基于沙粒佛汝德数相似原理推算沙波河床上推移质输沙率

基于沙粒佛汝德数相似原理,首先推导出利用模型试验结果估算原型沙波河床上推移质输沙率的推算公式;然后塑造与原型较为一致的床面形态,利用模型试验对推算公式进行了验证。结果表明,在保证原型与模型的粒径比尺较大,且模型与原型床面形态一致的条件下,运用该方法推算沙波河床上的推移质输沙率时,可以取得较为满意的结果。     

施用含硒有机肥对粉葛产量及硒吸收转运的影响

本研究采用随机区组试验,设置6个处理,研究增施不同量含硒有机肥对粉葛生长、产量及硒在粉葛不同器官中富集状况的变化,探讨增施含硒有机肥对粉葛产量和硒吸收转运的影响。结果表明：随着施肥量的增加,净光合速率先降低后升高,胞间CO₂浓度（C_i）、蒸腾速率（T_r）和气孔导度（G_s）则逐渐递增。施用含硒有机肥均显著提高了粉葛块根中的硒含量,块根硒含量最大值达0.084 mg/kg,比对照处理提高58.49%。藤/块根、芦头/块根中硒的转运系数均有降低,说明随着施肥量的增加,更多的硒被固定在块根中;根际土壤中总硒含量比对照提高6.9%~27.4%,有效态硒含量提高了9.5%~34.8%。施肥均显著提高了商品薯中的硒积累量,各处理分别比对照提高了39.64%、13.73%、29.79%、47.66%和69.95%。综合考虑肥料成本、产量及块根硒积累量等因素,实际生产中施肥量6000 kg/hm²较为合适。综上所述,增施生物有机肥可提高粉葛的光合作用,促进其生长,提高块根产量及硒积累量。研究结果为含硒有机肥调控下粉葛富硒栽培提供了理论参考。     

生物炭与化肥减量配施对玉米干物质、产量及氮、磷、钾积累转运的影响

采用田间小区试验,以先玉335为材料,设置5个处理,分别为CK(常规尿素+磷酸二铵+硫酸钾)、BF1(生物炭+80%尿素+80%磷酸二铵+80%硫酸钾)、BF2(生物炭+80%尿素+磷酸二铵+硫酸钾)、BF3(生物炭+尿素+80%磷酸二铵+硫酸钾)、BF4(生物炭+尿素+磷酸二铵+80%硫酸钾),玉米开花期、成熟期采集样品,分析不同处理干物质和养分积累转运特征,明确生物炭与化肥减量配施对玉米产量及氮磷钾养分积累转运的影响。结果表明,BF1、BF2、BF3、BF4处理均增加了植株干物质积累量、转运率及对子粒干物质积累贡献率,提高了玉米产量,促进了玉米植株氮磷钾素积累总量。因此,可应用生物炭与化肥减量配施实现玉米节肥增产。本试验条件下,减量20%硫酸钾配施生物炭对玉米产量效果最优。     

生化黄腐酸对土壤物理性质及水分运动特性的影响

为了探究生化黄腐酸(biochemical fulvic acid, BFA)在土壤结构改良方面的应用,通过向土壤中添加BFA,研究其在不同浓度处理下对土壤物理性质及水分运动特性的影响。结果表明:(1)随着BFA施加比例提高,土壤中0.25 mm的水稳性团聚体数量显著增多,施加比例为20 g/kg时,R_(0.25)、MWD、GMD分别增加284.98%,105.64%,35.06%,分形维数降低2.17%。(2)在温度与pH变化的影响下,随着施加比例增大,Zeta电位的绝对值逐渐增大,施加比例为20 g/kg时,Zeta电位的绝对值分别提高11.77%,59.70%。(3)向土壤中施加BFA可以显著增强土壤的入渗能力,提高累积入渗量与入渗率,随着施加比例的增大,累积入渗量提高28.83%;3种入渗模型均能较好地模拟土壤水分入渗过程。     

The high tolerance of different pomegranate cultivars to the excess of boron in irrigation water is due to their capacity to limit boron transport from the root to the leaves

Background : Presently, irrigation waters often have a high concentration of boron (B), and the fruit trees in the Mediterranean areas, in general, are exposed to a high risk of B toxicity. Aims : To test the hypothesis that pomegranate trees are very tolerant to the presence of B in the irrigation water, to elucidate the physiological mechanisms behind this tolerance, and to assess differences between different varieties. Methods : In this study, the physiological and nutritional behavior of three pomegranate cultivars (‘Mollar de Elche', ‘Valenciana', and ‘Wonderful'), treated with five B concentrations (0.25, 1.25, 2.5, 5.0, 10.0 mg L^?1), were studied. At day 30 and 60 after the start of the treatments, growth measurements, gas exchange parameters and organic solutes were recorded. Results : Almost no significant differences were observed between the B treatments for any of the cultivars. Increasing the B concentration in the nutrient solution increased B concentrations in the leaves, but they never exceed 40 mg kg^?1 of B. In the roots, however, B concentrations were very high, up to 400 mg kg^?1. Conclusion : Pomegranate trees are very tolerant to B excess due to their ability to accumulate B in great quantities in the root, without causing toxicity to this part of the plant, thus limiting its transport to the shoots.     

