Concentrations of foliar and surface soil in nutrients Pinus spp. plantations in relation to species and stand age in Zhanggutai sandy land, northeast China

The concentrations of the foliar and surface soil nutrients and the variation with species and stand age were studied inPinus spp. plantations in Zhanggutai area, northeast China. The results showed that the total N, total P and C: N ratio of the soil inP. sylvestris var.mongolica stands were significantly higher in comparison with those inP. tabulaeformis andP. densiflora stands. ForP. sylvestris var.mongolica, the foliar P concentration appeared to decrease with age, and the foliar N and K concentrations did not show a consistent change with age. As for the different tree species of the similar age, the foliar N and P concentrations were significantly different (p<0.05), being withP. sylvestris var.mongolica>P. densiflora>P. tabulaeformis. The foliar N: P ratio ofP. densiflora significantly was higher thanP. sylvestris var.mongolica andP. tabulaeformis, while the foliar K was no obvious difference between the three tree species. There were significant correlation (p<0.05) between soil total N and P, soil organic matter and total P, foliar N and P, but it did not show significant correlations between soil and foliar nutrient concentrations, which might attribute to the excessive litter raking, overgrazing and low soil moisture in this area. Based on the foliar N: P ratio, we introduced a combination threshold index of N: P ratio with their absolute foliar nutrient concentrations to determine the possible limiting nutrient. According to the critical N: P ratio and their absolute foliar N, P concentrations, theP. sylvestris var.mongolica stands showed a decreased N limitation degree with age, theP. densiflora stands showed unlimited by N and P in the whole, and theP. tabulaeformis stands showed co-limited by N and P. No significant difference in soil nutrient concentrations of the surface soils was found between 45, 29, 20-yr-oldPinus sylvestris var.mongolica plantation stands. Keywords coniferous trees - foliar nutrient concentration - limiting nutrients - N - P ratio - Zhanggutai sandy land CLC number S718.55 Document code A Article ID 1007-662X(2004)01-0011-08 Foundation item: This research was supported by Key Knowledge Innovation Project (KZCX3-SW-418) of Chinese Academy of Sciences.Biography: CHEN Guang-sheng (1978-), male, master candidate in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. ChinaResponsible editor: Song Funan

Eucalyptus grandis plantations:effects of management on soil carbon,nutrient contents and yields

The expansion of fast-growing tree plantations is a worldwide process,with consequences on soil fertility and soil carbon storage.Disparate results were found on the effects of afforestation with Eucalyptus on soil carbon and other nutrient contents.These discrepancies are usually caused by differences in climate,land use history,soil texture as well as by management related factors such as plantation age,number of rotations,method of establishment(plantation or coppice),harvest residue management and soil preparation.We studied the effect of plantation age,number of rotations,and method of establishment on soils and plant nutrient concentrations in Eucalyptus grandis plantations in NE Argentina on different textured soils.We also determined if yields changed with nutrient variations in soils,and compared soils under plantations to soils under grasslands they replaced.Thirty-one E.grandis stands of different ages,number of rotations and method of establishment were evaluated as well as eight grassland sites.Levels of carbon,nitrogen,phosphorus,potassium,calcium and magnesium were determined for soils and plants.Soil carbon and nitrogen decreased over the number of rotations and were more pronounced in soils with 50-60%sand than soils with>75%sand.Coppice stands showed higher soil carbon and nitrogen levels than plantations,suggesting a negative effect of site preparation before planting on soil nutrient conservation,especially in fine-textured soils.Foliar nutrient concentrations did not follow the trends observed for soil nutrients nor did they reflect nutrient limitations.There was no evidence of decreased yields over successive rotations.Soil carbon and nitrogen contents decrease when grasslands are replaced by E.grandis plantations,and therefore a yield limitation may occur in a medium to long-term frame,especially in stands re-established for short-rotation management.Harvest residue management and site preparation must be specifically designed for improving soil nutrient management.

