scholarly journals PERSISTENCE AND GROWTH OF MAKU LOTUS ON CONTRASTING ASPECTS AT HIGH ALTITUDE

Author(s):  
G.A. Dunbar ◽  
E.J. Costello

Maku lotus plants were grown in snow tussock grasslands at 1460 m altitude on steep ungrazed slopes. A total of 960 plants were transplanted in spring 1980 to five sites. In March 1984 survival was 72% and 68% on two NW sites and 66%, 56% and 46% on three ESE sites. Survival rates did not differ between 100 and 300 kg/ha sulphur enriched superphosphate applied in the transplant year, but dense native vegetation appeared to contribute to poorer survival on the eastern slopes. Mean lotus plant size, expressed as an index of ground spread was consistently larger on NW than on ESE, and in February 1984 was three times larger (1422 cm* cf. 429 cmZ). Mean DM yields per plant in February and March 1984 were from 1.3 to 3.0 times greater on NW sites. Ground spread indices and D.M. yields showed a response to the higher rate of fertiliser on some sites only. Higher air and soil temperatures on NW aspect, particularly in early spring and In autumn favouied a longer period of growth compared with E.S.E. The trials showed that Maku lotus could be a valuable herbage resource on warmer northerly aspects above 1000 m. In addition, the high variability amongst l.otus plants suggested that production for such cool environments could be improved by selection within existing populations. Keywords: Maku lotus, Lotus pendunculatus, aspect, high altitude, persistence, plant performance, plant selection.

2020 ◽  
Vol 68 (6) ◽  
pp. 439
Author(s):  
Julie Christine Scaloppi ◽  
Andréa Lúcia Teixeira de Souza

Seedling planting is the most common strategy used to reintroduce tropical native tree species; however, direct sowing has simplicity and operational ease advantages. Functional traits such as seed size and growth rates have been shown to be relevant for better plant performance. We evaluated the effects of intraspecific variation in seed size and the reintroduction strategy simultaneously on the development of Hymenaea courbaril (L.) and Enterolobium timbouva (Mart.) introduced in an abandoned eucalyptus plantation over 462 days. Plants from small, medium and large seeds were reintroduced by planting seedlings and direct seeding. Both species achieved high rates of emergence and survival was high in the two reintroduction strategies. Seed size was not related to emergence and mean time to emergence for either species. The survival of both species was higher than 74% in the field, and seed size had little effect on survival rates. In general, H. courbaril plants introduced by direct sowing had higher growth, and seed size correlated positively with stem size. In contrast, the growth of E. timbouva plants introduced by seedling planting was higher than in plants introduced by direct sowing regardless of seed size. The light requirements of this species seem higher than for H. courbaril. Our results suggest the feasibility of reintroducing species by direct sowing in eucalyptus understory, but since plant growth varies between species, there may be a balance between the advantage of the initial plant size provided by planting seedlings and the advantage of a better root development provided by direct sowing.


Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1355 ◽  
Author(s):  
RB Garnsey

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (<600 mm rainfall p.a.), and examines, for the first time in Australia, the behaviour and survival rates of aestivating earthworms. Earthworms were sampled from 14 permanent pastures in the Midlands from May 1992 to February 1994. Earthworm activity was significantly correlated with soil moisture; maximum earthworm activity in the surface soil was evident during the wetter months of winter and early spring, followed by aestivation in the surface and subsoils during the drier summer months. The two most abundant earthworm species found in the Midlands were Aporrectodea caliginosa (maximum of 174.8 m-2 or 55.06 g m-2) and A. trapezoides (86 m-2 or 52.03 g m-2), with low numbers of Octolasion cyaneum, Lumbricus rubellus and A. rosea. The phenology of A. caliginosa relating to rainfall contrasted with that of A. trapezoides in this study. A caliginosa was particularly dependent upon rainfall in the Midlands: population density, cocoon production and adult development of A. caliginosa were reduced as rainfall reduced from 600 to 425 mm p.a. In contrast, the density and biomass of A. trapezoides were unaffected by rainfall over the same range: cocoon production and adult development continued regardless of rainfall. The depth of earthworm aestivation during the summers of 1992-94 was similar in each year. Most individuals were in aestivation at a depth of 150-200 mm, regardless of species, soil moisture or texture. Smaller aestivating individuals were located nearer the soil surface, as was shown by an increase in mean mass of aestivating individuals with depth. There was a high mortality associated with summer aestivation of up to 60% for juvenile, and 63% for adult earthworms in 1993 in the Midlands. Cocoons did not survive during the summers of 1992 or 1994, but were recovered in 1993, possibly due to the influence of rainfall during late winter and early spring.


