Factors affecting survivorship, growth, and fruit production in a beach population of Xanthium strumarium

1984 ◽  
Vol 62 (10) ◽  
pp. 2122-2127 ◽  
Author(s):  
Jess K. Zimmerman ◽  
I. Michael Weis
Keyword(s):  
Soil Moisture ◽  
Plant Density ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Fruit Production ◽  
Xanthium Strumarium ◽  
Seedling Mortality ◽  
Factors Affecting ◽  
High Soil Moisture ◽  
High Plant Density

In a beach population of Xanthium strumarium, we assessed the effects of density, seedling emergence date, and soil moisture on seedling survivorship, plant growth, and fruit production. Seedling survival was largely density independent, while growth and fruit production declined significantly with increased density. Delayed seedling emergence resulted in significantly lowered survival but exhibited no significant effects on fruit production. Soil moisture was correlated positively with seedling survival, growth, and fruit production. Blowing sand was noted as an important cause of seedling mortality. Increased survival in areas of high soil moisture apparently resulted because of an absence of blowing sand in these areas. Consistent with a lack of density-dependent mortality, the density–yield relationship for the population had a slope near −1 and not −3/2. Hierarchy in fruit production among plants was least developed in areas of high plant density.

Germination, survival, and early growth of red alder seedlings in the central Coast Range of Oregon

1995 ◽  
Vol 25 (10) ◽  
pp. 1639-1651 ◽  
Author(s):  
Sybille Haeussler ◽  
John C. Tappeiner II ◽  
Brian J. Greber
Keyword(s):  
Soil Moisture ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Survival Rates ◽  
Moisture Stress ◽  
Coast Range ◽  
Seedling Mortality ◽  
Central Coast ◽  
Red Alder

Effects of forest disturbance and soil moisture levels on establishment of red alder (Alnusrubra Bong.) seedlings were studied at four sites representing a climatic moisture gradient within the central Coast Range of Oregon. On average, there was no difference in seedling emergence between recent clearcuts and second-growth forests, but emergence was much higher on mineral soil than on organic seedbeds. Emergence, on both types of seedbed, was positively correlated with spring soil moisture conditions (R2 = 0.60). Seedling survival, on the other hand, differed greatly between clearcut and forest. In clearcuts, heat and drought injuries were the primary causes of seedling mortality. In the forest, seedlings had poor vigour and quickly succumbed to pathogens, herbivores, and rain splash. First-year survival rates were strongly correlated with minimum summer soil moisture levels (R2 = 0.71). Height growth of seedlings on clearcuts (2–5 cm after 1 year; 8–23 cm after 2 years) was much slower than rates typically described for red alder. Best establishment occurred on skid trails and landings, suggesting that young seedlings may suffer less from heat or moisture stress on these heavily disturbed microenvironments.

Ecological Studies of the Endangered Rutidosis leptorrhynchoides. II. Patterns of Seedling Emergence and Survival in a Native Grassland

1995 ◽  
Vol 43 (1) ◽  
pp. 13 ◽  
Author(s):  
JW Morgan
Keyword(s):  
Soil Moisture ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Moisture Stress ◽  
Seedling Mortality ◽  
Themeda Triandra ◽  
Established Plant ◽  
Survival And Growth ◽  
Growth Of Seedlings

The emergence, survival and growth of seedlings of the endangered Rutidosis leptorrhynchoides F.Muell. were followed in a Themeda triandra grassland during 1991 and 1992. The effect of summer irrigation on seedling survival was also investigated. Seedling emergence occurred in both years within 2 weeks of the 'autumn break' when soil moisture rose above 20%. Ninety percent of emergence was observed within 4 weeks of the onset of germination and 87% of seedlings were within 20 cm of an established plant. No emergence was observed after 8 weeks. Thirteen percent of the 1991 cohort survived for 14 months. Mortality of most seedlings (63%) was attributed to soil moisture stress in summer. Small seedlings (Ͱ4 3 leaves) were no more susceptible to drought than larger seedlings. Seventy two percent of the 1991 cohort produced four leaves before subsequently dying. In 1992, however, most early seedling mortality was amongst cotyledonary seedlings. No seedlings flowered in their first year. Above-ground growth was slow and by 14 months, 60% of surviving seedlings had seven or fewer live leaves. Irrigation in a year of below-average rainfall had no significant effect on the survival and growth of seedlings. This suggests that seedling recruitment is not restricted to climatically favourable years (i.e. is not episodic) but rather, is potentially on-going provided suitable microsites are available for seedling survival.