Decreasing nutrient concentrations in soils and trees with increasing elevation across a treelineecotone in Rolwaling Himal, Nepal

At a global scale, tree growth in alpine treeline ecotones is limited by low temperatures. At a local scale, however, tree growth at its upper limit depends on multiple interactions of influencing factors and mechanisms. The aim of our research was to understand local scale effects of soil properties and nutrient cycling on tree growth limitation, and their interactions with other abiotic and biotic factors in a near-natural Himalayan treeline ecotone. Soil samples of different soil horizons, litter, decomposition layers, and foliage samples of standing biomass were collected in four altitudinal zones along three slopes, and were analysed for exchangeable cations and nutrient concentrations, respectively. Additionally, soil and air temperature, soil moisture, precipitation, and tree physiognomy patterns were evaluated. Both soil nutrients and foliar macronutrient concentrations of nitrogen(N), magnesium(Mg), potassium(K), and foliar phosphorus(P) decrease significantly with elevation. Foliar manganese(Mn) concentrations, bycontrast, are extraordinarily high at high elevation sites. Potential constraining factors on tree growth were identified using multivariate statistical approaches. We propose that tree growth, treeline position and vegetation composition are affected by nutrient limitation, which in turn, is governed by low soil temperatures and influenced by soil moisture conditions.

喷施不同营养元素叶面肥对蟠枣缩果病和品质的影响

为探讨喷施不同营养元素叶面肥对蟠枣(‘京沧1号’)缩果病发病率及品质的影响,对不同叶面肥处理蟠枣缩果病发病率及产量进行了调查,对蟠枣果实外观指标和营养指标进行了测定。结果表明:喷施不同营养元素叶面肥处理后蟠枣缩果病发病率显著降低,蟠枣果实产量、商品率分别较清水(对照组)提高8.73%~27.21%和3.53%~17.94%;除硫酸锰、四硼酸钠、富瑞朋流体硼叶面肥处理外,其他处理蟠枣果实硬度与对照处理差异不显著;喷施不同营养元素叶面肥处理对蟠枣果实色差参数影响差异不显著;喷施不同营养元素叶面肥处理对蟠枣果实中可滴定酸、可溶性糖、可溶性蛋白、维生素C、总酚和类黄酮含量积累有积极影响。整体看来,氮元素叶面肥对降低蟠枣缩果病发病率、提高蟠枣果实商品率、可滴定酸、可溶性蛋白和总酚含量作用显著,锰元素对提高蟠枣果实产量、硬度、可溶性糖和类黄酮含量作用显著,钾元素叶面肥处理对蟠枣整体作用效果不明显,硼元素叶面肥对提高蟠枣产量,增加蟠枣果实可滴定酸、可溶性蛋白和维生素C含量作用效果明显。因此,该结果可为蟠枣缩果病防控及品质调控提供理论依据和科学参考。

不同叶面肥对油茶幼苗的肥效研究

以广西国有博白林场2年生油茶幼苗为研究对象,设置不同氮、磷、钾及微量元素浓度配比及空白对照处理,测定嫁接幼苗期生长指标及根茎叶各部位营养元素含量,研究不同叶面肥对油茶幼苗生长及养分吸收的特征。结果表明,不同叶面肥处理对油茶苗木营养生长有显著影响,叶面肥对油茶幼苗有显著的肥效作用,处理(7)的叶片净增量比对照增幅最高,达47.16%。处理(8)的氮元素含量最多,比对照提高170.89%。在微量元素方面,处理(8)比对照处理的镁含量增幅最高,达101.47%。油茶苗期对养分的需求规律表现为N>K>P。表明当氮磷钾的比例在10∶15∶6、喷施浓度在2.5%时,与对照比较能够显著促进幼苗生长。

