scholarly journals Growth and Yield of Okra (Abelmoschus esculentus Moench) as Influenced by Compost Application under Different Light Intensities

2015 ◽  
Vol 7 (2) ◽  
pp. 217-226 ◽  
Author(s):  
Victor A. DADA ◽  
Sifau A. ADEJUMO
Keyword(s):  
Light Intensity ◽  
Leaf Area ◽  
Abelmoschus Esculentus ◽  
Growth And Yield ◽  
Dry Matter Accumulation ◽  
Low Light ◽  
Light Reduction ◽  
Low Light Intensity ◽  
Light Intensities ◽  
Leaf Formation

Okra (Abelmoschus esculentus) is one of the popular vegetables, especially rich in iron, vitamins and other minerals. Poor soil fertility and inconsistent light intensity, due to unfavorable weather condition, reduce okra performance. Response of two okra varieties (‘NH47-4’ and ‘Clemson spine’) to different rates of compost (0, 5, 10 and 15 t/ha), under different light intensities (L0: control (no reduction) or 100% light intensity, L1: 33%, L2: 46% and L3: 76%, light reduction) were assessed in pot and field trials. The experimental design was a factorial experiment fitted in a randomized complete block design (RCBD). Data on growth and yield attributes were collected. The results showed that the reduction in light intensity (L3) increased the numbers of fruits and leaf area by 50 and 47% respectively on the field, but delayed flowering. High light intensity (L0) though enhanced leaf area formation and early flowering, but hastened leaf senescence and abscission. Compost generally increased growth rate, leaf area and dry matter accumulation of the two okra cultivars compared to control under varying light intensities. Compost at 15 t/ha performed better and increased fruit number by 66% on the field. Between the two cultivars, ‘Clemson spine’ responded better than ‘NH47-4’ plants in terms of yield. Low light intensity (76% light reduction) in combination with higher compost rate however enhanced prolonged fruiting and leaf formation in the two okra varieties. The application of compost at 15 t/ha is therefore recommended for optimum yield of okra under low light intensity.

scholarly journals Light intensity regulates phototaxis, foraging and righting behaviors of the sea urchin Strongylocentrotus intermedius

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8001 ◽  
Author(s):  
Jiangnan Sun ◽  
Xiaomei Chi ◽  
Mingfang Yang ◽  
Jingyun Ding ◽  
Dongtao Shi ◽  
...  
Keyword(s):  
Light Intensity ◽  
Foraging Behavior ◽  
Sea Urchins ◽  
High Light Intensity ◽  
High Light ◽  
Strongylocentrotus Intermedius ◽  
Low Light ◽  
Low Light Intensity ◽  
Light Intensities ◽  
Significant Difference

Small sea urchins Strongylocentrotus intermedius (1–2 cm of test diameter) are exposed to different environments of light intensities after being reseeded to the sea bottom. With little information available about the behavioral responses of S. intermedius to different light intensities in the environment, we carried out an investigation on how S. intermedius is affected by three light intensity environments in terms of phototaxis, foraging and righting behaviors. They were no light (zero lx), low light intensity (24–209 lx) and high light intensity (252–2,280 lx). Light intensity had obvious different effects on phototaxis. In low light intensity, sea urchins moved more and spent significantly more time at the higher intensity (69–209 lx) (P = 0.046). S. intermedius in high light intensity, in contrast, spent significantly more time at lower intensity (252–690 lx) (P = 0.005). Unexpectedly, no significant difference of movement (average velocity and total distance covered) was found among the three light intensities (P > 0.05). Foraging behavior of S. intermedius was significantly different among the light intensities. In the no light environment, only three of ten S. intermedius found food within 7 min. In low light intensity, nine of 10 sea urchins showed successful foraging behavior to the food placed at 209 lx, which was significantly higher than the ratio of the number (two of 10) when food was placed at 24 lx (P = 0.005). In the high light intensity, in contrast, significantly less sea urchins (three of 10) found food placed at the higher light intensity (2,280 lx) compared with the lower light intensity (252 lx) (10/10, P = 0.003). Furthermore, S. intermedius showed significantly longer righting response time in the high light intensity compared with both no light (P = 0.001) and low light intensity (P = 0.031). No significant difference was found in righting behavior between no light and low light intensity (P = 0.892). The present study indicates that light intensity significantly affects phototaxis, foraging and righting behaviors of S. intermedius and that ~200 lx might be the appropriate light intensity for reseeding small S. intermedius.

