937 resultados para Pine root collar weevil


Relevância:

100.00% 100.00%

Publicador:

Resumo:

"February 1983."

Relevância:

100.00% 100.00%

Publicador:

Resumo:

This study investigated the ability of neonatal larvae of the root-feeding weevil, Sitona lepidus Gyllenhal, to locate white clover Trifolium repens L. (Fabaceae) roots growing in soil and to distinguish them from the roots of other species of clover and a co-occurring grass species. Choice experiments used a combination of invasive techniques and the novel technique of high resolution X-ray microtomography to non-invasively track larval movement in the soil towards plant roots. Burrowing distances towards roots of different plant species were also examined. Newly hatched S. lepidus recognized T. repens roots and moved preferentially towards them when given a choice of roots of subterranean clover, Trifolium subterraneum L. (Fabaceae), strawberry clover Trifolium fragiferum L. (Fabaceae), or perennial ryegrass Lolium perenne L. (Poaceae). Larvae recognized T. repens roots, whether released in groups of five or singly, when released 25 mm (meso-scale recognition) or 60 mm (macro-scale recognition) away from plant roots. There was no statistically significant difference in movement rates of larvae.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Tutkimus on osa Metsäklusteri Oy:n Future Biorefinery –tutkimusohjelmaa, jossa kartoitetaan mahdollisuuksia hyödyntää metsäteollisuuden raaka-aineita aiempaa tarkemmin ja uusissa tuotteissa. Tutkimuksen tavoitteena on selvittää männyn (Pinus sylvestris L.) ja kuusen (Picea abies [L.] Karst.) juurten ja kantopuun rakenne ja ominaisuudet. Tutkimuksessa selvitetään löytyykö männyn ja kuusen juurista reaktiopuuta ja määritetään asetoniliukoisten uuteaineiden osuus kantoja juuripuussa. Tutkimusaineistona oli viisi eri-ikäistä mäntyä ja viisi eri-ikäistä kuusta. Juuri- ja kantoaineisto kerättiin Metsäntutkimuslaitoksen toimesta Parkanon seudulta (62.017°N, 23.017°E) hakkuun jälkeen. Maanalaisista juurista otettiin näytteet kolmelta eri etäisyydeltä juurenniskaan nähden. Kummankaan lajin juurista ei löytynyt varsinaista reaktiopuuta, mutta joissakin näytteissä havaittiin lievää reaktiopuuta. Lievää reaktiopuuta löytyi enemmän männyn kuin kuusen juurista, eikä sitä löytynyt lainkaan kaikkein ohuimmista, noin 2 cm paksuisista juurenosista. Männyn kannoissa uuteaineprosentti oli korkeampi kuin kuusen. Männyn juurissa uuteaineprosentti kasvoi edettäessä kohti juuren kärkeä. Kuusella uuteaineprosentti laski aluksi, mutta lähellä juuren kärkeä taas kasvoi. Kuoren uuteainepitoisuus oli molemmilla puulajeilla korkeampi kuin puuaineen. Tutkimusaineisto oli suppea, eikä tutkimuksessa pyritty tilastolliseen yleistettävyyteen. Laajemmasta aineistosta tehdylle tutkimukselle on tarvetta, sillä turvekankailta saatavan puun tarjonta on Suomessa kasvussa, mutta juurten uuteaine- ja reaktiopuututkimuksia on tehty vain kivennäismailta kerätyistä aineistoista.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A study was conducted during 1997-99 at 2 sites in Sri Lanka (Rambukkana and Kurunegala) to investigate the responses of Swietenia macrophylla seedlings to wide, moderate and narrow openings of high to low shade conditions in a mature mixed mahogany plantations. Survival, stem growth and shoot phenology of seedlings were recorded monthly. Seedling survival a year after planting showed high mortality under high shaded gap (3-8% photosynthetically active radiation (PAR)). At 51 weeks after planting, final stem height and root collar diameter were highly significant under low shaded gaps. Increased number of shoots and shoot lenghts were observed under low shade (50-78% PAR). Increased flushing was seen in all shade regimes during the rainy period. This study illustrates that low shaded gap openings favour seeding survival, stem and shoot growth, and number of shoots. On the contrary, high shaded gaps reduce the growth of seedlings and therefore may be less attractive to shoot borers.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