叶面喷施氨基酸对水稻Cd转运特性和稻米氨基酸含量的影响

为了探讨氨基酸叶面肥的降Cd潜力,在湖南水稻开花期喷施6种氨基酸,对水稻Cd转运特性及其稻米Ca、Fe、Mn、Zn和氨基酸含量的变化进行了分析。试验结果表明:喷施2次10 mmol·L^(-1)苯丙氨酸(Phe)、甘氨酸(Gly)、异亮氨酸(Ile)、丝氨酸(Ser)、蛋氨酸(Met)和0.02 mmol·L^(-1)的色氨酸(Trp),能使稻米、穗颈、穗下节中的Cd含量显著下降,稻米中的Cd平均含量从0.63 mg·kg^(-1)分别下降至0.27~0.48 mg·kg^(-1)。其中喷施Ser、Trp和Met的降Cd幅度高达51.1%~57.3%,而Phe和Gly的降Cd幅度仅为24.7%~35.1%。与此同时,水稻各器官中Ca和Fe的含量显著上升,Mn的含量显著下降,Zn的含量无显著变化。喷施氨基酸对Cd在水稻器官间的转移系数无显著影响,但显著降低了稻米、穗颈和穗下节中Cd含量与Ca、Fe、Mn含量的比率。喷施Ser和Met使稻米中的必需氨基酸含量分别增加7.5%和10.5%、非必需氨基酸分别增加13.9%和5.5%;喷施6种氨基酸都能显著增加稻米谷氨酸(Glu)、亮氨酸(Leu)和半胱氨酸(Cys)的含量。稻米Cd含量与Cd∶Ca、Cd∶Fe、Cd∶Mn的含量比率呈极显著正相关,与Glu和Ca含量呈极显著负相关。综上所述,喷施Ser、Trp和Met能显著促进Ca、Fe转运和Glu合成,提高Ca、Fe、Mn离子通道对Cd的拦截能力,从而有效降低稻米、穗颈和穗下节中的Cd含量。

叶面喷施微生物制剂对油松幼苗生长的影响

分析叶面喷施不同剂量微生物制剂对油松幼苗生长,在山东省某油松林地开展试验,依据BGB微生物菌剂的剂量分为四个处理,CK(不做任何处理)A1(10g/株)A2(30g/株)A3(50g/株),观察不同量的微生物制剂对油松幼苗生长以及土壤养分的影响。结果证实,不同剂量微生物制剂均对油松幼苗生长产生影响。各处理的苗高、地径和冠幅从大到小排序是A3>A2>A1>CK(P<0.05)整体而言,A3处理的油松幼苗长势最好;不同剂量微生物制剂不同时期的幼苗成活率均高于CK组,随着微生物制剂剂量的增加,其成活率逐渐增高,呈正相关趋势。净光合速率、气孔导度、蒸腾速率对比,从大到小依次是A3>A2>A1>CK,整体而言,A3处理优势明显;A3处理的有机质、碱解氮、速效磷均高于其他处理(P<0.05),A3速效钾极显著高于CK组(P<0.01),显著高于A1组和A2组(P<0.05),呈A3>A2>A1>CK的趋势。由此可知,叶面喷施微生物制剂也促进油松幼苗的生长,改善土壤养分,以50g/株的剂量最佳。

Effects of Foliar Fertilizer Application on Quality of Tea (<I>Camellia sinensis</I>) Grown in the Kenyan Highlands

