桃树不同区位叶片SPAD值与叶绿素含量的相关性

采用SPAD-502PLUS叶绿素仪与分光光度法分别测定了桃树不同区位叶片的SPAD值与叶绿素含量,建立SPAD值与叶绿素a、叶绿素b和总叶绿素的二次方函数、线性函数、对数函数及乘幂函数的拟合方程,并根据决定系数(R~2)确定最佳拟合曲线,以探讨SPAD值与叶绿素含量之间的关系。结果表明:桃树叶片SPAD值与叶绿素a、叶绿素b及总叶绿素含量间均存在极显著正相关关系。SPAD值与叶绿素a含量的最优函数模型为y=0.537-0.002X+0.001X~2(R~2=0.643);SPAD值与叶绿素b含量最优函数模型为y=5.893-0.309X+0.004X~2(R~2=0.635);SPAD值与叶绿素总量的最优函数模型为y=0.179X-5.248(R~2=0.598)。通过对不同区位叶片SPAD值与叶绿素含量实测值与预测值的统计检验发现,总叶绿素含量的实测值与预测值间不存在显著差异,可以通过回归方程来预测桃树叶片叶绿素的绝对含量。     

专用肥对早熟禾叶片生长及叶绿素含量的影响

以城市正常生长的4年生早熟禾为试材,研究专用肥对早熟禾生长和叶绿素含量的影响。设计4个处理：CK,0kg／hm^2;ZH1,97．03kg／hm^2;ZH2,116．47kg／hm^2;ZH3,155．95kg／hm^2。每处理4m^2,3次重复。试验结果表明：ZH3处理可以极显著促进早熟未叶片的加长和加宽生长,外在表现出旺盛生长的景象,ZH2处理使叶片变得细长,ZH1处理则使叶片变短变宽,景观表现相反;叶片内叶绿素含量表现为ZH3〉ZH1〉ZH2〉CK,方差分析结果表明ZH3显著高于其他3个处理。综合分析认为,ZH5处理施肥量为4年生早熟禾最佳施肥量。     

Effects of nitrogen availability and supplementary light on the nitrate content of soil-grown lettuce

Summary

The effect of nitrogen availability and low level supplementary light on the growth and nitrate content of butterhead lettuce (Lactuca sativa var. capitata L.) grown in soil under greenhouse conditions in winter was studied. No significant interactions between nitrogen availability and supplementary light on yield, nitrate content, osmotic potential of expressed leaf sap and component osmotica were found. Supplementary light greatly increased plant growth and resulted in earlier harvest. When harvested with similar fresh weights, plant nitrate content was significantly reduced by supplementary light although the effect was slight. The reduced contribution of nitrate to sap osmotic potential at the higher light level was accompanied by a significant increase in the contribution of sucrose. While plant fresh weight was unaffected by the rate of nitrogen application, a positive correlation between nitrate content and nitrogen application rate was found. Reduced nitrate content at low nitrogen application rates was accompanied by increased contributions of chloride, glucose and sucrose to sap osmotic potential.     

Effects of nitrate,ammonium and chloride application on the yield and nitrate content of soil-grown lettuce

Summary

The effect of nitrogen availability and nitrogen form on the yield and nitrate content of butterhead lettuce (Lactuca sativa var. capitata L.) grown in soil under greenhouse conditions was studied. The extent to which chloride application can reduce nitrate content by supplying the plant with an alternative osmotically active anion, and whether the presence of ammonium in the soil is a necessary prerequisite for an effect of chloride, was also examined. Reducing NO₃-N availability from 260 to 200 kg N ha^–1 significantly reduced nitrate content while head fresh weight was unaffected. Further reducing NO₃-N availability to 120 kg N ha^–1 significantly reduced both nitrate content and fresh weight. Substituting 40% of the available NO₃-N with NH₄-N significantly reduced nitrate content while fresh weight was unaffected. The effect of NH₄-N application on plant nitrate content was enhanced by the application of the nitrification inhibitor dicyandiamide (DCD). Despite increasing chloride uptake, the application of chloride had no significant effect on head fresh weight or nitrate content when available nitrogen was in the nitrate form irrespective of the level of nitrogen application. Chloride application similarly had no effect on head fresh weight or nitrate content when applied together with ammonium without the nitrification inhibitor DCD, despite a greater uptake of chloride. Where both ammonium and DCD were applied, however, chloride application significantly reduced head nitrate content.     