研究了半干旱沙区不同滴灌带埋设深度下紫花苜蓿的生长特性。通过试验研究分析了滴灌带埋设深度对紫花苜蓿植株高度、茎粗、分枝数、根系生长、根系密度和产量等生长特性的影响。采用主成分分析法对不同滴灌带埋设深度的紫花苜蓿等生长特性进行了综合评价。结果表明,滴灌带不同埋设深度对苜蓿各个生育期生长特性指标影响不同。在苗期,埋设深度为10 cm的处理,有利于苜蓿生长。从分枝期起,埋设深度为30 cm的处理优于其它处理;在整个生育期内,不同埋设深度对苜蓿生长特性影响的综合评判结果为:埋深30 cm>埋深20 cm>埋深10 cm>埋深40 cm。

Relevância:

100.00% 100.00%

Publicador:

Resumo:

由于人类活动所引起的地球大气层中温室气体的富集已导致全球地表平均温度在20 世纪升高了0.6 ¡æ,并预测在本世纪将上升1.4-5.8 ¡æ。气候变暖对陆地植物和生态系统产生深远影响,并已成为全球变化研究的重要议题。位于青藏高原东部的川西亚高山针叶林是研究气候变暖对陆地生态系统影响的重要森林类型。森林采伐迹地和人工云杉林下作为目前该区人工造林和森林更新的两种重要生境,二者截然不同的光环境对亚高山针叶林不同物种更新及森林动态有非常重要的影响。 本文以青藏高原东部亚高山针叶林几种主要森林树种为研究对象,采用开顶式增温法(OTCs)模拟气候变暖来研究增温对生长在两种不同光环境下(全光条件和林下低光环境)的几种幼苗早期生长和生理的影响,旨在从更新角度探讨亚高山针叶林生态系统不同树种对气候变暖在形态或生理上的响应差异,其研究结果可在一定程度上为预测气候变暖对亚高山针叶林物种组成和演替动态提供科学依据,同时也可为未来林业生产管理者提供科学指导。 1、与框外对照相比,OTCs 框内微环境发生了一些变化。OTCs 框内与框外对照气温年平均值分别为5.72 ¡æ和5.21 ¡æ,而地表温度年平均值分别为5.34 ¡æ和5.04 ¡æ,OTCs 使气温和地表年平均温度分别提高了0.51 ¡æ和0.34 ¡æ;OTCs框内空气湿度年平均值约高于框外对照,二者分别为90.4 %和85.3 %。 2、增温促进了三种幼苗生长和生物量的积累,但增温效果与幼苗种类及所处的光环境有关。无论在全光或林下低光条件下,增温条件下云杉幼苗株高、地径、分支数、总生物量及组分生物量(根、茎、叶重)都显著地增加;增温仅在全光条件下使红桦幼苗株高、地径、总生物量及组分生物量(根、茎、叶重)等参数显著地增加,而在林下低光条件下增温对幼苗生长和生物量积累的影响效果不明显;冷杉幼苗生长对增温的响应则与红桦幼苗相反,增温仅在林下低光条件下对冷杉幼苗生长和形态的影响才有明显的促进作用。 增温对三种幼苗的生物量分配模式产生了不同的影响,并且这种影响也与幼苗所处的光环境有关。无论在全光或林下低光环境下,增温都促使云杉幼苗将更多的生物量分配到植物地下部分,从而导致幼苗在增温条件下有更高的R/S 比;增温仅在林下低光条件下促使冷杉幼苗将更多的生物量投入到植物叶部,从而使幼苗R/S 比显著地降低;增温在全光条件下对红桦幼苗生物量分配的影响趋势与冷杉幼苗在低光条件下相似,即增温在全光条件下促使红桦幼苗分配更多的生物量到植物同化部分—叶部。 3、增温对亚高山针叶林生态系统中三种幼苗气体交换和生理表现的影响总体表现为正效应(Positive),即增温促进了几种幼苗的生理活动及其表现:(i)无论在全光或林下低光环境下,增温使三种幼苗的光合色素含量都有所增加;(ii)增温在一定程度上提高了三种使幼苗的PSII 光系统效率(Fv/Fm),从而使幼苗具有更强的光合电子传递活性;增温在一定程度使三种幼苗潜在的热耗散能力(NPQ)都有所增强,从而提高幼苗防御光氧化的能力;(iii)从研究结果来看,增温通过增加光合色素含量和表观量子效率等参数而促进幼苗的光合作用过程。总体来说增温对幼苗生理过程的影响效果与幼苗种类及所处的光环境有关,增温仅在全光条件下对红桦幼苗光合过程的影响才有明显的效果,而冷杉幼苗则相反,增温仅在低光条件下才对幼苗的生理过程有显著的影响。 4、增温对三种幼苗的抗氧化酶系统产生了一定的影响。从总体来说,增温使几种幼苗活性氧含量及膜脂过氧化作用降低,从而在一定程度上减轻了该区低温对植物生长的消极影响;增温倾向表明使三种幼苗体内抗氧化酶活性和非酶促作用有所提高,从而有利于维持活性氧代谢平衡。但增温影响效果与幼苗种类所处的光环境及抗氧化酶种类有关,增温对冷杉幼苗抗氧化酶活性的影响仅在林下低光环境下效果明显,而对红桦幼苗抗氧化酶活性的影响仅在全光条件下才有明显的效果。 总之,增温促进了亚高山针叶林生态系统中三种幼苗的生长和生理表现,但幼苗生长和生理对增温的响应随植物种类及所处的光环境不同而变化,这种响应差可能异赋予了不同植物种类在未来气候变暖背景下面对不同环境条件时具有不同的适应力和竞争优势,从而对亚高山针叶林生态系统物种组成和森林动态产生潜在的影响。 Enrichment of atmospheric greenhouse gases resulted from human activities suchas fossil fuel burning and deforestation has increased global mean temperature by 0.6¡æ in the 20th century and is predicted to increase it by 1.4-5.8 ¡æ. The globalwarming will have profound, long-term impacts on terrestrial plants and ecosystems.The ecoologcial consequences arising from global warming have also become thevery important issuses of global change research. The subalpine coniferous forests inthe eastern Qinghai-Tibet Plateau provide a natural laboratory for the studying theeffects of climate warming on terrestrial ecosystems. The light environment differssignificantly between clear-outs and spruce plantations, which is particularlyimportant for plant regeneration and forest dynamics in the subalpine coniferous forests. In this paper, the short-term effects of two levels of air temperature (ambient andwarmed) and light (full light and ca. 10% of full light regimes) on the early growthand physiology of Picea asperata, Abies faxoniana and Betula albo-sinensis seedlingswas determined using open-top chambers (OTCs). The aim of the present study wasto understand the differences between tree species in their responses to experimentalwarming from the perspective of regeneration. Our results could provide insights intothe effects of climate warming on community composition and regeneration behavior for the subalpine coniferous forest ecosystem processes, and provide scientificdirection for the production and management under future climate change. 1. The OTCs manipulation slightly altered thermal conditions during the growingseason compared with the outside chambers. The annual mean air temperature andsoil surface temperature was 5.72 and 5.34 ¡æ (within the chambers), and 5.21 and5.04 ¡æ (outside the chambers), respectively. The OTCs manipulation increased airtemperature and soil surface temperature by 0.51 and 0.34 ¡æ on average, respectively.Air relative humidity was slightly higher inside the OTCs compared with the controlplots, with 90.4 and 85.3 %, respectively. 