EFFECTS OF LIGHT INTENSITY ON VEGETATIVE GROWTH OF LINGONBERRIES

1982 ◽  
Vol 62 (4) ◽  
pp. 965-968 ◽  
Author(s):  
PATRICIA S. HOLLOWAY ◽  
ROBERT M. VAN VELDHUIZEN ◽  
CECIL STUSHNOFF ◽  
DAVID K. WILDUNG

Lingonberries were grown in Fairbanks, Alaska for up to three growing seasons in containers under four treatments: 0, 44, 56 and 73% shade provided by various thicknesses of polypropylene shade cloth. Following three growing seasons, plants grown without shade produced the greatest number of stems and dry weight per plant. Leaf size and number of leaves per stem did not differ among treatments. Leafy rhizome branches were longer under 73% shade than under higher light intensities. Rhizomes were longer without shade than under lower light intensities. The results indicate that for maximum growth and dry matter accumulation lingonberries should be grown in full sunlight.

1982 ◽  
Vol 62 (4) ◽  
pp. 969-977 ◽  
Author(s):  
PATRICIA S. HOLLOWAY ◽  
ROBERT M. VAN VELDHUIZEN ◽  
CECIL STUSHNOFF ◽  
DAVID K. WILDUNG

Vegetative growth of lingonberries was observed on plants growing in four unsterilized, native-Alaskan substrates: coarsely-ground Lemeta peat, Fairbanks silt loam soil, a mixture of peat and silt loam soil and washed Chena very fine sandy loam soil. Following three growing seasons, plants in the peat treatment showed the greatest increase in vegetative growth as revealed by the number of new stems produced, stem length and dry weight per plant. Leaf size did not differ among substrate treatments. The leaves on plants grown in the peat substrate remained green throughout the entire experiment. The leaves of plants in all other treatments showed varying degrees of chlorosis followed by reddening and necrosis. Differences in concentration of N, P, K, Mn, Fe, Zn and Al in whole-plant tissue samples were recorded. The results indicate lingonberries should be grown in a peat substrate for maximum growth and dry matter accumulation.


1996 ◽  
Vol 121 (1) ◽  
pp. 115-122 ◽  
Author(s):  
K.I. Theron ◽  
G. Jacobs

Large Nerine bowdenii bulbs (>14 cm in circumference) were exposed to low ligbt intensities for different periods during two successive growing seasons. The flowering percentage and number of florets in the current season's inflorescence were recorded at anthesis. Small and large bulbs were subjected to continual defoliation starting at different times during the growing season. Bulbs were dissected at planting (26 Sept. 1992) and on 12 Jan. 1993 (nondefoliated control bulbs) to determine growth and developmental stage. At anthesis, inflorescences were harvested and the florets per inflorescence were counted. After anthesis in the fall, all bulbs were dissected and the following variables recorded: 1) percentage flowering, quiescence, or abortion of the current season's inflorescence; 2) developmental stage of quiescent inflorescences; 3) number of florets in the outermost inflorescence; 4) developmental stage of the innermost inflorescence; 5) number of leaves or leaf bases in each growth unit; 6) number of daughter bulbs; and 7) dry weight of new leaf bases. There were three reasons for nonflowering of the bulbs, viz., failure to initiate an inflorescence, inflorescences remaining quiescent, and inflorescence abortion. Individual florets that had not reached stage “Late G” (gynoecium elongated, carpels fused) at the start of rapid inflorescence elongation aborted. The more florets that aborted, the greater the probability that the entire inflorescence aborted. The inflorescence was more vulnerable to stress during the first half of the growing season due to its relatively weak position in the hierarchy of sinks within the bulb.


1958 ◽  
Vol 51 (3) ◽  
pp. 347-352 ◽  
Author(s):  
R. H. M. Langer

1. Swards of S. 48 timothy and S. 215 meadow fescue growing alone or together were sampled at intervals of 3 weeks throughout the season. The number and weight of leaves, stems and ears were determined, and leaf area was estimated.2. Despite high rainfall, the total number of tillers in both species declined from the beginning of the experiment until early July, but increased again from then onwards until the original complement had been approximately restored. The number of leaves failed to show a corresponding increase in the autumn because each tiller carried fewer leaves than earlier in the year.3. In the spring total dry weight increased more rapidly in meadow fescue than in timothy which in turn out-yielded meadow fescue later in the season. Both species attained their greatest dry weight soon after ear emergence, a period which was marked by considerable crop growth and relative growth rates.4. Leaf area index reached a maximum before total dry weight had increased to its highest level, but then declined in both species. Meadow fescue differed from timothy by producing a second crop of foliage after the summer with a leaf area index of about 7. This second rise appeared to be due mainly to increased leaf size in contrast to timothy whose leaves became progressively smaller towards the end of the season.5. The differences in growth between the species discussed with reference to their dates of ear emergence which in this experiment differed by about 6 weeks.