喷施磷酸二氢钾对桃叶片和果实性状的影响

以不同成熟期的桃品种豫甜、豫香、秋甜、秋蜜红为试材,研究了喷施磷酸二氢钾对其叶片叶绿素含量、干鲜质量比及果实的可溶性固形物含量、可溶性糖含量、可滴定酸含量、维生素C含量等品质特性的影响。结果表明,喷施磷酸二氢钾能提高叶片中叶绿素含量、干鲜质量比和果实可溶性固形物含量、可溶性糖含量;对果实的可滴定酸含量、维生素C含量影响不明显;叶片喷施不同浓度和次数的磷酸二氢钾均可推迟桃果实成熟期;喷施清水和对照处理间叶片性状和果实品质差异不明显;喷施磷酸二氢钾浓度和次数以500mg/L3次效果最显著,以300mg/L3次最经济有效。     

糯米糍荔枝花芽诱导期间叶片色素和结构的变化

以糯米糍荔枝为材料,研究了冬季花芽诱导期间叶片叶绿素含量、叶面腊质层厚度、叶片厚度及内部显微超微结构的变化。结果表明,糯米糍荔枝结果母枝老熟后,伴随营养生长转向生殖生长,叶片绿色逐渐减退,叶绿素含量降低;叶片厚度虽无明显变化,但其上下表皮和维管束细胞壁自发荧光加强,表明该组织木质化加强;叶肉细胞叶绿体内有大量的淀粉粒,并在花芽诱导期间增多增大。海绵组织较栅栏组织淀粉积累早且更为丰富。     

Effect of nitrogen fertilization on yield and fruit oil content of avocado trees

This work was carried out to study the effect of two nitrogen levels, 250 and 500 g of actual nitrogen per avocado tree per year. The nitrogen sources were calcium nitrate (as soil application) and urea (as foliage application).Nitrogen fertilization gave a highly significant increase in tree yield (kg/tree) in most treatments. Moreover, urea sprays seemed to be more effective on the yield than calcium nitrate added to the soil at the same nitrogen level. The 500 g nitrogen level of both sources gave a higher yield increase than 250 g nitrogen. Nitrogen fertilization gave a slight increase in mean avocado fruit weight and size, while urea sprays seemed to be more effective in increasing the mean fruit weight and size. A slight decrease in flesh oil content occurred as a result of nitrogen fertilization.     

Varying plant density and harvest time to optimize cowpea leaf yield and nutrient content

Plant density and harvest time were manipulated to optimize vegetative (foliar) productivity of cowpea [Vigna unguiculata (L.) Walp.] canopies for future dietary use in controlled ecological life-support systems as vegetables or salad greens. Productivity was measured as total shoot and edible dry weights (DW), edible yield rate [(EYR) grams DW per square meter per day], shoot harvest index [(SHI) grams DW per edible gram DW total shoot], and yield-efficiency rate [(YER) grams DW edible per square meter per day per grams DW nonedible]. Cowpeas were grown in a greenhouse for leaf-only harvest at 14, 28, 42, 56, 84, or 99 plants/m2 and were harvested 20, 30, 40, or 50 days after planting (DAP). Shoot and edible dry weights increased as plant density and time to harvest increased. A maximum of 1189 g shoot DW/m2 and 594 g edible DW/m2 were achieved at an estimated plant density of 85 plants/m2 and harvest 50 DAP. EYR also increased as plant density and time to harvest increased. An EYR of 11 g m-2 day-1 was predicted to occur at 86 plants/m2 and harvest 50 DAP. SHI and YER were not affected by plant density. However, the highest values of SHI (64%) and YER (1.3 g m-2 day-1 g-1) were attained when cowpeas were harvested 20 DAP. The average fat and ash contents [dry-weight basis (dwb)] of harvested leaves remained constant regardless of harvest time. Average protein content increased from 25% DW at 30 DAP to 45% DW at 50 DAP. Carbohydrate content declined from 50% DW at 30 DAP to 45% DW at 50 DAP. Total dietary fiber content (dwb) of the leaves increased from 19% to 26% as time to harvest increased from 20 to 50 days.     

