浅谈水溶肥在温室栽培中的应用

以黄瓜为试验材料,研究了腐植酸水溶肥的根施与叶面喷施对黄瓜苗期生长发育和产量的影响.结果表明,苗期施用腐植酸能提高黄瓜幼苗的株高、茎粗、干鲜质量和叶面积等指标,其中以喷施处理效果最佳.在黄瓜采收期,叶面喷施1?000倍稀释的腐植酸液肥可以显著提高黄瓜产量,增产率达?到8.93%.     

Effect of foliar applied phosphatic fertilizer on absorption pathways, yield and quality of sweet persimmon

Pot and field experiments were conducted to identify nutrient absorption pathways, growth, yield and quality of sweet persimmon using ³²P tagged fermented mono-calcium di-hydrogen phosphate (FMCP) and normal FMCP fertilizer, respectively. In pot experiment, lower surface treated leaf absorbed higher amount of radionuclide phosphorus than upper surface treated leaf and phosphorus absorption increased with the increase in duration. The highest radioactive phosphorus absorption obtained was 8.88 × 10⁴ and 3.57 × 10⁴ Bq/g dry weight of leaf against dorsal and ventral treated leaf surfaces at 96 h after fertilizer application. During experimentation, stomata were closed from 2 to 10 h after application of FMCP fertilizer and nutrient absorption was higher in the lower surface than the upper surface. As a result, phosphorus was absorbed through cuticle by diffusing in aqueous pores in lower surface of leaf. Alternate day and night (24–96 h), lower surface also performed higher amount of phosphorus absorption than upper surface of leaf due to stomatal activity and aqueous pores because lower surface contains higher number of stomata than upper surface of sweet persimmon. It may be concluded that aqueous pores as well as stomata can be important pathways for the absorption of foliar applied FMCP fertilizer. In field experiment, foliar application of normal FMCP fertilizer increased the vegetative growth, number of effective flowering buds and decreased insect–disease infestation of sweet persimmon over control. Sweet persimmon yield increased due to the fact of decreasing trend of fruit dropping by foliar fertilization. Maximum fruit number (1110 and 1449 per tree) was observed in T₄ (foliar spray @ 7.5 ppm P of FMCP fertilizer) and T₅ (alternate foliar spray of 10 and 7.5 ppm P of FMCP fertilizer) treatments in 2005 and 2006, respectively. In T₄ and T₅ treatments, the average fruit yield increased by 153.0 and 211.4 kg tree⁻¹ in 2005 and 2006 over control, respectively. FMCP fertilizer gave maximum fruit yield in T₄ and T₅ treatments in 2005 and 2006, respectively and it differed from other foliar treatments including control. Treatment T₅ increased fruit hardness (2.32 kg/Ø 5 mm), ⁰brix content (14.0%) and reduced acidity (0.018%) in 2005. These results allow us to infer that foliar application of FMCP fertilizer was not only augmenting the fruit yield of sweet persimmon but also improved the quality of produce.     

Quantifying bunch weights of the East African Highland bananas (Musa spp. AAA-EA) using non-destructive field observations

In banana on-farm studies in the East African Highlands, quantification of production has been difficult because plants are at different stages of development at any given time. Production is continuous and quantification would therefore require permanent presence of an observer. Hence, most on-farm surveys have resorted to estimations from farmers or ‘experts’ through recall or visual qualitative observations. These methods are highly inaccurate. This study aims to develop and validate allometric relationships for quantitative estimation of bunch weights, based on rapid, inexpensive and non-destructive methods of data collection that take into consideration genotypic, spatial and developmental variability. The study was conducted in 179 farmer fields in central, south, southwest, and east Uganda. Bunch weights were estimated through linear regression with log-transformed girth of pseudostem at base and 1m, number of hands, and number of fingers in the lower row of the second lowest hand. The number of hands and fingers relate to the potential sink size (i.e. bunch), and the girth at base and 1m were used as a proxy for pseudostem volume, which relates to the potential of the plant to fill the sink. Bunch weight was significantly (P ≤ 0.001) and positively (R² = 0.73) related to log-transformed pseudostem volume, and number of hands and fingers. When data were partitioned and regressed, regression coefficients did not differ significantly for cultivars (i.e. Enyeru, Kibuzi, Nakabululu and Nakitembe), developmental stages (flowering, early fruiting, late fruiting and full maturity), regions (central, south, southwest and east Uganda), foliar and soil N, P, K, Ca and Mg concentrations. Data partitioning improved the accuracy of prediction significantly for different cultivars, regions, and foliar Ca, but not for bunch developmental stages, foliar N, P, K and Mg and soil N, P, K, Ca and Mg concentrations. However, the residuals of all the regressions of partitioned data correlated highly (R² between 0.92 and 1.00) to those of the regression based on pooled data. On validation of the regression based on pooled data, the bias (−9.97%) and modeling efficiency statistic (0.64), suggested that predictions were not always accurate. Still, the total predicted bunch weights were higher than the observed bunch weight by only 2%. This study therefore concludes that the regression derived using pooled data is suitable for on-farm prediction of bunch weight, for the East African Highland cooking banana, regardless of genotypic, developmental and spatial variations.     