2. Warming generally stimulated the growth and biomass accumulation of thethree tree species, but the effects of warming on growth and development variedbetween light conditions and species. Irrespective of light regimes, warmingsignificantly increased plant height, root collar diameter, total biomass, componentbiomass (stem, foliar and root biomass) and the number of branches in P. asperataseedlings; For A. faxoniana seedlings, significant effects of warming on all the tested parameters (plant height, root collar diameter, total biomass, and component biomass) were found only under low light conditions; In contrast, the growth responses of B.albo-sinensis seedlings to warming were found only under full light conditions. Warming had pronounced effects on the pattern of carbon allocation. Irrespectiveof light regimes, the P. asperata seedlings allocated relatively more biomass to rootsin responses to warming, which led to a higher R/S. Significant effects of warming onbiomass allocation were only found for the A. faxoniana seedlings grown under lowlight conditions, with significantly increased in leaf mass ratio (LMR) and decreasedin R/S in responses to warming manipulation. The carbon allocation responses of B.albo-sinensis seedling to warming under full light conditions were similar with theresponse of A. faxoniana seedlings grown under low light conditions. Warmingsignificantly decreased root mass ratio (RMR), and increased leaf mass ratio (LMR)and shoot/root biomass ratio (S/R) for the B. albo-sinensis seedlings grown under full light conditions. 3. Warming generally had a beneficial effect on physiological processes of dominant tree species in subalpine coniferous forest ecosystems: (i) Warming markedincreased the concentrations of photosynthetic pigments in both tree species, but theeffects of warming on photosynthetic pigments were greater under low lightconditions than under full light conditions for the two conifers; (ii) Warming tended toenhance the efficiency of PSII in terms of increase in Fv/Fm, which was related tohigher chloroplast electron transport activity; and enhance non-radiative energydissipation in terms of in increase in NPQ, which may reflect an increased capacity inpreventing photooxidation; (iii) Warming may enhance photosynthesis and advancephysiological activity in plants by increasing photosynthetic pigment concentration,the efficiency of PSII and apparent quantum yield (Φ) etc. From the results, theeffects of warming on seedlings’ physiological performance varied between lightenvironment and species. The effects of warming on photosynthesis performance of B.albo-sinesis seedlings were pronounced only under full light conditions, while thephysiological responses of A. faxoniana seedlings to warming were found only underthe 60-year plantation. These results provided further support for the observationsabove on growth responses of seedlings to warming. 4. Warming had marked effects on antioxidative systems of the three seedlings.Warming generally decreased H2O2 accumulation and the rate of O2- production, andalleviated degree of lipid peroxidation in terms of decreased MDA content, whichalleviated to some extent the negative effects of low temperature on the plant growthand development in this region; Warming tended to increase the activities ofantioxidative enzymes and stimulate the role of non-enzymatic AOS scavenging,which helped to create an balance in maintaining AOS metabolites for the threeseedlings. Nevertheless, the effects of warming on antioxidative defense systems werepronounced only under the 60-year plantation for the A. faxoniana seedlings. Incontrast, the marked effects of warming on antioxidative defense systems for the B.albo-sinesis seedlings were found only under the full light conditions. In sum, warming is considered to be generally positive in terms of growth andphysiological process. However, the responses of growth and physiology performanceto warming manipulation varied between species and light regimes. Competitive and adaptive relationships between tree species may be altered as a result of responsedifferences to warming manipulation, which is one mechanism by which globalwarming will alter species composition and forest dynamics of subalpine coniferousforest ecosystems under future climate change.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

