【作者】 杨永辉；

【导师】 吴普特；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2011， 博士

【摘要】 保水剂是一种具有保水、抗旱,提高水肥利用效率的农业节水制剂,已逐步应用于农业生产,并具良好应用前景。本研究通过盆栽和田间小区试验相结合的方法,采用河南省农业科学院研制的营养型抗旱保水剂,较为系统地研究了该保水剂与氮肥配合施用对土壤结构特征、持水、供水能力、小麦生理生化特征及作物水肥利用状况的影响。初步得出如下研究结果:1、对小麦增产效应进行分析表明:田间试验条件下,土壤施用保水剂促进了小麦的生长,增加了小麦叶面积和穗长、提高了小穗数、降低了小麦耗水量、促进了小麦产量和水分利用效率的提高。保水剂与氮配施效果更佳,较对照增产最高达54.8%,水分利用效率提高71.5%。同时,保水剂与氮肥配施后显著提高了氮素生产力。各处理中均以保水剂60kg/hm2与氮肥225kg/hm2配施的处理效果为佳。盆栽实验表明,不同水分条件下,单施保水剂提高小麦产量不显著,但其与氮肥配施时小麦产量显著提高,以中氮(225kg/hm2)处理最佳,且充分灌水显著高于轻度胁迫的处理。轻度胁迫条件下,较对照最高增产为78.9%,水分利用效率提高77.6%;充分灌水条件下最高增产98.2%,水分利用效率提高97.6%。此外,轻度胁迫条件下的水分利用效率均高于充分灌水的处理。对N肥农学效率、表观回收率及N素生产力而言,轻度胁迫时以氮肥432mg/kg与保水剂配施的处理较高,保水剂处理间差异不显著,而充分灌水时以保水剂54mg/kg与氮肥432mg/kg配施的处理较佳。2、对土壤结构与孔隙特征进行研究表明:施用保水剂显著提高了土壤的结构的稳定性,降低了土壤容重,而氮肥的施用对土壤结构稳定性的提高有促进作用。田间试验条件下,以保水剂60kg/hm2处理和保水剂60kg/hm2与氮肥225 kg/hm2配施的处理>0.25mm土壤水稳性团聚体含量较高,土壤结构较其它处理稳定。而在盆栽实验条件下,随小麦生育期的推进,土壤结构稳定性有所降低。轻度胁迫条件下的土壤结构较充分灌水的处理稳定。各处理中均以保水剂54mg/kg与氮肥配施的处理>0.25mm水稳性团聚体含量较高。利用CT扫描技术对盆栽条件下的土壤孔隙特征进行定量研究表明:施用保水剂与N肥后,土壤大孔隙数、孔隙度及土壤孔隙成圆率均显著提高。与充分灌水相比,轻度胁迫处理的大孔隙数和大孔隙度均较高,且轻度胁迫条件下以保水剂54mg/kg与氮肥432mg/kg配施的处理的总孔隙度和大孔隙度均较高,分别比对照增加57.3%和60.7%,而充分灌水条件下以保水剂54mg/kg与氮肥864mg/kg配施的处理较高,分别比对照增加55.4%和116.7%,表明在不同水分条件下,保水剂与氮肥配施,其用量适宜时对于土壤孔隙的改善效果更佳,有利于土壤中水分与养分被作物吸收利用,促进作物生长。3、在盆栽实验条件下,土壤水分特征研究表明:保水剂与氮肥配施,其土壤含水量与土壤水吸力均符合方程:θ=a·S-b,且土壤持水能力提高更加显著。轻度胁迫条件下,土壤持水能力随保水剂用量的增加而提高;充分灌水时,对照持水能力最低,而其它处理间差异较小。同时,保水剂的施用提高了土壤的供水能力、导水能力及增加土壤水分的有效性。轻度胁迫条件下的土壤供水能力均小于充分灌水条件下的土壤。轻度胁迫和充分灌水条件下,保水剂所吸持的水分能被作物吸收利用的部分分别较对照增加36.8%(保水剂81mg/kg与氮肥864mg/kg配施)和13.41%(27mg/kg与氮肥864mg/kg配施)。4、保水剂与N肥配施对小麦生理生化特征的影响反映了其对小麦生长及增产的机理,研究发现:在田间天然降水条件下,保水剂和N肥配施均提高了小麦叶片相对含水量、叶片叶绿素含量,降低了小麦叶片和根系的可溶性糖含量、脯氨酸含量及细胞质膜透性,增强了小麦的抗旱能力。各处理综合表现为:保水剂用量为60kg/hm2及保水剂60kg/hm2与氮肥225kg/hm2配施的处理效果较为显著;在拔节期,以单施氮肥450kg/hm2和保水剂60kg/hm2与氮肥450kg/hm2配施的处理叶片水分利用效率较高,分别比对照提高60.7%和52.1%。在灌浆期,以保水剂用量为30kg/hm2处理及保水剂60kg/hm2与氮肥225kg/hm2配施的处理较高,较对照提高123.5%和120.4%。说明土壤施用保水剂提高了小麦不同生育阶段的抗旱性能,降低或减缓了因干旱胁迫带来的伤害,促进了干物质的积累。在盆栽实验条件下,不同水分条件小麦光合生理特征对复水前后的响应表现为:复水前,在拔节期,轻度胁迫条件下以单施高氮处理(864mg/kg)的光合速率、蒸腾速率和气孔导度等较高。而充分灌水条件下,高氮虽降低了光合速率和蒸腾速率,但蒸腾速率降低的幅度更大,因此其叶片WUE却较高,而保水剂与N肥配施的处理光合速率等较低,但均高于对照;在孕穗-扬花期和灌浆期,复水前单施保水剂有利于提高小麦的光合速率、蒸腾速率及气孔导度,且轻度胁迫条件下,均以保水剂的用54mg/kg时效果最佳。而充分灌水条件下,以保水剂27mg/kg处理光合速率等最高。复水后,各处理的光合参数均显著提高,但在不同生育期土壤水分降低到一定程度后,其光合速率、蒸腾速率、气孔导度及叶片WUE又继续增加。综合以上分析:在小麦生长发育的中后期,N肥施用增加了复水前对小麦的胁迫,导致气孔导度等光合参数降低,但复水后其对小麦光合生理的激发效应更为显著,而适度干旱胁迫有利于小麦叶片WUE的提高。5、对小麦产量与土壤物理、小麦生理及小麦生长各指标等进行通径分析发现:土壤持水能力、供水能力、导水能力及田间持水量成为小麦籽粒产量的影响因子之一,且以轻度胁迫条件下效果较佳。对保水剂经济效益分析表明:60kg/hm2保水剂用量增产效果最显著,最大产投比为7.05,每hm2最大增收1317.6元。更多还原

【Abstract】 The supperabsorbent polymer for water saving in agriculture is gradually applied to agricultural production, which has bright prospects of water conservation, drought resistance and improvement in water and fertilizer use efficiency.The nutritional and drought-resistant supperabsorbent polymer developed by Henan Academy of Agricultural Sciences was applied in the potted trial and field tests. In this paper, the influence of coupled utilization of supperabsorbent polymer and nitrogen fertilizer on the structural characteristics, water retention and delivery of soil, the physiological and biochemical characteristics of wheat and the water and fertilizer use efficiency is primarily analyzed.The preliminary results obtained from the tests are as follows:1. The stimulation effects of wheat in field tests indicate that the supperabsorbent polymer promotes the growth of wheat, manifested in the increase in the leaf area, wheatear and the decrease in the water consumption, which ultimately leads to bigger production and water use efficiency. The compound effects of supperabsorbent polymer and nitrogen fertilizer are better than the control group, with the increase in agricultural production by 54.8% and water use efficiency by 71.5%. And the productivity of nitrogen is also obviously increased. Among the treatments, the supperabsorbent polymer of 60kg/hm2 coupled by the nitrogen fertilizer of 225kg/hm2 can obtain the best results. The potted trial results show that the increase in wheat yield is not obvious with supperabsorbent polymer only added