The objective needs, subjective conditions, best benefits and competitive advantages should be considered in formulating breeding objectives. That is to say, under modern transportation conditions, it is very economical and convenient to transport apples from major production areas such as Liaoning, Hebei and Shandong to Jilin and Heilongjiang(plastic pots for plants wholesale). There is no need to expand the production area northward to unsuitable areas. It is difficult to cultivate cold resistant varieties that adapt to the harsh climate of Jilin and Heilongjiang and are competitive with apple varieties in major production areas. The law of survival of the fittest must be considered when formulating breeding goals.

For example, a unit that lacks the instruments and facilities to identify the virus and cannot obtain the necessary support from the cooperative unit is difficult to achieve the goal of antiviral breeding. The breeder's own quality, scientific and technological level, practical experience, and the degree of mastery of relevant information at home and abroad are more important subjective conditions. Economic and social benefits the breeding objectives of any crop should be reasonable in economics and biology.

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At the beginning of the 20th century, tomato breeding aims at high yield, high quality, regional adaptability and disease resistance of fresh food varieties(black plastic pots for plants). With the development of processing industry, processing adaptability has gradually increased.

Therefore, breeding objectives should be compatible with the technical strength, funds, facilities and other material conditions of breeding units. The current and long-term breeding objectives should not only focus on the reality and short-term development needs, but also take into account the needs of long-term development as far as possible. In addition to bringing economic benefits to producers and consumers in some way, successful breeding also has some breeding objectives that can produce greater social and ecological benefits

This breeding work began with the breeding of traits with good fruit hardness and collision resistance. The earliest breeding was red topv-p; At present, about 85% of the total tomato production in the United States is used for processing. Later, processing tomatoes have very urgent requirements for mechanical harvesting, and the breeding goal has shifted to processing mechanical harvesting. Hanna of the University of California set the goal of "one harvest" in 1943. It took about 20 years of efforts to achieve it.

Later, through many inter variety crosses, the long fruit variety vf13l with better resistance to mechanical impact was published in 1963; Later, the axillary bud free line non branching B was selected by repeated backcross with general processing varieties. On the contrary, if the target traits are dispersed, it will certainly distract the energy and delay the breeding progress. Therefore, we must grasp the main contradiction, and the target traits generally cannot exceed 2~3.

It can also provide objective and specific criteria for the final identification of breeding objectives. For example, the target character of yield can generally be implemented into biological yield and economic coefficient, and the crop yield using fruit can be implemented into the number of fruits per plant, per bearing branch or per unit area and the average weight of per fruit. At present, breeding objectives similar to mechanical harvesting for processing may not be a top priority in China, but China's future development trend should be carefully considered.

Humidity: cuttings dry and die before rooting, which is often the cause of failure of cuttings. If the target traits are concentrated, the relative selection pressure is greater and the breeding efficiency is higher. For example, in the target plan that needs to be achieved in 20 years, a number of transition varieties that may be accepted by the market will be developed within 8 to 10 years. Moreover, we should clarify the main target traits and secondary target traits according to the importance and difficulty of traits in breeding, so as to achieve primary and secondary differences and coordinated improvement.