【作者】 李开峰；

【导师】 张富仓；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2009， 硕士

【摘要】 水分和养分是作物生长的基础条件,是影响我国农业,特别是旱地农业可持续发展的主要因素。从水分和养分之间的关系看,水分和养分又是一对耦联因子,水肥之间存在较大的交互作用。过去人们对水肥与产量之间的相互关系进行了大量研究,取得了重要进展。但研究主要集中在水肥数量和时间的耦合方面,而对空间耦合研究资料相对较少。本研究针对陕西关中地区的农业水资源现状、现有灌水量和方式,通过管栽土柱试验,以冬小麦为指示作物,以土垫旱耕人为土(塿土)为供试土样,采用隔层管栽土柱试验,模拟土壤水分、养分空间分布的几种状况,研究根区土壤不同湿润方式(整体湿润、上湿下干、上干下湿)和施肥方式(整体施肥、上层施肥、下层施肥)空间耦合对冬小麦生长发育、光合特性、根系活力、养分分配利用、水分利用效率和产量及构成的影响。通过研究,获得以下主要结论:(1)与整体湿润和上湿下干处理相比,上干下湿处理显著降低了扬花-灌浆期冬小麦的株高;从不同施肥方式看,下层施肥处理降低了拔节期前的株高和叶面积,但在扬花-灌浆期,不同施肥方式处理之间的差异较小,且各施肥方式处理的叶面积均在该时期达到最大值。不同水肥耦合处理对冬小麦的生物量及器官分配影响不一,上湿下干处理显著增加了地上部干重和总生物量,但根干重和根冠比以上干下湿处理最大;上层施肥和整体施肥处理的地上部干重、根系干重和总生物量均大于下层施肥处理,而根冠比没有差异。(2)光合速率与气孔导度呈显著正相关关系,维持较高的光合速率是以水分散失为代价的。光合速率与籽粒产量之间也存在显著正相关关系,尤其以开花后的光合速率对产量的影响最大,二者的相关性达到P<0.01极显著水平,较高光合速率是作物高产的基础。上干下湿处理不同程度降低了冬小麦的产量和收获指数,但水分利用效率有较大幅度提高;上层施肥方式处理的籽粒产量和水分利用效率均高于下层施肥处理;不同水肥耦合处理主要通过影响单穗粒数来影响产量。(3)扬花-灌浆期,整体湿润处理的根鲜重分别较上湿下干和上干下湿处理增加了5.63%和18.09%。整体湿润与上湿下干处理的根系活力差异不显著,但二者均显著高于上干下湿处理;从不同施肥方式来看,在分蘖期和拔节期,上层施肥和整体施肥处理的根鲜重、干重及根系活力高于下层施肥处理。但在扬花-灌浆期,下层施肥处理的根系活力降幅小于其它两种施肥方式。(4)冬小麦不同部位的氮、磷含量表现为:成熟期前,茎叶>根系;成熟期,籽粒>茎叶>根系。茎叶和根系的氮、磷含量随着生育进程的推进,呈逐渐减小的趋势。上干下湿处理不同程度降低了分蘖期和拔节期的茎叶和根系的氮、磷含量,但在杨花-灌浆期则高于其他两种湿润方式处理,成熟期不同湿润方式对茎叶和根系氮、磷含量的影响不一。下层施肥处理的茎叶和根系氮、磷含量在不同生育时期均较低,整体施肥处理更有利于茎叶和根系维持较高的氮、磷含量。(5)不同水肥耦合方式对铵态氮的分布影响较小,且不同生育时期各土层的铵态氮含量差异不大;但不同施肥方式对硝态氮和有效磷在土层中的分布影响显著,土层中的硝态氮和有效磷含量与该土层施肥量密切相关。(6)从整个生育期来看,上层施肥处理的株高、叶面积、光合特性、根系活力及生物量和籽粒产量的值均显著高于下层施肥处理,与整体施肥处理差异不显著。但上层施肥处理减少了硝态氮和有效磷在下层土壤中的残留,从而有利于下茬作物根系的吸收和因淋溶污染地下水。从生产实际角度考虑,在石灰性土壤中肥料氮的终产物以硝态氮为主,且容易移动,而磷肥不易在土壤中迁移这一特点,无论对整体湿润,还是最常见的上干下湿土壤水分分布状况,氮磷配施时,仍以施入0-35cm土层较好。更多还原

