Wyniki wyszukiwania

1

Dependence of spring triticale yield of grain and yield structure on seed density and nitrogen fertilization

100%

Pilejczyk D., Sienkiewicz S., Krzebietke S., Zarczynski P.

Polish Journal of Natural Sciences

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2003

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tom 14

2

Mass and density as separation criteria of pedunculate oak (Quercus robur L.) seeds

86%

Tylek P., Kaliniewicz Z., Kielbasa P., Zagrobelny T.

Electronic Journal of Polish Agricultural Universities. Series: Forestry

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2015

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tom 18

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nr 4

3

Seed banks and forest recruitment after disturbance: the composition and abundance of seed after clear-cut of stone pine (Pinus pinea L.) plantations

72%

Arduini I., Orlandi C., Mariotti M., Masoni A.

Polish Journal of Ecology

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2013

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tom 61

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nr 3

Seed banks play a key role in the recruitment of forest vegetation after severe disturbance, but can originate an undesired plant community. Thus, investigations on seed bank structure, and early changes occurring after clearcut, are of primary interest for sustainable forest management. Researches were carried out in two mature stone pine (Pinus pinea L.) plantations located in Tuscany (Italy), along the Mediterranean coast. Soil samples were collected in March, July and October of the 2nd and 3rd year after clear-cut, in cut strips and adjacent intact stands. Seed bank size and composition were evaluated through the number of seedlings and species emerged from soil samples. Intact plantations differed in seed bank richness and composition, but not in abundance that was approximately 1,200 seeds m–2. Clear-cut doubled seed density in soil, did not change seed bank richness, and affected markedly composition. Seed banks of cut strips were richer in annual and open space species, and poorer in perennial, forest and disturbed sites species. Seeds of Erica scoparia dominated the seed bank, with a relative abundance of 60% in intact stands and 43% in cut strips. Proportion of annual seeds was slightly less than 20% in intact stands, but increased up to 50% after clear-cut. Between the 2nd and 3rd year from clear-cut, the proportion of seeds from species typical of stone pine forests decreased, while that of non-forest species and aliens increased. The scarcity of seeds from most forest species and the lack of tree seeds make the recruitment of understorey vegetation from seed banks critical. In addition, the increased seed density of alien and disturbed site species in intact seed banks with time from clear-cut, suggests that disturbance caused by cutting in narrow strips threatens the integrity of intact plantations.

4

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Effectiveness of the pneumatic separation of Norway spruce Picea abies (L.) Karst seeds

72%

Tylek P., Walczyk J.

Dendrobiology

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2004

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tom 51 Supplement

The paper presents the theoretical basis for the pneumatic separation of Norway spruce seeds along with the results of investigations into the effectiveness of separation conducted in a pneumatic separator with a vertical air column. Such a separator was designed and produced at the Department of Forest Works Mechanization of the Agricultural University of Kraków. The device makes it possible to separate a mixture into three fractions based on the differences in critical velocities. The variation in density among different seed fractions is about two times lower than the variation in seed mass. This result supports the suggestion that omitting the size calibration of seeds before their pneumatic separation could lead to the dominance of seed density as a distinguishing feature.

5

Seed predation on the ground or in the tree? Size-related differences in behavior and ecology of granivorous birds

58%

Parea R., Venturas M., Gil L.

Acta Ornithologica

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2014

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tom 49

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nr 1

Seed-eating birds may consume seeds in the tree (pre-dispersal predation) as well as on the ground (post- dispersal predation), usually at contrasting microhabitat conditions. We examined the foraging behaviour and contribution to seed predation of a whole assemblage of seed-eating birds (mostly Fringillidae) at both dispersal phases (pre- and post-dispersal) in a wind-dispersed tree, the European White Elm Ulmus laevis. We found that most seed predators were tree-feeding birds that prey upon seeds for longer periods in the tree and spend shorter periods in larger flocks foraging on the ground. We also obtained significant differences in predation speed among the seed predator species. The overall number of seeds consumed by birds, as well as the amount of time spent foraging in the tree, increased with increasing feeding heights. Seed availability increases with height, which seems to be the main reason why birds spend more time foraging on higher branches. Birds strongly differed in their perching coefficient (PC, ration of feeding height to distance from crown edge). Small finches such as Serins Serinus serinus and Goldfinches Carduelis carduelis had a very high value of PC in comparison to large finches such as Greenfinches Carduelis chloris, Chaffinches Fringilla coelebs, and Hawfinches Coccothraustes coccothraustes. In general, finches showed much higher values of PC than non-fringillid species, indicating a greater adaptation to perch and feed on more flexible stems. Birds increased their overall seed predation and the time allocated to foraging on the ground when they were in flocks. Small finches tended to follow larger finches and flock in multispecies groups when foraging on the ground. We suggest that this behaviour increases both feeding efficiency and safety. Further studies should take into account possible differences in behavior of seed-eating birds throughout the dispersal season since it may have important implications for their adaptive behavior to select new niches.

6

Soil seed bank and extant vegetation of a dry valley

58%

Li Y., Bao W., Wu N.

