Effects of soil temperature on shoot and root growth and nutrient uptake of 5-year-old Norway spruce seedlings

Soil temperature is a main factor limiting root growth in the boreal forest. To simulate the possible soil-warming effect of future climate change, 5-year-old Norway spruce (Picea abies (L.) Karst.) seedlings were subjected to three simulated growing seasons in controlled environment rooms. The seedlings were acclimated to a soil temperature of 16 degrees C during the first (GS I) and third growing seasons (GS III), but were assigned to random soil-temperature treatments of 9, 13, 18 and 21 degrees C during the second growing season (GS II). In GS II, shoot diameter growth was lowest in the 21 degrees C treatment and root growth was lowest in the 9 degrees C treatment. In GS III, shoot height and root length growth improved in seedlings that had been kept at 9 degrees C during GS II, indicating compensatory growth in response to increased soil temperature. The temporary decrease in soil temperature had no long-lasting significant effect on seedling biomass or total nutrient uptake. At the end of GS III, fine roots of seedlings exposed to a soil temperature of 21 degrees C in GS II were distributed more evenly between the organic and mineral soil layers than roots of seedlings in the other treatments. During GS II and GS III, root growth started earlier than shoot growth, decreased during the rapid shoot elongation phase and increased again as shoot growth decreased.     

Adaptive significance of intermittent shoot growth in Douglas-fir seedlings

We tested the hypothesis that intermittent (lammas) shoot growth in Douglas-fir (Pseudotsuga menziesii var menziesii (Mirb.) Franco) seedlings from dry regions of southwest Oregon is adaptively significant. Seedlings from open-pollinated families (160 total) from two inland (dry) and two coastal (wet) sources were grown under either well-watered or intermittent drought conditions (temporary drought followed by rewatering) for two growing seasons. In the first growing season, the results supported the hypothesis: the frequency of a second flush was genetically controlled (although weakly, h(f) (2) 相似文献   

大量元素缺乏对樟树幼苗生长的影响

为探讨不同营养元素缺乏对樟树幼苗生长的影响,以樟树当年生幼苗为材料,设置全素、缺N、缺P、缺K、缺Mg 5个处理,观测其营养缺乏症状及生长状况.结果表明:樟树幼苗缺N时症状出现较早,表现最为明显,其叶片偏小、变黄绿色,整株矮小,长势较弱,其次为缺Mg,而缺P和缺K幼苗症状出现缓慢,表现相对不明显.不同缺素处理的樟树幼苗的苗高、地径、各组织生物量、主根长、侧根数量和叶面积均显著低于全素处理(P<0.05),其中缺N影响最大,其次为缺Mg处理.缺素处理增加了幼苗叶生物量比,降低了根生物量比和根冠比,其中缺Mg对根系生长影响最大.因此,N和Mg是限制樟树幼苗生长的主要影响因子,在樟树苗期营养管理中,应及时施用N肥,并保证Mg、P和K肥的供应.     

The effect of carbon and nutrient loading during nursery culture on the growth of black spruce seedlings: a six-year field study

We tested the effects of exponential nutrient loading and springtime carbon loading during nursery culture on the field performance of black spruce (Picea mariana (Mill.) B.S.P.). Seedlings were grown from seed with a conventional, fixed dose fertilizer (10 mg N seedling⁻¹) or an exponential nutrient loading regime (75 mg N seedling⁻¹). The following spring, seedlings were exposed for two weeks to either ambient (370 ppm) or elevated levels of CO₂ (800 ppm) and then planted in the field; seedling growth was followed for the next six years. Exponential nutrient loading increased seedling height, stem diameter and leader growth, with the largest increases in height and leader length occurring in the first three years after outplanting. Carbon loading increased seedling height and leader length, but only in seedlings that had been exponentially nutrient loaded. A combination of carbon and nutrient loading increased shoot height 26%, stem diameter 37% and leader length 40% over trees that received neither treatment. These results demonstrate that the growth enhancement seen under exponential nutrient loading is maintained under field conditions for at least six years. Carbon loading just before outplanting was a useful supplement to nutrient loading, but was ineffective in the absence of nutrient loading.     

