黄土塬区夏玉米物质生产及水分利用对品种间作竞争的响应

品种间作竞争具有优化作物个体形态特征和生物量分配的生态效应。综合干旱环境、密度和降雨年际变化影响下的品种间作生物量分配机制研究,可为旱区作物增产增效栽培提供理论依据。试验于2011年(降雨量645.0 mm,湿润年份)和2012年(降雨量497.1 mm,干旱年份)调查了两个玉米品种(‘郑单958’和‘沈单16号’)、两种密度(4.5万株?hm-2和7.5万株?hm-2)隔行间作处理下,地上部生物量和地下部根系形态特征,并分析了品种间作下生物量分配策略、根系竞争机制与产量、水分利用效率的关系。结果显示:1)干旱显著降低玉米根系表面积(SA),低密度间作下‘沈单16号’扬花期SA显著降低而‘郑单958’显著增加,高密度间作‘郑单958’的SA显著下降25.3%,间作下根系对于水资源的竞争随种植密度的增加而加剧;两个种植密度和两个不同降雨年份,间作系统0~20 cm土层根长密度(RLD)显著增加,增加种植密度和雨水亏缺,刺激根系向深层土壤生长,导致30~40 cm土层RLD的增加,且‘郑单958’的RLD增加幅度远高于‘沈单16号’。2)间作竞争下生物量积累具有品种差异,‘郑单958’集中在营养生长期,而‘沈单16号’集中在生殖生长期;且随种植密度的增加,间作栽培下单株生物量显著降低。3)群体收获指数(HI)在高密度间作下,两个不同降雨年份出现平均6.0%的增加幅,雨水充足促进群体HI的提升;根冠比因降雨和种植密度而变,雨水充足、低密度间作下根冠比较大,干旱和高密度下资源竞争造成‘郑单958’根冠比显著下降。4)干旱年份玉米品种间作增产优势显著,高、低密度间作增产率分别为10.3%和21.4%,水分利用效率(WUE)分别增加28.2%和42.0%;且‘郑单958’增产和增效能力分别较‘沈单16号’高17.6%和50.0%。综上所述,品种间作栽培下‘郑单958’具有更合理的地上部生物量分配和响应机制,其根系通过减少冗余生长,降低资源消耗来应对土壤干旱,高效的根系自我调节能力和生物量分配机制在间作系统产量形成和WUE提升中起到了关键作用。     

高海拔(西藏)半干旱地区玉米全膜双垄沟播栽培技术探析

采用田间试验,设全膜双垄沟播、全膜平作和裸地平作3种种植方式,测定玉米各生育时期的土壤含水量、干物质量、光和速率、产量和产量构成因子,分析不同处理的土壤耗水量、贮水量、含水量垂直变化以及水分利用效率,探讨全膜双垄沟播下玉米土壤水分的动态变化和利用效率。结果表明,覆膜可使玉米出苗提前2 d,促进玉米前期营养生长并提前灌浆5 d,覆膜处理的整个生育期缩短8 d。全膜双垄沟播处理的产量和水分利用效率最高,分别为27 309 kg/hm~2、69.2 kg/(hm~2·mm),同时生育期耗水量最小(394.5 mm),能够提前灌浆,减少灌浆时期耗水量。收获后,全膜平作和裸地平作处理的土壤水分出现亏缺,各土层贮水量均减少,全膜双垄沟播处理的各土层土壤含水量均高于播前。全膜双垄沟播处理的玉米净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)显著高于其他处理,收获时各处理的子粒和秸秆干物质累积量均表现为全膜双垄沟播全膜平作裸地平作。     

半干旱区燕麦品种茎秆理化特性及其与抗倒性的关系研究

本研究以抗倒性不同的4个燕麦（Avena sativa L.）品种为材料,分析了乳熟期茎秆基部理化物质含量差异,探讨了茎秆理化特性与燕麦抗倒伏的关系。结果表明：4个燕麦品种田间倒伏分级和实际倒伏率差异显著（P<0.05）,抗倒伏品种与易倒伏品种在茎秆理化物质含量上差异显著（P<0.05）。抗倒伏品种茎秆基部第1节、第2节氮和镁低于易倒伏品种,而茎秆基部第1节、第2节钾、钙和硅高于易倒伏品种。另外,抗倒伏品种茎秆基部第1节、第2节木质素、纤维素和可溶性糖及C/N显著（P<0.05）高于易倒伏品种。4个燕麦品种茎秆基部理化物质与倒伏指数及其构成要素、茎秆基部形态特征间均存在显著（P<0.05）或极显著（P<0.01）相关关系,茎秆基部第1节与第2节钾、钙和硅,可溶性糖、木质素及纤维素含量的高低与燕麦抗倒伏关系密切。     

