秸秆或粉煤灰添加对砂姜黑土持水性及小麦抗干旱胁迫的影响

针对黄淮海平原典型中低产土壤砂姜黑土黏粒含量较高,土壤有效水分库容较低,严重限制作物生产的现状,该文采用盆栽试验,研究了不同外源改性物料的添加对土壤持水性能及小麦生理的影响,以期获得农田水分管理过程中的关键参数。盆栽试验设置常规氮磷钾(control,CK),常规氮磷钾配施下的添加秸秆(straw returning,SR)、秸秆碳(straw carbon,SC)和粉煤灰(fly ash,FA)处理,维持土壤相对含水率在80%,培育小麦至抽穗期,开展为期10 d的干旱胁迫试验。结果显示SR和SC处理提高了土壤持水能力,且处理间的差异较小;FA处理因其表面富含大量疏水性结晶矿物,土壤相对含水率下降较快,迟效水含量显著低于其余处理,但土壤速效水含量显著提高。不同改性措施均有提高小麦叶片相对含水率,减轻干旱胁迫的趋势,但在极端干旱胁迫下,FA处理叶片相对含水率不仅明显低于其余处理,且作物体内积累大量丙二醛、过氧化氢等有害物质。田间管理中砂姜黑土相对含水率应维持在38%(SR)、36.5%(SC)和24.5%(FA)以上,当土壤相对含水率低于30.78%(SC)、28.43%(SR)和22.5%(FA)时将会对作物生理产生不可逆的伤害。鉴于秸秆优良的保水性能,粉煤灰“富水,不保水”的特性,秸秆与粉煤灰的配合施用将利于砂姜黑土的改良。相关机制值得进一步研究。

Effects of straw or fly ash addition on water holding capacity of typical Shajiang black soil and drought stress tolerance in wheat

Shajiang black soil is a typical middle and low production soil in Huang-Huai-Hai Plain.Crop production has been seriously restricted due to the high clay contents and low available water capacity of Shajiang black soil,this paper studied the effects of different modified materials on soil water holding capacity and wheat physiology of anti-drought stress by wheat pot experiment carried out in March 2018,in order to provide technical supports for farmland water managements.According to local field fertilization and water management modes,4 treatments were designed in wheat pot experiment:chemical NPK fertilizer(CK),chemical NPK fertilizer with maize straw returning(SR),chemical NPK fertilizer with maize straw carbon(SC),and chemical NPK fertilizer with fly ash(FA).Referring to conventional amount of applying fertilizer in northern farmland in Anhui province,the application amounts of chemical fertilizer were 225 kg/hm2(N),120 kg/hm2(P2O5),and 60 kg/hm2(K2O),respectively,and the application amounts of fly ash,maize straw carbon,and maize straw returning to field were 45×103 kg/hm2,45×103 kg/hm2 and 6×103 kg/hm2,respectively.As for wheat pot experiment,in each pot,about 10 wheat seeds were transplanted into 30 kg soil after accelerating seeds germination.Soil relative water content was maintained at 80%field capacity until heading stage.When wheats grew up to the heading stage,irrigation stopped and then a drought stress experiment was carried out for 10 days.Wheat leaves collected regularly were stored at-80℃so as to determine wheat physiological and biochemical index.The results showed that both SC and SR improved soil water holding capacity,but both was not significantly different.Owing to the abundance of large amount of hydrophobic crystal minerals like the crystallographic silicon dioxide in the surface of fly ashes,FA had a fast decrease in relative soil water content.The delayed water content of FA was significantly lower than the other treatments,while the available water content was significantly improved.What’s more,different modification materials all had the tendency to increase saturated water content and alleviate the impairments of wheat leaves caused by drought stress.Under mild drought stress,the saturated water content of wheat leaves was higher than that of the control group,but no significant difference was found in the contents of proline(PRO),malondialdehyde(MDA),hydrogen peroxide(H2O2)and peroxide scavenging coenzyme in the wheats among the four treatments.However,under extreme drought stress,not only was FA significantly lower than the other treatments in wheat leaves saturated water content,but also FA treatments accumulated more harmful substances like MDA and H2O2 in wheats,which could lead to irreversible damages to wheat physiological conditions.In conclusion,the relative water content of Shajiang black soil was suggested to keep above 38%(SR),36.5%(SC)and 24.5%(FA),respectively.The plant physiology would get irreversible damage if relative soil water content was under 30.78%(SC),28.43%(SR)and 22.5%(FA),respectively.Because straws have better performance in holding water by significantly improving the content of soil capillary pore,and fly ashes can do better in providing more available water for soil in spite of holding water poorly,combined application of straws and fly ashes will be conducive to the improvement of Shajiang black soil.Relevant mechanism need to be furtherly studied.