Polish Journal of Ecology

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2011

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tom 59

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nr 3

Although crucial for guiding vegetation improvement efforts, soil seed bank (SSB) and extant vegetation (EV) in dry valleys remains poorly understood. A germination method and field surveys were applied to address this problem and investigate the characteristics of SSB and corresponding EV of eight sites across the dry Minjiang River valley in Southwest China. Furthermore, the relationships between SSB and EV were compared to provide guidance for vegetation enhancement. Eight sites were classified into two groups – central and transitional sites that differ according to moisture conditions. Seed density and species richness in SSB were lower in less moist central sites compared with those in more moist transitional sites of the valley as well as the coverage of the community. Moreover, species richness and litter thickness were lower in central sites. Comparing SSB strategies of species from eight sites, transient strategy was the most frequently observed category, followed by short-term persistent and long-term persistent strategies. In terms of both SSB and EV, the most abundant life forms were hemicryptophytes, intermediate phanerophytes, and therophytes, whereas less abundant were chamaephytes and cryptophytes. Low Sorenson’s similarity indices (22–32%) and significantly negative Kendall’s correlation in species composition indicate that species composition of SSB was not closely related to corresponding EV for each of the eight sites. Low seed density, especially the lack of viable dominant shrub seeds, dominant transient SSB strategy species, and low correspondence in species composition between SSB and EV imply that the potential for vegetation enhancement in the dry valley is weak, particularly in less moist central sites. To preserve the good EV of more moist transitional sites and introduce seeds of dominant species to improve poor EV in central sites, EV is likely to be a feasible standard for improving vegetation in dry valleys.

7

Charakterystyka właściwości fizycznych nasion marchwi i pietruszki po zbiorze kombajnowym

58%

Panasiewicz M., Sobczak P., Mazur J., Zawislak K., Nadulski R.

Acta Agrophysica

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2013

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tom 20

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nr 1

Przygotowanie wartościowego i kwalifikowanego materiału siewnego marchwi i pietruszki wymaga wiedzy z zakresu podstawowych właściwości fizycznych nasion gatunku podstawowego oraz pozostałych komponentów mieszaniny ziarnistej (zanieczyszczenia, nasiona innych gatunków roślin itp.). Znajomość cech fizycznych nasion wymagana jest ponadto przy doborze i ustalaniu parametrów techniczno-technologicznych procesów czyszczenia i separacji czy innych zabiegów ukierunkowanych na uszlachetnianie materiału siewnego. W pracy zestawiono i porównano wybraną grupę właściwości fizycznych oraz skład granulometryczny nasion marchwi i pietruszki pozyskanych w zbiorze kombajnowym. Wykazano zróżnicowanie niektórych cech fizycznych nasion marchwi i pietruszki, przy czym dotyczyło to głównie charakterystyk masowych (gęstość w stanie zsypu i gęstość utrzęsiona) oraz wymiarów geometrycznych najbardziej licznych i reprezentatywnych frakcji wymiarowych. Analiza składu granulometrycznego nasion obu warzyw, przeprowadzona równolegle na przesiewaczu sitowym i wibracyjnym, wykazała, że najbardziej liczną i reprezentacyjną z punktu widzenia wartości siewnej grupą były nasiona marchwi o wymiarach 1,3, 1,5 i 1,7 mm. Łączna ilość tych trzech frakcji stanowiła około 78% ogółu oczyszczonych wcześniej nasion. W przypadku nasion pietruszki najbardziej liczną grupę stanowiły nasiona o wymiarach. 1,1 i 1,3 mm, a ich sumaryczny udział w ogólnej masie nasion wyniósł około 84,46.

8

Właściwości fizyczne masy nasion soczewicy

58%

Szot B., Stepniewski A.

Acta Agrophysica

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2001

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tom 58

9

Technologiczne i fizjologiczne sposoby poprawy jakosci nasion rzepaku

44%

Podlaski S., Grabowska M.

Biuletyn Instytutu Hodowli i Aklimatyzacji Roślin

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1995

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tom 193

103-112

10

Wplyw jakosci i rozmieszczenia nasion na plonowanie buraka cukrowego

44%

Kostka-Gosciniak D.

Biuletyn Instytutu Hodowli i Aklimatyzacji Roślin

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1996

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tom 197

299-309

11

Wplyw sposobu uszlachetniania nasion na jakosc materialu siewnego i plon jeczmienia jarego odmiany Ars

37%

Podlaski S., Wzorek H.

Biuletyn Instytutu Hodowli i Aklimatyzacji Roślin

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1993

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tom 185

39-48

Ograniczanie wyników

Dependence of spring triticale yield of grain and yield structure on seed density and nitrogen fertilization

Mass and density as separation criteria of pedunculate oak (Quercus robur L.) seeds

Seed banks and forest recruitment after disturbance: the composition and abundance of seed after clear-cut of stone pine (Pinus pinea L.) plantations

Effectiveness of the pneumatic separation of Norway spruce Picea abies (L.) Karst seeds

Seed predation on the ground or in the tree? Size-related differences in behavior and ecology of granivorous birds

Soil seed bank and extant vegetation of a dry valley

Charakterystyka właściwości fizycznych nasion marchwi i pietruszki po zbiorze kombajnowym

Właściwości fizyczne masy nasion soczewicy

Technologiczne i fizjologiczne sposoby poprawy jakosci nasion rzepaku

Wplyw jakosci i rozmieszczenia nasion na plonowanie buraka cukrowego

Wplyw sposobu uszlachetniania nasion na jakosc materialu siewnego i plon jeczmienia jarego odmiany Ars