Effects of root temperature on growth and photosynthesis in conifer seedlings during shoot elongation

Growth and gas exchange characteristics were studied in pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) seedlings grown in hydroponic culture in the presence of N (50 mg l(-1)) and transferred at the start of their second growing season to tap water at 5, 8, 12, 16 or 20 degrees C (air temperature between 18-20 degrees C) for 3 weeks (pine) or 5 weeks (spruce). Root growth of both species was completely inhibited at root temperatures of 5 and 8 degrees C, but increased almost exponentially as root temperature increased. Shoot growth was maximal at 12 degrees C in both pine and spruce and decreased at low root temperatures. In both species, CO(2) uptake was decreased at low root temperatures and appeared to be influenced by the pattern of nitrogen retranslocation. In pine seedlings, as root temperature increased, an increasing proportion of the total nitrogen pool was retranslocated to the new shoot, whereas in spruce seedlings nitrogen was retranslocated to the roots. Differences in the retranslocation of nitrogen in the two species were reflected in the amount of soluble protein in needles, which at the end of the experiment increased with increasing root temperature in pine, but decreased in spruce. Our data suggest that in spruce, but not pine, CO(2) uptake was limited by the amount of Rubisco.     

Long-term prescribed burning increases nutrient uptake and growth of loblolly pine seedlings

Loblolly pine (Pinus taeda L.) seedlings were grown from seed in a greenhouse on A1 horizon soil collected from field plots that have been burned each winter or maintained in an unburned condition for 33 years. Soils from burned and unburned plots were treated with phosphorus (P), P and calcium (Ca), or left untreated. After 32 weeks, height, biomass, and nitrogen (N) and P uptake were greater on soil from burned versus unburned plots, although application of P masked these effects. Addition of P increased plant biomass, seedling height, and uptake of N and P, but depressed levels of soil NH₄N. These results suggest that long-term prescribed burning may have a positive effect on nutrient availability that will benefit seedlings of the next stand.     

Effects of nutrient loading and fertilization at planting on growth and nutrient status of Lutz spruce (Picea x lutzii) seedlings during the first growing season in Iceland

The low availability of nitrogen (N) is believed to be one of the major limiting factors of forest regeneration in Iceland and frequently under Boreal conditions. Lutz spruce (Picea x lutzii Littl.) seedlings were nutrient loaded using four fertilization regimes in the end of nursery rotation in autumn 2008 and planted in the following spring, with or without a single dose of fertilizer, on two treeless sites in N-Iceland with contrasting soil fertility. Measurements were made after one growing season. The highest loading level without additional field fertilization increased new needle mass by 122% and 152%, for the poor and more fertile site, respectively. The highest loading level with field fertilization increased new needle mass equally, by 188% and 189%, for the poor and more fertile site, respectively. Retranslocation of N, from old needles to current needles, increased with more loading. However, it was clear that nutrient loading could not replace field fertilization, as the seedlings generally showed an additive response to field fertilization and nutrient loading; doing both always gave the best results in seedling performance. As the study only covers field establishment during the first year, the long-term effect of nutrient loading of Lutz spruce cannot be predicted. However, it was concluded that loading might provide an additional input for faster plantation establishment during the first growing season after planting.     

Effects of chronic acid fog exposure with soil acidification or nitrogen loading on nutrient status in Abies firma seedlings

To clarify the nutrient status in momi fir (Abies firma Sieb. et Zucc.) seedlings under complex stress conditions of acid fog with soil acidification or nitrogen loading, we exposed seedling shoots to simulated acid fog (pH 3) and simultaneously loaded the soil with acid or excess nitrogen for 17 months. Proton and nitrogen loading reduced K concentration in soil, but these treatments had little effect on the nutrient status of fine roots in momi fir seedlings. Acid fog exposure resulted in reduced concentrations of Mg, Al, and Fe in current-year needles and Mg, Al, Cu, Fe, and Zn in 1-year-old needles. The complex effects of acid fog exposure with proton or nitrogen loading on nutrient status were relatively slight. However, elements such as Al and Cu notably reflect the effects of proton loading. These results show that the nutrient status of trace elements, rather than major elements, in needles of momi fir seedlings is sensitive to exposure to acid fog or proton loading.     