生物碳促进水稻土镉吸附并阻滞水分运移

该文以研究生物碳施加对中国南方酸性水稻土中镉的吸附能力和水分运移能力的影响为研究目的。以中国南方稻田耕层(0～20cm)和下层(>60～80cm)的土壤为研究对象,采用批量平衡法研究不同的生物碳添加量及其粒径对土壤中重金属镉吸附的影响;采用柱法研究生物碳对土壤水分运移能力的影响。结果表明,生物碳添加可提高土壤pH值,对于耕层土壤,细碳(粒径为<0.075mm)添加量为3%、6%、9%时,土壤pH值分别提高了1.04、1.45和1.50;粗碳(粒径为0.5～1mm)添加量为3%、6%、9%时,土壤pH值分别提高了0.42、0.97和1.15;但pH值的增量会随生物碳添加量的增加而减缓。利用Freundlich、Henry、Langmuir和Temkin模型对土壤中镉的吸附进行拟合,可得在试验浓度范围内,Freundlich模型的拟合结果最好,其相关系数R2均在0.99以上。生物碳可提高土壤对镉的吸附能力且细碳对于提高土壤对镉吸附能力的效果更为显著。耕层土壤中细碳添加量为3%、6%、9%时,Freundlich模型中的吸附系数K分别增加了106.63%、182.32%和240.51%;下层土壤中细碳和粗碳添加量为3%时,Freundlich模型中的吸附系数K分别增加了39.72%和7.12%。就2种粒径的供试生物碳而言,生物碳的添加比例越大、颗粒越细越容易导致土壤的水分运移能力降低。细碳添加量为1%时,即可造成土壤水分运移能力明显降低,而粗碳添加量为3%时,土壤水分运移能力没有显著变化。因此,实际生产中应综合考虑生物碳对土壤理化性质的影响来确定生物碳添加量及粒径范围,宜施加粗碳且适宜的添加量为3%左右。该研究可为水稻土中生物碳的施加量及粒径选择提供参考。     

缺铁条件下酵母中铁转运转录水平的研究进展

铁作为生物体内重要元素,在很多细胞功能以及生化过程中具有重要作用。尽管多数土壤中铁含量较为丰富,但在碱性或中性土壤中可以吸收利用的可溶性铁量却无法满足植物需要。在这种情况下所导致的缺铁胁迫不利于植物生长发育。本文从铁吸收系统的激活、胞内铁源的启动和铁相关代谢活动的调控三个方面阐述了酵母细胞中铁转运转录水平上的研究现状,最后展望了其发展前景。     

Genotypic Differences in Selenium Accumulation in Rice Seedlings at Early Growth Stage and Analysis of Dominant Factors Influencing Selenium Content in Rice Seeds

The paper deals with the selenium (Se) accumulation of different genotypes of rice (Oryza sativa Japonica) seedlings at early growth stage and its correlation with the Se content in grains in 151 rice varieties. A field trial showed the Se content in brown rice to range from 29 μg/kg to 103 μg/kg. The results from hydroponic culture with representative varieties of high-, moderate- and low-Se content showed that total Se values for the high-Se genotypes were markedly higher than those of the low-Se varieties. This was true of Se content of the whole plant, Se content of shoots, biomass of shoots, and rate of Se accumulation in shoots. There were, however, no significant differences in values for total Se in roots, rate of accumulation in roots, and biomass of roots between high- and low-Se groups. Selenium content in brown rice was positively correlated with the total Se of the whole plant, shoot, and biomass of shoots. We concluded that the total Se transported from roots to shoots was more important than other factors in Se accumulation and content in brown rice.     

SIMULATION MODEL OF WATER AND SOLUTE TRANSPORT IN TWO TYPES OF ROCKWOOL

The aim of this study is to present a two dimensional model for describing the movement of water and solute transport in two types of rockwool slabs – Floriculture, a high density type; and Expert, which has a low density. Water movement is described by the Richards equation, which is implicitly solved using the control volume finite element method. The governing convection dispersion equation describing the solute transport is explicitly solved. Numerical solutions are obtained for the distribution of water and also for the concentration of solute. The model is validated by comparing the results of water transport developed by this model with numerical results obtained by CFD that are validated by experimental results. A composite substrate is tested and validated, and is shown to give good conditions for development of plants.     

嘉陵江流域输沙时空变化及归因分析

河流输沙过程变化对河流系统的功能发挥具有重要意义,因此探究嘉陵江流域输沙时空变化及其驱动因素,对嘉陵江流域进一步治理具有重要指导作用。基于嘉陵江流域实测降雨输沙资料,采用Mann-Kendall趋势检验、Pettitt突变检验分析输沙时空变化特征,采用双累积曲线法定量分析了典型区间内水文站点气候变化与人类活动对输沙变化贡献率。结果表明：嘉陵江流域各子流域年代输沙模数整体呈减少趋势,2007—2015年,仅武都—碧口区间输沙模数高达3 323.48 t/(km²·a)。典型区间内北碚、武胜、罗渡溪、小河坝4站1960—2015年输沙量呈极显著下降趋势,分别以3.40×10⁶,1.80×10⁶,4.0×10⁵,3.40×10⁵t/a的速率下降,以水土保持与水利工程措施为主的人类活动减沙贡献率为75.93%～96.43%,其输沙序列分别于1990年、1990年、1988年、1984年发生极显著突变。嘉陵江流域各子流域年代输沙模数整体呈减少趋势,干流修建多座大型控制性水库对河道输沙的影...