to soil under various moisture conditions. But the yield can increase significantly with nitrogen fertilizer and supperabsorbent polymer added to the trial. The treatment with medium nitrogen fertilizer and sufficient irrigation is higher than that under mild water stress. Under mild water stress condition, it results in the increase in yield by 78.9% and water use efficiency by 77.6% while the increase in yield by 98.2% and water use efficiency by 97.6% under sufficient irrigation. Moreover, the water use efficiency under mild water stress is higher than that under sufficient irrigation.As to the agricultural efficiency, apparent recovery and productivity of nitrogen fertilizer, the treatment with supperabsorbent polymer of 27mg/kg and nitrogen fertilizer of 432mg/kg under mild water stress condition can achieve best results but the treatment with supperabsorbent polymer of 54mg/kg and nitrogen fertilizer of 432mg/kg under sufficient irrigation can also obtain good results.2. The structural characteristics and porosity of soil in the tests proves that the supperabsorbent polymer obviously improves the stability of soil structure and reduces the bulk density. The utilization of nitrogen fertilizer can also promote the structural stability of soil. In field tests, it results in higher content of the water-stable aggregates (d>0.25mm) and more stable soil structure under the treatment of supperabsorbent polymer of 60kg/hm2 and coupled utilization of supperabsorbent polymer of 60kg/hm2 and nitrogen fertilizer of 225 kg/hm2. But in potted trial, the stability of soil structure decreases with growth of wheat. The structural stability of soil under mild water stress condition is more stable than that under sufficient irrigation. It shows significant increase in water-stable aggregates under the treatment of coupled utilization of supperabsorbent polymer of 54mg/kg and nitrogen fertilizer among the treatments.In potted trial, the quantitative examination in soil porosity by CT scanning technique indicates that the coupled utilization of supperabsorbent polymer and nitrogen fertilizer leads to remarkable increase in the number of macro void, macro porosity and circle forming ratio of soil. The number of macro void and macro porosity under mild water stress condition is much higher than that under sufficient irrigation. And the total porosity and macro porosity tend to grow under the treatment of coupled utilization of supperabsorbent polymer of 54mg/kg and nitrogen fertilizer of 432mg/kg under mild water stress, which results in the increase in the total porosity by 57.3% and macro porosity by 60.7% as to the control group. But under sufficient irrigation, it can achieve better results with supperabsorbent polymer of 54mg/kg and nitrogen fertilizer of 864mg/kg, manifested in increase in the total porosity by 55.4% and macro porosity by 116.7%. It shows that under various moisture contents, the appropriate utilization of supperabsorbent polymer and nitrogen fertilizer can effectively improve the soil porosity and promote the moisture and nutrient assimilation and growth of crop.3 The moisture characteristics of soil in potted trial show that the relationship between moisture content and soil water suction under the coupled utilization of supperabsorbent polymer and nitrogen fertilizer can be described by the functionθ=a·S-b and the water retention tends to be more obvious. Under mild water stress condition, the water retention is enhanced with quantity of supperabsorbent polymer while the water retention in control group is lowest under sufficient irrigation but the difference among the other treatments tends to diminish. While the utilization of supperabsorbent polymer improves the water retention, water conductivity and the water use efficiency. The water delivery under mild water stress is inferior to that under sufficient irrigation. The moisture absorbed and used by crop from the supperabsorbent polymer under mild water stress can be increased by 36.8% with the coupled utilization of supperabsorbent