Steady-state nutrition of Pinus resinosa seedlings: response to nutrient loading, irrigation and hardening regimes

To test effects of fertilization on late-season growth and nutrient content of container-grown red pine (Pinus resinosa Ait.), seedlings were subjected to a factorial combination of two fertilization regimes (exponentially increasing concentrations providing 25 (1N) and 75 (3N) mg N seedling(-1), respectively) and two irrigation regimes (well-watered and water-stressed) followed by drought-hardening or nonhardening. The fertilization treatments gave rise to steady-state nutrition in the seedlings during the prehardening phase. The 3N treatment increased macronutrient uptake significantly more than dry matter production, particularly in the roots, giving rise to what has been called luxury consumption of nutrients, or nutrient loading. Nutrient loading was higher in well-watered seedlings than in water-stressed seedlings. Among well-watered seedlings, relative growth rate of nutrient-loaded seedlings was more sensitive to drought during the hardening phase than that of nonloaded seedlings. However, when watering was resumed at the end of the hardening treatment, the relative growth rate of the nutrient-loaded seedlings (421%) exceeded that of the nonloaded seedlings (213%). Nitrogen accumulation was also higher in nutrient-loaded seedlings than in nonloaded seedlings during the post-hardening phase.     

Genetic variation in nutrient utilization and growth traits in picea abies seedlings

Genetic variation in nitrogen (N) and phosphorus (P) utilization (amount of total biomass produced per unit nutrient in the needles) and growth traits in seedlings from 30 open‐pollinated families of Picea abies (L.) Karst. was estimated. Seedlings were grown under two nutrient regimens: free access to nutrients and restricted access. There was a strong treatment effect on most growth traits. With free access, families allocated relatively more biomass to the stem and less to the roots than they did with restricted access. Heritabilities for growth traits were higher with free access treatment (0.33–0.81) than with restricted access treatment (0.20–0.45). Family variance components for N and P utilization were significant (p < 0.05) with restricted access but not with free access. Genetic correlation between nutrient utilization and height traits with restricted access ranged from none to moderate ( — 0.31 to 0.56). Genetic correlations between the same trait assessed in the two treatments were strong for height and moderate for biomass.     

Influence of seed-borne fungi on the nutrient composition and growth of conifer seedlings

Seed-borne fungi induce conspicuous changes in the concentrations of various nutrients (N, P, K, Mg, Na, Ca, Fe, Zn and Mn), thus affecting the growth in height and biomass of seedlings of two conifer species. The data indicates that the changes may be caused by interference in the physiology of the infected seeds and seedlings. The response of the change in the nutrient levels and total height growth towards the pre-chilling treatment of the seeds was not consistent to indicate any trend.     

广宁红花油茶叶片营养DRIS诊断

为给广宁红花油茶的田间管理和合理施肥提供理论依据,以广宁红花油茶1年生播种苗为研究对象,运用DRIS指数法对其叶片进行营养诊断。结果表明,以6～11月份广宁红花油茶叶片N、P、K元素浓度测定值为依据,采用N和P、K和P、N和K的比值作为诊断指标,广宁红花油茶叶片N和P元素浓度最佳比值为10.21±1.30;N和K元素浓度最佳比值为2.11±0.08;K和P元素浓度最佳比值为5.29±0.64。建立了广宁红花油茶DRIS营养诊断指数表,得出结论:广宁红花油茶对N、K肥的反应要比P肥更为灵敏。     