1993 ◽  
Vol 9 (3) ◽  
pp. 313-320 ◽  
Author(s):  
Antonio Carlos Miranda ◽  
Heloisa Sinátora Miranda ◽  
Inês de Fátima Oliveira Dias ◽  
Braulio Ferreira de Souza Dias

ABSTRACTAir and soil temperatures were measured during dry season heading fires in three different physiognomic forms of native vegetation common in Central Brazil: cerrado sensu stricto (dense scrub of shrubs and trees), campo cerrado (open scrub), and campo sujo (open grassland with scattered shrubs). The vegetation was protected from fire for 15 y in some areas, had been burned once every two years, and once each year in other areas. The temperatures were measured with type-k thermocouples and recorded at intervals of 22.5 sees. Air temperature measurements were taken at 1, 60 and 160 cm. Maximum air temperatures ranged from 85°C to 840°C, and the duration above 60°C varied from 20 to 270 seconds. In the soil, negligible temperature increases were recorded below 5 cm depth, whereas at 2 cm maximum soil temperatures varied from 29 to 38°C. Possible influences of fuel load and moisture on the recorded data and on the behaviour of fire in the cerrado ecosystems are discussed.


2007 ◽  
Vol 146 (3) ◽  
pp. 301-310 ◽  
Author(s):  
M. S. KOUTSIKA-SOTIRIOU ◽  
E. A. TRAKA-MAVRONA ◽  
G. L. EVGENIDIS

SUMMARYCultivated tomato has a narrow germplasm base because of several population bottlenecks in the form of founder events, as well as natural and artificial selections that occurred during domestication and evolution of modern cultivars. The F2 of commercial single-cross hybrids, as well as locally well-adapted varieties, provide germplasm for developing recombinant lines and exploiting genetic variability, respectively. The present study aims to discriminate the breeding value of tomato source material, i.e. commercial hybrids or well-adapted varieties, by (i) estimating tolerance to inbreeding of hybrids or estimating heterosis of diallel hybrids between varieties, (ii) determining undesirable traits and (iii) determining general combining ability (GCA) and specific combining ability (SCA) effects from diallel crosses between hybrids and between varieties. Two hybrids and four varieties were assessed. One hybrid showed 0·03 inbreeding vigour, which was not combined with undesirable traits in the F2 generation. However, negative GCA and positive SCA values did not support the hybrid as source material, provided that hybrids with low inbreeding depression, positive GCA and negative SCA correspond to an F2 capable of developing recombinant lines. The assessment of the varieties showed positive GCA and 0·34 heterosis in one variety, indicating agreement between yield and GCA, and that high-yielding varieties may produce high-yielding hybrids. In conclusion, the proposed mating design, taking into account the tolerance to inbreeding for hybrids and the heritability of general worth for both resources, provides a mechanism for ensuring continued improvement in plant performance through plant selection programmes.


The Auk ◽  
1988 ◽  
Vol 105 (4) ◽  
pp. 727-736 ◽  
Author(s):  
André Desrochers ◽  
Susan J. Hannon ◽  
Kelly E. Nordin

Abstract We assessed the effects of winter food supplementation on differential survival between sex, age and dominance classes, and the effects of feeding and territorial defense on breeding density in a northern population of Black-capped Chickadees (Parus atricapillus). Survival rates were higher in a food-supplemented area than in a control area, which suggests that food abundance limited winter survival. Survival was greater among males than lower-ranking females in 1 of 2 years, and greater in dominants than in subordinates, within sex and age classes. Survival of adults and first-year birds, however, did not differ significantly. In the 2 years of this study, a sharp decline of population size occurred at the onset of territoriality in spring. Birds that disappeared in spring were mainly subordinates of each sex. Breeding densities in control and feeder areas were similar in the two years. Eight of 14 territorial birds removed in 2 years were replaced, implying that a nonbreeding surplus was present in early spring.


