保水剂与肥料互作及保水缓/控释肥料研究展望

保水剂在农业上的作用日益重要,肥料与保水剂一体化使用是水肥调控的重要技术,是肥料研究的国际前沿。保水剂是吸水量超过自身重量数百倍以上的亲水性高聚物。保水剂一般分为天然的,合成的及半合成的。保水剂与肥料可以通过物理混合、包膜或化学合成三种方式结合为一体化的保水缓/控释肥料。保水剂具有吸水吸肥功能,保水剂可吸附大量中性分子,对阳离子养分也有较强吸附作用,对阴离子养分吸附弱。肥料种类与盐浓度影响保水剂的吸附作用与膨胀能力。保水缓/控释肥料在土壤中对肥料养分有延迟释放作用。保水缓/控释肥料可改善土壤持蓄水分和水肥交互作用,促进植物对养分的吸收和作物增产。保水缓/控释肥料发展方向是包膜和化成保水缓/控释肥料。保水缓/控释肥料湿润及养分控释机理研究也需要加强。     

西安市菜田施肥现状与土壤肥力状况

为摸清西安市菜田施肥及土壤养分现状,按不同种植年限,调查了西安市8个涉农区县露地、大棚和日光温室全部菜田(共422个样本)肥料施用情况,并采集0~20cm土样进行土壤养分、pH及盐分分析。结果表明,露地蔬菜氮、磷、钾肥平均用量分别为N 327.0kg/hm~2、P_2O_5186.0kg/hm~2、K_2O 138.0kg/hm~2,氮、磷肥用量偏高,钾肥用量适宜。大棚蔬菜氮、磷、钾肥平均用量分别为N 868.5kg/hm~2、P_2O_5 544.5kg/hm~2、K_2O 496.5kg/hm~2,日光温室蔬菜氮、磷、钾肥平均用量分别为N 883.5kg/hm~2、P_2O_5 684.0kg/hm~2、K_2O 724.5kg/hm~2,设施蔬菜化肥用量严重超量,特别是磷肥最为严重。随种植年限增长,露地蔬菜氮、磷、钾肥施用量有明显提高趋势,而大棚与日光温室蔬菜化肥施用量与种植年限长短关系不大;菜田有机质质量分数均属于较低水平,应加大有机肥投入;露地蔬菜土壤养分质量分数适中,设施蔬菜土壤养分质量分数属于偏高水平,这与施肥现状调查中设施蔬菜过量施用化肥的结果相一致;设施蔬菜土壤硝酸盐质量分数超过露地蔬菜的2.2~2.3倍,盐分质量分数超过露地蔬菜的2.2~3.3倍,土壤硝酸盐和盐分累积十分明显,对蔬菜生产已形成潜在不良影响。今后应严格控制化肥的施用,通过测土配方施肥技术优化施肥结构、用量与比例,防止土壤次生盐渍化等的发生。     

氮钾配施对花菜产量、品质和养分吸收的影响

花菜氮、钾配施试验研究结果表明:氮、钾肥料配合施用不仅能够增加产量,提高果实中Vc和糖分含量,改善品质,而且能够促进花菜对氮、磷、钾等养分的吸收,提高肥料利用率.     

不同配方复混肥对辣椒产量和经济效益的影响

开展了不同配方的复混肥对辣椒产量影响的试验,并比较了投入成本和产出效益,以期为生产辣椒专用配方肥提供参考和指导农户科学配方施肥提供依据。试验结果表明,以硝铵磷肥配制的复混肥对辣椒有显著的增产效果,产量最高,667 m2产量达780.82 kg,效益最好,投产比1∶16.48,利润为2640.4元,比常规肥增加利润1185.7元;其次是以尿素加微量元素配制的复混肥,增加纯利润1054.17元;以氯化铵与尿素（不加微量元素）配制的复混肥有增产效果,但差异不显著,有待进一步研究。     

Effect of cropping sequence,fertilizers and farmyard manure on vesicular-arbuscular mycorrhizal fungi in different crops over three consecutive seasons

Summary The influence of cropping sequence with and without fertilizer and farmyard manure application on vesicular-arbuscular mycorrhizae was studied over three consecutive seasons. In the first season maize was grown on all the plots. In the second season cowpea, groundnut and finger millet were raised on the same plots and in the third season, sunflower was grown on all the plots. The groundnut grown in the second season stimulated mycorrhizal root colonization, sporulation and infective propagules in the soil, and these effects were carried over to the next season. The plots cropped to finger millet in the second season had the lowest number of mycorrhizal spores. The application of farmyard manure stimulated vesicular-arbuscular mycorrhizae while fertilizers at the recommended level decreased the mycorrhizal propagules.     