硒处理对土壤理化性质及杭白菊品质的影响

以纳米硒为外源硒处理杭白菊,分别采用土壤施硒（T）、叶面喷施硒肥（Y）以及土壤与叶面相结合施硒肥（T+Y）3 种施硒方式,以不施硒处理为对照（CK）,研究不同施硒方式对土壤理化性质、杭白菊营养成分、硒含量和产量的影响。结果表明：不同处理下土壤容重、土壤孔隙度和土壤含水量与CK无显著差异。T、Y、T+Y处理下土壤脲酶活性显著低于CK,土壤蔗糖酶活性显著高于CK,土壤碱性磷酸酶活性和土壤过氧化氢酶活性与CK差异不显著。CK处理下菊花花序中Vc含量显著高于其他处理。T、Y、T+Y处理下黄酮和绿原酸含量显著高于CK。T、Y和T+Y处理下花序中硒含量极显著高于CK。T+Y处理下杭白菊单株开花量和单产量显著高于CK。T、Y、T+Y三种施硒方式相比,T+Y处理下杭白菊富硒效果最佳。综合分析比较三种施硒方式对土壤理化性质、杭白菊营养成分、硒含量和产量的影响,确定以土壤与叶面相结合施硒肥（T+Y）效果最佳。这一结果可为富硒杭白菊生产提供实践和理论依据。     

Restoring the iconic Ulmus americana to urban landscapes: Early tree growth responds to aboveground conditions

Native trees provide a range of benefits, from supporting native wildlife to climate regulation, and many urban natural resource managers prioritize native tree planting and restoration. Ulmus americana (American elm) was once widely planted in American cities but has been decimated by Dutch elm disease (DED; Ophiostoma ulmi). Our study evaluated U. americana establishment and growth across urban landscapes. We planted ramets from three DED-tolerant U. americana genotypes (RV16, RV474, and Sunfield) along an urbanization gradient in Newark, DE and Philadelphia, PA, and assessed physiological and morphological responses. We analyzed how U. americana clone growth, chlorophyll fluorescence, and foliar chemistry relate to impervious surface area, ozone (O₃) concentrations, and soil characteristics. The one-year post planting mortality rate was low (4%) demonstrating these elms can withstand urban environmental conditions when provided ample water supply and protection from deer. As expected, the elms differed in growth rate, chlorophyll fluorescence, and foliar chemistry between the cities. Elms planted in Philadelphia had greater photosynthetic capacity in July (F_v/F_m = 0.76) and September (F_v/F_m = 0.75), while Newark elms had greater photosynthetic capacity in August (F_v/F_m = 0.78). Depleted foliar δ¹³C signatures in Philadelphia suggest elms are experiencing greater fossil-fuel derived atmospheric CO₂ than in Newark, possibly contributing to the greater growth rates observed in Philadelphia compared to Newark. Enriched foliar δ¹⁵N and greater foliar %N in Philadelphia clones suggest they are experiencing greater N deposition from NO_x-derived sources compared to Newark clones. Clones growing in Philadelphia had greater foliar nutrient concentrations despite growing in soils with greater heavy metal concentrations. These foliar-soil chemistry patterns suggest that clones growing in Philadelphia respond positively to urban environmental conditions in a large city, whereas clones growing in Newark may be experiencing N limitation in the first year of growth after planting.     

叶面喷施铁和镁微肥对玉米幼苗碳代谢及生长的影响

为了探讨铁镁微肥对北方旱地玉米幼苗期碳代谢和生长的影响,对盆栽的玉米幼苗单独和混合喷施不同质量浓度的FeSO_4·7H_2O(250、500、750mg/L)和MgSO_4·7H_2O(0.5、1.0、1.5g/L)溶液,于2周后分析叶片中与碳代谢相关的生理生化指标以及生长指标的变化。结果表明,叶面喷施铁、镁微肥可以有效提高叶片的叶绿素质量分数、光合能力以及可溶性糖和淀粉的质量分数,增强玉米的碳代谢能力;同时,可以显著促进根系的生长,提高根冠比。其中,适合玉米幼苗生长的最佳喷施质量浓度分别是500 mg/L的FeSO_4·7H_2O、1g/L的MgSO_4·7H_2O和250mg/L的FeSO_4·7H_2O与0.5g/L的MgSO_4·7H_2O混合溶液。因此,叶面喷施适当质量浓度的铁或镁微肥可以有效提高玉米幼苗的碳代谢能力,促进植株、特别是根系的生长,这对于玉米后期的生长发育也具有积极的意义。     

叶面喷施硅和硒对水稻砷积累及光合参数的影响

本文采用盆栽试验，研究了在砷污染土壤上，水稻叶面分别喷施硅溶液、硒溶液和硅硒混合溶液对籽粒砷含量相对较低的水稻品种旌1优华珍和C两优华占以及籽粒砷含量相对较高的水稻品种丰优香占砷积累和光合参数的影响。试验结果表明，3种叶面喷施处理相比较而言，以叶面单独喷施硅降低水稻籽粒砷含量效果最好，优于叶面单施硒和叶面喷施硅硒混合液处理。叶面单独喷施硅与对照相比，显著降低了籽粒砷含量相对较低的两个水稻品种的籽粒砷含量，但对籽粒砷含量相对较高的水稻品种则没有显著影响。籽粒砷含量相对较低的水稻品种更多比例的砷固定在茎中使其稻米砷积累量较低。3种叶面喷施处理与对照相比均提高了水稻光合参数(如光合速率、气孔导度、胞间CO₂浓度)，光合参数与水稻砷浓度呈负相关关系，叶面喷施硅或硒对水稻叶片光合参数的影响差异可能是造成籽粒砷含量差异的重要原因，不同水稻品种叶片光合参数对外源硅或硒的敏感度或响应度不同。总之，叶面喷施硅溶液对改善水稻光合参数的效果最好，是减少水稻籽粒砷含量一项经济有效的措施，在生产应用实践中，要注意作物品种间的差异。