Investigations into the increased rust (Puccinia helianthi) intensity on some hybrid sunflower cultivars grown in Queensland

1984 ◽  
Vol 35 (1) ◽  
pp. 99
Author(s):  
KC Goulter ◽  
JK Kochman ◽  
JF Brown
Keyword(s):  
Light Intensity ◽  
Leaf Area ◽  
Liquid Nitrogen ◽  
Low Light ◽  
Puccinia Helianthi ◽  
Low Light Intensity ◽  
Generation Times ◽  
Race 1 ◽  
Hybrid Sunflower

Sunflower rust intensity in crops of several hybrid cultivars in Queensland during the 1980, 1981 and 1982 seasons ranged from 30 to 60% of leaf area. In previous years, these cultivars had rust ratings of 2-5%. Rust was also found on some crops of usually immune hybrids grown during winter in central Queensland. A number of rust differential lines were inoculated with several isolates collected from throughout Queensland during 1981 and 1982, as well as with isolates stored in liquid nitrogen from the years 1976, 1978 and 1980. Because all isolates failed to infect the differentials possessing either the R1 or R2 genes for resistance, all collections were allocated to race 1. Comparisons of the temporal isolates revealed that no differences could be detected among the generation times, pustule number and pustule size produced by isolates on a range of sunflower rust differentials and hybrid cultivars. These data indicated that the composition of the pathogenic population had not altered. The application of higher inoculum densities shortened generation times and produced more pustules; both relationships were linear. The development of race 1 rust on seedlings of the immune hybrid Hysun 30 was induced by maintaining the plants under low light intensity or short photoperiods.

Differential Regulation of Flavone Glycosylation during Ontogeny of Silene pratensis

1983 ◽  
Vol 38 (7-8) ◽  
pp. 544-548 ◽  
Author(s):  
J. M. Steyns ◽  
G. van Nigtevecht ◽  
G. J. Niemann ◽  
J. v. Brederode
Keyword(s):  
Light Intensity ◽  
Differential Regulation ◽  
Low Light ◽  
Leaf Pair ◽  
Low Light Intensity ◽  
Light Intensities ◽  
Flower Stem ◽  
Pair Number ◽  
Silene Pratensis ◽  
Effect Of Light

Two isovitexin glycosides have been found in the cotyledons and foliage leaves of Sitene pratensis plants that are unable to glycosylate isovitexin in their petals (genotype gg glgl fgfg). The glycosides (isovitexin 7-O-galactoside and isovitexin 7-O-galactose 2″-O-arabinoside) were present only in the lower leaves: leaves produced later in the development of the flower stem accumulated only the aglycon isovitexin. The transition in the flavone composition during the ontogeny of the plants could be influenced by light intensity. In plants grown at low light intensity, glycoside production continued until a higher leaf pair number than in plants grown at higher light intensities. However, the effect of light intensity is indirect: the transition in the flavone composition is correlated with the transition from rosette leaves to stem leaves. The presence of the 7-O-galactosides in cotyledons and rosette leaves suggests that in addition to the g, gl and fg loci, there are further glycosylating loci which are not expressed in stem leaves and petals.