Zn、B、Mn微肥提高玉米产量与品质的研究

研究结果表明,不同浓度Zn、B、Mn微肥处理对促进玉米生长、提高玉米产量与秸杆品质,增加生物学产量及经济产量均有效果。     

氮、磷、钾肥不同施用量对水稻产量和品质性状的影响

采用3因素5水平正交试验设计,研究了氮、磷、钾不同施用量对水稻产量和品质性状的影响。结果表明：氮素对产量性状的影响顺序为地上干重〉单株有效穗数〉单株粒重〉根干重〉谷草比〉经济系数,对品质性状的影响顺序为蛋白质含量〉食味值〉胴割粒率〉正常粒率〉粉状粒率。若以高产为目标,纯氮施用量应为276～414 kg/hm^2,与目前天津地区生产上实际的施肥水平相符;若以优质为目标,纯氮施用量应≤138 kg/hm^2,即水稻优质栽培应降低氮肥的施用量。     

磷钾配合施用对茼蒿品质的影响

为研究不同磷肥和钾肥耦合对蔬菜品质的影响,以茼蒿为实验材料,通过盆栽试验,研究不同浓度磷肥施用并配施不同种类钾肥下茼蒿维生素C(Vc),还原糖和氨基酸含量。结果表明：同等磷肥施用量条件下,配施不同钾肥处理茼蒿Vc、还原糖、氨基酸含量整体上分别表现为KH2PO4＞KNO3＞KCl＞K2SO4＞CK、KH2PO4＞K2SO4＞KNO3＞KCl＞CK和KH2PO4＞KNO3＞CK＞K2SO4＞KCl;不同磷肥施用量配施同种钾肥时,茼蒿Vc、还原糖、氨基酸含量普遍表现为随磷肥用量的增加而增加;配合KH2PO4施用在不同磷肥施用量条件下茼蒿Vc、还原糖、氨基酸含量均最高,其中在高水平Ca(H2PO4) 2条件下配施KH2PO4,茼蒿Vc、还原糖、氨基酸含量达最大值。     

富硒花生品种筛选及外源调控花生富硒生产技术研究

本研究通过田间试验,测定不同花生品种的自然富硒能力及对外源硒的利用指数,然后通过施用外源硒,研究不同调控措施对花生籽粒硒含量及外源硒利用率的影响,为富硒花生生产提供技术参考。研究结果表明:自然条件下,12个花生品种春花生籽粒的硒含量在0.041～0.180 mg/kg,秋花生籽粒的硒含量在0.039～0.066 mg/kg,外源硒的利用指数为2.3～3.7。施用外源硒肥均能显著提高花生籽粒硒含量,含硒肥料基施、淋施和叶面喷施情况下,花生籽粒对外源硒的利用率分别为0.056%～0.064%、0.23%～0.25%和3.74%～4.99%。可见,不同花生品种间硒的富集能力和对外源硒利用能力均有差异,而叶面喷施的硒肥施用方式下花生对外源硒的利用率最高。     

Biochemical aspects of nitrogen use efficiency: An overview

Crop productivity relies heavily on nitrogen (N) fertilization. N is an essential macronutrient limiting the growth and development of plants in agriculture. Both organic and inorganic forms of N are metabolized in plants; nitrate and ammonia are common forms of inorganic N that can be metabolized in all plants. In the last 40 years the amount of synthetic N applied to crops has risen dramatically, resulting in significant increases in yield but with considerable impacts on the environment. Production and application of N fertilizers consume huge amounts of energy, and excess is detrimental to the environment. A requirement for crops that require decreased N fertilizer levels has been recognized in the call for a ‘Second Green Revolution’ and research in the field of nitrogen-use efficiency (NUE) has continued to grow. Nitrogen-use efficiency is inherently a complex trait, as each step-including N uptake, translocation, assimilation, and remobilization-is governed by multiple interacting genetic and environmental factors. The limiting factors in plant metabolism for maximizing NUE are different at high and low N supplies, indicating great potential for improving the NUE of present cultivars. Decreasing environmental losses and increasing the productivity of crop-acquired N requires the coordination of carbohydrate and N metabolism to give high yields. This has prompted a search to identify genes that improve the NUE of crop plants, with candidate NUE genes existing in pathways relating to N uptake, assimilation, amino acid biosynthesis, carbon (C)/N storage and metabolism, signaling and regulation of N metabolism and translocation, remobilization and senescence. In this review, we present the over view of N metabolism, relation of C/N metabolism and future prospects of improving NUE in crops using various complementary approaches.