O presente trabalho é constituído por uma revisão bibliográfica e uma série de estudos científicos experimentais visando a melhoria do conhecimento da ecologia de germinação e resposta ao estresse hídrico em arbustos autóctones. Estes estudos pretendem contribuir para o conhecimento da ecologia de espécies autóctones na fase de germinação e estabelecimento inicial das plântulas através da comparação da resposta de sementes de diferentes proveniências. Os primeiros três capítulos focam-se no estudo dos efeitos de pré-tratamentos na germinação de espécies arbustivas com diferentes estratégias de regeneração e dormência da semente, enquanto os dois últimos capítulos incidem sobre o efeito de diferentes condições de disponibilidade de água na germinação e estabelecimento inicial de plântulas com potencial para restauro ecológico. Este estudo procura abordar aspetos importantes para o estudo e validação do uso de espécies alvo para o restauro ecológico em zonas Mediterrânicas, contribuindo deste modo para a melhoria do conhecimento da ecologia destas espécies. A germinação foi estimulada por pré-tratamentos de calor em quatro das cinco espécies cuja época de dispersão da semente na primavera-verão. As sementes provenientes do sul tenderam a germinar melhor, sendo ao mesmo tempo mais pequenas. Por outro lado, a germinação em espécies cuja dispersão da semente ocorre no outono-inverno variou de acordo com o tipo de dormência da semente. A germinação foi em geral favorecida pela estratificação a frio na espécie apresentando dormência fisiológica mas foi negativamente afetada na espécie que não apresenta dormência. Esta resposta não foi, no entanto, inequívoca pois foi dependente da proveniência estudada. O efeito da estratificação a frio teve em geral um efeito mais positivo ou menos negativo nas sementes provenientes do norte em comparação com as outras proveniências. O stress-osmótico teve um efeito negativo consistente na germinação de Pistacia lentiscus e outro fator que também afetou significativamente a germinação foi a variabilidade intra-populacional entre plantas mãe. As duas proveniências apresentaram diferentes graus de associação entre a germinação e/ou caracteres morfológicos da semente ou planta mãe. Quanto à fase de estabelecimento inicial, o baixo conteúdo em água teve um claro efeito negativo no investimento relativo em biomassa acima do solo e um efeito positivo no investimento relativo em biomassa abaixo do solo em Arbutus unedo. Esta resposta não foi inequívoca, uma vez que as proveniências diferiram em adaptações morfológicas ao baixo conteúdo em água. As plântulas da proveniência mais húmida revelaram uma taxa de crescimento relativo superior mas, ao mesmo tempo, uma fraca adaptação às condições de baixa disponibilidade de água, quando comparadas com as outras proveniências. Ao contrário, as plântulas da proveniência seca com verão mais quente apresentaram semelhantes diâmetro do colo da raiz, peso seco de folhas e performance fisiológica sob os dois regimes de irrigação. Os resultados obtidos revelam diferenças significativas na germinação e desenvolvimento inicial entre as distintas proveniências que poderão estar relacionadas com adaptações ao clima dos locais de origem. Os desenvolvimentos futuros do estudo dos mecanismos subjacentes às adaptações observadas poderiam contribuir para a melhoria das previsões de sucesso do estabelecimento inicial em diferentes populações de plantas, permitindo aumentar a confiança e efetividade de custos nas decisões relacionadas com ações de restauro ecológico em cenários de alterações climáticas.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Nitrogen (N) mineralization dynamics in no-till systems is affected, among other factors, by N amount and quality in the mulch and by climatic conditions. Leaching of NO3-N and NH4-N from six plant species used as soil cover crops in tropical environments were evaluated when the straw was submitted to rainfall after chemical desiccation. Millet (Pennisetum glaucum), guinea sorghum (Sorghum vulgare), black oat (Avena strigosa), triticale (Triticum secale), Indian hemp (Crotalaria juncea), and brachiaria (Brachiaria decumbens) were grown in a greenhouse, in Botucatu-SP, Brazil. Forty-five days after emergence, the plants were cut at the root collar, oven-dried, and submitted to simulated rainfalls of 4.4, 8.7, 17.04, 34.9, and 69.8 mm, considering an amount of straw equivalent to 8 t ha(-1) of dry matter. The amounts of N-NO3- extracted from the straw by rainwater were very small. However, accumulated rainfall around 70 mm caused ammonium leaching ranging from 2.5 to 9.5kg ha(-1), depending on the species. Plant residues of triticale and black oat (grasses) and Indian hemp (legume) showed high N leaching intensity with the first rains after chemical desiccation. The amount of N leached from straw was highly correlated with N tissue content.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The present study aimed to assess the behavior of seedlings of Schizolobium parahyba (Vell.) Blake growing on different substrates and irrigation levels, and to study the use of urban waste compost in substrates. The experiment was carried out in the College of Agricultural Sciences, Universidade Estadual Paulista (UNESP), Department of Agricultural Engineering, Jaboticabal Campus, state of São Paulo, Brazil. The experimental design used was completely randomized, consisting of 30 treatments in a factorial design with 15 substrates and two irrigation levels in four replicates. The substrates were composed of different materials: urban waste, Plantmax®, dry cattle manure, vermiculite and soil. For the study of seedling growth, the following characteristics were evaluated: height (H), root-collar diameter (D), number of leaves, shoot dry weight, root dry weight, total dry weight, H/D ratio, Dickson's quality index, and the ratio between height and shoot dry weight (H/SDW). Assessments of the first three characteristics were carried out 20, 35, 50 and 65 days after sowing. Results showed that urban waste compost increased the growth of Schizolobium parahyba. There were significant differences for the irrigation levels tested; with better results for 150% ET compared to 100% ET irrigation level.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