半干旱地区菊芋品系植株表型与光合特性分析

为了加快半干旱地区的新型资源作物菊芋品种的选育进程,探讨菊芋产量及相关性状表型和光合生理基础是必要的。选用本课题组收集和培育的4个品系( 2个高产,2个低产品系),设置随机区组试验,比较菊芋高产和低产品系与产量形成相关的生物量累积、植株表型和光合特性的差异。结果表明,高产菊芋品系的地上生物量、块茎产量及根生物量显著高于低产品系;高产品系整体表现出明显的生长优势,其株高、基径、叶面积和叶片数均显著高于低产品系。气体交换参数分析表明,高产品系的光补偿点和暗呼吸速率显著小于低产品系,而其他各项参数差异不显著。相关性分析表明,菊芋块茎产量与株高、基径、叶面积、叶片数、地上生物量和根生物量呈显著正相关,而与光补偿点和暗呼吸速率呈显著负相关。建议多的叶片数、大的叶面积和发达的根系作为半干旱地区菊芋高产品系田间选育指标,而低的光补偿点和暗呼吸速率在高产品系选育中也具参考价值。     

陇中半干旱区全膜覆土穴播小麦的土壤水分及产量效应

提高作物对自然降水的利用效率是干旱半干旱区提高粮食产量、增强农田系统抵御干旱胁迫的主要途径之一。试验研究了在大田条件下陇中半干旱区小麦全膜覆土穴播栽培对土壤含水量、水分利用效率及产量的影响。结果表明:全膜覆土穴播处理的产量可达3518.61kg/hm2,比裸地提高29.13%,比传统地膜覆盖处理提高24.63%;水分利用效率为12.59kg/hm2.mm,比裸地提高19.90%,比传统地膜覆盖处理提高18.76%。全膜覆土穴播栽培技术能够显著提高小麦产量及水分利用效率,在小麦生育前期有效保持土壤水分,中后期可以将深层土壤(40～120cm)水分提到上层供小麦生长所需。     

吉林省半干旱区45年气候变化及基于Hybrid-Maize的玉米品种熟期选择

本研究分析吉林省西部半干旱地区1971~2015年气候要素变化特征,用Hybrid-Maize模型估算该区域品种熟期(GDD)不同玉米品种的产量潜力。结果表明,该区域近45年温度、降水和日照时数年均变化与玉米生长季变化趋势类似,但生长季变幅与年均值变幅差异较大,且生长季时间序列上突变点明显不同,温度和降水具有滞后性,日照时数具有超前性,其中,生长季温度增幅高于全年温度增幅,但突变时间滞后10年;长期年均降水波动性大,而生长季降水较全年呈现明显上升趋势,且2010年以来生长季均为较湿润阶段。生长季日照时数减少比年均减少趋势慢,为其下降速率的40%。以4月30日为适播期,种植密度60 000株/hm~2时,乾安、洮南、前郭推荐熟期相对较长品种(GDD=1656-1672),扶余、镇赉推荐熟期相对较短品种(GDD为1606和1500)。洮南、扶余、前郭玉米R/V值接近1.0,乾安和镇赉R/V超过1.15,利于获得较高产量。     

Modeling hydrologic responses using multi-site and single-site rainfall generators in a semi-arid watershed

Hydrologic response in a watershed is driven by precipitation. Multi-site rainfall generators can be used to model watersheds using spatially varied rainfall inputs to better analyze how the rainfall variability affects runoff generation. This study adopted both a single-site rainfall generator (CLIGEN) and a multi-site rainfall generator to generate two rainfall data sequences, which were then used to drive the Soil and Water Assessment Tool (SWAT) for runoff simulation. The 148-km² Walnut Gulch Experimental Watershed and its two sub-watersheds were selected to evaluate the hydrologic response. Runoff calibration was done against measured runoff in the watershed. Statistics showed that the single-site and multi-site rainfall generators gave similar results regarding annual precipitation. However, the multi-site generator performed much better than the single-site generator in both mean summer flow and for the different return period flows. The runoff derived from the single-site generator was significantly over-estimated in all three watersheds. As for the multi-site generator, the derived runoff was satisfactorily predicted in the smaller watersheds but only overestimated in the largest watershed. This indicated that in small to medium sized watersheds, the spatial variability of rainfall could play an important role for hydrologic response because of the heterogeneity of convective rainfall in this semi-arid region, which makes the application of multi-site rainfall generator a better option than the single-site generator.     

The feasibility of using soil seed bank for natural regeneration of degraded sandy grasslands

Desertification in degraded grasslands is manifested through the development of bare sandy patches, which eventually lead to habitat fragmentation. The ability of these bare sandy patches to regenerate naturally through in-situ soil seed banks is not well understood. To fill this knowledge gap, we randomly selected 24 bare sandy patches with areas ranging from 19 to 898 m² in a desertified grassland of the Horqin sandy land, Northern China to determine whether soil seed bank can be used for natural regeneration of bare sandy patches. Species composition and density of soil seed bank as well as aboveground vegetation composition, abundance and coverage were investigated. We then determined their relationships with in-situ habitat characteristics. Our observations showed that the studied area had low soil seed bank density and species richness, as well as depauperate soil seed bank communities. Consequently, local soil seed bank was not able to provide sufficient seed source for natural regeneration. This was indicated by the relationships between aboveground vegetation, soil seed bank and the in-situ habitat characteristics. For bare patches with an area between 300 m² and 900 m², increase the soil seed bank density and species richness should be the main restoration measures. For bare patches with a small area of less than 50 m², restoration of vegetation density should be the main measure. Our data highlighted that different extents of desertification, indicated by different bare patches, are requiring distinct restoration measures.