思茅松种子与农作物种子混合撒播造林试验研究

思茅松种子与农作物种子混合撒播造林，其发芽率（播种2个月）为75．70％，与直播造林没有显著差异；幼苗成活率（0．5a）和保存率（1．5a）明显低于直播造林。但是随着林龄的增长，差异越来越小，到幼树阶段（2．5a）时保存率为3．82％．只比同期直播造林的保存率低0.29％，到3a以后，保存率几乎一样。同时思茅松种子与4种农作物种子混合撒播造林的发芽率几乎一样。与4种农作物种子混合撒播造林对思茅松幼苗成活率和幼树保存率影响较大，其中与旱稻、玉米种子混合撒播造林时幼苗成活率明显高于与黄豆和花生混合撒播。混合撒播造林有利于思茅松生长，其树高和地径的生长量都高于直播造林。其中与旱稻混合撒播造林的思茅松生长最快。进行抚育管理的林地恩茅松的保存率和幼树的生长量都明显高于未进行抚育管理的林地，特别是到林龄为2．5a时，其差异更为显著。此外，混合撒播造林不但有利于思茅松幼树生长和提高其成活率，而且有较好的经济效益。     

Germination requirements of <Emphasis Type="Italic">Allanblackia parviflora</Emphasis> seeds and early growth of seedlings

Allanblackia parviflora A. Chev, is an indigenous fruit tree species that could be used in agroforestry systems with both environmental and economic benefits. The seed oil is of prime importance as a foreign exchange earner and is being developed as a rural based enterprise in many African countries notably Ghana, Nigeria, Cameroon and Tanzania. Methods for propagation and conservation of the species are therefore of prime importance. The seeds of the species are however difficult to germinate hindering its domestication process. Allanblackia parviflora seeds were collected from seven different populations in Ghana and were subjected to four different seed germination trials at the nursery of CSIR-Forestry Research Institute of Ghana at Fumesua, Kumasi. This was followed by studying the effect of stage of seed germination on establishment after potting. Intact seeds began germination at 7 months after sowing and at 24 months, significant (P < 0.001) variations were observed in the seed germination ability of 74 accessions. Mean seed germination ranged from 0 to 35%. Significant differences in seed germination percentages among populations (P < 0.001) and provenances (P < 0.05) were also observed. Removal of seed coat significantly (P < 0.001) enhanced seed germination. Germination percentages of seeds with seed coat removed ranged from 6 to 43% while seed germination percentages for intact seeds were less or equal to 3%. Incubation of seeds with seed coat removed in polythene bags gave an added advantage. Seeds with seed coat removed and kept in polythene bags started germinating from 2 weeks and within 10 months, 75 and 68% germination were obtained for plane and black polythene bags, respectively. Removal of germinants and potting when shoot length was at least 1 cm gave significantly higher growth (P < 0.001 for shoot height, P < 0.05 for stem diameter, P < 0.001 for number of leaves produced) compared to when only radicle had emerged. It became evident in this study that seeds should be classified as fully germinated only when shoots begin to grow.     

云南甜龙竹和黄竹种子灭菌条件和萌发特性初步研究

目的]筛选云南甜龙竹和黄竹种子最佳表面灭菌条件,研究其萌发特性。[方法]筛选NaClO(2%、3%、4%)与HgCl_2(0.01%、0.1%)最佳消毒浓度组合;采用流水冲洗时间(6、12、18 h)、2%NaClO浸泡时间(5、10、15 min)和0.1%Hg Cl_2浸泡时间(5、10、15 min),设计正交试验实验,探讨2种竹种最佳表面灭菌处理的时间组合,并对竹种分别在滤纸、MS培养基以及经3 mg·L~(-1)GA_3浸泡后在MS培养基上的发芽率进行了探讨。[结果]NaClO、Hg Cl_2最佳消毒浓度组合为2%NaClO+0.1%HgCl_2;2种竹种最佳表面灭菌时间组合均为:流水冲洗6 h、2%Na Cl O浸泡10min、0.1%HgCl_2浸泡15 min,经此处理后云南甜龙竹和黄竹的发芽率分别为84.4%、72.2%,污染率分别为18.7%、29.6%。不同处理种子萌发率差异t检验结果显示:2种竹子种子是否经过3 mg·L~(-1)GA_3浸泡,对其在MS培养基上的发芽率无显著影响,但种子在MS培养基上的发芽率显著高于滤纸上的发芽率。经相同处理黄竹的发芽率均低于云南甜龙竹。[结论]云南甜龙竹、黄竹最佳表面灭菌组合均为:流水冲洗6 h、2%NaClO浸泡10 min、0.1%HgCl_2浸泡15 min;3 mg·L~(-1)GA_3浸泡处理对云南甜龙竹和黄竹种子在MS培养基上的发芽率无显著影响,但MS培养基上种子的发芽率显著高于其在滤纸上的发芽率。     