With the objective of evaluating the response of baru (Dipteryx alata Vog.) to nutrient limitation and to the different levels of fertilization, seven experiments were conducted. Experiment 1: Nutritional limitation in greenhouse. We employed 12 treatments in a completely randomized design with eight replicates. Experiment 2: Levels of liming and P in greenhouse. The experimental design was completely randomized in a factorial scheme with four levels of liming (V23.2% (natural soil), V45%, V65% and V85%) and four doses of P (0, 100, 300 and 500 mg kg -1 of P). Experiment 3: Doses of N in greenhouse. We used seven treatments (0, 75, 150, 225, 300, 375 and 450 mg kg -1 of N) in a completely randomized design. Experiment 4: Doses of K in greenhouse. We used seven treatments (0, 75, 150, 225, 300, 375 and 450 mg kg -1 ) in a completely randomized design. Experiment 5: Levels of liming under field conditions. We used four treatments (V6.7% (natural soil), V35%, V55% and V75%) in a randomized blocks design. Experiment 6: doses of P under field conditions. We used five treatments (0, 23.67, 53.34, 106.67 and 213.36 kg ha -1 of P 2O5) in a randomized blocks design. Experiment 7: Doses of N under field conditions. We used five treatments (0, 30, 60, 120 and 240 kg ha -1 of N) in Latin square. In greenhouse, the evaluations were conducted at eight months (for experiments 1 and 2) and 12 months (for experiments 3 and 4) after seeding, when the measurements of height and root collar diameter of the seedlings. Subsequently, the plants were harvested and separated into shoot and root system, for weighing and evaluating dry biomass gain. In the field, the evaluations were conducted at six, 12, 18, 24 and 30 months (for experiments 5 and 6) and at six, 12 and 18 months (for experiment 7). In these experiments, we evaluated the survival of the seedlings, height of the plants and diameter of the stem at soil height. The data obtained were submitted to analysis of variance, mean tests and regression analysis. In conclusion, during the phase of seedling formation, the species is little demanding in S and B, negatively responds to liming, positively responds to phosphate fertilization and does not respond to nitrogen and potassium fertilization. In the field, in general, the species does not respond to the application of P or to liming, and is negatively influenced by the application of elevated doses of nitrogen.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Physic nut (Jatropha curcas L.) is a perennial oilseed species that has aroused economic interest for biodiesel production. Among other factors, it is essential to determine the nutritional demands of this species to facilitate raising it as a crop. This study aimed to evaluate the early growth and mineral nutrition of physic nut, as well as soil fertility, as affected by phosphorus fertilization. The study was carried out in a plastic greenhouse in a completely randomized block experimental design with four replicates. The plants were grown in plastic pots filled with 50 dm³ of Latossolo Vermelho (Rhodic Hapludox). Application rates of 0, 50, 100, 150 and 200 mg dm-3 of P were tested, plus a control. Evaluations of plant height and root collar diameter were performed monthly. The experiment was ended 150 days after transplant of the seedlings, at which time leaf area, dry weight, leaf contents and total accumulation of macro- (N, P, K, Ca, Mg and S) and micronutrients (B, Cu, Fe, Mn and Zn) were performed, and soil chemical properties were analyzed. We concluded that absence of P fertilization alone is as limiting to early growth of physic nut as simultaneous absence of soil amendment and fertilization. The rate of 57 mg dm-3 of P may be recommended for initial growth of physic nut. The total accumulation of nutrients in physic nut seedlings exhibited the following order: K>N>Mg>Ca>P>S>Fe>Mn>B>Zn>Cu. Phosphorus fertilization resulted in increased soil cation exchange capacity (CEC).

