春笋幼竹期毛竹地上生物量格局及养分动态变化规律

研究毛竹关键生理阶段春笋幼竹期各龄级母竹地上生物量分配格局与养分动态变化规律,并同小年期的相应值进行比较。结果表明,该时期,光合器官竹叶生物量分配比例随竹株年龄增大而减小,其干质量占地上器官生物量干重的7.09%,比小年期的相应值增大了36.4%。在春笋幼竹生长初期,母竹叶片中氮含量呈下降趋势,而竹根中则略有升高,此后均趋于稳定;钾元素在母竹叶片中的含量随春笋幼竹生长而迅速升高,5月份达最大值12.21 mg/g,磷在叶片和根部的含量均较低。同小年期相比,含量最高的氮元素在叶、枝、秆、根中的含量均较低。春笋幼竹期,新竹的快速生长对母竹生物量格局与养分分配产生了重要影响。     

不同结球莴苣品种养分吸收及产量品质差异研究

为研究不同结球莴苣品种的养分吸收规律以及产量、品质差异,对7个结球莴苣品种的产量、养分吸收、营养品质、矿质元素含量和硝酸盐含量5类指标进行了测定评价。结果表明,不同结球莴苣品种养分吸收存在较大差异,产量和品质也有所不同。养分吸收对产量及品质有一定的影响,养分吸收较好的品种,其产量与品质也相对较好。7个品种中,亚特兰大和裕生2号的养分吸收量较好,其产量和品质也相对优于其他品种,综合表现佳;而养分吸收较差的飞翔,其产量及品质表现也比较差。     

犊牛维生素C缺乏症临床诊治研究

维生素C缺乏症也叫坏血病,由动物体内抗坏血酸不足或缺乏引起,导致毛细血管壁通透性增大,而引起的一种出血性疾病。此病在20世纪90年代为一种常发病,由于养殖技术的提高,此病的发病率显著下降,以至于较为少见。近年来,随着我国奶牛养殖模式的变化,日粮中饲料的多样性受到一定限制,但产奶量大幅提升,导致奶牛维生素C缺乏症发病率呈上升趋势,尤其是犊牛维生素C缺乏症的发病率显著提升,造成的损失增大。本文针对犊牛维生素C缺乏症的发病原因、症状、诊断、预防作了研究分析,希望对该病诊治有所启示。     

巨桉幼树器官组织中养分元素的分布与积累特点

通过对造林1 a~3 a巨桉幼树的器官生物量调查、器官组织中大量元素N、P、K、Ca、Mg和微量元素Fe、Zn的含量测定及其积累量的分析结果表明:大量元素总含量在各器官中的分布为干韧皮部、叶枝、根干木质部,微量元素主要富集于叶和根器官中;单株木器官中大量元素的累积量排序为叶枝干韧皮部根或干木质部干木质部或根,各养分元素积累量的规律不受林龄的影响,大量营养元素依次为CaNKMgP;微量元素累积量FeZn;林龄1 a~3 a巨桉平均单株木大量元素累积总量分别是12.45 g·株-1、136.19 g·株-1和420.23g·株-1;各养分元素的年净积累量以Ca为最大,N、K养分元素次之,Mg元素较少,P元素最小。     

Integrated crop and livestock systems in Western Europe and South America: A review

For many years, we have seen an increasing specialization of agricultural systems and territories, with a clear separation between territories with very high animal densities and those devoted to the growing of annual crops. This development is explained by market and sector economic logic and has been reinforced by the availability of low-cost inputs and animal housing systems based on direct grazing not requiring straw. It has, however, also involved negative environmental impacts and, in some cases, the impoverishment of soil fertility, a loss of biodiversity, and excesses of N and P, leading to eutrophication and hot spots of ammonia emission in livestock-breeding territories. Having recapped the mechanisms behind the specialization of systems and territories, we examined the extent to which the development of innovative mixed-farming systems that reconnect livestock and crop production on various territorial scales (farm, district, region) can reduce the negative impacts of agriculture on the environment, produce valuable ecosystem services and achieve acceptable economic efficiency for farming enterprises. Examples from temperate regions will be used to show that mixed-farming systems increase the possibilities of better recycling of nutrients within systems, limiting recourse to the purchase of increasingly expensive inputs and safeguarding the biodiversity of agricultural ecosystems.     

