歙县山区山核桃低产成林改造技术初探

本文简要概括了歙县山区山核桃栽培历史,客观分析了山核桃低产成林普遍存在的主要问题,系统论述了山核桃低产成林密度调整、水土保持、整形修剪、土肥水管理、病虫害防治五大实用改造技术,促使成林山核桃能够克服"大小年"现象达到稳产高产的目的。     

宁国山核桃结果大小年成因及对策

宁国市是山核桃之乡，现有山核桃面积23．8万亩，年产量可达3800吨，已成为宁国市林农经济收入的主要来源。但山核桃结果大小年十分明显，如何消除大小年的差别根据笔者多年的观察和试验，并走访了果农，找出造成结果大小年的原因。并采取相应的管理措施：     

山核桃嫁接技术研究初报

临安县昌北区栽培山核桃已有二百年历史。全区有山核桃林六万余亩,产量占全县一半。1979年达四万担,是产区社员经济收入主要来源。但山核桃存在始果期迟,大小年明显,产量不稳;树冠高大,采收困难;嫁接不易成活等弊病,影响了它的发展和经营管理程度。为了加速发展山核桃生产,改变半野生状态,达到“矮化、密植、早实、     

山核桃保花保果技术研究

山核桃Carya cathayensis Sarg.是我国特有的一种名贵干果和木本油料树种,浙江省临安县是山核桃重点产区,有面积约1.27ha,大年产5000-6000t,产值5000多万元。但由于管理粗放,加上花期常遇低温多雨天气,座果率普遍很低。大小年极明显,据对临安县14年产量统计,年变异系数达53.3-92.2％。为了提高座果率和现有林产量,近年来我们在产区进行了人工辅助授粉、施肥、外源激素应用以及农业技术措施以提高座果率的试验研究,取得良好效果。     

库尔勒香梨树修剪技术问答(五)

50、大小年树如何修剪？答：产量不稳定，忽高忽低，这种现象叫大小年或隔年结果。大小年结果的树寿命短，总平均产量低。造成大小年的原因很多，如冻害、病虫危害、盛果年份肥水跟不上，修剪过轻、留花因果过多等，造成大小年的根本原因是生长与结果失调。消灭大小年的原则是：提高树体的上藏营养水平，培养独立性强的技组结构；修剪时，旺长部位应轻剪缓放，去旺校留壮技，增加分枝级数，增加短校董。弱技组应先养后更新，不要回缩过急。①大年树修剪：按比例破花芽，减少花量，大年结果不致过多。大年树内膛枝轻剪或不剪，配合肥水管理，…     

北五味子天然林的经营管理

北五味子天然林分布较多，其生长枝蔓密集，交叉重叠，光照、通风不良，营养不足，结实率低，大小年现象严重，人工集约经营，可改善北五味子的生长条件。提高其产量。     

山核桃丰产栽培技术

山核桃 (ＣａｒｙａｃａｔｈａｙｅｎｓｉｓＳａｒｇ .)是华东地区著名干果和木本油料树种 ,具有寿命长、产量高的特点。随着市场经济的日益发展 ,山核桃愈来愈受世人的认识和喜爱 ,市场前景看好 ,已成为产区农民的致富树和摇钱树 ,历来是产区的重要经济来源。但长期以来 ,山核桃生产却得不到较大的发展 ,究其主要原因是山核桃的种植和管理仍是粗放经营 ,要提高山核桃的质量和产量 ,达到丰产的目的 ,就必须走科学栽培管理的路子。现将其丰产栽培技术介绍如下。1　壮苗培育选择优良品种 ,培育壮苗造林是发展山核桃生产的重要物质基础。山核桃…     

杨梅树的夏季管理要点

浙江省的时鲜水果杨梅一直深受生产者和消费者喜爱 ,但杨梅产量有大小年之分 ,品质也不稳定。杨梅果实于初夏 (宁波市一般在 6月底 )采收后 ,其树体内的营养、生理物质都要发生一系列变化 ,及时抓好此时的培育管理 ,可以减轻大小年现象 ,取得较好的种植效益。1　采后施肥又称采果肥。 6月份是杨梅果实成熟期 ,此时春梢生长基本停止 ,夏梢已开始缓慢生长 ,而 7～ 8月份的高温时期又是下一年的花芽开始分化期 ,也是树体营养 1年中消耗最大的时期。因此必须施好采果肥 ,一般株产 5 0kg的健康树 ,采后株施草木灰 15～ 2 0kg ,菜籽饼 4kg ,硫酸钾…     