Effects of seed water content and storage temperature on the germination parameters of white spruce, black spruce and lodgepole pine seed

The effect of seed water content (WC) (2–3, 5–6 and 22–25%, on a fresh weight basis), storage temperature (+4, −20, −80 and −196°C) and storage duration (6, 12, 24, 48 and 60 months) on the germination of white spruce (Picea glauca (Moench) Voss), black spruce (Picea mariana (Mill.) B.S.P.) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) seed was investigated. Germination of white spruce control (untreated) seeds and seeds adjusted to 2–3% and 5–6% WC declined after 48 months of storage at −80 and −196°C, with a further decline at 60 months at −20, −80, −196°C. Germination remained high when control white spruce seeds and seeds with 2–3, 5–6% WC were stored at +4°C, over all storage durations. Generally, black spruce and lodgepole pine exhibited high germination at all storage temperatures at 2–3% and 5–6% WC as well as the control (untreated) seed, for up to 60 months in storage. Germination declined for all three species when seed was conditioned to 22–25% WC. This loss in germination was partially recovered in white spruce seed stored at +4, −20 and −80°C after storage durations of 24, 12 and 48 months, respectively, and in black spruce seeds stored at −20 and −196°C after storage durations of 24 months. Mean germination time (MGT) was relatively constant for all species, under all conditions, except for seed conditioned to 22–25% WC, where MGT increased for white spruce seed stored 48 months at −80 and −196°C, and for black spruce seed stored 24 months at +4 and −80°C and 60 months at −196°C. These results show that the optimal storage temperatures are 4°C for white spruce, and 4, −20, −80, and −196°C for black spruce and lodgepole pine, and 2–6% water content is optimal for all 3 species at these temperatures.     

Effects of presowing treatments, desiccation and storage conditions on germination of Strychnos nux-vomica seeds, a valuable medicinal plant

Seeds of Strychnos nux-vomica have slow and erratic germination; thus different presowing treatments were applied to enhance the germination of its seeds collected from Tamaraikulam, Tamil Nadu, India. In addition, the effects of desiccation and different storage conditions on the germination of S. nux-vomica seeds were investigated. The results show that soaking in 500 ppm gibberellic acid (GA₃) for 24 h, incubation of seeds at 40 °C for 3 days and alternate water soaking (16 h) and drying (8 h) for 14 days significantly increased the percentage germination compared to the control. Desiccation of seeds down to 10% moisture content resulted in better germination. Germination of S. nux-vomica seeds differed significantly between different storage periods, moisture contents of the seed and for first and second order interactions (p<0.001). The highest germination (92%) was achieved when seeds with 10% moisture content were stored at ambient temperature for 30 weeks. Evidence from the present study indicates that S. nux-vomica seeds possess physiological dormancy that can be broken effectively by after-ripening. As seeds of S. nux-vomica are found to be desiccation tolerant, dry seed (10% moisture content) can be hermitically stored at ambient temperature for 30 weeks without losing their viability.     

Effects of tallowtree seed coat on seed germination

We measured physiological parameters including water uptake, in-vitro embryo germination ratio, and seed coat structure observed by scanning electron microscopy (SEM) to explore the influence of seed coat on the germination of seeds of tallow tree (Sapium sebiferum (Linn) Roxb.). Tallow tree seeds had good water permeability. We found that germination of cabbage seeds was inhibited when cabbage seeds were soaked in extracted solutions from tallow tree seed coat. Seed coat structure at the side of the radicle appeared to be a barrier to seed germination. We tested methods to break tallow tree seed dormancy. Dormancy of tallow tree seeds was overcome by soaking the seeds in 500 mg·L-1 or 1000 mg·L-1 GA3, followed by 100 days of cold stratification.     