黄瓜椰糠栽培营养液的适宜浓度探索

为了探索黄瓜椰糠栽培中适宜的流出液EC值指标,根据流出液EC值的高低来调节灌溉液浓度,实现肥料的合理施用。试验设置了1.8、2.2和2.6 mS·cm^-1三个流出液EC值指标,灌溉液浓度的“增减量(/g·L^-1)=(EC值设定值-EC值测定值)×流出率/%”。此模型不仅考虑了EC值设定值与测定值的差异,而且考虑了流出率因素。通过“配液浓度=在用浓度+增减量”,对灌溉液浓度进行连续调控。结果显示,伴随灌溉液浓度的升高与降低,流出液EC值围绕设定值上下波动,基本实现了稳定。流出液中氮、磷、钾、钙、镁元素的含量与EC值设定值正相关,反映了肥料供应水平的高低。当流出液EC值设定在2.2和2.6 mS·cm^-1时,黄瓜的产量差异不显著,却又都比EC值在1.8 mS·cm^-1设定值时显著增加。所以,2.2~2.6 mS·cm^-1可作为黄瓜椰糠栽培适宜的流出液EC值控制区间。     

Wheat plants invest more in mycorrhizae and receive more benefits from them under adverse than favorable soil conditions

Soil chemistry and biota heavily influence crop plant growth and mineral nutrition. The stress-severity and optimal resource allocation hypotheses predict mutualistic symbiotic benefits to increase with the degree of metabolic imbalance and environmental stress. Using two cross-factorial pot experiments with the same biologically active calcareous soil, one time highly saline and nutrient-deficient, and the other time partially desalinated and amended with mineral soil fertilizer, we explored whether these general predictions hold true for zinc (Zn) nutrition of bread wheat in mycorrhizal symbiosis. Increased arbuscular mycorrhizal (AM) fungal root colonization positively correlated with plant Zn nutrition, but only when plants were impaired in growth due to salinity and nutrient-deficiency; this was particularly so in a cultivar-responsive to application of mineral Zn fertilizer. Evidence for direct involvement of AM fungi were positive correlations between Zn uptake from soil and frequency of fungal symbiotic nutrient exchange organelles, as well as the quantitative abundance of AM fungi of the genera Funneliformis and Rhizophagus, but not Claroideoglomus. Combined partial soil desalination and fertilization swapped the dominance ranking from Claroideoglomus spp. to Funneliformis spp. Positive growth, nitrogen, and Zn uptake responses to mycorrhization were contingent on moderate soil fertilization with ZnSO₄. In agreement with the predictions of the stress-severity and optimal resource allocation hypotheses, plants limited in growth due to chemically adverse soil conditions invested relatively more into AM fungi, as evident from heavier root colonization, and took up relatively more Zn and nitrogen in response to mycorrhization, than better growing and less mycorrhized plants. It thus appears that crop plant cultivar-dependent mycorrhization and Zn fertilizer-responsiveness may reinforce each other, provided that there is bioavailable Zn in soil and plant growth is impaired by suboptimal chemical soil conditions.     

内蒙古灌溉马铃薯施肥现状及肥料利用效率

内蒙古马铃薯的生产面积及总产量均居全国前列，但单产低于全国平均水平，养分管理不合理是限制马铃薯产量的 重要因素。2013～2016 年在内蒙古9 个马铃薯主产旗（县）对灌溉马铃薯养分投入情况进行调查。结果表明：内蒙古灌溉 马铃薯生产中，氮肥投入过高，磷、钾肥投入过量与不足并存；58% 的农户氮肥偏生产力低于100 kg · kg^-1，具有较大的提 升空间。农户种植规模、产量、氮肥施用量与氮肥偏生产力存在显著相关关系。     

缺镁诱导的纽荷尔脐橙叶脉肿裂初报

以1年生枳砧纽荷尔脐橙为材料进行盆栽沙培,观察缺镁植株叶脉肿裂与叶片黄化症状的进程,测定不同枝梢叶片相对叶绿素和镁硼元素含量,探讨缺镁对纽荷尔脐橙叶脉肿裂、叶片黄化的影响。结果显示,第3个月时缺镁组2龄秋梢叶出现叶脉肿裂、叶片黄化的症状,而且随着时间延长症状加重;第3个月时对照组和缺镁组1龄春夏梢叶的叶色无明显差异,在第4个月时缺镁组出现明显黄化症状。第3个月时缺镁组各枝梢叶的相对叶绿素含量均显著降低,并且下降幅度随着时间延长而明显增大。第4个月时缺镁组和对照组的硼含量均处于高量水平,而缺镁组各枝梢叶镁含量均处于严重缺乏水平。表明,缺镁不仅会导致纽荷尔脐橙叶片黄化,也会导致叶脉肿裂。     

Differential response of corn inbreds to calcium

Abstract

Differential responses were noted among several corn (Zea mays L.) inbreds for Ca when grown in nutrient solutions at varied Ca stresses. Properties of one of the more “Ca‐efficient”; inbreds (Oh43) compared to one of the more “Ca‐inefficient”; inbreds (A251) are reported.

Oh43 produced more dry matter and developed fewer Ca stress symptoms when grown at both low and high Ca or with high Mg and K than A251. Comparable dry matter was produced by Oh43 at 4 times less Ca than A251. Oh43 also produced more dry matter per unit Ca than A251. Oh43 leaves and roots had lower Ca concentrations than A251 leaves and roots. With added Ca to solutions, Mg, K, Mn, Zn, and Cu concentrations decreased more in A251 than in Oh43. A251 contained higher P concentrations than Oh43. Functional and critical Ca concentrations appeared to be lower in Oh43 than in A251. Oh43 should grow and adapt better to Ca stress conditions than A251.