Selection for light preference during ovipositing in Drosophila pseudoobscura

1983 ◽  
Vol 25 (5) ◽  
pp. 446-449 ◽  
Author(s):  
Marvin B. Seiger ◽  
Amelia Broach Sanner
Keyword(s):  
Light Intensity ◽  
Genetic Variability ◽  
High Light Intensity ◽  
High Light ◽  
Drosophila Pseudoobscura ◽  
Low Light ◽  
Original Population ◽  
Low Light Intensity ◽  
Light Intensities ◽  
Light Preference

Selection was carried out on a population of Drosophila pseudoobscura to obtain lines preferring high-light intensity or low-light intensity during oviposition. This species is generally characterized as preferring low-light intensities. It was possible to select for increased preference for high-light intensity, but not for low-light intensity during oviposition. However, additive genetic variability exists in preferences for both high- and low-light intensities. The original population was probably operating at a photonegative extreme for oviposition, yet maintained enough genetic variability to permit selection toward a photopositive preference.

Corrigendum - Investigations into the increased rust (Puccinia helianthi) intensity on some hybrid sunflower cultivars grown in Queensland

1984 ◽  
Vol 35 (1) ◽  
pp. 99
Author(s):  
KC Goulter ◽  
JK Kochman ◽  
JF Brown
Keyword(s):  
Light Intensity ◽  
Leaf Area ◽  
Liquid Nitrogen ◽  
Low Light ◽  
Puccinia Helianthi ◽  
Low Light Intensity ◽  
Generation Times ◽  
Race 1 ◽  
Hybrid Sunflower

Sunflower rust intensity in crops of several hybrid cultivars in Queensland during the 1980, 1981 and 1982 seasons ranged from 30 to 60% of leaf area. In previous years, these cultivars had rust ratings of 2-5%. Rust was also found on some crops of usually immune hybrids grown during winter in central Queensland. A number of rust differential lines were inoculated with several isolates collected from throughout Queensland during 1981 and 1982, as well as with isolates stored in liquid nitrogen from the years 1976, 1978 and 1980. Because all isolates failed to infect the differentials possessing either the R1 or R2 genes for resistance, all collections were allocated to race 1. Comparisons of the temporal isolates revealed that no differences could be detected among the generation times, pustule number and pustule size produced by isolates on a range of sunflower rust differentials and hybrid cultivars. These data indicated that the composition of the pathogenic population had not altered. The application of higher inoculum densities shortened generation times and produced more pustules; both relationships were linear. The development of race 1 rust on seedlings of the immune hybrid Hysun 30 was induced by maintaining the plants under low light intensity or short photoperiods.

Adaptation of Melampsora medusae to increasing temperature and light intensities on a clone of Populus deltoides

1986 ◽  
Vol 64 (4) ◽  
pp. 834-841 ◽  
Author(s):  
C. S. Prakash ◽  
W. A. Heather
Keyword(s):  
Low Temperature ◽  
Light Intensity ◽  
Populus Deltoides ◽  
High Light Intensity ◽  
Disruptive Selection ◽  
Low Light ◽  
Environmental Selection ◽  
Melampsora Medusae ◽  
Low Light Intensity ◽  
Light Intensities

Race 4A of Melampsora medusae Thum. produces an incompatible reaction on Populus deltoides Marsh. cv. W-79/307 when incubated at high temperature and low light intensity (26 °C and 100 μE∙m−2∙s−1) or low temperature and high light intensity (17 °C and 700 μE∙m−1∙s−1), but a compatible one at low temperature and low light intensity 17 °C and 100 μE∙m−2∙s−1). When in separate studies, a population of this race was sequentially cultured on detached leaves, at increasing temperatures (17, 20, 23, or 26 °C) or light intensities (100, 300, 500, or 700 μE∙m−2∙s−1), isolates that were adpated to each of these regimes were selected. Such isolates, particularly those from low temperature and low light intensity, exhibited some specificity to their "own" environments, although isolates selected at 26 °C and 500 μE∙m−2∙s−1 were most aggressive at all temperatures and light intensity regimes, respectively. Such adaptation appeared to result from pathogen response to host-mediated environmental selection pressure. Isolate, incubating environment, and their interaction were significant contributors to the variation in aggressiveness traits (disease timing and intensity). This rust demonstrates considerable ability to adapt to varying environmental conditions. Thus physical environmental variables may be important selective forces in the regulation of this pathosystem, as spatial and temporal heterogeneity of the environment in nature may result in polymorphism of the pathogen by disruptive selection.