Influence of Microbial Inoculants on Seedling Production in Teak (Tectona grandis L.f.)

Abstract

An experiment was conducted in forest college campus, Mettupalayam, India with an objective of studying the influence of microbial inoculants on seedling growth of teak. The fruits were collected from the seed production area in top slip (Tamil Nadu) from 63-year mother trees. The microbial inoculants viz., Azospirillum, Azotobacter, phosphobacteria, AMF, Azospirillum + AMF, Azotobacter+ AMF, phosphobacteria + AMF and an uninoculated control formed the treatments. The inoculants were mixed sand and red soil at 1:1:3 ratio, respectively, for preparing nursery mixture for filling the poly pots. The seeds were sown into the poly pots @ two seeds per pot. The experiment was set up in a randomized Block Design with three replications. Biometric observations on various growth attributes were recorded six months after treatment and also their survival in the main field-tested for one year. Azotobacter gave best performance with respect to shoot length, shoot weight and leaf area and combined inoculation of phosphobacteria and AMF gave higher root length and biomass, dry matter production and fine root weight. The survival was better in seedlings that were inoculated with phosphobacteria and AMF. However, below ground biomass and out planting survival during early phase are critical in any tree species. Hence it is concluded that inoculation of phosphobacteria and AMF conjointly be done for better survival and growth of teak seedlings.     

Evaluation and selection of multipurpose tree for improving soil hydro-physical behaviour under hilly eco-system of north east India

Soil hydro-physical behaviour was studied under a 20-year old agroforestry plantation consisting of five multipurpose tree species (Pinus kesiya Royle ex-Gordon, Alnus nepalensis D.Don, Parkia roxburghii G.Don, Michelia oblonga Wall. and Gmelina arboria Roxb.) maintained under normal recommended practices at Indian Council of Agricultural Research (ICAR) Complex, Umiam, Meghalaya, India. The aim was to select tree species, which could act as better bio-ameliorant as well as provides higher economic return in highly degraded soil of northeastern hill region of India. A site without vegetation (no tree) nearby the plantation was also selected as control for comparison. Soil samples for various hydro-physical analysis, were taken from 0–15 and 15–30 cm soil depth at a distance of 1 m from respective tree species during wet and dry season of 2003–2004. No appreciable differences in relative contents of textural separates of sand, silt and clay were observed among various tree covers. Surface cover with constant leaf litter fall and extensive root system increased soil organic carbon, helped in better soil aggregation, improved water transmissivity and infiltrability and in turn, reduced soil erosion in the present study. However, due to variation in quantity of leaf litter fall and root biomass, these parameters differed among tree species. Of the tree species, P. kesiya, M. oblonga and A. nepalensis were found to be rated best for bio-amelioration of soils as these tree covers had more root and shoot biomass and more litter fall compared to other species. However, considering both timber production and improvement in hydro-physical behaviour, M. oblonga was found best among the tested tree species. The study, thus, suggested that inclusion of tree species M. oblonga in agroforestry system is a viable option for natural resource management and could sustain long-term soil productivity in a highly degraded soil of this region as well as for food security of the resource poor people of North East India.     

Effect of different pre-sowing seed treatments on the germination of <Emphasis Type="Italic">Leucaena leucocephala</Emphasis> (Lam.) and <Emphasis Type="Italic">Acacia farnesiana</Emphasis> (L.)

