土壤氮素矿化及其对烤烟品质的影响研究进展

在所有必需营养元素中,氮素是对烤烟产量和品质影响最大、最敏感的元素.在烟草生产中,维持烟株生长发育和形成优良品质的氮素来源,不仅仅是人为施入的肥料氮,土壤矿化氮在烤烟氮素营养中也占有重要地位.关于土壤矿化氮对蔬菜和粮食作物生产的贡献已有较多研究,但对烤烟产量和质量影响的研究尚不多见.针对此问题,笔者总结了现阶段土壤有机氮矿化及烤烟氮素营养的研究结果,详细阐述了土壤氮素矿化的影响因素和研究方法,分析了土壤矿化氮对烤烟氮素累积分配和烟叶烟碱含量的影响,并在文章最后对未来的研究方向作了展望.     

高浓度锌对植物根端细胞的毒性检测

从显微水平及亚显微水平研究了锌处理对植物细胞毒性的影响，实验结果表明，不同浓度的锌对植物根端细胞的损伤不甚显著，细胞内主要细胞器结构完整，液泡呈轻至中度凝集，微核形成率很低。     

Effect of Low Temperature of Irrigation Water on Rice Growth and Nutrient Uptake

The study was designed to investigate the effect of cold irrigation water on rice growth and on uptake of N, P, K and Zn applied ca. 50, 20, 35 and 5 mg kg⁻¹ soil, respectively. Cold temperature of irrigation water reduced rice shoot and root dry weight and plant height, significantly compared to hot temperature treatment. Under low temperature stress N was a major rice growth determinant. Increased shoot concentrations of both P and Zn allevated the low temperature stress. The uptake of N, P, K and Zn reduced significantly at low temperature (16.5–20 °C soil and 20–24 °C flood water) compared to high temperature (24.5–27 °C soil and 26.5–29.0 °C), with the strongest effect being noticed for N, followed by P, K and Zn. Application of N, P, K and Zn increased their uptake in rice shoots. Nitrogen and K had synergistic effect on their uptake. Responses to N and K application and their uptake behavior were well marked at higher than at low temperature whereas reverse was true for P and Zn.     

Dietary strategies to improve the iron and zinc nutriture of young women following a vegetarian diet

Dietary strategies to enhance the content and bioavailability of iron and zinc in vegetarian diets were compiled. Strategies included increasing promoters and decreasing antagonists of iron and zinc absorption, adopting food preparation and processing methods which hydrolyze the phytate content of cereals and legumes, and using iron cookware. These strategies were used to devise two vegetarian menus based on food consumption patterns derived from three day weighed food records of 78 Canadian lacto-ovo-vegetarian adolescents. The iron and zinc, as well as calcium, phosphorus, thiamin, riboflavin, niacin, vitamin A, protein and energy content of the devised menus were all higher than the actual intakes and the corresponding Canadian recommended nutrient intakes. Results show the overall nutrient adequacy of the recommended vegetarian menus and indicate that young lacto-vegetarian women can potentially meet their estimated dietary requirements for absorbed iron and zinc through modest modifications to the diet. Laboratory studies designed to measure the total amount of iron and zinc absorbed from these diets by young vegetarian women are needed to verify the efficacy of the devised menus.     

锌与氮磷平衡施用对大麦营养效应的研究

采用氮、磷、锌3因素5水平最优回归设计,在田间条件下探讨了钙质紫色土中氮、磷、锌对大麦量产及肥效的影响。结果表明,当施氮量在75kg/ha以下时,不必施用锌肥;氮用量超过75kg/ha时,施锌能较大度幅地提高大麦产量。锌在平衡氮、磷养分中起着重要作用,锌与氮、磷间对大麦产量存在较大的正连应。在每公顷施75—112.5N、60—120公斤P_2O_5、30～75公斤ZnSO_4·7H_2O的最优施肥方案下,可获得3225kg/ha以上的产量,且大麦品质良好,肥料利用率较高。     

锌胁迫对虞美人种子萌发的影响

[目的]研究水培条件下重金属锌胁迫对虞美人种子萌发的影响。[方法]用浓度为05、01、00、1502、002、50、3003、50、400 mg/L的硫酸锌溶液对虞美人种子进行胁迫处理,测定锌胁迫对虞美人种子的发芽势、发芽率、发芽指数等发芽指标的影响。[结果]在锌胁迫条件下,虞美人种子的发芽指标随着锌浓度的增加均表现出先升高后降低的变化趋势。发芽势、发芽率、发芽指数均在锌浓度为200 mg/L时达到最大;种子活力指数在锌浓度为150 mg/L时达到最大。[结论]浓度为200 mg/L的锌可以更好地促进虞美人种子的萌发。     

