First, the economic and human resources invested in large sheds are much more labor-intensive and material-intensive than open-field cultivation. Using greenhouses for cultivating vegetables is for the benefit of most farmers. Therefore, when deciding on the types of vegetables to be grown, the first thing to consider is the return on investment. For example, some rare, rare and slightly grown vegetables generally have higher economic benefits, but often there is not much consumer market; some conventional vegetables, as long as the selection of suitable varieties, to determine a reasonable sowing (cultivation) season Plus, scientific management can also achieve better results.
Second, resistance to poor light properties Although the greenhouse cover material has a certain degree of light transmission, the light transmittance of a generally large greenhouse film reaches more than 85%. However, the light transmittance is limited by the type of film, the use time, and the use environment, and the light transmittance that is not high is greatly reduced. In addition, when the rainy weather occurs in winter and spring, the light is insufficient. In addition, some growers use multi-layered coverage, and the light is even less. Therefore, considering the light, vegetables suitable for greenhouse cultivation should be relatively light-resistant. Requires light saturation compensation points to be low. Otherwise, vegetables are prone to prolonged growth under low light, with serious drop and fruit loss and more diseases.
Third, moisture resistance (resistance) strong disease due to the high temperature in the greenhouse, the large amount of water evaporation, coupled with the airtightness of the greenhouse film is good, permeability permeability is poor, the humidity within the greenhouse is high. Especially when cultivated under closed conditions at low temperature, the humidity inside the greenhouse is relatively high, and the relative humidity of the air is generally above 90%. Under such high humidity conditions, most vegetables are poorly grown, and they provide favorable conditions for the occurrence and spread of various diseases. conditions of. Therefore, the vegetables cultivated in the greenhouse should be more resistant to moisture and stronger in disease resistance.
Fourth, the strong adaptability to temperature is mainly reflected in the low temperature and large day and night temperature requirements are not sensitive. The varieties are required to be tolerant to low temperatures, allowing them to normally grow in the winter and early spring. However, this species is also required to have strong high-temperature burn-resistance at high temperatures. For example, during the period of January to February, when the weather is fine, before sunrise in the morning, the temperature in the greenhouse can be as low as 5°C. In the noon sunshine, the temperature in the greenhouse can quickly exceed 30 °C or even 40 °C. Such a large temperature change requires a strong adaptability of vegetable varieties.
V. Meeting the requirements of the market The purpose of cultivation of greenhouse vegetables is not only the production of vegetable products, but also the smooth sales of the products. To achieve this goal, the cultivated vegetable species (variety) must cater to consumer and market requirements, and the harvest period of these species (varieties) must also meet the market's needs. For example, people in some areas like to eat eggplant with red skin. In some areas, people like to eat inked eggplant. In some areas, people like to eat bamboo silk eggplant; some people eat red Tomato, but some people like to eat pink tomato fruit. This requires growers to fully grasp the spending habits of the sales market.
Medical Grade Weighted Warm Blanket Double Side Fleece
adventure medical emergency blanket
Medical Blanket,Warm Blanket,Emergency Blanket,Medical Emergency Blanket
Luck Medical Consumables Co.,LIMITED , https://www.luckmedical.com