Rice (Oryza sativa) accumulates silicon (Si) in the tops to levels up to 10.0% of shoot dry weight, but the mechanism responsible for high Si uptake by rice roots is not understood. We isolated a rice mutant (GR1) that is defective in active Si uptake by screening M2 seeds (64,000) of rice cv Oochikara that were treated with 10−3  m sodium azide for 6 h at 25oC. There were no phenotypic differences between wild type (WT) and GR1 except that the leaf blade of GR1 remained droopy when Si was supplied. Uptake experiments showed that Si uptake by GR1 was significantly lower than that by WT at both low and high Si concentrations. However, there was no difference in the uptake of other nutrients such as phosphorus and potassium. Si concentration in the xylem sap of WT was 33-fold that of the external solution, but that of GR1 was 3-fold higher than the external solution at 0.15 mm Si. Si uptake by WT was inhibited by metabolic inhibitors including NaCN and 2,4-dinitrophenol and by low temperature, whereas Si uptake by GR1 was not inhibited by these agents. These results suggest that an active transport system for Si uptake is disrupted in GR1. Analysis of F2 populations between GR1 and WT showed that roots with high Si uptake and roots with low Si uptake segregated at a 3:1 ratio, suggesting that GR1 is a recessive mutant of Si uptake.

The high accumulation of silicon (Si) protects plants from biotic and abiotic stresses. Two different types of Si transporter [Low Silicon 1 (Lsi1) and 2 (Lsi2)] involved in the uptake and distribution of Si have been identified. Lsi1, a Si permeable channel, belongs to the Nod26-like major intrinsic protein (NIP) III subgroup of the aquaporin membrane protein family with a distinct selectivity, whereas Lsi2, an efflux Si transporter, belongs to an uncharacterized anion transporter family. These transporters are localized to the plasma membrane, but, in different plant species, show different expression patterns and tissue or cellular localizations that are associated with different levels of Si accumulation. A recent mathematical modeling study revealed that cooperation of Lsi1 and Lsi2, which show a polarized localization, is required for the efficient transport of Si in rice.Copyright © 2015 Elsevier Ltd. All rights reserved.

本研究旨在阐明硅素穗肥调控盐碱地水稻抽穗期矿质元素分配的作用机制。以常规粳稻淮稻5号为材料, 于2019年和2020年在江苏沿海大丰盐碱地(盐分3.4 g kg^-1, pH 8.3)开展大田试验, 设置3个硅肥用量(0、60和100 kg hm^-2), 于幼穗分化期随穗肥施入。结果表明: (1) 硅素穗肥促进抽穗期植株养分吸收, 提高成熟期干物质量和产量, 与Si0相比, Si60平均增产4.3%, Si100平均增产8.6%; (2) 硅素穗肥优化了水稻不同部位K⁺、Na⁺分配, 提高水稻叶片、上部叶鞘、中下部茎秆K⁺含量, 降低穗、上部叶片、叶鞘、茎秆Na⁺含量, 提高各部位的K⁺/Na⁺, 进而提高离子稳态; (3) 硅素穗肥促进叶片大量元素N、P、Ca、Mg和微量元素Fe、Mn的积累, 与Si0相比, 硅素穗肥显著提高了16.5%的P含量、18.5%的Mg含量、22.4%的Ca含量、19.8%的Fe含量, 缓解盐碱胁迫对水稻叶片的不利影响。综上所述, 硅素穗肥优化了盐碱胁迫下水稻矿质元素的吸收分配, 减轻幼嫩器官盐胁迫程度, 促进叶片多种有益元素积累, 促进水稻养分吸收, 且100 kg hm^-2效果最佳。