Leucaena leucocephala and Acacia farnesiana are tree species used for several agricultural purposes in the Mediterranean region. The seeds of these species exhibit dormancy, causing delayed germination. Two experiments were conducted to investigate the effect of pre-sowing treatments (scarification, hot water, or soaking) on seed germination of L. leucocephala and A. farnesiana. In one experiment, seeds were exposed to three pre-sowing treatments: control, sandpaper scarification, or soaking in 70°C water for 4, 8, 12, 16, 20, or 24 min. In another experiment, seeds were soaked in 70°C water for 20 min, and then soaked in water at room temperature for an additional 24, 48, or 72 h or blade scarified. In general, soaking the seeds of the two species in hot water was more effective in breaking seed dormancy than scarification. Sandpaper scarification was not effective for either species. Blade scarification increased A. farnesiana seed germination to 56%, indicating that seed dormancy was mainly a consequence of hardseededness. L. leucocephala seeds collected from Jordan University of Science and Technology (JUST) site and soaked in 70°C water for 20 min and then soaked for 24, 48, or 72 h had germination rates above 97%. Our results suggest that blade scarification of A. farnesiana seeds and soaking of L. leucocephala seeds in 70°C water for 20 min are effective treatments to break seed dormancy and enhance seed germination of these vital species.     

华中樱桃种子生物学特性研究初探

为探究华中樱桃 Cerasus conradinae种子生物学特性,以 湖北省赤壁市的野生华中樱桃的自然成熟未落地的果实为试验 材料,观察其种子形态,并测定种子长度、宽度、厚度、千粒 重、吸水特性和发芽特性。结果表明：华中樱桃种子为卵形,长 7.64±0.73mm,宽5.28±0.55mm,厚4.39±0.47mm,千粒重 62.77±2.91g,属中粒种子;种子浸种0~4 h吸水较快,后渐趋 缓,浸种24 h近饱和,吸水率为33.23%,种子饱和状态时吸水率 为33.30%;用750 mg/L 赤霉素（GA3）溶液浸种处理的种子发芽 效果较清水浸种好,但差异不明显,两者发芽率分别为65.3%和 62.7%;华中樱桃幼苗个体间差异大。     

An assessment of heterozygosity and fitness in Chir pine (<Emphasis Type="Italic">Pinus roxburghii</Emphasis> Sarg.) using isozymes

A correlation between heterozygosity of genotypes and survival (fitness) was studied in eight natural populations of Pinus roxburghii through isozyme analysis using horizontal starch gel electrophoresis. Under each population, 20 mother trees of different ages (30 to more than 100 years) were selected which were at least 50 m apart. From each tree, eight seeds were assayed for eleven enzyme systems viz., Aconitase, Aspertate aminotransferase, Glutamate dehydrogenase, Isocitrate dehydrogenase, Leucine-amino peptidase, Malate dehydrogenase, Menadione reductase, Phosphoglucose isomerase, Phosphoglucomutase, 6-Phosphogluconate dehydrogenase and Shikimic acid dehdrogenase which were found to be encoded by 18 polymorphic loci. Genetic constitution of the mother trees was determined by analysing endosperms and embryos separately. The number of alleles in the progeny (embryos) and the mother trees varied from 38 to 42 and 34 to 37, respectively, in all the populations. Distribution of degree of heterozygosity and fixation index for the progeny and the mother trees were calculated. The mother trees showed a substantial shift towards higher degree of heterozygosity as compared to the progeny. Fixation index values were significantly higher and negative for the mother trees as compared to the progeny, which revealed that heterozygosity was positively correlated with survival in P. roxburghii. Application: Heterozygous geneotypes in tree species are shown to have better survival over homozygotes under diverse environmental conditions. Every year, millions of Pinus roxburghii saplings are planted in India. However, the fact that survival is very low might possibly be due to inbred/homozygous plants that suffer from fitness disadvantage. Our study indicates that heterozygotes have a better chance of survival under environmental conditions. The use of heterozygotes should lead to effective establishments of Pinus roxburghii plantations.     