【Abstract】 Water and nutrient are the basic conditions for crops growth, and the main factors for the agricultural sustainable development in China. There is interaction function between water and nutrient, which is a pair of coupling factors. Over the past years, Lots of researches on water and fertilizer coupling in quantity and time had been made and many important results had been acquired, but research on water and fertilizer spatial coupling are relatively insufficient.The studied carried out the pipe string experiment and took the winter wheat as indicator crop and the Lou soil as tested soil according to the status quo of agricultural water resources, the irrigation quantity and irrigation methods in the central of Shaanxi plain. The spatial distribution statuses of water, soil and nutrient were simulated by the barrier pipe string experiment in this study. The pipe consisted of two layers with each layer of 35cm depth and a 2cm layer of coarse sand between soil layers for obstructing water and nutrients exchange. The effect of the spatial coupling between the wetting modes (the overall soil wetting, the upper soil wetting, and the lower soil wettings) and fertilization modes (the overall soil fertilization, the upper soil fertilization and the lower soil fertilization) on winter wheat growth, photosynthetic characteristics, root vigor, nutrient distribution and utilization, water use efficiency, yield and composition was studied. The main results are shown as follows:(1) Compared to the overall soil wetting treatment, the upper soil wetting and lower soil drying treatment made the height of winter wheat decreased significantly during the flowering-filling stage; viewing from the different fertilization modes, the lower soil fertilization made the height and leaf areas decreased before jointing stage, while during the flowering-filling stage, there were no significant differences between the fertilization treatments and the leaf areas reached to the maximum; different water-fertilizer coupling had different effects on the distribution of biomass and organs for winter wheat. The upper soil wetting and lower soil drying treatment increased the above ground parts dry matter and the total biomass, while the maximum root dry matter and ratio of root cap was attributed to the upper soil dry and lower soil wetting; compare to the upper soil fertilization treatment and the overall soil fertilization treatment, the lower soil fertilization treatment was the minimum in terrestrial dry matter, root dry matter and total biomass, while there were no significant differences in root-shoot ratios.(2) There was significantly positive correlation between photosynthetic rate and stomata conductance, and a higher photosynthetic rate was at the expenditure of water vapor. There was also significantly positive correlation between photosynthetic rate and grain yield, especially, after flowering, the effect of photosynthetic rate on yield reached to maximum and the correlation (P<0.01) was extremely significant level. A higher photosynthetic rate was the base of a higher yield. The upper soil drying and lower soil wetting treatment decreased the yield and harvest index of the winter wheat, while increased the water use efficiency greatly; compared to the lower soil fertilization, the yield and water use efficiency in the upper soil fertilization treatment were higher. The water-nutrient coupling treatment affected the yield by single grain number.(3) Compared to the upper soil wetting and lower soil drying treatment and the upper soil drying and lower soil wetting treatment, the overall soil treatment increased the root fresh weight by 5.63% and 18.09% respectively. There were no significant differences in root vigor between the overall treatment and the upper soil wetting and lower soil drying during the flowering-grouting stage, but both of them were significantly higher than the lower soil treatment. Viewing from the fertilization methods, during the filleting stage and jointing stage, the root fresh weight, dry matter and root vigor were lowest in the lower soil fertilization treatment compared to the upper soil fertilization treatment and the overall soil fertilization treatment. But during the flowering-filling stage, the decreasing amplitude of root activity in the lower soil fertilization treatment was the lower than the other fertilization treatments.(4) In different parts of winter wheat, the contents of N, P were just as follow: before the maturing stage, the content in stem and leaf was greater than the one in root; during the maturity, the contents in the order grain>stem and leaf >root. In stem and leaf and root, the content of N, P decreased gradually with growth process. During the tillering stage and jointing stage, the upper soil drying and lower soil wetting decreased the contents of N, P in stem and leaf and root. But during the flowering-filling stage, the contents of N, P in stem and leaf and root in this treatment was higher compared with the other wetting treatments. During the maturity, different wetting treatment had different effects on the contents of N, P in stem and leaf and root. In the lower soil fertilization treatment, the contents of N, P in stem and leaf and root were lowest in different growth periods. The overall soil fertilization treatment could maintain the contents of N, P in stem and leaf and root better.(5) Different water-fertilizer coupling treatments had little effect on the distribution of NH4+-N, and during the different growth periods, the contents of NH4+-N in soil layers were no significant changes; different fertilization treatments had significant effects on the distribution of nitrate-N and available-P in soil layers. The contents of nitrate-N and available-P were revelation with the fertilization amount in the soil layers.(6) Viewing from the over whole growth period, the crop height, leaf area, photosynthetic characteristics, root activity, biomass and grain yield in the upper soil fertilization treatment were significantly higher than those in the lower fertilization treatment, while compared to the overall soil fertilization treatment, there were no significant differences. The upper soil fertilization treatment reduced the residual content of the nitrate -N and available-P in the next soil layers, which was benefit for the crop root absorption and kept the ground water from being contaminated resulting in leaching. On the production practice point of view, in the calcareous soil, the N fertilization finally formed the nitrate-N, which is movable easily. P is hard to transfer in soils, so it would be better to put the P fertilizer in the soil layer ranged from 0 cm to 35 cm.更多还原