In Kenya, foliar fertilizers have not found use in tea production despite their numerous advantages as exhibited in other crops. A fertilizer trial test was established in three sites of the major tea growing regions, with 36 plots per site to determine the effects of foliar fertilizer application on tea quality. Two foliar fertilizers were tested;foliar fertilizer 1 (FF1) and foliar fertilizer 2 (FF2), with a positive control of soil fertilizer (SF) and a blank. Two leaves and a bud tea samples were collected every two weeks after each foliar fertilizer application. These were then analyzed for tea quality (total polyphenols, TP), nutrient residues for the different clones and geographical locations. The TP contents for clone TRFK 31/8 were as follows: FF1 = 17.8%, FF2 = 17.9%, SF = 16.56% and Zero = 17.4%. Tukey-Kramer pair wise comparison test results between the foliar fertilizers and SF showed that the FF1 (HSD = 4.78) and FF2 (HSD = 5.27) fertilizers had significantly (P < 0.05) higher levels of TP content as compared to control SF fertilizer. Nutrients analyzed had average means as follows: N = 4% - 5%, P = 0.25% - 0.28%, K = 1.35% - 1.69%, Ca = 0.3 - 0.5 ppm, Mg = 0.19 - 0.27 ppm, Mn = 0.05 - 0.13 ppm, Zn = 25 - 40.5 ppm, Cu = 11 - 17 ppm and Fe = 72 - 122 ppm. The nutrient residue levels had non-significantly statistical differences at P < 0.05 level between pairs of zero applied plots and the FF1, FF2 and SF applied plots respectively. It was concluded that the foliar fertilizers increased the TP content in tested tea samples and the nutrients analyzed were all within the dietary reference intake (DRI) levels for SF, FF1 and FF2. Overall, the foliar fertilizer increased the quality of the tested tea samples.

Effects of Copper-based Nutritional Foliar Fertilizers on Photosynthetic Characteristics,Yield and Disease Control Efficiency of Cotton

[Objectives] The effects of copper-based nutrient foliar fertilizer on photosynthetic characteristics,yield,accumulation and distribution of trace elements in various organs,disease prevention effect and soil enzyme activity were studied,so as to provide a theoretical basis for the application of foliar fertilizers in cotton production. [Methods]Through two years of field experiments,six treatments were set in total,namely spraying water( CK),traditional Bordeaux mixture( BDM),Kocide 2000( KCD),copper-based nutrient foliar fertilizer( CF),iron-copper-based nutrient foliar fertilizer( CFFe),and zinc-boron-copper-based nutrient foliar fertilizer( CFZnB). Randomized block arrangement was adopted. Chlorophyll content in leaves was measured at each growth stage of the cotton. Photosynthetic characteristics of leaves were measured at the peak bolling stage. Plants were sampled at initial boll opening stage. The whole plant was divided into root,stem,leaf and cotton boll parts,in which the total copper,total zinc,total iron contents and accumulations were determined. Soil samples were collected from each plot,followed by the determination of soil enzyme activity. Disease index was investigated at bud,flowering and boll-forming and boll opening stage. [Results]( 1) Spraying CFFe,CFZnB,CF and KCD could significantly improve chlorophyll content of cotton leaves,and the CFFe treatment had the highest increase up to13. 30%,followed by the CFZnB treatment,which was 11. 40% higher than the CK; and photosynthetic rate,stomata conductance and transpiration rate could be improved significantly,and the CFFe treatment showed the highest photosynthetic rate,which increased by 26. 35% compared with the CK,followed by the CFZnB treatment,which increased by 17. 96% compared with CK; and intercellular CO2 concentration was significantly reduced.( 2) Spraying BDM,KCD,CF,CFFe and CFZnB can significantly increase total copper content and accumulation in various cotton organs( except the total copper content in the stem part of the CFZnB treatment; the CFZnB and CFFe treatments can significantly increase total zinc content and accumulation in various cotton organs; and spraying CFFe,CFZnB and CF can significantly increase total iron content and accumulation in various cotton organs( except the total iron content in the stem part of the CF treatment).( 3)Spraying CFFe,CFZnB,CF,KCD and BDM greatly reduced the disease index at flowering and boll-forming and boll opening stages.( 4) The CFZnB and CFFe treatments had the highest soil urease activity,which was 7. 14% higher than that of the CK,but the difference from the CK was not significant; the catalase activity of each treatment was significantly higher than that of the BDM treatment; and the sucrase activity of each treatment was significantly higher than that of the CK.( 5) Spraying CFFe,CFZnB,CF and KCD significantly improved lint yield of cotton,and the CFZnB treatment showed the highest yield increase up to 12. 34%,followed by the CFFe treatment,with an increase in the range of 8. 77%-10. 20%. [Conclusions]Copper-based nutrient foliar fertilizers have dual functions of disease control and prevention and plant nutrition and health care,and not only can significantly increase cotton yield,but also has certain disease prevention effect.It is recommended to use copper-based nutrient foliar fertilizers.

