【作者】 严菊芳；

【导师】 张嵩午；

【作者基本信息】 西北农林科技大学 ， 作物栽培学与耕作学， 2009， 硕士

【摘要】 作物总是生长在某一特定的小气候环境中,创造适宜的小气候环境,有助于作物的生长发育及产量的提高和品质的改善;同时,分析逆境对作物生长发育的影响,可以探究作物对不利环境的适应能力,有利于优良品种的筛选及培育。自冷型小麦提出以来,在不同温型小麦灌浆结实期的代谢生理特性、显微结构特征、氮磷营养特征、干旱阴雨条件下表观特征、正常天气条件下的小气候及热量平衡等方面进行了研究,但干旱胁迫下的农田热量平衡及其小气候特征尚未进行研究。为此,作者以典型的冷型小麦为主,以在温度上反差最为强烈的暖型小麦为对比设置本试验,研究了干旱胁迫下冷型小麦的农田小气候特征及热量平衡,以揭示冷型小麦对干旱胁迫的适应机制,为丰富和完善冷型小麦的研究并逐步将冷型小麦推向生产提供理论依据。试验于2005～2007年在西北农林科技大学农作站进行,以典型的冷型小麦和暖型小麦为材料。为保证充分的干旱条件,在大田开展试验的同时,人工搭建干旱棚,在小麦拔节期以后断绝外界水分供应。通过对不同温度型小麦灌浆结实期群体冠层温度、气象要素、热量平衡各分量、叶片生理代谢参数—绿叶面积、叶绿素含量、蛋白质含量、净光合速率及有关产量参数等指标的测定,研究了干旱条件下冷型小麦的农田热量平衡及小气候特征。试验结果表明:1.干旱条件下冷型小麦农田净辐射低于暖型小麦,午后冠顶上方0.5m和1.0m处净辐射辐照度,冷型小麦较暖型小麦分别偏低16.35～47.57w/m2和14.45～60.25w/m2,二者差异不显著;株间潜热通量在0.2m～2/3株高和2/3株高～冠顶处冷型小麦“小偃6号”较“NR9405”均偏高,湍流热通量则都偏低。0.2m～2/3株高和2/3株高～冠顶冷型小麦的潜热通量较暖型小麦分别偏高29.09～48.61W/m2和47.41～134.89W/m2;湍流热通量分别偏低12.48～62.57W/m2和29.37～85.81W/m2。经t检验,两种温度型品种除棚外2/3株高～冠顶处潜热通量和湍流热通量在0.1显著性水平上存在较明显差异外,旱棚内、外0.2m～2/3株高处潜热通量和湍流热通量以及旱棚2/3株高～冠顶处潜热通量和湍流热通量均存在显著或极显著差异(P<0.01～0.05)。活动层与大气之间的潜热通量,冷型小麦较暖型小麦偏高50.3～120.2W/m2(P<0.1),湍流热通量偏低30.5～102.4W/m2(P<0.05)。2.干旱条件下冷型小麦的土壤热通量比暖型小麦偏低24.60～65.19W/m2,差异达0.01极显著水平。3.干旱条件下冷型小麦的株间气温低于暖型小麦,二者的温差在白昼气温14:00左右最大,距地面0.05m高处达3.4℃。同时,冷型小麦具有较低的冠层温度、土壤温度和较小的株间光照度,且株间水汽压、相对湿度明显高于暖型小麦,田间小气候环境显示出冷、湿的特点。4.冷型小麦冷湿的田间小气候环境,为其在叶绿素含量、蛋白质含量、绿叶面积、净光合速率、籽粒饱满指数以及有关产量参数等方面的表现优于暖型小麦创造了有利条件。尤其在干旱胁迫下,冷型小麦的优势愈明显。由本研究株间光照度的观测结果可知,冷型小麦由于地面接受太阳辐射较弱,使得地面(第二热源)增温不剧,长波辐射不强,减弱了对冠层的烘烤,导致冠层温度较低(外因),这有利于减轻小麦植株早衰。5.相对暖型小麦而言,冷型小麦具有较高的潜热通量和较多的同化热,从农田活动层热量平衡方程式R = P +LEC + Qs +IA+QT+QA看,若净辐射R的能量大部分且更多地消耗于蒸腾潜热LEC时,则加热叶片和株茎的能量QA和QT必然变小,结果导致冠温偏低;暖型小麦与此相反,消耗于+LEC的能量相对较少,则QA和QT相对增多,结果导致冠温偏高。经计算旱棚内冷型小麦“小偃6号”和暖型小麦“NR9405”的QA +QT分别为67.7W/m2和97.8W/m2,棚外分别为54.4 W/m2和75.1 W/m2。这是干旱条件下从能量平衡角度所揭示的冷、暖型小麦冠温出现重要差异并引起一系列小气候要素发生相应改变的机理。6.我国北方旱区在小麦灌浆结实期间易出现高温和干热风等灾害性天气,对小麦千粒重和产量影响很大,而冷型小麦小气候冷、湿的特点则会明显减轻这些灾害性天气的危害。因此,冷型小麦对干旱条件较强的适应能力,为我国北方干旱半干旱地区的小麦生产提供了良好的发展前景。更多还原