Efficiency of neem and groundnut oils in protecting leguminous tree seeds against seed beetles in the Sahel

The objective of our study was to test the comparative efficiency of neem (Azadirachta indica) kernel oil, groundnut oil and a synthetic insecticide, K-Othrine®, in protecting stocks of leguminous tree seeds against seed beetles under Sahelian conditions. The following insect/seed combinations were used as models: Caryedon acaciae/Acacia nilotica, C. longispinosus/A. raddiana and C. serratus/Tamarindus indica. Neem oil, when used at concentrations of 5 to 20 ml per kg of seeds, had pronounced adulticidal and ovicidal effects which were maintained for five months. No significant fall in seed viability was observed except in the case of C. acaciae/A. nilotica. Groundnut oil, when used at concentrations of 5 to 20 ml per kg of seeds, had pronounced adulticidal and ovicidal effects which were relatively short-lived. A significant fall in seed viability was observed over five months. K-Othrine®, when used at concentrations ranging from 25 to 100 mg per kg, had high adulticidal effects which were maintained for five months. However, K-Othrine® was found to have no ovicide properties. No significant fall in seed viability was observed. This study concluded that it is possible to use neem oil, a product that can be obtained locally at low cost, to efficiently protect tree seed stocks in the Sahel.This revised version was published online in November 2005 with corrections to the Cover Date.     

Enrichment of big-leaf mahogany (Swietenia macrophylla King) in logging gaps in Bolivia: The effects of planting method and silvicultural treatments on long-term seedling survival and growth

To insure adequate regeneration and future timber yields of mahogany (Swietenia macrophylla King), many logged forests will have to be restocked through enrichment planting and managed using silvicultural techniques that maintain this species’ long-term survival and growth. This study compared the effects of planting method and two silvicultural treatments on the survival and growth of mahogany seedlings in logging gaps in Bolivia. We tested the hypotheses that survival and growth will be higher among transplanted seedlings than seedlings established from sown seeds and higher in silvicultural treatments that reduce competing vegetation and increase light. The first silvicultural treatment consisted of gaps logged 6 months prior to planting, gaps logged just prior to planting, and gaps treated with herbicide prior to planting. The second treatment, applied 12 months after planting, consisted of manual vegetation cleaning around mahogany seedlings in half of the gaps. The first hypothesis was supported in terms of initial seedling growth but not survival, which was similar between planting methods during the 12-92 months after planting. Transplanted seedlings grew significantly faster than those established from sown seeds during the first year, but this growth advantage disappeared by the second year. Although transplants were 84 cm taller than seed-sown seedlings by the end of the study, this height gain was probably not worth the cost of growing and transplanting seedlings. The second hypothesis was supported in terms of both survival and growth. A significantly greater proportion of seedlings survived in herbicide (62%) compared to 6-month-old (46%) and recent gaps (18%) and in cleaned (51%) versus control gaps (39%). Seedlings initially grew faster in herbicide and recent gaps than in 6-month-old gaps. These differences among silvicultural treatments were largely explained by canopy cover, which, throughout the study, was at least 14% lower in herbicide gaps and 9% lower in cleaned gaps relative to their respective alternatives. By 64 months growth diminished to near zero and no longer differed among gap treatments, despite lower canopy cover in herbicide gaps. By 92 months, saplings in herbicide gaps were only 145 and 77 cm taller than those in recent and 6-month-old gaps, respectively. To maximize survival and growth of mahogany seedlings in logging gaps while minimizing costs, silvicultural strategies should focus on direct seed sowing and appropriately timed interventions (i.e. manual cleaning) to control competing vegetation.     

Ecophysiological characteristics of the seed of the tropical forest pioneer Urera caracasana (Urticaceae)

Urera caracasana (Jacq.) Griseb is a small, fast-growing evergreen pioneer tree which colonizes openings in the tropical rain forest of 'Los Tuxtlas', Veracruz, Mèxico. Annual seed production by 10 trees was estimated to range from 0.4 x 10(5) to 1.6 x 10(6) seeds per tree. Fifteen species of resident and migratory birds were observed to visit the plants and disperse the seeds. Most seeds imbibed in petri dishes placed on the forest floor beneath a small opening in the canopy, where the red/far-red ratio of the light was around 1.0, germinated within 2 weeks. Germination beneath the forest canopy, where the red/far-red ratio of the light was approximately 0.2, was much slower and did not exceed 40%. A minimum of 4 h daily exposure to unfiltered natural light was required for rapid germination in the forest. In the laboratory rapid germination at 25 degrees C required a minimum of 4 h white light. However, if temperature during the light period was 35 degrees C, 30 min exposure to white light daily was sufficient to induce germination. Seeds that failed to germinate when imbibed for 60-360 days in petri dishes placed on the forest floor beneath the forest canopy, germinated rapidly in the laboratory when held at 25 degrees C and exposed daily to 12 h white or red light. Seeds imbibed for 120 days or more beneath the forest canopy were also induced to germinate by 12 h daily exposure to far-red light when this was combined with a 35/25 degrees C day/night temperature regime. Seeds buried in vermiculite-filled nylon mesh bags disappeared rapidly with few remaining after 2 months. Seeds that survived remained viable and germinated when incubated in petri dishes at 25 degrees C. Initially, buried seeds required light for germination. However, after 17 months' burial, seeds germinated in darkness when transferred to the laboratory and incubated on agar at 25 degrees C.     

