土壤水分对两个冬小麦品种产量和竞争能力的影响

研究了黄土塬区两个旱作冬小麦品种(长武135和平凉40,前者是后者的换代品种)在不同土壤水分条件下竞争能力和产量形成的关系。研究设2种土壤水分条件(土壤含水量为田间最大持水量的75%～80%和40%～45%),采用生态替代法设计了同一播种密度的6个播种比例组合的盆栽试验。低水分单播条件下,长武135具有较高的产量(长武135为27.59g/pot,平凉40为24.91g/pot),而混播条件下平凉40在产量和相对产量上较长武135品种具有明显的竞争优势。高水分条件下,平凉40产量随播种比例的减小下降较快(长武135产量曲线斜率35.468,平凉40为36.237)。平凉40低水分单播时花后干物质积累量较少(长武135为0.67g/pot,平凉40为0.55g/pot),而混播时较多(长武135各比例均值0.58g/pot,平凉40为0.71g/pot),导致了平凉40品种单播时产量较低和混播时产量较高。平凉40地下生物量显著大于长武135(高水分条件下,长武135为10.03g/pot、平凉40为11.51g/pot;低水分条件下二者分别为8.41g/pot和10.69g/pot),且耗水量大(高水分条件下平凉40多耗水2.72kg/pot,低水分条件下多耗0.98kg/pot),而耗水量/地下生物量的比值平凉40低于长武135,从而平凉40品种单位根量消耗的水分低于长武135。总之,在两个生长属性接近的冬小麦品种中,老品种以较大的根系生物量赢得了较高的竞争能力,消耗了较多的水分,而新品种虽然根系生物量较低,耗水量较少,但籽粒产量却较高。亦即,小麦新品种籽粒产量的提高是与根系的减少和对水资源竞争能力的下降相伴随的。

Effects of soil water contents on competitive abilities and yield of two winter wheat cultivars

The aim of this research is to study the effects of different soil water contents on competitive abilities and grain yields of two winter wheat cultivars(Triticum aestivum L.),i.e.(modern cultivar "Changwu135"(A)and old cultivar "Pingliang40"(B)).In the pot experiment,we adopted the ecological replacement series to design 6 seeding proportions with the same density,and two soil water contents were 75%-80% and 40%-45% of field capacity for dry wet conditions,respectively.The results showed that the modern cultivar Changwu135 had higher yield than the old cultivar Pingliang40 under dry conditions(A:27.59 g vs.B:24.91 g),however,there was no significant difference in grain yield between two cultivars under wet conditions(A:35.86 g vs.B:36.46 g).The cultivar Pingliang40 had significant higher relative yield than modern cultivar Changwu135 under two water treatments with mixed-seeding way.Linear slopes were used to describe the variation of seeding proportion versus grain yield.The grain yield value decreased more steeply in Pingliang40(slope 36.237)than Changwu135(slope 35.468)under wet conditions.It is showed that Pingliang40 had a stronger competitive ability on grain yield in mixed-seeding way.The value of relative total yield increased with the seeding proportion of old cultivar increasing under two water treatments.And the other biological characteristics related to yield also had the same variations as grain yield.It is showed that the dominant cultivar in mixed seedling had lower grain yield than that in monoculture,and there was a negative relationship between the competitive ability and productivity.The accumulated dry matter weight after anthesis of old cultivar Pingliang40 was lower in monoculture(A:0.67 g/pot vs.B:0.55 g/pot)but higher in mixed seeding than modern cultivar Changwu135(average of A:0.58 g/pot vs.B:0.71 g/pot),which led to Pingliang40 had lower yield in monoculture but higher yield in mixed seeding.However,the modern cultivar Changwu135 had a reverse result on the accumulated dry matter weight after anthesis.And the accumulation coefficient had the same variations as the accumulated dry matter weight after anthesis.Shoot biomass and root biomass of Pingliang40 were significantly higher than Changwu135 under wet conditions(shoot biomass increased 22.80 g/pot,root biomass increased 1.48 g/pot)and dry conditions(shoot biomass increased 13.93 g/pot,root biomass increased 2.28 g/pot).The value of water consumption of old cultivar Pingliang40 was significantly higher than that of Changwu135(increased 2.72k g/pot under wet condition and 0.98k g/pot under dry condition).In addition,the cultivar Pingliang40 had a lower ratio of water consumption to root biomass than Changwu135(decreased 0.02 kg/g under wet condition and 0.23 kg/g under dry condition),which indicated that old cultivar Pingliang40 had developed roots,higher shoot biomass and lower yield,thus it can consume less water to grow unit root biomass.However,the modern cultivar Changwu135 had reverse results in mixed seeding.In conclusion,the two cultivars which had similar biological characters,the old cultivar Pingliang40 had stronger competitive ability than the modern cultivar Changwu135 under two soil water content treatments because of its developed root biomass and more water consumption.And the competitive ability of Pingliang40 under wet condition was weaker than that under dry treatment.Although modern cultivar Changwu135 had lower root biomass and less water consumption,it had a higher grain yield.The experiment also suggested that the crop productivity increased as the root biomass decreased and the competition ability for water resource weakened.