山茱萸“大小年”形成原因及克服措施

伏牛山是我国山茱萸主要产区 ,产量长期低而不稳的一个原因 ,就是“大小年”结果问题。近几年来 ,我们在西峡县二郎坪和米坪两个山茱萸老产区 ,对山茱萸“大小年”现象进行了观察 ,并采取了以科学施肥为中心的综合技术措施 ,连续 4年平均座果率提高 32 % ,“大小年”产量差在 2 0 %左右 ,取得了明显的增产稳产效果。1　山茱萸“大小年”结果的原因1 1　与山茱萸自身营养调节有关山茱萸果实成熟前 ,供翌年开花的花芽已经明显可见到 ,这说明花芽的分化早在果实采收前就已经进行了。结果与花芽分化在营养分配上存在着矛盾 ,当营养条件充足时 ,…     

美国山核桃引种研究

美国山核桃属胡桃科山核桃属,主要分布于美国和墨西哥北部.美国山核桃为果材两优的树种,具有较高的经济价值,其果实味美,营养丰富,种子油脂含量高达70%(核桃为60%).与中国山核桃相比,美国山核桃壳薄易剥,食用方便.其树干通直,材质强韧,纹理细密,可作国防用材、供雕刻和制作家具.其树姿优美,颇具观赏价值.     

Determining nitrogen status of young loblolly pine by leaf reflectance

Five-year-old lobloliy pine (Pinus taeda L.) seedlings were grown in sand culture in a completely randomized experimental design with eight nitrogen concentrations and three replications. Nitrogen concentration in the nutrient solution varied from 2 to 400 ppm. After a full growing season under treatment, percent reflectance of sunlight by new foliage was determined. Foliar samples were analyzed for nitrogen and chlorophyll. There was a strong positive correlation between nitrogen content and chlorophyll content (r = 0.895). The natural logarithm of percent reflectance was negatively correlated with both percent nitrogen content (r = -0.845) and chlorophyll content (r = -0.838). From these results, prediction equations for estimating nitrogen and chlorophyll content, as a function of reflectance, were formulated by regression analysis.     

Exploring the relationship between reflectance red edge and chlorophyll concentration in slash pine leaves

Chlorophyll concentration is related positively to the point of maximum slope in the reflectance spectra of leaves and this point is termed the red edge. The reflectance spectra of slash pine (Pinus elliottii Engelm.) needles were measured in the field and the chlorophyll concentrations of the same needles were measured in the laboratory. The measurement errors for red edge and chlorophyll concentration were determined to be 2.2 nm (3% of mean) and 0.35 mg g(-1) (19% of mean), respectively. The red edge-chlorophyll concentration relationship was strong (r(2) = 0.82, n = 152). A red edge-chlorophyll concentration relationship for n = 100 was used with red edge measurements to estimate chlorophyll concentration with an rms error of 0.31 mg g(-1) (17% of mean, n = 52). The entire red edge-chlorophyll concentration relationship for n = 152 was also used with red edge measurements to estimate the chlorophyll concentration of samples from an earlier experiment with an rms error of 0.47 mg g(-1) (30% of mean, n = 38). We conclude that measures of red edge can be used to estimate the chlorophyll concentration of detached needles in the field with an accuracy similar to that obtained by conventional laboratory measurements.     

Differentiation among effects of nitrogen fertilization treatments on conifer seedlings by foliar reflectance: a comparison of methods

Analysis of reflectance can be used to estimate foliar concentrations of photosynthetic pigments, thus providing information on the physiological status of green plants. We compared several methods of reflectance analysis for the capacity to differentiate among effects of fertilization treatments across different irradiances on seedlings of Engelmann spruce (Picea engelmanii Parry ex Engelm.). Seedlings were grown in two light treatments (0 and 60% shade) and three nitrogen (N) treatments (10, 25 and 100 mg N l-1) for one growing season, after which foliar reflectance of the needles was measured. Five indices were tested: R550 (% reflectance at 550 nm); red edge position; the ratio R698:R760; the structure independent pigment index (SIPI); and the photochemical reflectance index (PRI). Both the light and nutrient treatments significantly affected foliar chlorophyll a and b and carotenoid concentrations. Among the indices tested, R550, red edge position and R698:R760 ratio were related to chlorophyll concentration, and were significantly affected by both light and N treatments. Both SIPI and PRI were related to chlorophyll and carotenoid concentrations. Among these relationships, PRI was affected by both treatments, whereas SIPI was sensitive to N treatment but not to light treatment. All five indices were weakly but significantly correlated with growth as measured by dry weight.     