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The use of physical protectors has been considered as an efficient technique for tillage farming of different species, mainly native ones. Based on the importance of the species, Peltophorum dubium for revegetation of degraded areas, this study evaluated the emergence, survival and initial development of P. dubium seedlings under the influence of physical protectors with different filters. Thus, the following treatments were adopted: absence of physical protector (APP), transparent physical protector (TPP), transparent physical protector + blue cellophane (BPP) and transparent physical protector + red cellophane (RPP). The evaluated characteristics were: emergence velocity index (EVI), seedling survival and emergence percentage, plant height, leaf area and root collar diameter. All of these physical protectors increased the mean values of EVI and survival. In conclusion, the emergence speed and initial development of P. dubium (Spreng.) seedlings grown in the interior of physical protectors, independent on the filters, presented positive results. The reduction on the light intensity interferes positively in the initial growth of these plants.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A greenhouse experiment was installed with bait cultures to extract the AMF species present in a rhizosphere soil sample of a native Araucaria angustifolia forest in Campos do Jordao, Brazil. The experimental design was completely randomized, with four increasing phosphorus doses (0, 20, 50, and 150 mg kg(-1), as triple superphosphate), with five replicates, the bait plant was araucaria, and all pots were inoculated with 100 g of rhizospheric soil collected in an araucaria forest. After twelve months the spores were extracted, counted and identified, and the percent root colonization was also determined. When taking all four P doses into account, eleven AMF species could be identified: Acaulospora bireticulata, Acaulospora morrowiae, Acaulospora sp., Entrophospora colombiana, Gigaspora margarita, Glomus diaphanum, Glomus etunicatum, Glomus macrocarpum, Scutellospora calospora, Scutellospora gilmorei, and Scutellospora pellucida. There was no effect of the P dose on the total amount of spores neither on the percent root colonization. However, the correspondence analysis showed that the different AMF species were selectively associated mostly to either one or another P dose.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

