烟草是自花授粉作物,自然杂交率为1～3%,在生产实践中存在着“一年纯、二年杂、三年以后起变化”的严重问题。由于混杂退化往往造成产量比良种减产一成,烟质降低一个等级的后果。因此,搞好烟草选种、留种工作,非常重要。在技术上要注意如下要点: 1.建立留种基地,进行统一供种。烟草繁殖系数高,为有限聚伞花序,一般每株有蒴果300～400个,每个蒴果有种子2000～3000粒。按每株留果30～40个计算,可生产种子6～12万粒。如果出苗20%,每株种子可育1.2～2.4万株苗,可移栽5～10亩。由于用种量小,又易自然杂交,故应由种子公司选点建立留种基地,实行统一供应。如果暂时做不到,也应以乡统一供种。在生产上一般按生产 Tobacco is a self-pollinated crop with a natural hybridization rate of 1 to 3%. In production practice, there are serious problems of “one year of pure, two years of miscellaneous, and changes after three years”. As a result of mixed degeneration often result in a 10% reduction in yield than the elite, reducing the level of a result of the smoke quality. Therefore, it is very important to do a good job of selecting tobacco seeds and keeping seeds for work. In the technology should pay attention to the following points: 1. To establish a base to stay species for a unified supply. Tobacco breeding coefficient is high, limited cymes, generally each capsule has 300 to 400 capsules, each capsule has seeds of 2000 to 3000. According to the calculation of 30 to 40 per plant leaves, 6 to 120,000 seeds can be produced. If 20% seedlings per plant fertile 1.2 to 24,000 seedlings, transplanting 5 to 10 acres. As a result of small species, but also easy to natural hybrid, it should be set up by the seed companies to stay seed base, the implementation of a unified supply. If temporarily unable to do, but also for the unity of the township species. In production generally according to production