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品种是人类在一定的生态和经济条件下,根据自己的需要而创造的某种作物的一种群体。它具有稳定的遗传性和性状的相对一致性,在一定地区和栽培条件下,它的产量、品质和适应性等方面符合生产的要求。由此可以看出:品种是经济上的类别,而不是植物学上的分类单位。为什么一个优良品种在一地表现增产,在另一个地方可能不增产甚至减产呢?这是因为尽管品种是人类根据自己的需要而选择出来的,但它的优良性状和增产潜力有一定的局限性,主要表现以下几方面: 一、因为品种是一定的自然条件(温度、光照、降雨)和生产条件(施肥、灌水、耕作制度)的作用下选育出来的。因此,品种的适应性是有地区性的,并要求一定的栽培条件。不同品种的适应性有广有窄,但没有一个品种能适应所有地区和一切栽培方法。二、品种的利用价值有一定的时间性。因为每个地区随着经济,自然和栽培条件的变化,对品种就有新的要求。如一个较耐瘠薄的小麦品种,在较低的肥水条件下能得到较其它品种高而稳产的产量;但是,当肥水条件改善后,就可能因倒伏而减产,或因穗子小不能进一步提高产量。所以,任何品种在生产上被利用的时间都是有限的,人们必须不断地创造新品种,保证及时地进行品种更换。
Varieties are a group of crops that people create under their own needs under certain ecological and economic conditions. It has a stable genetic and trait relative consistency, in certain areas and cultivation conditions, its yield, quality and adaptability, etc. meet the production requirements. It can be seen: Variety is an economic category, rather than a taxonomic unit. Why a good breed grows in one area and may not increase or even cut output in another? This is because although the breed is selected by mankind according to his own needs, its good traits and yield potential have some limitations , Mainly in the following aspects: First, breeds are bred under the action of natural conditions (temperature, light and rainfall) and production conditions (fertilization, irrigation and farming systems). Therefore, the adaptability of varieties is regional and requires certain cultivation conditions. Different varieties have a wide range of adaptability, but no one species can adapt to all regions and all cultivation methods. Second, the use of varieties have a certain time value. Because each region changes with economic, natural and cultural conditions, there is a new demand for variety. For example, a barren wheat variety can produce higher and stable yield under lower fertilizer and water conditions than other varieties. However, when fertilizer and water conditions are improved, the yield may decrease due to lodging or the yield can not be further increased due to smaller ears . As a result, the time it takes to make any variety available for production is limited, and people must continually create new varieties and ensure timely changes of varieties.