Grading monogerm sugar-beet seed and its influence on performance

1974 ◽  
Vol 83 (1) ◽  
pp. 125-133 ◽  
Author(s):  
P. C. Longden ◽  
R. K. Scott ◽  
D. W. Wood
Keyword(s):  
Sugar Beet ◽  
Seed Weight ◽  
Field Experiments ◽  
Plant Density ◽  
Seedling Emergence ◽  
Growth And Yield ◽  
Viable Seed ◽  
True Seed ◽  
High Plant Density ◽  
Fruit Diameter

SUMMARYFrom monogerm sugar-beet seed as harvested non-viable fruits have to be eliminated, multigerm ones rejected and the size made sufficiently uniform for use in precision drills. Seed which had been gently rubbed to remove some of the cortex was graded for diameter, thickness and by aspiration, either singly or in combination. Effects of grading were determined by laboratory germination tests, radiography and field sowings in which seedling emergence and crop growth and yield were recorded.Grading by thickness was effective in removing multigerm fruits. Grading by aspiration and diameter rejected non-viable seed and reduced the variation in size. By combining all three grading methods, samples of seed of 80% germination and 90% monogermity were produced, provided the seed lot as threshed gave at least 50% germination. True seed weight increased with fruit diameter but only the first aspiration was effective in removing light true seeds. Radiography showed that both aspiration and, to a less extent, grading by diameter were effective in removing most empty fruits but neither eliminated those with shrivelled seed. The field experiments confirmed that increase in fruit diameter or aspiration gave more seedlings. Even at uniform, high plant density, sugar yields were less from the smallest (less than 3 mm diameter) than from the other grades of seed. The initial aspiration also improved sugar yield but further aspiration decreased yield.

The Effects of Plant Density, Spatial Arrangement and Time of Harvest on Yield and Root Size in Carrots

1979 ◽  
Vol 93 (2) ◽  
pp. 431-440 ◽  
Author(s):  
P. J. Salter ◽  
I. E. Currah ◽  
Jane R. Fellows
Keyword(s):  
Plant Density ◽  
Potential Evapotranspiration ◽  
Seedling Emergence ◽  
Spatial Arrangement ◽  
Root Weight ◽  
Root Yield ◽  
High Plant Density ◽  
Plant Arrangement ◽  
Root Size ◽  
Time Of Harvest

SUMMARYFour experiments were carried out over a 2-year period to investigate the effect of plant density and spatial arrangement and the time of lifting on yield and root size of carrots. Plant arrangement was varied by growing the plants in 1-, 2-, 3-, 4-, 5- and 10-row systems in beds with rows 12–5 and 37–5 cm apart. With each row arrangement crops were grown at target densities of 108, 323 and 537 plants/ma. There were three times of harvest. Total root yield was not significantly affected by plant arrangement or, in three out of the four experiments, by plant density but yields progressively increased with later harvests at all density levels. Yields of canning-size roots (20–30 mm diameter) were influenced by plant density and time of harvest and there were highly significant interactions between these variables on canning root yields. Highest absolute yields were obtained from the latest harvests from the medium and high plant density treatments; with the lowest density treatments the highest yields of canners were obtained from the earliest harvests. Mean root weight was significantly affected by plant density and harvest time. Row system effects on mean root weight were shown to be largely accounted for by differences in percentage seedling emergence and hence the plant density obtained under the different row system treatments and a possible reason for this effect is discussed. The relationship between mean root weight and plant density was not affected by the pattern of plant arrangement in these experiments. Total root yields were shown to be related to cumulative potential evapotranspiration from sowing rather than to chronological time. It is concluded that with the range of row systems used in these experiments, row spacing had little effect on root yield but confirmed previous work that plant density and time of harvest were the most important variables controlling mean root size and hence the yield of roots of any particular size grade.

Factors affecting growth and reproduction of Noogoora burr (Xanthium occidentale Bertol.)

1984 ◽  
Vol 35 (2) ◽  
pp. 271 ◽  
Author(s):  
RJ Martin ◽  
JA Carnahan
Keyword(s):  
Plant Density ◽  
Unit Area ◽  
Dry Weight ◽  
Low Light ◽  
Factors Affecting ◽  
Shoot Dry Weight ◽  
High Plant Density ◽  
Low Levels ◽  
Net Assimilation ◽  
Growth And Reproduction

Plant density and availability of light and water significantly affected growth and reproduction of Noogoora burr plants grown in a glasshouse. Burr yield was reduced most by low levels of available water. Low light intensity, low water availability and high plant density reduced net assimilation rates and, in combination, caused the greatest reduction in burr production. Under field conditions the ratio of burr dry weight to total shoot dry weight decreased with increasing plant density. In terms of production per unit area, dry weight of main stems and main stem leaves increased with increasing plant density at the expense of burr dry weight. We conclude that the success of Noogoora burr as a fleece contaminant could be attributed, in part, to: the insensitivity of burr production to variation in soil fertility and length of growing season; the ability to regulate plant density under conditions of limiting light or water; and the ability to regulate plant components so that the efficiency of burr production increases with a decrease in plant density.

