Chongqing has diverse terrain and strong three-dimensional sense. The altitude is generally between 250- 1000 meters, the lowest is 176 meters, the highest is more than 2000 meters, and the altitude difference is about 2000 meters. Geomorphology is divided into four basic types: Zhongshan, low mountains, hills and flat dams. The diversity and three-dimensional nature of this terrain create a favorable natural three-dimensional climate for vegetable production, especially in low mountains and Zhongshan areas, where the temperature difference can be used to produce anti-season vegetables.
1. altitude: the suitable altitude for off-season vegetable production is 800- 1500m. These areas are cool in summer and cold in winter, which are suitable for delayed cultivation of spring vegetables and early cultivation of autumn and winter vegetables.
2. Water source conditions: vegetable cultivation needs more water than ordinary crops, and most vegetables are not drought-tolerant. Therefore, off-season vegetable producing areas must have sufficient and convenient water sources for irrigation.
3. Soil conditions: Generally speaking, loam, sandy loam and clay loam are all suitable for vegetable production. Most vegetables are suitable for growing in slightly acidic and neutral soil, and the PH value is in the range of 6.5-7.5. The soil in some mountainous areas is acidic and not suitable for vegetable production.
(B) Several technical principles of anti-season cultivation
1. Selection of suitable vegetable varieties: mountainous areas are generally far away from the market and have long transportation distance, so they are suitable for planting vegetables such as melons, eggplant, Chinese cabbage and root vegetables which are relatively resistant to storage and transportation, and it is not suitable to choose fast-growing leafy vegetables as anti-season vegetable cultivation varieties in mountainous areas.
2. Choose suitable varieties: According to the climatic characteristics of mountainous areas, generally choose varieties with early maturity, heat resistance, strong disease resistance, stable commodity and storage and transportation resistance.
3. Strictly control the suitable sowing date: according to the climate characteristics of Chongqing in summer and autumn and the requirements of various vegetable varieties for environmental conditions, strictly control the sowing date, and arrange the formation, flowering and fruiting (pod) and fruit expansion period of leaves, stems, leaf bulbs and flower bulbs in the appropriate growth and development period, which is the key to the success of anti-season cultivation.
4. Meet the demand of vegetables for fertilizer and water: the temperature is high and the drought is serious during the growing period of out-of-season vegetables in mountainous areas. It is necessary to meet the demand for fertilizer and water for vegetable growth in time, let crops grow under suitable fertilizer and water conditions, ensure the quality of vegetable products and improve the commercialization of vegetable products, so as to ensure a better market.