铝对马尾松菌根苗生长及营养元素吸收的影响

以接种褐环乳牛肝菌和未接种的马尾松幼苗为试验材料,采用水培法研究不同浓度铝(Al^3+)处理(0、0.2、0.4、0.8和1.2 mmol·L^-1)对菌根化和非菌根化马尾松幼苗生长、营养元素吸收的影响,揭示菌根化马尾松苗木对Al^3+的适应机制,为减轻马尾松苗木铝毒害现象提供理论和技术依据。结果表明,在相同浓度Al^3+胁迫下,接种褐环乳牛肝菌的马尾松幼苗苗高、生物量、根系形态以及对氮(N)、磷(P)、钾(K)的吸收能力均优于不接种的马尾松苗。马尾松幼苗苗高、干物质量积累以及根系生长随着Al^3+浓度的增大均呈现先升后降再升的趋势,随着Al^3+浓度的逐渐增大,马尾松幼苗根、茎、叶中的N、P、K含量呈现出低促高抑的趋势,根、茎、叶中Al^3+含量的分配为根>茎>叶。Al^3+胁迫下,接种褐环乳牛肝菌的马尾松幼苗,通过改变马尾松幼苗根系结构,促进了幼苗的生长,特别是根系的生长,以及对N、P、K等营养元素的吸收,抑制了根系吸收Al^3+,提高了马尾松幼苗的耐铝能力。     

Evaluating root growth potential of tree seedlings with an automated measuring system

Root growth of tree seedlings was quantified as change in root area index by using a video camera and digitizing area meter system that sums scanning line and root intersections. Number and total length of roots 0.5 cm and area index change were measured over a wide range of values. Linear regressions indicated that the automated and manual quantification methods yield essentially the same result. The automated method reduces measurement time, minimizes observer subjectivity, and estimates all new root growth. However, the equipment is costly, and the method does not provide information on the origin or size of new roots.     

Effects of aluminum on growth and nutrient status of Douglas-fir seedlings grown in culture solution

Effects of Al on growth, nutrient uptake and proton efflux were studied in Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings grown for about nine months in culture solutions with a pH between 3.4 and 3.6 and with both calcium and magnesium (Ca + Mg) at a concentration of 0.1, 0.5 or 2.5 mM. In the absence of Al, plant dry matter production and root development increased with increasing concentrations of (Ca + Mg) in the culture solution. At the low and intermediate (Ca + Mg) concentrations, optimal root and shoot development were observed at an Al concentration of 4 mg l(-1). At the highest (Ca + Mg) concentration, Al up to 4 mg l(-1) did not affect growth, but at higher concentrations, it significantly reduced both shoot and root growth. As the concentration of (Ca + Mg) in the nutrient solution increased, the concentrations of Ca and Mg increased in shoots and roots also. The concentrations of Ca and Mg in the roots were unaffected by the presence of Al, whereas in the shoots they were either unaffected, or increased, by Al. Concentrations of Al in, or on, roots, or in shoots, did not change in response to changing concentrations of Ca + Mg in the nutrient medium. In general, concentrations of P and K in shoots and roots were higher in seedlings grown in nutrient solutions containing Al. Stimulation of growth by moderate concentrations of Al, which was observed at suboptimal (Ca + Mg) concentrations, was associated with a low NH(4) preference and a low root proton efflux. The Al-induced increase in internal K concentration and reduction in NH(4) preference may be explained by a lower efflux of K and NO(3), respectively.     

绿竹笋营养成分的测定与分析

为给人们认识绿竹笋的营养价值提供参考依据,根据有关食品检测标准,对绿竹笋的蛋白质、氨基酸、维生素、微量元素等34个营养成分指标进行了测定与分析。结果表明:绿竹笋的平均蛋白质含量为2.23%,粗纤维含量为0.77%;绿竹笋主要含有16种氨基酸,氨基酸总含量约为1.76%,其中天冬氨酸、谷氨酸的含量最多;各样本的总糖含量在1.10%～2.40%之间,其含量差异较大;绿竹笋主要含有磷、铁、钙,其含量均值分别为435、8.6、86.3 mg/kg,各地绿竹笋中磷与钙含量的差异较大;绿竹笋主要含有维生素C,其维生素C含量为73.0 mg/kg。     

Modified exponential nitrogen loading to promote morphological quality and nutrient storage of bareroot-cultured Quercus rubra and Quercus alba seedlings