Influence of Seedbed Tilth on Emergence and Root and Shoot Growth of Seedlings of Some Crops

1985 ◽  
Vol 21 (1) ◽  
pp. 59-65 ◽  
Author(s):  
R. S. Malik ◽  
B. S. Jhorar ◽  
I. S. Dahiya
Keyword(s):  
Soil Moisture ◽  
Root Growth ◽  
Shoot Growth ◽  
Soil Moisture Content ◽  
Seedling Emergence ◽  
High Moisture ◽  
High Soil Moisture ◽  
Root And Shoot Growth ◽  
Growth Of Seedlings ◽  
Zone Temperature

SUMMARYWheat (Triticum aestivum), mustard (Brassica juncea), gram (Cicer arietinum) and barley (Hordeum vulgare) seedlings were raised in soils of different tilth created in microplots during 1981 and 1982. Amplitude in diurnal seed-zone temperature and soil moisture content increased with tilth coarseness. At low soil moisture levels, seedling emergence of wheat and mustard decreased with increasing clod size while that of gram and barley increased. These effects were not significant at high soil moisture levels. Shoot growth of all the crops was higher under coarse tilth than under fine tilth at both moisture levels. Root growth of wheat and mustard decreased with increasing clod size while that of gram and barley increased, at both moisture levels. Mustard had the highest seedling emergence at the low moisture level. Seedling emergence and shoot growth were higher under high moisture than under low moisture for all crops. Root growth varied depending upon the type of crop.

scholarly journals Microhabitat and ectomycorrhizal effects on the establishment, growth and survival of Quercus ilex L. seedlings under drought

2020 ◽  
Author(s):  
Laura García de Jalón ◽  
Jean-Marc Limousin ◽  
Franck Richard ◽  
Arthur Gessler ◽  
Martina Peter ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Quercus Ilex ◽  
Seedling Survival ◽  
Light Availability ◽  
Summer Drought ◽  
Ambient Conditions ◽  
Seedling Mortality ◽  
Tree Recruitment ◽  
Growth And Survival ◽  
Exploration Types

AbstractThe success of tree recruitment in Mediterranean Quercus ilex forests is threatened by the increasing intensity, duration and frequency of drought periods. Seedling germination and growth are modulated by complex interactions between abiotic (microhabitat conditions) and biotic factors (mycorrhiza association) that may mitigate the impacts of climate change on tree recruitment. To better understand and anticipate these effects, we conducted a germination experiment in a long-term precipitation reduction (PR) field experiment where we monitored seedling establishment and survival, micro-environmental conditions and ectomycorrhizal (ECM) colonization by different mycelia exploration types during the first year of seedling growth. We hypothesized that (i) the PR treatment decreases seedling survival relative to the control with ambient conditions, (ii) the underlying mechanisms for seedling survival are better understood with detailed information of microhabitat water and light availability irrespective of the PR treatment, (iii) the PR treatment will favour the development of ECM exploration types with drought-resistance traits such as differentiated rhizomorphs. Contrary to our first hypothesis, seedling survival was lower in control plots with overall higher soil moisture. Micro-site light and soil moisture conditions were better predictors of seedling survival and growth than the plot-level PR treatment, confirming our second hypothesis. Furthermore, in line with our third hypothesis, we found that ECM with longer extramatrical mycelia were more abundant in the PR treatment plots and were positively correlated to survival, which suggests a potential role of this ECM exploration type in seedling survival and recruitment. Although summer drought was the main cause of seedling mortality, our study indicates that drier conditions in spring can increase seedling survival, presumably through a synergistic effect of drought adapted ECM species and less favourable conditions for root pathogens.