Applying the IDS method to remove seeds infested with the seed chalcid,Megastigmus spermotrophus Wachtl,in Douglas-fir,Pseudotsuga menziesii (Mirb.) Franco

Douglas-fir seedlots were treated with the Incubation Drying Separation (IDS) method to test whether seeds infested with the seed chalcid, Megastigmus spermotrophus Wachtl, could be separated from non-infested seeds. Seeds were soaked in distilled water for 24 h, drained, placed in plastic bags and incubated at 15 °C for 3 days. The seeds were dried for either 0.5, 1, or 2 h at 25 °C, and then separated into floaters and sinkers in a water column. An average of 97% of the infested seed floated. The drying period did not affect the separation of infested seeds but significantly fewer sound seeds floated in the seedlots dried for 0.5 h than those dried for 1 h. Germination capacity of IDS-treated seeds did not differ from that of untreated seeds but the germination rate was significantly faster for IDS-treated seeds when all lots were stratified.     

Effects of seed quality and seed location on the removal of acorns and beechnuts

We examine whether different guilds of foragers remove seeds differentially according to seed quality (seed size and insect infestation) and seed location (habitat and microhabitat) in a mixed oak-beech forest. Video recordings indicated that the wood mouse (Apodemus sylvaticus) was first to encounter seeds. Foragers preferred acorns to beechnuts, large to small size and sound to infested. Nevertheless, infested seeds were removed by rodents even when sound seeds were present. Seeds that were not preferred by scatter-hoarding rodents remained longer on the ground and were more vulnerable to predation and desiccation (4% moisture loss per day). However, seeds that were removed by scatter-hoarders were moved away from their mother trees (96%) and cached individually (32%), increasing their moisture content (3% per day). Buried seeds, simulating scatter-hoarding behavior, experienced only a 17% removal after 4 months. Seed removal differences among habitats were not due to habitat attributes but to the spatial distribution of rodent-preferred microhabitats. Thus, a significant lower seed removal was observed under the tree canopy with no shrubs. However, seed removal in forest gaps with deadwood cover was not significantly different from the preferred microhabitat (under shrub cover). In pure beech forests, seed removal by rodents only occurred under Ilex aquifolium (the only perennial cover) and under woody debris. This study concludes that seed quality and seed location determine the contribution of different removers (predators vs. dispersers), their seed selection and their removal speed, leading to different seed fates which will eventually affect tree regeneration.     

Inbreeding depression in <Emphasis Type="Italic">Eucalyptus tereticornis</Emphasis> Sm. due to cleistogamous flowering

A provenance cum progeny trial comprising 13 provenances and 91 families of Eucalyptus tereticornis Sm. of Australian and Papua New Guinean (PNG) origin was laid out in India in 2002. In one family emanating from CSIRO seed lot no. 13418, (tree no. DS000141) Sirinumu Sogeri Plat, PNG cleistogamy was observed earlier. This trait appears to be under genetic control, and presumably results in obligate selfing. In the present study, the effect of forced selfing, was examined in this family after 48 months of field planting. Severely depressed seed set, germination percent, field growth and survival in relative comparison to other out crossing families was noticed. Inbreeding depression was noticed in growth traits viz. height, clean stem height, DBH, branching and survival per cent, which increased with age. High coefficient of variation was observed in family bearing cleistogamous flowers than the other predominantly out-crossed families.     