Toxins ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 38 ◽  
Author(s):  
Marcella Mesquita ◽  
Miquel Lürling ◽  
Fabiane Dorr ◽  
Ernani Pinto ◽  
Marcelo Marinho

Cylindrospermopsis raciborskii is a potentially toxic freshwater cyanobacterium that can tolerate a wide range of light and temperature. Due to climatic changes, the interaction between light and temperature is studied in aquatic systems, but no study has addressed the effect of both variables on the saxitoxins production. This study evaluated the combined effect of light and temperature on saxitoxins production and cellular quota in C. raciborskii. Experiments were performed with three C. raciborskii strains in batch cultures under six light intensities (10, 40, 60, 100, 150, and 500 μmol of photons m−2 s−1) and four temperatures (15, 20, 25, and 30 °C). The growth of C. raciborskii strains was limited at lower temperatures and the maximum growth rates were obtained under higher light combined with temperatures equal or above 20 °C, depending on the strain. In general, growth was highest at 30 °C at the lower light intensities and equally high at 25 °C and 30 °C under higher light. Highest saxitoxins concentration and cell-quota occurred at 25 °C under high light intensities, but were much lower at 30 °C. Hence, increased temperatures combined with sufficient light will lead to higher C. raciborskii biomass, but blooms could become less toxic in tropical regions.


Weed Science ◽  
1972 ◽  
Vol 20 (6) ◽  
pp. 588-592 ◽  
Author(s):  
Ellery L. Knake

Field studies were conducted with giant foxtail(Setaria faberiiHerrm.) under shade intensities of 0, 30, 60, 70, 80, and 98%. Seed weight, dry weight of plant tops exclusive of seed, and total dry weight per plant decreased linearly with increasing shade intensities. These decreases were due primarily to decreases in number of leaves, number of stems per plant, and number of heads per plant. Height of main culm was less affected than other morphological characteristics. Shading affected the length of internodes but had little influence on number of internodes on the main culm. The amount of shade required to control giant foxtail completely, once it is established, appears to be above 95%. Expressed as 2-year means, plants grew to as much as 135 cm, had as many as 188 leaves, 41 stems, and 31 heads, and produced 73 g of dry matter per plant including 6 g of seed. Maximum number of seeds per head was 1405.


Author(s):  
Shalini Shalini ◽  
V. K. Singh ◽  
Brij Bhooshan

A field experiment was conducted during rabi season of 2010-2011 and 2011-12 at Pantnagar in tarai soil of Uttarakhand to study the effect of different herbicides on plant growth, weed dynamics, nutrient uptake and yield of dwarf fieldpea. Results revealed that uncontrolled weeds caused 27.3 and 39.4 per cent reduction in grain yield of dwarf fieldpea during first and second year, respectively as compared to two hand weedings done at 20 and 40 days after sowing (DAS). Among the chemical treatments, minimum nutrient removal of 3.0 kg N,0.5 kg P and 3.3 kg K ha-1by weeds was recorded under pendimethalin 1.0kg ha-1 (PE)+ imazethapyr 0.05 kg ha-1 (POE,30 DAS) as against 11.4 kg N, 1.96 kg P and 12.6 kg K ha-1, respectively in weedy check Two hand weedings done at 20 and 40 DAS, which remained at par with pendimethalin1.0 kg ha-1 (PE) + imazethapyr 0.05 kg ha-1 (POE, 30 DAS) and pendimethalin 1.0kg ha-1(PE) + quizalofop ethyl 0.05kg ha-1(POE, 30 DAS) caused significant reduction in weed dry weight and increased the value of plant height, number of leaves per plant and dry matter accumulation per plant as compared to weedy check. These treatments produced 27.1, 23.1 and 16.0 per cent more number of pods/plant and yielded 50, 40 and 35.7 per cent higher grain yield, respectively over weedy check. The maximum weed control efficiency was computed under two hand weedings followed by pendimethalin 1.0 kg ha-1 (PE)+ imazethapyr 0.05kg ha-1 (POE, 30 DAS) and pendimethalin 1.0kg ha-1 (PE)+ quizalofop ethyl 0.05 kg ha-1 (POE, 30 DAS).


HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 493g-493
Author(s):  
M.E. Ragab ◽  
Kh. A. Okasha

This study was earned out on strawberry (Fragana × ananassa, Duch.) during the tow successive season of 1988/1989 and 1989/1990, at the strawberry Improvement Center Experimental Farm at Omm saber, south Tahreer, El Behira Governorate. The objective of this work was to study the effect of strawberry cultivar Douglas A split-plot design with four replicates was adopted. The results indicated a substantial increase in the content of the available macro and micro nutrients in the fumigated soils compared to the non fumigated ones. A significant increase in the number of leaves per plant, fresh and dry weight, early and total yield per plant was recorded. Fumigation accompanied by fertilization increased the available content (N,P and K and (Fe, Mn, Zn, and Cu) in the soil in the both growing seasons compared to fumigated only or the control. Plants grown in the fumigated fertilized plots contained the highest amount of macro and macro nutrients in both the growing seasons. Fumigated non fertilized plots had the highest amount of available P and K than all other treatment The maximum early and total yield per plant was obtained from the fumigated non fertilized plots.


1972 ◽  
Vol 50 (4) ◽  
pp. 883-889 ◽  
Author(s):  
F. D. H. Macdowall

Marquis wheat was grown in growth rooms with four different concentrations of carbon dioxide and four to seven different intensities of light in a 16-h photoperiod at 25 °C. Growth was expressed quantitatively as the pseudo-first-order rate coefficient. Carbon dioxide stimulated growth, but the effect was greater the lower the light intensity in opposition to the known effect on photosynthesis. Carbon dioxide and light, in effect, did not influence the "rate" of growth of wheat additively but, rather, mutually compensated over a wide range. The growth coefficient of the roots was a little less than that of the shoots at all carbon dioxide concentrations and light intensities, probably owing to the cost of translocation. However, root growth benefited most from carbon dioxide enrichment at low light intensities. At intermediate light intensity there appeared to be a carbon dioxide concentration optimal for shoot growth. Carbon dioxide enrichment did not influence the maximum growth coefficient of Marquis wheat with respect to light intensity. The light-using efficiency of growth, calculated for vanishingly low light intensity at which it is maximal, was maximal for shoots at 1300 ppm CO2 but that for laminal area and root dry weight increased with CO2 to 2200 ppm at which the value for "leaves" was nearly fourfold that for roots. Unlike photosynthesis, the stimulation of growth by raised CO2 concentration was accomplished by increased efficiency of, and not capacity for, the net photosynthetic use of light.


1984 ◽  
Vol 102 (2) ◽  
pp. 333-340 ◽  
Author(s):  
R. Haycock

SummaryA field trial of five contrasting types of white clover grown in monoculture was established in August 1978. Measurements commenced in October and continued for 12 months during which time no additional treatments were applied.Seasonal trends of dry-matter accumulation and distribution were recorded and particular reference was made to the components of harvestable yields, which showed a strong seasonal trend. During the summer the density of growing points decreased in all types except D while the number of leaves per growing point and mean dry weight per leaf increased. The principal component of yield, mean dry weight per leaf, increased later than number of leaves per growing point. Stolons did not show the same cyclical pattern and produced an overall increase during the experiment. The five genotypes also showed large variation in the distribution of dry matter between leaves, flowers, stolons and roots.


1991 ◽  
Vol 116 (6) ◽  
pp. 1046-1051 ◽  
Author(s):  
J.G. Norcini ◽  
P.C. Andersen ◽  
G.W. Knox

Leaf physiology and plant growth of Photinia x fraseri Dress were assessed when grown under full sunlight or (100% sun) or polypropylene shadecloth with a light transmittance of 69%, 47%, or 29% sun. Plants in 69% or 47% sun usually had the highest midday net CO2 assimilation rates (A). Net CO, assimilation rate was most dependent on photosynthetic photon flex (PPF R2 = 0.60), whereas stomata] conductance to water vapor was primarily influenced by vapor pressure deficit (R2 = 0.69). Stomatal conductance was often inversely related to sun level, and intercellular CO2 concentration was often elevated under 29% sun. Midday relative leaf water content and leaf water potential were unaffected by light regime. Light-saturated A was achieved at ≈ 1550 and 1150 μmol·m-2·s-1 for 100% and 29% sun-grown plants, respectively. Under 29% sun, plants had a lower light compensation point and a higher A at PPF < 1100 μmol·m-2·s-1. Total growth was best under 100% sun in terms of growth index (GI) increase, total leaf area, number of leaves, and dry weight (total, stem, leaf, and root), although plants from all treatments had the same GI increase by the end of the experiment. Plants in all treatments had acceptable growth habit (upright and well branched); however, plants grown in 29% sun were too sparsley foliated to be considered marketable. There were no differences in growth among the four treatments 7 months after the Photinia were transplanted to the field.


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