High density: the United States, Russia, Central Asian countries, North Africa, Egypt and China. Xinjiang The planting density is more than 120 thousand hm-2. These cotton growing areas have shorter frost free periods and rely on large groups for more Bolling.

Low density: with the India land cotton area, China's Yangtze River Basin and Southern China cotton area as the representative, the planting density is only about 30 thousand plants and hm-2. These cotton growing areas have long frost free period or no frost. The water and fertilizer conditions are good. With the unlimited growth habit of cotton, fruit branches are kept to more than 20 and rely on large individuals to win more bolls. Because "sparse planting big", pruning requirements are not strict.

　　 Medium density type It includes Pakistan, South Africa, Cameroon and Mali, which are most typical in North China, with a density of 50 thousand to 90 thousand hm-2. In these areas, the frost free period is moderate, the rainfall distribution varies greatly in the year, and the human resources are abundant. In order to make full use of the heat resources during the elongating growth period, the management is intensive and intensive, and the nitrogen fertilizer is applied repeatedly, and the pruning is strict (the so-called "five step pruning method"). The characteristics of cotton boll forming period vary greatly, and artificial control of plant type. The formation and development of cotton planting technology in Hebei has gone through 3 stages.

1 the cotton planting technology in ancient China started in the Tang Dynasty and started in the Ming Dynasty and flourished in Hebei. Cotton cultivation technology system has basically formed in the early Qing Dynasty. In the Qing Dynasty Qianlong years, Fang Guan Cheng's cotton drawings and articles summarized the cotton planting technology of cotton farmers systematically. There were six aspects of cultivation techniques: (1) seed treatment (seed dressing), seed drying (seed selection, black kernel, and winter month), seed selection (solid seeding) and wood ash seed dressing (WB, cold and wood ash).

(2) farming, ploughing and turning to the border (the soil with sand, the spring in the autumn, the plough in the spring, the row in the ditch), the irrigation (cotton seed must be first well, the well can be irrigated forty mu), hoe hoe (one month three weeding, seven wells and the flowers are numerous and thin).

(3) sowing, deep seeding, deep seeding, restoring soil to be solid, this method is suitable for protecting seedlings in dry land.

(4) scattered seedlings, the density of retained seedlings is about 30 thousand hm-2, 75 thousand new hm-2.

(5) beat the top, the height of the seedling is one or two feet to the top, and the branches and feet are half to the sharp point, and explain the effect of preventing each other from covering up.

(6) picking, picking at any time after picking, drying in order to store, the price is different to distinguish white cotton. It can be seen that in eighteenth Century, Hebei province had formed a systematic cotton cultivation technology system, belonging to the middle density type.

Two Intensive and meticulous farming In twentieth Century, with the introduction of upland cotton, the modern cotton planting technology was introduced and formed supporting technology, which was mainly reflected in the construction of improved seed farm, pest control and chemical fertilizer application. In 50s, due to the extensive attention paid to cotton, the preliminary results of physiological research were combined with the experience of model workers and cotton planting experts, and the measures that were considered beneficial were brought into full play.