CORN YIELD RESPONSE TO IRRIGATION, PLANT POPULATION AND NITROGEN IN A COOL, HUMID CLIMATE

1986 ◽  
Vol 66 (3) ◽  
pp. 453-464 ◽  
Author(s):  
D. M. BROWN
Keyword(s):  
Zea Mays ◽  
Soil Moisture ◽  
Zea Mays L ◽  
Plant Density ◽  
Plant Population ◽  
Yield Response ◽  
Corn Yield ◽  
Subsequent Paper ◽  
Southern Ontario ◽  
High Plant Density

Summer dry spells in some areas of southern Ontario during the last decade have increased interest in supplemental irrigation. Field studies were conducted in a 2500 heat unit area of southern Ontario on Orthic/Brunisolic Grey Brown Luvisol soils to determine the yield response of field corn (Zea mays L.) to irrigation in midsummer when combined with increased plant density and N rates. The yield responses, phenological records and soil moisture measurements are to be used in the calibration and validation of a corn yield estimation model, to be published in a subsequent paper. Two to four irrigations were applied each year using the line method when soil moisture pressure potential reached −40 to −60 kPa at 22.5 cm depth. Development stages were unaffected by irrigation. Yield increases from irrigation were directly proportional to water applied in midsummer and the intensity of dry weather. Yields increased with plant density in 4 of the 5 yr and were usually consistent over irrigation levels. Additional nitrogen above the recommended rate increased yields in 1982 and 1983, decreased yields in 1981, and resulted in no differences the other two years. In years of positive response to extra nitrogen, there was usually a greater response with irrigation and the responses were greatest at high plant density and for the longer season hybrids. Harvest indices decreased as irrigation amount increased and were exceptionally high in 1983.Key words: Corn, Zea mays L., line-source irrigation, plant population, nitrogen, harvest index

Effects of overstory tree density, site preparation and ground vegetation on natural Scots pine seedling emergence and survival in northern boreal pine forests

2021 ◽  
Author(s):  
Mikko Johannes Kyrö ◽  
Ville Hallikainen ◽  
Sauli Valkonen ◽  
Mikko Hyppönen ◽  
Pasi Puttonen ◽  
...  
Keyword(s):  
Seedling Survival ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Site Preparation ◽  
Ground Vegetation ◽  
Seedling Mortality ◽  
Bottom Part ◽  
High Coverage ◽  
Efficient Treatment ◽  
Seedling Emergence And Survival

Natural regeneration is commonly used forest regeneration method in Northern Finland. It is not known however, what would be the optimal overstory density and ground vegetation composition for seedling emergence and survival, and if site preparation is needed to accompany overstory density manipulation. We studied the effects of overstory density (unthinned control and thinning to 50, 150 and 250 trees ha-1) and ground vegetation removal (mechanical site preparation with disc trenching) on the number of naturally germinated pine seedlings and survival of individual seedlings during 8-11 years. Bare mineral soil was a superior seedbed compared to intact vegetation cover, even though also mortality rate was high on mineral soil. Greater cover of lingonberry, crowberry and slash had a negative effect on seedling number. Seedling mortality was initially high (60% died during the first two years) but decreased throughout the first five years. The mineral soil in the elevated part of disc trencher track showed twice the survival rate in the bottom part of the track. High coverage of small haired mosses was associated with poorer seedling survival. An overstory density of 50-150 trees ha-1 with site preparation seems to be an efficient treatment to promote regeneration under these circumstances.

scholarly journals Effects of Shade and Planting Methods on the Growth of Heracleum moellendorffii and Adenophora divaricata in Different Soil Moisture and Nutrient Conditions

Plants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2203
Author(s):  
Woo Bin Youn ◽  
Jonathan Ogayon Hernandez ◽  
Byung Bae Park
Keyword(s):  
Soil Moisture ◽  
Competitive Ability ◽  
Soil Nutrient ◽  
Factors Affecting ◽  
High Soil Moisture ◽  
Planting Methods ◽  
Light Levels ◽  
One Year ◽  
Moisture Conditions ◽  
Nutrient Conditions

In this study, the interacting effects of shade and planting methods on the growth and competitive ability of two understory plants Heracleum moellendorffii Hance and Adenophora divaricata Franch. & Sav. were investigated under different soil moisture and nutrient conditions. One-year-old seedlings were subjected to different light levels (0%, 35%, and 55% shade) and planting methods (monoculture and mixed) under contrasting soil moisture (1.2 L/m2 and 2.3 L/m2 of water) and soil nutrient conditions (unfertilized and fertilized). Here, shading significantly improved the height growth of H. moellendorffii (10–20 cm increase) in unfertilized and fertilized plots and at high soil moisture conditions. Contrarily, A. divaricata seedlings planted singly at full sunlight yielded a higher aboveground biomass growth (8–17 g plant−1), compared with those shaded and intercropped seedlings (0.9–3.9 g plant−1). The increased competitiveness of H. moellendorffii suppressed the growth of A. divaricata across different light conditions when planted together. The amount of light, soil moisture, and nutrients and their interactions significantly affected the growth of the seedlings, resulting in asymmetric interspecific competition between the two species. Results provide us with a better understanding of the environmental factors affecting plant growth for forest farming in the understory.

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