polymer of 81mg/kg and nitrogen fertilizer of 864mg/kg while 13.41% increase under sufficient irrigation with the supperabsorbent polymer of 27mg/kg and nitrogen fertilizer of 864mg/kg.4. The influence of supperabsorbent polymer and nitrogen fertilizer on the physiological and biochemical characteristics reveals the compound effects in the mechanisms of growth of wheat and the increase in yield.With natural precipitation in field tests, the utilization of supperabsorbent polymer and nitrogen fertilizer increases the relative moisture content of wheat leaf and chlorophyll content while the soluble sugar content, proline content and permeability of membrane of wheat leaf and root system are decreased and ultimately enhance the drought resistance of wheat. The comprehensive reflection of all treatments shows that the coupled utilization of supperabsorbent polymer of 60kg/hm2 and nitrogen fertilizer of 225kg/hm2 can attain good results. In jointing stage, the water use efficiency of wheat leaf is higher with the simple treatment of nitrogen fertilizer of 450kg/hm2 with the increase by 60.7% as to the control group and 52.1% with the utilization of supperabsorbent polymer of 60kg/hm2 and nitrogen fertilizer of 450kg/hm2. In the watery stage, the water use efficiency with the simple treatment of supperabsorbent polymer of 30kg/hm2 with the increase by 123.5% as to the control group and 120.4% with the utilization of supperabsorbent polymer of 60kg/hm2 and nitrogen fertilizer of 225kg/hm2. It shows that the supperabsorbent polymer can improve drought resistance of wheat in the different growth stage, retard the damage caused by water stress, and promote the accumulation of dry matter.In potted trial, the photosynthetic and physiological responses of wheat before and after rehydration under various moisture contents are as follows:Before the rehydration, the photosynthetic rate, evapotranspiration rate and stomata conductance in jointing stage with the nitrogen fertilizer of 864mg/kg only added to soil under mild water stress are higher. But under sufficient irrigation, the nitrogen fertilizer with high content slows the photosynthetic rate and evapotranspiration rate but the greater decrease amplitude results in higher water use efficiency of leaf. The photosynthetic rate of wheat with supperabsorbent polymer and nitrogen fertilizer is relatively low but higher than the control group. In booting-flowering stage and watery stage, it can promote the photosynthetic rate, evapotranspiration rate and stomata conductance of wheat with supperabsorbent polymer applied to potted trial before rehydration while it attains good results with supperabsorbent polymer of 54mg/kg under mild water stress. But under sufficient irrigation, the photosynthetic rate with supperabsorbent polymer of 27mg/kg is maximizing. After rehydration, the photosynthetic parameters of all treatments obviously improves but the photosynthetic rate, evapotranspiration rate, stomata conductance and water use efficiency of leaf increase with the soil water decreased to a certain degree in different growth stages.The comprehensive analysis indicates that the utilization of nitrogen fertilizer intensifies the moisture stress for the growth of wheat in mid-later stage, which leads to decrease in the photosynthetic parameters, e.g. stomata conductance, but the photosynthetic and physiological stimulation effects after rehydration tends to grow and the proper moisture stress can promote the water use efficiency of wheat leaf.5. Path analyze on the relationship between grain yeild and indexes such as soil physical, wheat physiological and wheat growth indicates: soil hold water ability, water supply capacity, hydraulic conductivity and field capacity become the influencing factors on wheat grain yield, and the effect of mild stress condition is better. Economic benefit analysis shows that there is the most significant effect of the 60kg/hm2 dosage wih supperabsorbent polymer for yield, and the maximum VCR and income are 7.05 and 1317.6 yuan respectively.更多还原