耕作方式对华北冬小麦.夏玉米周年产量和水分利用的影响

在冬小麦季设置秸秆不还田翻耕(CT)、秸秆还田翻耕(CTS)、秸秆还田旋耕(RTS)和免耕秸秆覆盖(NTS)4种处理,研究耕作方式对华北小麦-玉米两熟区作物周年产量和水分利用的影响。结果表明:耕作方式对当季冬小麦产量和水分利用影响显著,对夏玉米产量和水分利用影响不大,但秸秆还田提高了夏玉米产量。RTS、CTS、CT 3个处理小麦季产量差异不显著,而NTS由于有效穗数不足,产量显著低于其他处理;与CT相比,NTS周年产量平均减产5.13%,RTS增产2.69%,CTS增产2.33%。耕作方式对当季小麦土壤水分含量影响大,而对后茬夏玉米土壤水分含量的影响较小。NTS提高了小麦季土壤水分含量,增加了土壤储水量,与CT相比,0~60 cm土壤储水量2010年和2011年分别增加39.07 mm和26.65 mm。从耗水构成来看,土壤水在冬小麦耗水中所占比例最大,其次为灌水和降水;而夏玉米耗水以降水为主,且降水中有一部分转化为土壤水储存起来。NTS提高了冬小麦季土壤储水量,降低了土壤水分的消耗,冬小麦季耗水最少。与CT相比,NTS小麦季平均节水22.40 mm,周年耗水量也以NTS最少;但NTS冬小麦产量降低导致其小麦季和周年水分利用效率均最低。从作物周年产量和水分利用的角度来看,如何提高免耕秸秆覆盖小麦季产量,进而提高周年产量,发挥其节水优势,是该耕作模式在华北地区冬小麦?夏玉米两熟区推广应用亟需解决的关键问题。     

基于高频探地雷达的土壤表层含水量测定

高精度快速探测土壤表层水分状况,对于精准农业生产、水资源精确管理及防治坡耕地水土流失具有重要意义。现有探地雷达(ground penetrating radar,GPR)低频探测技术不能满足表层土壤含水量高精度要求,需要发展和应用高精度探测技术。本研究采集江宁某蔬菜地水稻土表层(0~20cm)土壤(粉砂质黏壤土),通过室内模拟试验,利用高频(1 GHz和2 GHz)探地雷达在不同土壤含水量状况下进行探测,获取GPR数据图像信息,提取电磁波谱特征参数,分析其与土壤含水量之间的定量关系。结果表明:1 GHz和2 GHz频率GPR探测的土壤介电常数ε与实测土壤含水量θ拟合的ε~θ模型决定系数R2分别为0.94与0.97,高频探地雷达技术预测粉砂质黏壤土表层土壤含水量是可行的;与低频探地雷达技术相比,高频探地雷达技术能够高精度探测表层土壤含水量。     

不同含盐量土壤盐分对蒸发的影响试验研究

土壤地表蒸发是一个复杂的过程,它的正常进行受到诸多因素的影响,其中土壤盐分是蒸发的主要影响因素之一。以内蒙古河套灌区永联试验站含盐土壤为例,通过室内试验盐分含量分别为0.2%、0.6%、1.0%、5.0%的土壤水分、盐分的变化以及对蒸发的影响进行了分析。试验结果表明:实验进行的初始阶段土壤剖面中含水率变化是比较显著,地下水补给对土壤蒸发的影响较大,实验持续到第15天之后随着土壤含水率的稳定变化,土壤蒸发量慢慢下降,这个时间段土壤水分迁移主要被土壤盐分控制。实验开始的前一段时间土壤水分对盐分的影响不太明显,实验持续到15天之后,尤其是,土壤表层形成盐壳之后,土壤水分对含盐量的影响以及盐分对水分的相应反馈比较明显。同一个时间来看,盐分含量高的土壤水分比较低。不同盐分含量的土壤中随着含盐量的增加,土壤蒸发速率减小。通过分析可知土壤含盐量与蒸发量具有很好的相关性,盐分越高,相关性越好。     