scholarly journals Response of Photosynthesis and Chlorophyll Fluorescence Parameters of Castanopsis kawakamii Seedlings to Forest Gaps

Forests ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 21
Author(s):  
Zhong-sheng He ◽  
Rong Tang ◽  
Meng-jia Li ◽  
Meng-ran Jin ◽  
Cong Xin ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Light Intensity ◽  
Seedling Growth ◽  
Group Treatment ◽  
Control Group ◽  
Low Light ◽  
Chlorophyll Fluorescence Parameters ◽  
Forest Gaps ◽  
Low Light Intensity ◽  
Weak Light

Light is a major environmental factor limiting the growth and survival of plants. The heterogeneity of the light environment after gap formation in forest influences the leaf chlorophyll contents, net photosynthetic rate (Pn), and chlorophyll fluorescence, thus influencing the growth and regeneration of Castanopsis kawakamii seedlings. The aim of this study was to explore the effects of weak light on the photosynthetic physiology of C. kawakamii seedlings in forest gaps and non-gaps. The results showed that (1) the contents of chlorophyll a (Chl-a), chlorophyll b (Chl-b), and total chlorophyll (Chl-T) in forest gaps were lower than in non-gaps. Seedlings tended to increase chlorophyll content to absorb light energy to adapt to low light intensity in non-gap environments. (2) The Pn values of C. kawakamii seedlings in forest gaps were significantly higher than in non-gaps, and forest gaps could improve the seedlings’ photosynthetic capacity. (3) The C. kawakamii seedlings in forest gaps were more sensitive to weak light and control group treatment, especially the tall seedlings, indicating that seedlings require more light to satisfy their growth needs in the winter. The seedlings in non-gaps demonstrated better adaptability to low light intensity. The light intensity was not adequate in weak light conditions and limited seedling growth. We suggest that partial forest selection cutting could improve light intensity in non-gaps, thus promoting seedling growth and regeneration of C. kawakamii more effectively in this forest.

A laboratory study of vertical migration

1955 ◽  
Vol 144 (916) ◽  
pp. 329-354 ◽  
Keyword(s):  
Light Intensity ◽  
Vertical Migration ◽  
Time Course ◽  
Tap Water ◽  
Low Light ◽  
Overhead Light ◽  
Light Intensities ◽  
Orientation Response ◽  
Reduced Light ◽  
Characteristic Maximum

In a tank filled with a suspension of indian ink in tap water, a population of Daphnia magna will undergo a complete cycle of vertical migration when an overhead light source is cycli­cally varied in intensity. A ‘dawn rise’ to the surface at low intensity is followed by the descent of the animals to a characteristic maximum depth. The animals rise to the surface again as the light decreases, and finally show a typical midnight sinking. The light intensities at the level of the animals in this experiment are of the same order as those which have been reported in field observations; the time course of the movement also repeats the natural conditions in the field. The process is independent of the duration of the cycle and is related only to the variation in overhead light intensity. At low light intensity the movement of the animal is determined solely by positive photo-kinesis; the dawn rise is a manifestation of this, and is independent of the direction of the light. At high light intensities there is an orientation response which is superimposed upon an alternating positive (photokinetic) phase and a negative phase during which movement is inhibited. The fully oriented animal shows a special type of positive and negative phototaxis, moving towards the light at reduced light intensities and away from it when the light intensity is increased. In this condition it follows a zone of optimum light intensity with some exactness. Experiments show that an animal in this fully oriented condition will respond to the slow changes of intensity characteristic of the diurnal cycle, while being little affected by tran­sient changes of considerable magnitude.

Sign in / Sign up

Export Citation Format

Share Document