlings in the pit, bury them tightly and compact them with soil.
Rainfall in northern China is generally concentrated from July to August, accounting for more than 70% of the total precipitation of the whole year. Therefore, the seedling stage of summer cucumber in the last sentence from the end of May to June is often dry early, and it is easy to accumulate Waterlogging from July to August. However, the existing experience shows that the selection of superior trees is effective, and the selection of superior trees can be combined with the popularization process of reproduction and independence, so as to make the seed selection work effective in production as soon as possible.
Abundant breeding resources will not only limit the development of multi generation breeding, but also can not adapt to the breeding objectives that change with the needs of production and life. By observing the development process of forest abandonment and considering the characteristics of forest breeding, it can be expected that introduction, seed selection and cross breeding will still be the main ways of Forest Improvement for a long time.
If the climate is good and the soil in the 12cm plant pots is fertile, the nutrients in the tree will accumulate quickly and the seed setting interval will be shortened. Disastrous weather will disturb and destroy the normal physiological function of trees, so as to delay seed setting. Canopy density directly affects the light, temperature and nutritional status of forest land. The age at which the same tree species begins to bear fruit will also be different due to the changes of environmental conditions, forest origin, growth and development and other conditions.
We must pay attention to the collection and preservation of breeding resources. With the development of economic conditions, the reform of technological process and the change of market, the requirements for new forest varieties will also change. With the increase of population and the massive deforestation, many precious breeding resources have been destroyed. Therefore, collecting breeding resources, especially rescuing endangered tree species, is an urgent event.
According to China's relevant documents, all reproductive materials collected within the same county (banner) belong to the same origin (provenance). In fact, there are many different stands within a county. There are many variations in the same tree species, especially in a wide range of geographical distribution. If the setting of seed collection points in provenance test is reasonable, it itself is representative.
If the proportion of male trees is too small or unevenly distributed, and the proportion of male flowers of trees with the same male plant is small, it will affect the effect of pollination and the quantity and quality of seeds. Seed collection is an important process of obtaining seeds. All preparations must be made before seed collection. Otherwise, it will not only reduce the yield and quality of 9cm plastic plant pots seeds in that year, but also affect the harvest of seeds in the coming year.
In addition, the abundant supervision years of poplar, plum, elm, shuttle and other tree species are not obvious, and the seed yield of each year is relatively stable: the seed setting interval of Masson pine, Chinese fir, bubble maple, Robinia pseudoacacia and other tree species is short, generally 1 ~ 2 years. The size of the seed orchard should be determined according to the afforestation plan and seed demand in the seed supply area, as well as the prediction of the yield per unit area of the seed orchard, and leave some room for further development and adjustment of the seed orchard.