Improvement of flower color by means of leaf treatments in lily

Flower color, an important feature biologically and commercially, is based on four natural pigments – flavonoids, carotenoids, betalains and chlorophylls. Temperature, light, nutrition – as well as additions of sugar, salt, or metals to the conservation water – have an effect on pigmentation. We investigated the effects of K-sulphate and/or sucrose on flower color in leaf treatments applied 30–10 days before harvest to four Asiatic lily (Lilium × elegans Thunb.) cultivars during the winter and summer. Colors of tepals were evaluated by a portable spectrocolorimeter that calculates the standard CIE L*a*b* coordinates and the color differences (E). After leaf treatments during both seasons, cultivars with flowers with high red components (e.g. the purple ‘Fangio’ and the pink ‘Brindisi’) showed significant improvements in color quality. The orange-flowered ‘Tresor’ showed improvement only if K-sulphate and Mix (K-sulphate and sucrose) solution treatments were applied during the summer. The yellow-flowered ‘Menorca’ was not affected by treatments during either summer or winter forcing season. Especially in the winter, a significant reduction in flower abortion was observed for cut flowers of all cultivars. In summer only ‘Fangio’ and ‘Tresor’ showed a reduction in flower abortion. Also, flower size and longevity were improved by the leaf treatment. The results, obtained from a commercial nursery operation, demonstrate that lily growers can adopt a very simple and inexpensive treatment to improve important qualitative traits of their product.     

Indicators of nitrogen status for ornamental woody plants based on optical measurements of leaf epidermal polyphenol and chlorophyll contents

Indicators of plant nitrogen (N) status adapted to woody ornamental plants are essential for the adjustment of fertilization practices in nurseries. The objective of this study was to investigate whether optical measurements of leaf epidermal polyphenol (EPhen) and chlorophyll (Chl) contents could be used as N status indicators for woody deciduous and evergreen ornamental plants. One-year-old plants of Lagerstroemia indica, Callicarpa bodinieri and Viburnum tinus were grown outdoors in containers. They received low (TN₁, 4 mg L⁻¹) or high (TN₂, 105 mg L⁻¹) levels of N during 2 months in spring and summer. TN₁ treatment limited shoot growth from 28 to 37 days after treatment initiation in Lagerstroemia and Callicarpa, respectively. Shoot growth was unaffected until day 176 in Viburnum. The mass-based leaf N content (N_M) of a sample of young expanded leaves exposed to direct sunlight was tightly correlated with shoot N content and differentiated treatments several weeks before shoot growth reduction for the three species. N_M was therefore used as an index of plant N status. EPhen and Chl contents were recorded with Dualex™ and SPAD-502 leaf-clip meters, respectively. Dualex values were strongly and negatively correlated with N_M, and differentiated the treatments early in the experiment, in all three species. SPAD values were positively correlated with N_M for Lagerstroemia and Callicarpa, but not for Viburnum, because large variations in leaf mass per area (LMA) in this species compensated for variations in leaf dry mass invested in Chl. The SPAD/Dualex ratio was used to assess changes in the proportion of leaf dry mass allocated to proteins and polyphenols in response to fertilization. It differentiated between the treatments early in the experiment and was correlated with N_M in all three species.     

Effects of shading on gas exchange,specific leaf weight and chlorophyll content in four kiwifruit cultivars under field conditions

Diurnal changes of incident photosynthetic photon flux density (PPFD), transpiration rate (E), photosynthetic rate (Pn), stomatal conductance (Cs) and water use efficiency (WUE), together with a number of environmental factors, were measured on individual leaves at well exposed and shaded positions within the canopy for four cultivars of kiwifruit (Actinidia sinensis, P.). Pn and E rates were'much lower in the shaded leaves for all cultivars due to extremely low PPFD values reaching these leaves. Cs followed a trend similar to that for Pn. Exposed leaves showed a significantly higher WUE in the morning, while no difference was observed between exposed and shaded leaves around midday. Specific leaf weight (SLW) was lower in shaded leaves, which had a greater chlorophyll content than exposed leaves.     

Comparison of fluorescent and high-pressure sodium lamps on growth of leaf lettuce

Radiation from high-pressure sodium (HPS) lamps provided more than a 50% increased yield (fresh and dry weight of tops) of loose-leaf lettuce cultivars Grand Rapids Forcing and RubyConn, compared to that obtained by radiation from cool-white fluorescent (CWF) lamps at equal photosynthetic photon flux; yet, input wattage was approximately 36% less. It was postulated that the considerable output of 700 to 850 nm radiation from the HPS lamp was a significant factor of the increased yield. Under HPS lamps, the leaves of both cultivars were slightly less green with very little red pigmentation ('RubyConn') and slightly elongated, compared to CWF, but plant productivity per unit electrical energy input was vastly superior with HPS.     