Effects of Fermented Nori (<i>Pyropia yezoensis</i>) Liquid Fertilizer on Plant Growth Characteristics and Nutrient Content of Komatsuna (<i>Brassica rapa</i>L. var. Wakana Komatsuna) Cultivated in Vermiculite

We conducted plant growth experiments in microbe-free vermiculite to study the effects of four types of fermented seaweed liquid fertilizer (SLF) made from nori (Pyropia yezoensis) seaweed on the germination, plant growth characteristics, SPAD value, and nutrient content and uptake of komatsuna (Brassica rapa L. var. wakana komatsuna). The four types of fermented nori SLF used in this study were prepared by anaerobic fermentation of unwashed nori (SLF1), aerobic fermentation of unwashed nori (SLF2), anaerobic fermentation of washed nori (SLF3), and aerobic fermentation of washed nori (SLF4). Komatsuna seeds treated with 200-, 300-, and 400-fold dilutions of SLFs exhibited improved relative germination ratios (RGRs) at 3 and 4 days after sowing (DAS). At 4 DAS, the RGRs of seeds treated with 10-, 100-, 200-, 300-, and 400-fold SLF dilutions showed no differential effect. Seeds treated with undiluted SLFs did not germinate by 4 DAS. SLF1 may promote komatsuna seed germination. The nitrogen (N), calcium, magnesium, sodium (Na), and iodine (I) contents of plants treated with SLF1 were significantly increased relative to plants treated with the other SLFs. Moreover, the I and Na contents of plants were significantly increased by foliar spray application of different dilutions of SLF1. However, SLF treatment markedly reduced the shoot dry weight compared with 1/2-strength modified Hoagland nutrient (MHN) solution, although the same amounts of N and K were applied. SPAD values of the plants treated with SLFs were significantly higher than those of plants treated with MHN. Foliar treatment with SLFs had no significant effect on plant growth, SPAD value, or uptake of nutrients (except Na) relative to the control, but the I content was increased. Plants treated with SLF1 and SLF2 exhibited the highest Na uptake. Foliar spray treatments with SLF1 resulted in the highest I contents in plants. Based on our results, SLF1 is suitable for use as a liquid fertilizer to promote germination and increase nutrient content in komatsuna. These results need to be followed up in soil experiments in the presence of microbes in the rhizosphere.

Effects of Fermented Nori (<i>Pyropia yezoensis</i>) Seaweed Liquid Fertilizers on Growth Characteristics, Nutrient Uptake, and Iodine Content of Komatsuna (<i>Brassica rapa</i>L.) Cultivated in Soil

We investigated the effects of fermented nori (Pyropia yezoensis) liquid fertilizers on plant growth, soil plant analysis development (SPAD) values, and nutrient uptake of komatsuna (Brassica rapa L. var. wakana komatsuna) plants. The four types of fermented nori seaweed liquid fertilizers (SLFs) evaluated in this study were prepared by anaerobic fermentation of unwashed nori (SLF1), aerobic fermentation of unwashed nori (SLF2), anaerobic fermentation of washed nori (SLF3), and aerobic fermentation of washed nori (SLF4). In Experiment 1, the highest plant growth, SPAD, and nutrient uptake values were obtained from treatment with SLF2 and SLF4. There were no significant differences between the effects of basal and foliar application of SLFs, except for iodine (I) content;plants treated with SLF1 had the highest I content. In Experiment 2, plant growth and nutrient uptake decreased with higher concentrations of SLFs. Plants treated with 25% SLF2 + 75% chemical fertilizer (CF) or 25% SLF4 + 75% CF exhibited significantly higher plant growth and nutrient uptake. The highest I content resulted from treatment with 75% SLF1 + 25% CF or 100% SLF1. Taken together, our results showed that 25% SLF + 75% CF produced the best plant growth characteristics, nutrient uptake, and I content relative to the controls. Therefore, basal application of these liquid organic fertilizers can be used to increase productivity, nutrient uptake, and I content and to reduce nitrate-nitrogen content in komatsuna production.