【目的】比较硅锌肥及其施用方式对南粳46稻米产量和品质的影响，为调优栽培提供参考依据。【方法】以优良食味粳稻品种南粳46为材料，倒4叶期土壤追施和孕穗期(抽穗前5~7 d)叶面喷施硅肥和锌肥，设置土壤追施硅肥(Si-B)、土壤追施锌肥(Zn-B)、土壤追施硅肥+叶面喷施硅肥(Si-B+Si-L)、土壤追施锌肥+叶面喷施锌肥(Zn-B+Zn-L)、土壤追施硅肥+土壤追施锌肥(Si-B+Zn-B)、叶面喷施硅肥(Si-L)、叶面喷施锌肥(Zn-L)、叶面喷施硅肥+叶面喷施锌肥(Si-L+Zn-L)8个处理，以不施硅锌肥(CK)为对照，调查分析不同处理对南粳46籽粒产量及其构成因素、加工品质、外观品质、食味品质和香味物质2-乙酰-1-吡咯啉(2-AP)含量的影响。【结果】施用硅锌肥对南粳46均有明显的增产作用，增幅为0.8%~11.9%，增产的原因主要是增加了每穗粒数和千粒重，而对穗数和结实率没有明显影响。施用硅肥使糙米率和精米率下降，施用锌肥则使糙米率和精米率增加，施用硅肥和锌肥都可使整精米率提高，施用锌肥提高整精米率的效果比施用硅肥更明显。硅锌肥对直链淀粉含量和RVA特征值的影响随处理不同而异，但施用硅锌肥可以提高崩解值，降低消减值，使胶稠度显著增加，食味值明显提高，稻米2-AP含量显著增加，香味明显变浓。【结论】倒4叶期土壤追施硅肥与孕穗期叶面喷施锌肥相结合，既可增加南粳46的产量，又能提高整精米率和食味品质，增加香味。

元麦膳食纤维含量丰富,β-葡聚糖含量高,保健功效强,是重要的功能性农产品。为了全面了解不同地区元麦β-葡聚糖含量的差异性及其影响因素,本研究对全国7个不同省份元麦棱型、粒色、β-葡聚糖含量进行了整理和归纳,分析了气候、遗传育种和栽培措施等方面对元麦β-葡聚糖含量的影响。针对有关元麦β-葡聚糖合成筛选的有效基因少,气候与栽培措施对元麦β-葡聚糖的影响较大等问题,提出如下解决建议：（1）通过全基因组关联分析定位筛选相关位点与候选基因,挖掘与利用和β-葡聚糖合成相关的关键或主导基因,为元麦营养育种提供分子基础。（2）实际生产中根据当地气候条件,选择高产高β-葡聚糖含量的加工用营养元麦品种,采用适宜的栽培措施,缓解不良生长环境的影响。元麦分子育种和适宜的栽培措施有助于提高元麦生长适应能力,稳定元麦β-葡聚糖的含量,保障高品质元麦原料,推动健康农业的发展。

To better understand the impact of converting native forests to intensively managed plantations on soil carbon (C) and nitrogen (N) dynamics in subtropical China, we examined the seasonal patterns of water-soluble organic C (WSOC) and N (WSON) concentrations in soils in Chinese chestnut (Castanea mollissima Blume) (CF) and bamboo (Phyllostachys praecox C.D. Chu & C.S. Chou) plantation forests (BF) and adjacent native evergreen broadleaf forests (NF) in Ling-long Mountain, Zhejiang Province, China. The plantations were disturbed through surface soil removal and were fertilized and/or mulched, from which economic products (such as nuts and bamboo shoots) were annually harvested. We found that WSOC and WSON had large seasonal variations and were lower in the warmer than in the colder season. Average WSOC concentrations followed the order of BF (58.6) > NF (35.1) > CF (18.1 mg C kg-1), a pattern mainly caused by mulching in BF in winter and the removal of surface soil in CF. Soil total C and N followed the order of BF > NF > CF. The extensive inorganic and organic fertilizer application in BF caused WSON concentrations to be 21 and 14 times higher than those in NF and CF, respectively. Conversion of native forests to plantations lowered soil WSOC:WSON and soil C:N ratios. The seasonal dynamics of WSOC:SOC (soil organic C) and WSON/TN ratios followed the same patterns of WSOC and WSON, respectively. The impacts of forest types on WSOC/SOC ratio, which is a measure of the quality of organic matter, were dependent on seasonal changes of management practices and/or tree growth. Nevertheless mean annual WSON/TN ratios of BF and CF were 2 and 12 times that of NF, indicating that a greater proportion of the total soil N pool became solubilized in the intensively managed plantations. We conclude that land-use conversion and associated management practices had a profound impact on WSOC, WSON, and total C and N concentrations in the studied forest soils in subtropical China.Key words: Forest management, water-soluble organic C, water-soluble organic N, WSOC/WSON ratio