Abstract

Exponential nutrient loading has been used to improve nursery fertilizer uptake efficiency of conifer seedlings, but the technique has received little attention in the culture of temperate deciduous hardwoods. This study examined responses of northern red oak (Quercus rubra L.) and white oak (Q. alba L.) seedlings to modified exponential nitrogen loading during bareroot nursery culture using a broad range of nutrient supply from 0 to 3.35 g nitrogen (N) per plant per season for 18 weeks in Indiana, USA. Seedling growth and nutritional parameters followed a curvilinear pattern that ranged from deficiency to toxicity with increased fertilization consistent with trends depicted in the proposed model for nutrient loading. Fertilization increased plant dry mass by 113–260% for red oak and 49–144% for white oak. Severe nutrient deficiency occurred under indigenous soil fertility, and limited phosphorus and potassium uptake were found to inhibit seedling growth at higher N supply. The sufficiency and optimum rates were determined to be 0.84 and 1.68 g N per seedling per season, respectively, under the current cultural conditions. Fertilization at 1.68 g N per plant increased N content by 40% in red oak and 35% in white oak. This approach may be used to help refine nursery fertilization practices in hardwood culture to produce high-quality seedlings for field planting.     

Root and shoot allometry of bareroot and container Douglas-fir seedlings

Detailed root and shoot development of bareroot and container Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedling stocktypes were compared during the first growing season after outplanting. The study was installed in raised beds with ideal environmental conditions and at a field reforestation site. Survival at both sites was 98% and did not differ between stocktypes. Seedlings were excavated in spring (5, 8, 12, and 16 weeks after planting) and in fall (35, 40, and 45 weeks after planting). In spring, container seedlings had more numbers of new roots and greater new root and shoot biomass than bareroot seedlings at both sites. In fall, bareroot seedlings consistently averaged more new root growth (though nonsignificant) than container seedlings suggesting that stocktype differences may not continue long-term. Container seedlings had significantly greater water percent than bareroot seedlings at the field site (all sample dates) and the raised bed site (weeks 5, 8, and 40 only). Regardless of environmental conditions or season, seedlings at both sites maintained water percent between 60 and 70% of fresh weight. Seedlings grown in the raised beds had much greater growth than those grown in the field. However, relative growth patterns for the two stocktypes were very similar on each site. The data generated establish baseline differences between stocktypes for root initiation, growth, and allometry during the first year after planting. Challenges associated with root development research are discussed.     

俄罗斯的沙棘嫩枝扦插育苗技术

介绍了俄罗斯的沙棘嫩枝扦插繁殖技术。沙棘扦插需掌握扦插期、剪条、插条处理、插床与扦插、抚育管理、生根插条的越冬及继续培育、建立母本种植园等七方面技术。     

Optimizing the growth and N status of containerized Australian Blackwood (Acacia melanoxylon) seedlings with exponential nitrogen loading

Exponential nitrogen(N) loading approach has been used to optimize seedling growth in container seedling production. However, the response of seedling growth to N loading and optimal N loading rates are species-dependent. There is a lack of information on optimal N loading in container production of Australian Blackwood(Acacia melanoxylon) seedlings. In this study, 7 exponential N loading at rates of 0, 50, 100, 200, 300, 400, and 600 mg N seedling-1, respectively, were applied at the week 3, 6, 9, 12 and 14 after transplanting to determine optimal loading approach based on seedling height, root collar diameter(RCD), biomass accumulation and N uptake in tissue-cultured Australian Blackwood(A. melanoxylon) seedlings. Seedlings did not respond to N loading 3 wk after transplanting, then the accumulative addition of N loading for improved RCD and seedling height was 12.99 and 28.02 mg N seedlings-1 in the 100 N and 400 N treatment 6 wk after transplanting, respectively, and on 9 and 12 wk, that for improved seedling growth was 63.64 and 400 mg N seedling-1 in the 200 N and 400 N treatment, respectively. Vector diagnosis of final biomass and N status indicated that the dose of 100 and 400 mg N seedling-1 was characterized to be deficient and optimum dose of exponential N loading for Blackwood seedlings. These conclusions promise to figure out a precise fertilization regime for Blackwood seedlings and the demonstration of dynamic seedling performance could be used for other tree species.