Insights from in vitro exploration of factors influencing iron,zinc and provitamin A carotenoid bioaccessibility and intestinal absorption from cereals

Developments in genetics, agronomics and processing has positioned staple cereals as important sources of iron, zinc and provitamin A (pVA) carotenoids for nutritionally vulnerable populations. Significant effort has been placed on understanding the bioavailability of these micronutrients from cereal foods, including the exploration of underlying mechanisms by which their bioavailability can be modified. While micronutrient bioavailability is preferably assessed in clinical trials, relevant in vitro digestion and intestinal cell culture models have been applied to study effects of genetic, agronomic, post-harvest and food processing on micronutrient bioavailability. This review (1) critically assesses the application of in vitro models in the exploration of mechanisms associated with iron, zinc and provitamin A carotenoid bioaccessibility and intestinal absorption from cereal foods, and (2) identifies remaining gaps in order to frame future strategies to improve the nutritional impact of cereal foods.     

不同Zn源及水平对肉兔生长性能和组织Zn沉积的影响

为了研究不同水平ZnSO4和Met-Zn对家兔生产性能及组织Zn沉积的影响,选用2.5月龄布列塔尼亚肉兔120只,随机分成10组,基础日粮中分别以ZnSO4和Met-Zn形式添加70、105、140、1752、10 mg/kgZn,预试期7 d,正试期30 d。结果表明,在Zn添加量为70~140 mg/kg时,Met-Zn对家兔生产性能的影响优于ZnSO4。日粮Zn含量在70~210 mg/kg时,肉兔肝脏、肾脏、脾脏及背最长肌的Zn含量不呈现明显的变化趋势。     

Effect of Zinc Toxicity on Lymphoid Organs in Chickens

The experiment was conducted with the objective of studies on effects of zinc toxicity on lymphoid organs by the methods of experimental pathology and flow cytometry (FCM). 200one-day-old Avian broilers were divided into four groups randomly, and fed on diets as follows: controls (Zn 100mg kg-1)and zinc toxic (Zn 1 500mg kg-1, zinc toxic group Ⅰ; Zn 2 000 mg kg-1, zinc toxic group Ⅱ; Zn 2 500 mg kg-1, zinc toxic group Ⅲ) for seven weeks. The weight and growth index of the thymus, spleen and bursa of Fabricius were reduced in both zinc toxic group Ⅱ and zinc toxic group Ⅲ when compared with those of control group. The G0/G1 phase of the cell cycles of the lymphoid organs was higher, and S, G2+M phases lower in zinc toxic groups Ⅱ and Ⅲ than in control group. Lymphocytes were depleted and degenerate in the lymphoid organs. The reticular cells of the bursa of Fabricius proliferated and the reticular cells of the thymus were also degenerate and necrotic,particularly in zinc toxic groups Ⅱ and Ⅲ. The results demonstrated that more than 1 500 mg kg-1 impaired the progression of lymphocytes from the G0/G1 phase to S phase obviously, inhibited the development of lymphoid organs and caused marked pathological changes in the lymphoid organs. Potential mechanisms underlying these observations are also discussed.     

Rotifers enriched with iodine,copper and manganese had no effect on larval cod (Gadus morhua) growth,mineral status or redox system gene mRNA levels

It currently remains unclear if rotifers contain sufficient mineral levels to meet larval fish requirements. In this study, rotifers were enriched with a commercial enrichment (control), or with additional iodine, iodine and copper, or iodine, copper and manganese, and the effects of feeding these rotifers to Atlantic cod (Gadus morhua) larvae from 3 to 18 days post hatch were investigated. Rotifer enrichment with minerals was successful, but Mn enrichment also increased rotifer zinc levels. No differences were observed between treatments in larval growth or survival, or in the mRNA levels in the majority of the redox system genes analysed. Only Zn levels increased in cod larvae in response to mineral enrichment of rotifers. Apart from Zn, little evidence was found to suggest that cod larvae require increased concentrations above the control rotifer levels of the essential elements studied here.