Lactic acidosis can occur when large amounts of cereal grains are given to sheep without adequate adaptation. Virginiamycin has been shown to reduce lactic acid accumulation in vitro and in the rumen of sheep following ingestion of readily fermentable carbohydrates. The aim of this experiment was to determine if virginiamycin would prevent acidosis in hungry sheep given wheat, barley or oat grain without any adaptation. Merino wethers, penned individually and given wheat chaff 300 g/day for 9 days, were offered 2.1 kg of wheat, barley or oat grain, with or without virginiamycin. Rumen fluid was collected before and 6 and 24 h after grain feeding. Blood samples were obtained before and 24 and 48 h after grain feeding. 24 h after grain feeding, rumen pH was lower (P0.001) and rumen L-lactate higher (P0.05) in sheep given wheat without than with virginiamycin. D- and L-lactate were produced in equal proportions in sheep given grain plus virginiamycin, while sheep fed on grain without virginiamycin produced more of the L-lactate isomer 24 h after grain feeding. There was no effect of virginiamycin on grain intake, although intake of sheep given oat grain was lower (P0.01) than intake of sheep given wheat or barley. The number of sheep withdrawn from the experiment after grain feeding was lower (P0.05) when wheat was given to sheep with virginiamycin compared with untreated wheat grain. Feeding virginiamycin with grain did not reduce grain intake, but reduced the severity of acidosis in sheep given wheat grain.

用从纤维酶中提纯的β-葡聚糖酶测定了燕麦、大麦样品中的β-葡聚糖。和控制样品的示值相差不超0.1%;和用AOAC方法测定的结果相比,相差不超过0.2%,本文介绍的方法具有和标准方法相比拟的准确度,且费用较少。

为探明沿海滩涂极重度盐土盐分动态规律及其影响因子,并探讨盐生植被和秸秆覆盖下土壤的脱盐及控盐效果,2014年5月—2015年5月,在江苏沿海滩涂极重度盐土中进行田间试验,设置4种处理:对照(裸地,CK)、种植碱蓬(PS)、15 t·hm^-2秸秆覆盖(SM-A)和30 t·hm^-2秸秆覆盖(SM-2A),监测气候因子和土壤盐分的动态变化.结果表明: (1)滩涂裸地表层土壤盐分具有显著的季节性变化特征,表现为在6—8月盐分降低至最低值(8.69 g·kg^-1),9—12月呈现积盐作用,最大值为26.66 g·kg^-1;表层土壤盐分变化比亚表层更剧烈,而且亚表层盐分变化相对于表层具有一定的滞后性;(2)相关分析表明,滩涂裸地表层盐分变化与采样前15 d的累积降雨量及蒸降比具有显著的线性关系;多因子及互作逐步分析表明,降雨量增加可以显著促进脱盐作用,大气温度升高可加剧盐分积累,降雨量和大气温度的互作效应增加会对盐分累积产生正效应;(3)PS处理没有显著改变土壤盐分的季节性变化规律,但降低了表层土壤盐分;(4)SM-A和SM-2A条件下,土壤脱盐率与覆盖处理天数回归拟合符合Logistic曲线,且经过雨季覆盖处理90～100 d后表层土壤脱盐率均可达到95.0%以上,覆盖处理120 d后亚表层土壤脱盐率均可达到92.0%以上,之后表层和亚表层土壤盐分分别在0.60和1.00 g·kg^-1以下波动.综合考虑脱盐效果和经济投入,在梅雨季节前(4—5月)采用15 t·hm^-2秸秆覆盖,可能是未来滩涂极重度盐土进行快速脱盐和改良的重要措施.

【目的】施肥是影响农田土壤溶解性有机碳、氮的重要因子。探讨在不同利用方式、熟制、土壤pH等条件下长期施肥对土壤溶解性有机碳（DOC）、溶解性有机氮（DON）含量的影响,为农田土壤碳氮管理提供指导。【方法】收集2000—2019年已发表文献72篇,获得相对独立数据（510组DOC和208组DON）,采用整合分析（Meta-analysis）方法定量分析不同利用方式、熟制和土壤pH下施肥对DOC和DON含量的影响。【结果】与不施肥相比,施肥均能显著提高土壤DOC和DON含量,其中施有机肥（单施或配施）的提高幅度（60%和93%）是化肥（13%和29%）的4.6倍和3.2倍。不同利用方式下,施肥能显著提高旱地土壤DOC和DON含量,且旱地施用有机肥提升土壤DOC和DON的幅度显著高于水旱轮作。不同熟制比较,一年一熟下施用有机肥后DOC含量提高85 %,显著高于一年两熟（38%）;不同pH土壤比较,碱性土壤（pH>7.5）上施用有机肥后DOC和DON含量分别提高了85%和162%,显著高于6.5＜pH＜7.5的中性土壤（48%和70%）和pH＜6.5 的酸性土壤（32%和61%）。【结论】施用有机肥（单施或配施）可显著提高DOC和DON含量,但其效果会因利用方式、熟制、土壤pH等的不同有较大差异,因此,有机肥的施用应综合考虑相应的土壤和环境条件。