1981 ◽  
Vol 71 (4) ◽  
pp. 583-590 ◽  
Author(s):  
A. J. Burn ◽  
T. H. Coaker

AbstractPsila rosae (F.) overwinters in Britain in both the larval and pupal stages. Overwintering pupae formed in October and November at soil temperatures of between 10 and 16°C entered diapause. A period of similar temperature in the laboratory during the prepupal stage also caused pupae to enter diapause. Overwintering larvae continued to feed and gain weight; they pupated in early spring at soil temperatures of 2–8°C but did not enter diapause. The sensitivity to diapause-inducing conditions decreased between November and March, associated with changes in developmental temperatures and pupal weight. The differential effects of temperature on larval, pupal and diapause development together serve to synchronise adult emergence from the overwintering population. The mechanisms which allow overwintering by a variable proportion of larvae and pupae also provide the opportunity for the development of a third generation of adult flies in October and November.


1988 ◽  
Vol 111 (2) ◽  
pp. 273-283 ◽  
Author(s):  
J. L. Brock ◽  
M. J. M. Hay ◽  
V. J. Thomas ◽  
J. R. Sedcole

SummaryThere has been little study on the growth and morphology of individual plants constituting the population of white clover in mixed swards under grazing. Such information is required if the mechanisms governing plant productivity and persistence are to be understood.Intact white clover plants were sampled from intensively sheep-grazed pastures under set stocking, rotational grazing, and a combination of both systems, by taking turves (250 × 250 mm), and washing out the plants, every month for a year. Characters measured for every stolon of each plant were: presence of a growing point; numbers of leaves, roots and axillary buds; stolon length. Total plant leaf and stolon dry weight were also recorded. Plants were classified according to degree of branching, and the contribution of each branching order to the population determined.There were strong seasonal variations in plant size (leaf and stolon dry weight, stolon length, and numbers of stolons and leaves per plant) which showed a significant decrease in spring with recovery over the following summer. This was paralleled by a rapid increase in the proportion of less branched plants (1st and 2nd branching order) in the population from 60 to 80% in spring, as higher-order plants broke up into smaller- and lower-ordered plants at this time. Numbers of roots per plant increased over winter to peak in early spring then declined in the following summer-autumn. While system of grazing management had no significant effect on branching structure of plants, it had a large effect on plant dry weight; rotationally grazed plants were 2·5 times larger than set stocked plants (0·182 cf. 0·073 g respectively).Other general features of plant morphology were that each successive order of branch stolons was shorter and length before branching was less than that of their preceding parent stolon. The highest branching order observed was 6th order. There was no relationship between branching and numbers of roots; in branched plants only 55% of stolons were rooted regardless of plant order, but rooted stolons accounted for 85% of total stolon length and carried 62, 48 and 90% of the leaves, growing points and axillary buds per plant, respectively.Comparison with other studies suggests that the processes outlined in this report may be common to white clover growth under grazing over a wide range of favourable environments.


2011 ◽  
Vol 21 (5) ◽  
pp. 586-592 ◽  
Author(s):  
Julie Guckenberger Price ◽  
Stephen A. Watts ◽  
Amy N. Wright ◽  
Robert W. Peters ◽  
Jason T. Kirby