印度阿鲁纳恰尔邦温带阔叶混交林树桩周长和高度对受干扰的树形杜鹃再发芽的影响

Sprout contribution to natural regeneration of Rhododendron arboreum following the tree felling for fuel wood and other purposes was studied in two disturbed sites (Paipraw and Falockchar) of Rhododendron forest in Arunachal Pradesh, northeast India. Cut stumps were categorized into seven girth and height classes to evaluate the effect of stump girth and height on production of sprouts. Effect of stump girth on survival of sprouts was also investigated. Results show that highest number of cut stumps is recorded in medium girth classes (50–80, 80–110, and 110–140 cm) in both Paipraw and Falockchar stands. However, density of cut stumps is higher in Paipraw (1 210 stumps·ha⁻¹) than Falockchar (1 154 stumps·ha⁻¹). Nevertheless, a little higher percentage of sprouting is recorded in Falockchar (18%) than that of Paipraw (15%). Similarly, maximum number of cut stumps is observed in the medium height classes (50–80, 80–110 and 110–140 cm) in both the sites. Cut stumps with lower girths show greater ability of sprouting than that of larger girth classes. Significant correlations are observed between stump girth and sprout number and between stump height and number of sprouts. Survival of sprouts also depends on stump girth. Survival of sprout shows significant variations between different sampling times in both the sites. Though overall sprout regeneration of R. arboreum is very poor, sprouts arising from lower girth classes survive well than those of higher girth classes. The findings of this investigation signify that stump sprouting is not playing much role in the natural regeneration of R. arboreum though it has the ability to sprout. Sprout survival is not adequate to restore a stand where indiscriminate tree felling is continued and the species may be considered as a poor coppicer. Therefore, regeneration through seeds and seedlings should be preferred over regeneration through sprouting.     

Evaluating methods for storability assessment and determination of vitality status of container grown Norway spruce transplants after frozen storage

ABSTRACT

Autumn sown small seedlings for later transplanting into large containers have been introduced in Swedish forest tree nurseries. Containerized transplants of Norway spruce (Picea abies (L.) Karst.) from three Swedish nurseries were frozen stored during the autumn of 2014 to find out storability and post-storage vitality. Seedling storability was determined by measuring electrolyte leakage after freezing shoots to ?25°C (SE L _diff?25), by measurements of dry matter content (DMC) of seedling shoots and by the commercial molecular test ColdNSure?. Vitality of seedlings after storage was determined by measuring the leakage of electrolytes from shoots (SEL), and seedlings were also tested in regrowth tests. All three methods for storability assessment gave similar predictions, except in one case where DMC showed “not storable” for successfully stored seedlings. Our results indicated that young transplants can be successfully short term stored before reaching the target levels for safe long-term storage of conventional seedlings. Early storage of young transplants resulted in low post-storage survival and vitality expressed as root growth capacity and shoot electrolyte leakage (SEL). A prolonged duration in storage generally resulted in lower survival as well as lower root growth capacity and higher levels of SEL, especially for seedlings stored at earlier dates.     

Optimizing nursery and plantation methods to grow <Emphasis Type="Italic">Cedrela odorata</Emphasis> seedlings in tropical dry agroecosystems

Cedrela odorata (Spanish cedar) is a valuable multi-purpose tree which Central American rural communities and farmers give priority to introducing in pastures and home gardens. In order to propose realistic methods for C. odorata production in local nurseries in the dry tropical region of Nicaragua, we studied: (a) the ability of locally collected C. odorata seeds to germinate, (b) seed response to storage under ambient conditions or under cold storage, (c) the effects of irradiance and watering during cultivation on seedling morphology and post-transplantation survival, and (d) the effects of competition from grasses on C. odorata seedlings transplanted to pastures. Seed germination ranged from 55 to 66% and remained constant after 6 months of storage under ambient conditions or cold storage. C. odorata seedling morphology was sensitive to irradiation and watering in the nursery growing period. Deep shade reduced seedling biomass and leafiness and increased specific leaf area and root-to-shoot ratio. Water shortage increased root mass ratio and root-to-shoot ratio and decreased leaf mass ratio. Post-transplantation success was favored by weeding, and was the highest for seedlings grown under deep shade and water restrictions.