【Abstract】 Crops always grow in a particular microclimate environment, the creation of which will promote crop growth, a yield enhance and quality improvement. Furthermore, analyses of adverse effects on crop growth and development can probe into the crops’adaptability to adverse environments so as to optimize the breed selection and cultivation. Since the cold type wheat has been proposed, the relevant studies focus mainly on metabolic physiological features of different warm type wheat in a grouting and fructifying phase, micro-structural features, features of nitrogen and phosphorus nutrient, exterior features under dry or rainy conditions, micro-climate and heat balance under normal climatic conditions. However, research into heat balance of cold type wheat farmland under drought conditions and micro-climate characteristics has not been conducted yet. Therefore, the author has set experiment mainly on typical cold type wheat in contrast to warm type wheat highly sensitive to temperature contrast, and studied the subject mentioned above, aiming at adding to enrichment and perfection of cold type wheat studies and providing theoretical foundation of cold type wheat production.From 2005 to 2007 the experiment has been carried out at the agricultural experimental station of Northwest Agriculture and Forestry University. The typical cold type wheat and warm type one are the subjects. To maintain adequate drought conditions, while unfolding the experiment in farmland dry shed has been put up artificially and exterior water supply has been cut off after a jointing season of the wheat. Farmland heat balance and micro-climate characteristics have been studied by surveying and evaluating quota of the different temperature-type filling stage of wheat canopy temperature, weather elements, the heat balance components, physiological and metabolic parameters, green leaf area, chlorophyll content, protein content, net photosynthetic rate, the output parameters and the like. The experimental results are:(1) Under the arid condition the net radiation of cold type wheat fields is lower than that of the warm wheat. At 2:00 PM or so the net radiation flux density of the cold type wheat is 16.35～47.57w/m2 and 14.45～60.25w/m2 lower than that of the warm type measured at the two locations, 0.5m above plant top and 1.0m above the plant top respectively. The distinction of the two kinds is not apparent. The latent heat flux in row of the cold type wheat,“XY 6’’measured at the Space 1 above 0.2m from the ground to 2/3 plant height, and the Space 2 above 2/3plant height to the plant top is 29.09～48.61W/m2 and 47.41～134.89W/m2 higher than NR9405, the turbulent heat flux of which is lowerr than“NR9405”by 12.48～62.57W/m2 and 29.37～85.81W/m2. Through T test the two types presented rather evident difference in the latent heat flux and the turbulent heat flux above 0.1 prominent horizontal level except at the Space2. The others displayed prominent or rather prominent difference.(P<0.01～0.05). The latent heat flux between the active layer of the cold type“XY 6”and atmosphere is 50.3～120.2W/m2 higher than an amount between the active layer of the warm type“NR9405”and atmosphere in a drought-simulating shelter(P<0.1) , the turbulent heat flux of the cold type poured into the atmosphere is 30.5～102.4W/m2 less than that done by the warm type“NR9405”(P< 0.05).(2) Under drought conditions the soil heat flux of the cold type is 24.60～88.92W/m2 lower than that of the warm type, reaching 0.01 prominence standard.(3) Also under drought conditions the temperature among cold type wheat is lower than that of the warm type. Around 14: 00 AM at the location above soil 0.05m the temperature difference will reach 3.4℃. At the same time, cold type wheat showed lower temperature at plant top location and lower soil temperature, smaller illumination among plants, higher relative humidity, and the micro-climate in the field featured coldness and humidity.(4) The microclimate environment of the cold type wheat field forged advantages over that of the warm type concerning better performance in chlorophyll contents, protein contents, green leaf areaes, net photosynthetic rate, plumpness indexes and output parameter. Especially under drought conditions these advantages become more prominent. The study come by from illumination among plants tells that the soil temperature (second heat source) will not turn up intensely and the long wave radiation is not that strong due to the cold type’s weak reception of solar radiation. Easing up baking the plant layer leads to low canopy temperature (external cause), which is beneficial to mitigating premature senility of wheat plant,(5) Compared with warm type wheat, the cold type wheat has higher latent heat flux and more assimilation heat. From the point of the field active layer heat balance formula R = P +LEC + QS +IA+QT+QA, if the rising latent heat LEC consumes a main joint of energy of net radiation R, the heating leaf blade and stem energy QA and QT will necessarily turn down, which leads to decline of crown top temperature. QA+ QT of the cold type wheat“XY 6”and NR9405 in a drought-simulating shelter is 67.7W/m2 and 97.8W/m2 respectively. The related value in a field land is 54.4 W/m2 and 75.1 W/m2 respectively. This is a revelation of mechanism that the cold type wheat is different from the warm one in the value of the canopy temperature, which activates a series of changes in the microclimate elements.(6) The grouting season in drought farmland of Northern China often sees disastrous weather as high temperature and hot wind, affecting wheat grain weight and output. Fortunately, cold and humid features of the cold type wheat can ease up the threat a great deal. Therefore, the adaptability of the cold type wheat to drought conditions provides a promising prospect for wheat production in arid or semiarid area of Northern China.更多还原