Green roofs are becoming increasingly prevalent in the United States due to their economical and environmental benefits as compared with conventional roofs. Plant selection for green roofs in the variable climate of the southeastern United States has not been well evaluated. Shallow substrates on green roofs provide less moderation of temperature and soil moisture than deeper soils in traditional landscapes, necessitating empirical evaluation in green roof environments to make informed recommendations for green roof plant selection. Nineteen species and cultivars, including succulents, grasses, and forbs, were evaluated under seasonal irrigated and non-irrigated conditions in experimental green roofs. Plants were planted on 26 Oct. 2009 and each evaluated for survival and increase in two-dimensional coverage of the substrate during establishment, after overwintering, and after the first growing season. The winter 2009–10 was colder than normal, and some plants, such as ice plants (Delosperma spp.), considered to be cold-hardy in this climate did not survive through the winter. Irrigation influenced survival for the summer period and only succulent plants like stonecrops (Sedum spp.) survived without irrigation. Irrigated experimental green roofs had significantly lower summer substrate temperatures (up to 20 °F lower) and plants survived in irrigated conditions. Plants that survived both winter and summer under irrigated conditions include pussytoes (Antennaria plantaginifolia), mouse-ear tickseed (Coreopsis auriculata), eastern bottlebrush grass (Elymus hystrix), glade cleft phlox (Phlox bifida stellaria), and eggleston's violet (Viola egglestonii). Irrigation is recommended on extensive green roofs to increase the palette for plant selection by protecting against plant mortality due to drought and extreme soil temperatures.


2011 ◽  
Vol 21 (2) ◽  
pp. 230-235 ◽  
Author(s):  
Filippo Rimi ◽  
Stefano Macolino ◽  
Bernd Leinauer ◽  
Umberto Ziliotto

Winter dormancy is the main impediment to a wide acceptance of warm-season turfgrasses in the Mediterranean countries of Europe due to a loss of color during the winter months. Scalping during late winter or early spring has been recommended anecdotally to enhance spring green-up of bermudagrass (Cynodon dactylon); however, information is lacking on the effectiveness of this practice. A study was conducted to investigate the effects of spring scalping on spring green-up of eight bermudagrass cultivars (Barbados, Contessa, La Paloma, Mohawk, NuMex Sahara, Princess-77, SR 9554, and Yukon) grown in a transition zone environment. The trial was carried out in Spring of 2009 and 2010 on plots established in July 2005 at the experimental farm of the University of Padova (northeastern Italy). Half of the plots for each cultivar were subjected to spring scalping, which was applied in both years on 13 Mar. with a rotary mower set at a height of 28 mm. Soil temperatures were recorded hourly during the research period at a depth of 2.5 cm. The percentage of green cover was estimated weekly from 0 to 98 days after spring scalping (DASS). Soil temperatures in scalped plots were greater than in unscalped plots. Among the cultivars tested, ‘Yukon’ showed earliest spring green-up, with no difference between the scalping treatments, reaching 80% green cover by the end of April. For all other cultivars, scalped plots reached 80% green cover 10 to 18 days earlier than unscalped plots. Results showed that scalping enhanced spring green-up, primarily for cultivars that recover slowly from winter dormancy.


2018 ◽  
Vol 5 (4) ◽  
pp. 149-154 ◽  
Author(s):  
O M Fediuk ◽  
N O Bilyavska ◽  
E K Zolotareva

In the natural conditions early-spring period development of Galanthus nivalis L., the leaves germination from bulbs was carried out in the soil surface layer, mainly, covered with snow, so the leaves were exposed to low soil temperatures. It was found, that at the leaf germination stage, when exposed to minus soil temperature, the mitochondria were predominantly elongated, that is, functionally active. Under the influence of positive temperature, the mitochondria form changed to a round one, which indicates their transition to low functional activity. A similar tendency was manifested even during the budding stage, in particular, when the soil temperature was lowered to an average of –3.47 °C, the mitochondria changed their form to an elongated one, that is, they passed into an active functional state. Wherein, the temperature of the leaves was higher by 3.84 °C compared to the soil. At the stages of germination and budding of G. nivalis under natural conditions, a direct correlation was found between the soil surface layer temperature and the leaves temperature, and at the flowering stage this relation was reverse. During the flowering stage, despite the influence of predominantly positive soil temperatures, leaves growth was significantly slowed, and their temperature was only slightly higher by 0.38 °C compared to the soil. At the same time, the mitochondria changed their shape to a round one. Thus, the increase in their long axis at different stages in spring development, are aimed at adapting to influence low temperatures of the soil surface layer.


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