A espécie Spondias tuberosa Arr. Cam. (umbuzeiro) destaca-se como uma das espécies arbóreas de maior potencial do semiárido brasileiro. Apesar de sua relevante importância socioeconômica e ambiental, há falta de estudos voltados para o estabelecimento de um modelo de produção de mudas da espécie. O objetivo desse trabalho foi avaliar a produção de mudas de Spondias tuberosa utilizando diferentes substratos e tamanho de recipientes. O experimento foi conduzido no viveiro do Laboratório de Ecologia Vegetal (LEV) do Centro de Ciências Agrárias (CCA) da Universidade Federal da Paraíba (UFPB), Areia - PB. O delineamento experimental usado foi em blocos casualizados em esquema fatorial 2 x 7 e parcelas subdivididas, sendo que os recipientes representaram as parcelas e os substratos as subparcelas. Foram utilizados substratos formulados a partir da mistura de terra de subsolo (37,5-100%), areia lavada (12,5- 25%) e esterco bovino curtido (10-50%). Os recipientes utilizados foram sacos de polietileno preto com volumes de 1900 cm3 (15 x 27 cm) e 5000 cm3 (25 x 26 cm). Para a obtenção das plântulas, sementes de Spondias tuberosa foram semeadas em sementeira de alvenaria até a repicagem (90 dias após o semeio). Aos 78 dias, após a repicagem, as mudas foram avaliadas quanto à altura, diâmetro do colo, relação altura/ diâmetro do colo, diâmetro do xilopódio, comprimento de raiz, massa seca da parte aérea e raiz. Os dados obtidos foram submetidos à análise de variância e ao teste F, sendo as médias comparadas pelo teste de Tukey ao nível de 5% de probabilidade, utilizando o software SISVAR®. Os substratos com esterco bovino curtido proporcionaram os maiores valores em altura e comprimento de raiz. Para a produção de mudas de Spondias tuberosa, é recomendado o substrato contendo terra de subsolo (45%) + Areia (15%) + Esterco bovino (40%).