喷施不同浓度硅肥对闽东红壤区玉米产量及其构成因素的影响

研究不同浓度的叶面硅肥(OBFs)喷施下密花甜糯12号玉米产量及其构成因素的变化,以期为闽东红壤区玉米高产栽培提供理论指导。在常规施肥的基础上,以不施硅肥为对照(T_(0),CK),设置5个叶面硅肥喷施浓度1.34(T_(1))、6.67(T_(2))、10.00(T_(3))、13.34(T_(4))、16.67 mL OBFs L^(-1)(T_(5)),研究不同浓度的OBFs叶面硅肥对玉米籽粒养分吸收、产量及构成因素的影响。结果表明:喷施不同浓度的OBFs叶面硅肥可以显著促进玉米籽粒吸收钾和硅元素。T_(2)、T_(3)、T_(4)和T_(5)处理比T_(0)(CK)玉米籽粒钾吸收量分别增加7.4%、4.9%、10.4%和15.3%;与T_(0)(CK)相比,T_(1)、T_(2)、T_(3)、T_(4)和T5处理玉米籽粒硅吸收量分别提高2.1、2.5、2.4、2.3和3.4倍。玉米籽粒钾和硅吸收量的增加进一步改善了玉米棒长和棒粗。相比T_(0)(CK),T_(1)、T_(2)、T_(3)、T_(4)和T_(5)处理玉米棒长分别增加15.2%、19.2%、24.2%、26.6%和29.7%,棒粗分别提高1.3%、1.6%、3.1%、2.7%和5.5%。T_(1)、T_(2)、T_(3)、T_(4)和T_(5)处理玉米产量分别比T_(0)增加1.9%、3.1%、13.1%、17.4%和18.7%。由线性回归分析可知,玉米增产过程中起主导作用的因子是玉米籽粒钾和硅吸收量的增加。综上,喷施不同浓度的OBFs叶面硅肥有助于增加玉米籽粒吸收钾和硅元素,改善玉米棒长和棒粗,从而提高玉米产量,尤其是13.34、16.67 mL·L^(-1)为闽北红壤区玉米种植OBFs叶面硅肥较佳的喷施浓度。

利用CND法进行荔枝、龙眼叶片营养诊断研究的适宜性

【目的】确定作物高产水平是建立作物叶片营养诊断指标的前提。探讨组分营养诊断法(Compositional Nutrient Diagnosis,CND)在计算荔枝、龙眼高产水平时存在的问题,明确该法是否适用于荔枝、龙眼叶片营养诊断。【方法】2016—2019年在华南荔枝、龙眼主产区分别采集荔枝、龙眼末次梢老熟期和果实膨大期共511、262份叶片样本,准确记录每株采样树的果实产量,测定叶片大中微量养分含量。按照CND法原理,拟合荔枝和龙眼叶片养分含量累积方差比例函数-产量模型,分析模型中出现异常值对模型的影响,并比较剔除异常值前后养分拐点值的变化以及不同高产临界值选定原则对高产群体的影响。【结果】荔枝、龙眼不同生育期部分产量模型存在异常值。剔除这些异常值对产量模型和养分拐点值影响显著,且影响缺乏规律性。不论根据什么原则确定高产临界值,均存在高产群体样本量少、占比太低以及与实际产量水平差距太大等问题。不同年份相同生育期和相同年份不同生育期计算获得的高产临界值差异大、稳定性差。此外,无论对异常值的处理,还是高产临界值的选择,均存在较强的主观性。【结论】在荔枝、龙眼上应用CND法划分高产群体存在明显局限性。这可能是研究的样本量、作物叶片养分含量状况和计数量纲三者共同制约的结果。建议在年际产量变幅大的多年生木本果树上谨慎采用该法进行叶片营养诊断研究。