Determination of lignin,holocellulose, and organic solvent extractives in fresh leaf,litterfall, and organic material on forest floor using near-infrared reflectance spectroscopy

We report the results of a study regarding the near-infrared reflectance spectra of various leaf stages from fresh to senescing, and to decomposing leaf. A broad absorbance feature increased in the region of 1100–1400nm with the advance of the leaf senescence and leaf decomposition. A decrease was seen in the region over 1440nm during the senescence and decomposition process. These differences of spectra showed the changes in constituents of leaf in terms of the degree of the senescence and decomposition. A comparison of multiple linear regression between the near-infrared reflectance spectra and proximate chemical analyses showed that near-infrared reflectance spectroscopy achieved a certain level of useful accuracy. We consider that near-infrared reflectance spectroscopy has the potential to predict the contents of carbon fractions in plant materials, and that this method can replace previous methods due to faster determination of carbon fractions, and its ability to significantly increase the number of samples that can be collected and measured.     

Discrimination of viable and empty seeds of Pinus patula Schiede & Deppe with near-infrared spectroscopy

Sustainable forest production demands a continuous supply of high quality seeds for the production of seedlings in the nursery or for direct sowing. Here, we demonstrated the potential of near infrared spectroscopy as a rapid technique to discriminate viable and empty seeds of Pinus patula Schiede & Deppe. Near infrared spectra were collected from single seeds in transmittance and reflectance modes. To discriminate viable and empty seeds, multivariate classification models were developed with partial least squares (PLS) regression using the digitized spectra as a regressor and a y-vector of artificial values (1 for viable and –1 for empty seeds) as a regressand. Viable and empty seeds were perfectly distinguished by PLS models computed on full and selected transmittance spectroscopy data, while those derived from full NIR reflectance spectra recognized 96 % of viable and 88 % of empty seeds. Analyses made on selected NIR reflectance spectra improved the classification rate of empty seeds to 100%. Difference spectra and PLS weights indicated that the origin of spectral differences between viable and empty seeds was attributed to differences in fatty acids and proteins that were totally absent in empty seeds. The result shows the prospect of developing rapid filter-based sorting equipment that can easily be automated.     

A theoretical analysis of the influence of heterogeneity in chlorophyll distribution on leaf reflectance

Attempts to determine the vitality of vegetation and to detect vegetation stress from remotely sensed data have focused on chlorophyll concentration, because it influences the reflectance of vegetation and tends to correlate with vegetation health and stress. Pollution, pathogens and pests can cause localized regions of chlorosis and necrosis across a leaf surface, but the extent to which these patches influence the overall reflectance and spectral signature of the leaf and canopy has not been tested. A conifer leaf model (LIBERTY), which simulates the influence of leaf biochemical concentrations of chlorophyll, water, lignin, cellulose and protein on the reflectance of leaves from 400 to 2500 nm, was used to determine the effect of patches of chlorosis on leaf reflectance. A fraction of the leaf f is assumed to be chlorotic with a chlorophyll concentration C(1). The remainder of the leaf has chlorophyll concentration C(2) such that mean leaf chlorophyll concentration, C(mean) = fC(1) + (1 - f)C(2), is constant for a range of f and C(1) values. LIBERTY can be used to estimate the reflectance of a leaf with a particular chlorophyll concentration at a particular wavelength R(lambda,C) (assuming other leaf properties remain constant), thus we can estimate the reflectance of the chlorotic leaf as fR(lambda,C(1))+ (1 - f)R(lambda,C(2)). The model indicated that small areas of chlorosis have a disproportionately large influence on overall leaf reflectance. For example, a leaf with 25% of its area chlorotic can have the same reflectance (400-700 nm) as a homogeneous leaf with 60% less chlorophyll. Thus, determination of chlorophyll concentration from remotely sensed data is prone to underestimation when chlorophyll is nonuniformly distributed. Hence, attempts to model leaf and canopy reflectance using radiative transfer models will need to consider how to incorporate nonuniform chlorophyll distribution.     