古尔班通古特沙漠人工梭梭林群落生态特征研究

为探究古尔班通古特沙漠南缘莫索湾地区33年来人工梭梭林群落(依靠天然降水)的生态特征,本文对两种造林技术(积雪-客沙造林和秋灌造林)人工梭梭林地梭梭的长势、草本植物、土壤水分进行了调查和监测。结果表明:(1)积雪-客沙造林和秋灌造林梭梭至今生长良好,目前植株高度和冠幅均大于2 m和2 m~2,当年新生枝条长度均大于20 cm;初始造林梭梭存活率较高,分别为40%和63%;经过自然更新,现有密度均有所提高,人工林形成异龄复层混交林,林下生长有不同优势种的草本植物;土壤含水量均2.00%,能够满足梭梭生长。(2)由于两种造林技术的土地处理方式和初期水分供给量不同,导致两种林地梭梭生长、林下草本植物盖度和多样性以及天然更新梭梭植株数量均有很大差异,整体秋灌造林地的状况优于积雪-客沙造林地。(3)两种造林技术对于当地生态条件均有很好的适应性,虽然积雪-客沙造林密度相对较低,但优于自然植被状况,且造林成本低;秋灌造林密度较大,天然更新植株数量较多,但造林成本高,后期生长较缓慢,需要采取一定的人工措施调整密度。综上可知,积雪-客沙造林和秋灌造林梭梭目前生长均较稳定,后者对该区生态条件适应性更强。     

基于声学特性的西瓜糖度检测系统

该研究优化了由包裹橡皮的金属小球、压电式加速度传感器、电荷放大器、光电式触发电路、数据采集卡和计算机等组成的西瓜声学特性测试系统。由所获取的声波信号幅值谱计算出声透过率,采用TQ软件中SMLR(逐步多元线性回归)函数选取6个特征频率:752、869、1001、4556、322、3950Hz,由其对应的声透过率值建立了西瓜品质检测的多元线性回归模型。对47个西瓜样本的试验数据分析表明:将敲击点和接收点分别放置在西瓜自然生长状态的中部对侧可获得最佳的测定模型,模型的校正相关系数R、校正均方根误差RMSEC和预测均方根误差RMSEP分别是0.80753、0.646和0.655。实现了西瓜糖度检测目的,为声学无损检测西瓜成熟度提供了参考。     

Effect of Preharvest Sprays of Calcium on Cracking and ‘Schattenmorelle’ Sour Cherry Fruit Quality Harvested Mechanically

The aim of the study was to examine effect of preharvest sprays of calcium (Ca) in the form of Ca-chloride (CaCl₂), Ca-nitrate [Ca(NO₃)₂], or a mixture of Ca-formate, Ca-acetate, CaCl₂, and Ca(NO₃)₂ on cracking and quality of ‘Schattenmorelle’ sour cherry fruit harvested mechanically. The experiment was conducted in 2008–2009 at a commercial orchard in central Poland. Mature trees grew on a coarse-textured soil poor in organic matter, at a spacing of 4.0 × 1.5 m. The spray treatments of Ca were performed at 7-day intervals, starting 28 days before harvest, at the rates of 5.0–5.6 kg Ca ha^?1 per season. The trees sprayed with water were treated as the control. Fruit were harvested mechanically when peduncle-fruit detachment force dropped below 3 N. The results showed that preharvest Ca sprays caused no leaf damage. This measure did not affect yield, mean fruit weight, soluble solids concentration and titratable acidity of fruit, and weight loss of fruit during 24 h after harvest. Fruit sprayed with Ca had improved status of this nutrient, and were less liable to juicy leakage from the stem scar, rain-induced cracking, and preharvest decay caused by Glomerella cingulata. The above effects of Ca sprays did not depend on the tested material. It was concluded that preharvest sprays of Ca as CaCl₂ and/or Ca(NO₃)₂ should be recommended in ‘Schattenmorelle’ sour cherry orchards to reduce fruit losses resulting from rain-induced cracking, leakage of juice, and the incidence of cherry bitter rot.     