涪江中游4种造林树种碳氮磷化学计量及养分重吸收特征

【目的】探究涪江中游不同造林树种间植物-凋落叶-土壤连续体的生态化学计量以及叶片养分重吸收特征,为该区域人工林的经营管理提供理论支持。【方法】以涪江中游4种常见造林树种(柏木Cupressus funebris、马尾松Pinus massoniana、桉树Eucalyptus robusta、构树Broussonetia papyrifera)为研究对象,探讨不同树种植物叶片、凋落叶和土壤碳(C)、氮(N)、磷(P)生态化学计量及叶片氮磷养分特征。【结果】①构树叶片和凋落叶的N含量均显著高于其他树种;桉树和构树的叶片及凋落叶P含量显著高于柏木和马尾松,且马尾松土壤P含量最低;②桉树和构树叶片的养分重吸收效率总体上高于马尾松和柏木;③叶片和凋落叶N、P含量分别与土壤N、P含量呈显著正相关,N重吸收效率与叶片N和P含量、凋落叶P含量呈显著正相关,P重吸收效率与叶片N、凋落叶N∶P、土壤C∶P和N∶P呈显著正相关。【结论】在涪江中游地区,这4种造林树种的叶片-凋落叶-土壤之间存在显著的相关关系,构树和桉树叶片N、P含量相对较高,养分重吸收能力较强,对养分限制具有较高的适应能力。因此,在研究区域内改造马尾松、柏木等低效人工林时可以适量补植构树和桉树,有助于提升该区域人工林质量。

叶面肥对水稻养分吸收、产量和二化螟危害的影响

施用合适的叶面肥有利于水稻生长和产量提高。本试验以5种不同类型的叶面肥为材料,分析比较了施用不同叶面肥对水稻养分吸收、产量及二化螟危害的影响。结果表明,5种叶面肥均能提高水稻体内氮(N)、磷(P)、钾(K)、钙(Ca)、镁(Mg)、铁(Fe)、锌(Zn)和钼(Mo)等营养元素的含量,显著提高水稻产量3.88%~7.47%,其中,瑞普生和丰瑞达牌叶面肥的增产效果较为显著,其次为彪榜、行万里和天需牌叶面肥。通过分析产量构成因子后发现,施用叶面肥增产的主要原因在于提高了每穗粒数。行万里牌叶面肥可以显著降低二化螟引起的水稻枯心丛率和枯心株率,其余叶面肥对降低水稻枯心丛率和枯心株率没有显著效果。施用不同叶面肥处理的经济效益表现为丰瑞达>瑞普生>彪榜>天需>行万里。在实际生产中可根据需要选择适宜的叶面肥品种。

亚热带杉木(Cunninghamia lanceolata)人工林生长与土壤养分对氮沉降的响应

为探讨亚热带森林对氮沉降增加的响应,项目在杉木人工林中开展了野外模拟N沉降试验,分N0(对照)、N1、N2、N3等4种处理,N沉降量分别为0、60、120、240(kgNhm-2a-1)。通过3a的研究发现,中高氮处理(N2、N3)明显促进了杉木胸径的生长,而低氮处理(N1)则没有产生明显影响。氮沉降对树高生长也有明显的促进作用,但随着氮沉降水平的增加其影响有减弱趋势。通过各水平N处理后,杉木年平均蓄积增长量分别为28.82、28.96、32.63m3hm-2和33.68m3hm-2,表明N沉降在一定程度上增加了林分蓄积量的积累,但处理之间的差异没有达到统计上的显著性水平。随着氮沉降水平的增加,NH4+-N和NO3--N含量明显上升,而土壤pH值、有机质、速效P、速效K和交换性Ca、Mg含量则呈下降趋势。杉木针叶养分状况对氮沉降的响应也比较敏感,N1、N2、N3处理使针叶平均N含量分别增加18.25%、11.68%和13.14%,但对P、K、Ca、Mg含量表现出一定的抑制作用。