森林叶绿素含量的高光谱遥感估算模型的建立

高光谱遥感提供一个通过窄波段的地物光谱反射率、诊断和检测植被叶绿素光谱特征波段的手段,为精确反演森林叶绿素含量提供更高光谱分辨率的数据。利用Epp-2000地物光谱仪测量叶片的反射光谱,并用SPAD-502对观测叶片进行叶绿素含量的同步测量;采用统计相关分析方法,分析叶片反射光谱、光谱特征参数及其各种植被指数与叶片叶绿素含量的相关关系,并建立相应的估算模型。结果表明：叶绿素含量的敏感性参数分别为Diff（R749）、Log（R466）、红边参数RVP以及比值叶绿素指数PSSR。通过多元统计回归分析,剔除不相关和存在共线性的参数后,得到叶绿素含量的估算模型为：SPAD=54．559—0．865×PSSR＋65．146×Diff（R749）-6．030×Log（R466）-0．238×RVP模型及其参数均通过统计检验,模型的决定系数砰达到0．812,均方根误差RMSE=13．35379,模型精度为88．743258％。     

Tree species classification from fused active hyperspectral reflectance and LIDAR measurements

A new terrestrial laser system was tested for tree species classification. A dataset consisting of shape parameters of three boreal tree species was collected with Light Detection and Ranging (LIDAR) and integrated with an actively measured reflectance hyperspectra. Tree species were classified using parameters derived from reflectance spectra and point cloud shape distribution. Classification performance was tested with individual, paired, and mixed combinations of both reflectance and shape parameters. The best classification results were obtained with combined datasets consisting of two reflectance and two shape parameters. Of all tested classification parameter combinations, 67.5% were able to classify all trees with over 90% accuracy. The best reflectance spectrum bands for the examined species were located around 550 and 700 nm. The best shape parameters described the upper midsection or the tops of the trees. This study was a successful step in developing classification algorithms for integrated LIDAR and hyperspectral data.     

Predicting crown damage to Eucalyptus grandis by Paropsis atomaria with direct and indirect measures of leaf composition

A genetic basis for variation in resistance to defoliating insects within Eucalyptus species has been identified in many studies. This variation has frequently been ascribed to variation in secondary metabolites but studies investigating variation in resistance to defoliation by paropsine chrysomelids have failed to correlate foliar chemistry with resistance. We found that the extent of crown damage due to defoliation by Paropsis atomaria (Chrysomelidae: Colepoptera) in two matched progeny trials of Eucalyptus grandis was a heritable trait that exhibited a strong correlation with provenance latitude. Despite this, neither foliar nitrogen or concentrations of a recently discovered group of compounds, formylated phloroglucinol compounds, could account for significant variation in defoliation. We also investigated whether defoliation in the field could be predicted from foliar near-infrared reflectance spectra. Such an approach takes into account all compositional variation simultaneously rather than relying on a restricted number of measured traits. Modified partial least squares regression models performed poorly in predicting variation in crown defoliation between trees within a site primarily due to the high level of variability and coarseness of the calibration data. Discriminant analyses however demonstrated a consistent difference between spectra from trees in families suffering low level defoliation from families more susceptible to defoliation by P. atomaria suggesting chemical differences between the two groups are important in determining resistance to this insect.     

Infrared spectroscopic study of alkaline oxygen treatment of lignin with ATR technique in aqueous state 1: method for determining quantitative spectra of oxygen-degraded lignin

For the fundamental study of oxygen delignification of kraft pulp, structural changes of kraft lignin during alkaline oxygen treatment were investigated with the use of infrared measurement with attenuated total reflectance (ATR) technique. In the neutralized reaction mixture of alkaline oxygen-treated kraft lignin, there is a significant amount of NaCl, so that the spectral changes of water due to the coexistence of NaCl was investigated, and how to remove the huge absorption of NaCl solution is discussed. Sodium vanillate–NaCl solutions were employed as model solutions for the reaction mixture. Partial least square (PLS) regression was applied for the prediction of NaCl concentration, and the spectrum of NaCl solution was subtracted from the spectrum of sodium vanillate–NaCl solution as background measurement. This allowed us to obtain the vanillate spectra free from the absorption of NaCl solution. In addition, the mathematical method for reconstructing the spectrum of NaCl solution is discussed. The spectrum of NaCl solution is reconstructed as the linear combination of basic spectra calculated by singular value decomposition (SVD), and it was subtracted from that of the sodium vanillate–NaCl solution. By this procedure, the vanillate spectra were also obtained quantitatively, as has been demonstrated in PLS regression study. It was also confirmed that the quantitative spectra of high molecular weight fraction of alkaline oxygen-treated kraft lignin were obtained by the use of this reconstruction technique.Parts of this report were presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, Japan, April 2002 and the 12th International Symposium on Wood and Pulping Chemistry, Madison, USA, June 2003