Effect of reducing the infrared radiation of sunlight on greenhouse temperature,leaf temperature,growth and yield

Infrared radiation, which is responsible for leaf temperatures that exceed the optimal for photosynthesis, was reduced by absorption in an aqueous CuSO₄ solution. A small greenhouse was constructed of double acryl plates through which a 0.5% CuSO₄ solution was circulated for infrared radiation filtration and cooling. The air temperature in this greenhouse never exceeded 30° C and the leaf temperature of the plants grown in this house was 10% lower than in a glass greenhouse. The yield of tomato plants grown in the acryl greenhouse, with infrared radiation filtration and receiving CO₂ enrichment during the entire light period, was not significantly increased as compared with the yield in the glass greenhouse with a similar CO₂ concentration. This may have been due to long periods with low light levels caused by extremely rainy and cloudy weather conditions, and by condensation on the inside surfaces of the acryl greenhouse caused by the high humidity.     

锦橙叶片氮含量可见近红外光谱模型研究

以单系枳砧蓬安100号锦橙为试材,采用田间试验的方法开展利用鲜叶可见近红外光谱估测叶片氮素营养状况的研究。运用偏最小二乘法(PLS)分析叶片反射光谱与氮含量之间的关系。结果表明,在可见光350～700nm,随着氮肥用量的增加,叶片光谱反射率呈下降趋势;而在750～1075nm范围内,叶片光谱反射率随着氮肥用量增加而增加。通过对叶片反射光谱、一阶微分、二阶微分和倒数对数光谱进行变量标准化(SNV)处理,运用偏最小二乘法(PLS)与内部交叉验证建立的氮含量预测回归模型,其中反射光谱的一阶微分光谱氮含量定标模型具有最好的预测能力,其建模与预测均方根误差和标准差都较低且接近,偏差绝对值最小。因此,可以利用叶片反射光谱的一阶微分值来预测蓬安100号锦橙叶片氮含量。     

Effect of soil amendments and sawdust mulching on growth,yield and leaf nutrient content of highbush blueberry plants

The effects of soil amendments (elemental S, peat, crushed pine bark or crushed pine bark plus elemental S) mixed into the planting hole, with or without a sawdust mulch over the soil surface, on the early growth and yield of highbush blueberry bushes (Vaccinium corymbosum L., ‘Bluecrop’) grown in a mineral soil were investigated in a 3-year field study.Plant growth and yields were increased by additions of all amendments and generally followed the order: bark plus S > bark = peat = elemental S > control. The reasons for the positive growth responses probably differed among the treatments. In the control treatments, growth appeared to be limited by Mn and possibly Fe deficiency. For the S treatment, a decrease in the soil pH with a concomitant increase in levels of Mn and Fe probably stimulated the response. However, concentrations of both leaf Al and Mn were very high in the S treatment, and toxicities of these elements may have been limiting a further growth response. For the peat amendment, the growth response was probably related to both a decrease in soil pH and an improvement in soil physical conditions. For the bark amendment, the growth response is likely to have been pricipally related to improved physical conditions and also to the reasonably high Mn content of the bark itself. For the bark plus S treatment, the additional effect of reduced pH provided for an even greater response than that for bark alone. It was concluded that additions of organic matter and an acidifying agent to the planting hole can greatly increase early growth and yields of blueberries in mineral soil.     

Weed control and yield response of soil solarization with different plastic films in lettuce

Phase out of most chemicals available for weed management renewed the interest in soil solarization as a technically effective and environmentally safe practice for lettuce weed control in hot summer areas. Properties of solarizing films and lettuce crop system may considerably affect weed control and yield response of soil solarization. Different solarizing films, including low-density polyethylene, ethylene-vinyl acetate copolymer, low-density polyethylene–ethylene-vinyl acetate coextruded and a biodegradable corn starch-based film, were evaluated in 2003 and 2004 for weed control and lettuce yield response under field and greenhouse conditions in Southern Italy. Soil solarization strongly reduced weed density and biomass in both greenhouse and in the field, with no significant differences among the tested plastic films. Most annual weeds were completely controlled by soil solarization, except amaranth, Amaranthus spp., in soil solarized with biodegradable film in the field. Emergence of mediterranean sweetclover, Melilotus sulcatus, was stimulated by soil solarization in greenhouse. In the field, Cyprus vetch, Lathyrus ochrus, was found in solarized plots though absent in untreated soil. Perennial weeds were not affected by soil solarization, except a strong control of canadian thistle, Cirsium arvense, in the field. Lettuce yield resulted significantly higher in solarized soil than in control plots, with no significant differences among the solarizing materials. All tested materials proved to be technically effective for soil solarization in lettuce, though low resistance and short durability of biodegradable film may suggest its application mainly to soil solarization in greenhouse or in organic systems.     