尾叶桉叶片氮磷钾钙镁硼元素营养诊断指标

采用临界值法对尾叶桉幼林材积生长进行叶片营养诊断。试验结果表明 ,氮、磷、钾、钙、镁和硼等营养元素的临界浓度分别为 1 5 .3 g/kg、1 .2 g/kg、4.2 g/kg、1 6.1 g/kg、2 .5 g/kg和 0 .0 1 9g/kg;最适浓度范围分别为 1 5 .3～ 1 8.1 g/kg、1 .2～1 .7g/kg、4.2～ 5 .6g/kg、1 6.1～ 1 9.8g/kg、2 .5～ 3 .0 g/kg和 0 .0 1 9～ 0 .0 3 1 g/kg。而对树高生长进行营养诊断时 ,上述结果稍微有些变化。

长白山林线主要木本植物叶片养分的季节动态及回收效率

植物叶片养分含量的季节动态和回收效率对植被生态系统的养分循环和植物生长策略具有重要意义。以长白山高山林线上分布的3种主要木本植物——岳桦(Betula ermanii),牛皮杜鹃(Rhododendron aureum)和笃斯越橘(Vaccinium uliginosum)为研究对象,通过测定叶片中N、P、K、Ca、Mg、Fe等6种养分元素含量,分析在林线处植物叶片养分含量的季节动态及其与土壤养分含量的关系。结果表明岳桦和笃斯越橘叶片中养分元素的季节动态基本一致,即:N、P、K含量在生长季内逐渐降低,而Ca的含量逐渐增加;Mg在生长季旺盛期最低,而Fe含量却最高。牛皮杜鹃作为常绿灌木,叶片养分的季节动态与其余两种植物明显不同,表现为在生长季初期6种养分元素含量最低。岳桦和笃斯越橘植物叶片中N、P、K、Fe都有一定程度的回收,但笃斯越橘叶片的养分回收率更高,反映了笃斯越橘更能适应相对贫瘠的环境。3种林线植物叶片中养分含量与土壤养分并不存在显著的相关性,说明长白山林线上土壤中养分的分布没有对林线上3种主要的木本植物的生长和分布产生直接的影响。

两个苹果品种不同枝类叶营养含量年周期变化及营养诊断方法研究

通过对瓦里短枝和长富2号两个品种不同枝条类型叶片取样,测定分析了苹果树不同生育阶段叶片营养元素含量变化特征,为营养诊断采集标准叶样和指导施肥提供依据。结果表明,不同采样时期、不同枝类叶片营养元素含量差异很大,以新梢停止生长期的各类枝条叶片营养元素含量最为接近。在年周期中,叶片营养元素含量变异系数从小到大顺序为营养枝<中枝<长枝<短枝<叶丛枝。常量营养元素含量周年变化幅度小于微量元素,氮含量变幅最小,锰变幅最大。品种间除硼元素含量变化有差异外,其它营养元素含量变化趋势相近或相同。随树体生育进程,叶片营养元素含量变化规律为氮、磷、铜含量呈降低趋势;钾、锌、铁、硼含量呈波动状态;钙、镁含量至新梢停止生长期最高,且枝条长度越小,含量越高;锰含量变化近似"正态分布"。苹果新梢停止生长期是叶片养分最稳定时期,营养枝是叶最佳采样枝类。

林木叶片最适养分状态的模拟诊断

为研究叶片最适养分状态,提出了模拟诊断方法。将砂姜黑土上Ⅰ-69杨(Populus deltoides Bartr.cv.“Lux”)的改土培肥试验各处理作为模拟诊断的样地。用典型相关分析方法选择采样时间、确定与林木生长有密切关系的叶片养分元素。用抛物线函数作为叶片最适养分状态的诊断函数。选择变量同时考虑叶片养分的含量和养分之间的比例。经过4年多的研究得出Ⅰ-69杨最适叶片养分状态为:造林第1年7月叶片含P_2O_50.55—0.75％;造林后第2年7月叶片含N3.20—4.20％;造林后第3年5月含N3.00—3.70％;造林后第4年5月叶片中的N/K为1.00—1.60。