土壤持水特性参数与土壤质地尺度关系的联合多重分形分析

Soil water-retention characteristics at measurement scales are generally different from those at application scales, and there is scale disparity between them and soil physical properties. The relationships between two water-retention parameters, the scaling parameter related to the inverse of the air-entry pressure (αvG, cm-1) and the curve shape factor related to soil pore-size distribution (n) of the van Genuchten water-retention equation, and soil texture (sand, silt, and clay contents) were examined at multiple scales. One hundred twenty-eight undisturbed soil samples were collected from a 640-m transect located in Fuxin, China. Soil water-retention curves were measured and the van Genuchten parameters were obtained by curve fitting. The relationships between the two parameters and soil texture at the observed scale and at multiple scales were evaluated using Pearson correlation and joint multifractal analyses, respectively. The results of Pearson correlation analysis showed that the parameter αvG was significantly correlated with sand, silt, and clay contents at the observed scale. Joint multifractal analyses, however, indicated that the parameter αvG was not correlated with silt and sand contents at multiple scales. The parameter n was positively correlated with clay content at multiple scales. Sand content was significantly correlated with the parameter n at the observed scale but not at multiple scales. Clay contents were strongly correlated to both water-retention parameters because clay content was relatively low in the soil studied, indicating that water retention was dominated by clay content in the field of this study at all scales. These suggested that multiple-scale analyses were necessary to fully grasp the spatial variability of soil water-retention characteristics.     

Ameliorative effect of potassium on mice and tomato subjected to sodium salinization

Rice (Oryza sativa L. cv. Yamabiko) and tomato (Lycopersicon esculentum Mill cv. Saturn) plants subjected to Na-salinization (NA: 80 mmol( + ) kg^-1 Na) in hydroponics were grown after the addition of K at five concentrations (K1: 10, K2: 20, K3: 30, K4: 40, K5: 50 mmol( + ) kg^-1). The effect of K on their growth was analyzed in terms of transpiration, cation uptake, and transport. A similar tendency for the above parameters was obtained in both species. The addition of 10 mmol( + ) kg^-1 K improved the growth by decreasing the content of Na and increasing the K content of the plants. The growth of the plants, however, was reduced along with the increase of the K concentration and became comparable to that of NA at K5. The total cation content increased with the increase of the K concentration, which was due to the increase of the K content.

A close relationship was observed among the osmotic potential of the solution, cumulative transpiration, and dry weight for both species among the K treatments.

Addition of K suppressed the uptake of other cations by rice and tomato in the order of Na>Mg>Ca, with a very small suppression for Ca and Mg. The depression of Na uptake by K could be due to the antagonism between the two cations.

In rice, the addition of K resulted in a decrease of the uptake concentration (UC) of Na and an increase of that of K, but did not bring about any changes in the UC of Ca and Mg. It was worth noting that K1 and K2 led to a higher UC of Na than NA in tomato, while the trend of the UC of K, Ca, and Mg was similar to that in rice. The transport of Na and Ca to the tops of rice was not affected by the addition of K, while that of Mg increased by K addition. In tomato, the transport of all the cations was promoted by the increase of the K concentration.     

Prediction of grain protein content in winter wheat through leaf color measurements using a chlorophyll meter

A field trial was conducted over a 3-year period at the Hokkaido Kitami Agricultural Experiment Station to examine whether the grain protein content (GPC) of a winter wheat cultivar (Triticum aestivum L. cv. Chihokukomugi) suitable for Japanese noodle-making could be predicted before harvest. The prediction of the GPC was accurate based on the color of the second leaf (just below the flag leaf) at the end of the emergence of the inflorescence, when nitrogen application was graded. In order to evaluate the reliability of this test, a survey of 95 wheat fields in the eastern part of Hokkaido was also carried out during a 3-year period. The prediction of the GPC for this cultivar based on the color of the second leaf was less accurate across many sites. The results of this survey, however, suggested that the leaf color could be used as an index for ranking the GPC as low or high in relation to processing requirements. When the leaf color value of the second leaf measured with a chlorophyll meter at the end of the emergence of the inflorescence was less than 40, it was predicted that the GPC would be lower than the processing requirement. This index could be applied to the cultivars grown in the eastern part of Hokkaido, except for those grown on peat soils.     

烟草含钾量反射仪-钾离子试纸法快速测定研究初报

比较了反射仪—K 试纸法(K ts-fl)、原子吸收光谱法、ICP-aeS法测定烟株叶脉汁液中的K 含量的三种方法,确定反射仪—K 试纸法测定烟株钾含量的可行性及其最佳测定范围;在烤烟不同生育期,应用反射仪—K 试纸法对烟株叶片不同部位含K 水平的测定,确定其最佳测定时期及部位。研究结果表明,反射仪—K 试纸法与原子吸收光谱法、ICP-aeS法测定结果差异不显著,应用反射仪—K 试纸法进行烟株钾素快速诊断可行,且具有时间短,简单快速,易操作等优点。反射仪测定K 的稳定线性范围是0.30～0.9g/L;在不同时期对烟株不同部位测定研究表明,最佳诊断部位为烟株第二平展叶叶脉基部2cm段。