氮磷钾肥对红富士苹果产量、品质和叶片矿质元素含量的影响

研究了氮、磷、钾不同施肥处理对红富士苹果产量、品质和叶片矿质元素含量的影响。结果表明,对于苹果的产量,钾肥效应最大,其次为氮肥,磷肥最小;对于苹果的单果重,氮肥的效应最大,其次为钾肥,磷肥最小。氮、磷、钾肥的配合施用效果最好。     

腐殖酸水溶性肥料对莴苣产量和效益的影响

为了解施用腐殖酸水溶性肥料对莴苣产量和效益的影响,以便在生产上推广应用,笔者在莴苣生长期进行了施用试验。结果表明,在莴苣旺盛生长期和茎部肥大期,每667m2用腐殖酸水溶性肥料100mL加水50kg进行叶面喷施,能够使莴苣产量提高170kg以上,增产率在7%以上,667m2可增加收入200元,投入产出比达到1∶10。莴苣喷施该肥料,技术简单实用,增产增效明显,建议在生产上推广应用。     

Growth,yield and essential oil content of three cultivars of basil grown under different levels of nitrogen in the field

A field experiment was conducted in Southern Italy to investigate the effect of different nitrogen (N) rates (0, 100 or 300 kg ha⁻¹) on the number of branchings and leaves per plant, plant height, yield of above-ground fresh biomass, total leaf area, dry weight, leaf-to-stem ratio, leaf essential oil content and the essential oil quality at commercial harvest (full bloom) of the three cultivars of basil (Ocimum basilicum L.): (i) “Mostruoso mammouth” (MM); (ii) “Genovese profumatissimo” (GP); (iii) “Napoletano a foglia di lattuga” (NFL). Nitrogen fertilization up to 300 kg ha⁻¹ increased yield of above-ground and leaf fresh biomass, leaf essential oil yield, but it did not affect leaf-to-stem ratio, plant height and the number of branchings per plant. The increase in essential oil yield induced by N fertilization depended on an increase in both leaf essential oil concentration and leaf biomass. The increase in LAI with increasing N fertilization was due to an increase in leaf number per plant rather than in individual leaf expansion. The cultivar GP was different in morphology from MM and NFL, since it had greater leaf number and plant height, but lower leaf-to-stem ratio and LAI. The physiological efficiency of N use (PE) in producing above-ground biomass was not related to N application whereas PE in producing essential oil (PE-oil) tended to increase with increasing levels of N applied. With regard to the effect of the cultivar, GP was less efficient in N use for oil production than MM and NFL since PE-oil of GP was lower while leaf N and PE-biomass were higher than the other cultivars. NFL was the richest in methyl chavicol but the lowest in linalool, whereas MM and GP contained linalool and eugenol.     

钾锌营养对水培生菜生长、产量和品质的影响

通过增施钾肥、锌肥和钾锌同增,研究钾锌肥对生菜生长、产量和品质的影响,以期为生菜优质、高效生产模式下的施肥管理提供理论支撑。结果表明,钾、锌肥对生菜生长均有促进作用,钾锌同增效果最显著,较对照株高显著增长23.71%;钾肥和锌肥均可提高生菜可溶性蛋白和可溶性糖含量,钾锌同增处理的可溶性蛋白和可溶性糖含量较对照分别增长23.82%、115.54%;但维生素C含量会因为钾水平过高而降低,对照较增施钾肥处理显著增长68.30%,锌肥对生菜维生素C含量有促进作用;钾、锌肥均可提高生菜硝酸还原酶活性,降低硝酸盐含量,且钾锌肥互作的协同效果更佳,较对照高42.78%;钾、锌肥通过影响生菜叶绿素的合成进而影响生菜产量,钾锌同增处理生菜产量最高,较对照高77.93%,其次是增钾处理,对照处理产量最低。