scholarly journals Light, temperature and sowing depth on germination of garden spurge

2021 ◽  
Vol 51 (10) ◽  
Author(s):  
Naira Moreli de Freitas ◽  
Vanessa Francieli Vital Silva ◽  
Celso Augusto Sato Teixeira ◽  
Luiz Augusto Inojosa Ferreira ◽  
Lucas Matheus Padovese ◽  
...  
Keyword(s):  
Weed Management ◽  
Plant Cover ◽  
Continuous Light ◽  
Weed Biology ◽  
Sowing Depth ◽  
Abstract Knowledge ◽  
Seed Placement ◽  
Plant Emergence ◽  
Oat Straw ◽  
Effect Of Light

ABSTRACT: Knowledge on weed biology and ecology is fundamental to provide suitable control practices in weed management systems. The objective of this research was to understand the effect of light and temperature on germination of Chamaesyce hirta, as well as to evaluate the effect of depth of seed placement in the soil in the emergence of the plant. Two experiments were conducted. In the first one, in the laboratory, the seeds were placed to germinate in plastic boxes and kept in a B.O.D. germination chamber, under constant temperatures of 20, 25, 30 and 35 ºC, either in the dark or under continuous light. Daily germination assessments were performed. The percentage of germinated seeds in the 10-day period and the germination speed index (GSI) were calculated. In the second trial, carried out in greenhouse conditions, 100 seeds were planted, under six levels of seeding depth (0, 1, 2, 3, 4 and 5 cm) and three soil cover conditions: no straw, under black oats (Avena strigosa) straw and under corn (Zea mays) straw. Daily plant emergence was counted along 30 days and total emergence and GSI were calculated. Germination of C. hirta seeds occurs both in the presence and absence of light. For the highest temperature, both increased germination and GSI were reported in the presence of light. The highest levels of emergence were obtained with the absence of plant cover and under corn straw at 0 cm depth. The presence of black oat straw on the soil reduced the emergence of C. hirta.

INTERACTIONS OF THE PINEAL AND EXPOSURE TO CONTINUOUS LIGHT ON ORGAN WEIGHTS OF FEMALE RATS

1961 ◽  
Vol 36 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Richard Jay Wurtman ◽  
Willard Roth ◽  
Mark D. Altschule ◽  
Judith J. Wurtman
Keyword(s):  
Light Exposure ◽  
Continuous Light ◽  
Female Rats ◽  
Constant Light ◽  
Ovarian Weight ◽  
Organ Weights ◽  
Bovine Pineal Extracts ◽  
Pineal Extracts ◽  
Effect Of Light

ABSTRACT Either exposure to constant light for 80 days or pinealectomy produced similar changes in the weights of the ovaries and adrenals of female rats. These were not additive when both procedures were employed. Pinealectomy did not share with light-exposure the capacity to induce uterine hypertrophy. Rats exposed to constant light for 56 days had lighter pineals than animals kept in darkness; this decrease was not affected by administration of bovine pineal extracts. The increase in ovarian weight produced in rats by exposure to light for 56 days was prevented by bovine pineal extracts, but these extracts were without effect on the uterine hypertrophy produced under the same conditions. These data suggest that the effect of light upon the weight of the ovary is mediated via the pineal.

scholarly journals Optimizing Sowing Depth of Tef for Irrigated Mediterranean Conditions: From Laboratory to Field Studies

Agronomy ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1983
Author(s):  
Shiran Ben-Zeev ◽  
Shane Kerzner ◽  
Onn Rabinovitz ◽  
Yehoshua Saranga
Keyword(s):  
Field Experiments ◽  
Field Studies ◽  
Field Trials ◽  
Eragrostis Tef ◽  
Sowing Depth ◽  
New Crops ◽  
Different Depths ◽  
Plant Emergence ◽  
Increasing Demand ◽  
Mediterranean Conditions

Developing new crops adapted to arid conditions is a promising approach to meet the increasing demand for food production under expanding aridity. Tef [Eragrostis tef (Zucc.) Trotter] is a C4 cereal crop cultivated mainly in Ethiopia and the Horn of Africa, and known for its high resilience to stressful environments. Due to their tiny size, tef seeds are traditionally sown by broadcasting and lightly covering with soil. Under semiarid Mediterranean conditions, a deeper sowing may guarantee seedling establishment while saving on irrigation water. The objective of this study was, therefore, to determine the effects of sowing depth on tef emergence, development, lodging, and productivity. Tef seeds were sown at different depths in test tubes and pots, and in two field experiments. In tubes and pots, time from sowing to emergence increased about twofold and emergence rate decreased in the deepest sowing (3 cm) treatment compared to controls (0 cm). In the pot and field trials, deep sowing (3 cm) significantly reduced plant height, shoot and root biomass, and lodging. Sowing depths of 1–2 cm allowed successful plant establishment while not exacting penalties on plant emergence or development; hence this range appears to be optimal for sowing irrigated tef.

scholarly journals Floristic and Phytosociology of Weeds in Upland Rice in the Humid Tropics

2018 ◽  
Vol 35 (0) ◽  
Author(s):  
M.R.M. SILVA ◽  
E.A. COSTA ◽  
M.J.P. CORRÊA ◽  
A.A.C. RODRIGUES ◽  
M.L.R. MESQUITA
Keyword(s):  
Weed Management ◽  
Upland Rice ◽  
Management Strategies ◽  
Floristic Composition ◽  
Humid Tropics ◽  
Reproductive Stage ◽  
Rice Crop ◽  
Weed Species ◽  
Floristic Similarity ◽  
Abstract Knowledge

ABSTRACT: Knowledge of the floristic composition and vegetation structure are essential conditions for development of more efficient and economic weed management strategies in crops in the humid tropics. The objective of the research was to carry on floristic and phytosociological surveys to know the main weeds in upland rice fields in the humid tropics of the Brazilian State of Maranhão. Weed samples were done by means of an open metal rectangle of 0.15 m2 thrown at random in the vegetative and reproductive stages of rice crop in 2009/10 and 2010/2011 harvest. A total of 65 species from 23 families was identified 35 (53.85%) from the eudicotyledons botanical group, 29 (44.06%) from the monocotyledonous and one (1.53%) belonged to the pteridophytes. The most representative families were from the monocotyledonous botanical group including Poaceae and Cyperaceae, followed by Amaranthaceae and Malvaceae, both from the eudicotyledons group. The weed species with higher importance values in the upland rice crop vegetative stage were Urochloasp., Panicumsp., C. flavus, C. benghalensis and C. argutus whereas in the reproductive stage the higher importance values were recorded for S. latifolia, C. argutus, L. octovalvis, A.tenella and P.maximum. The most important weeds in the crop vegetative phase were mainly from the monocotyledonous group, while in reproductive one they were the eudicotyledons. Weed diversity was high and the floristic similarity was lower in the vegetative one compared to the reproductive stage of upland rice cultivation in the humid tropics.

LIGHT-STIMULATED LEAF GROWTH ON INTACT AND EXCISED BEAN PLANTS (PHASEOLUS VULGARIS L.) III. EFFECT OF LIGHT INTENSITY

1999 ◽  
Vol 47 (4) ◽  
pp. 231-236
Author(s):  
Shimon Lavee ◽  
Elizabeth Van Volkenburgh ◽  
Robert Cleland E.
Keyword(s):  
Light Intensity ◽  
Leaf Growth ◽  
Energy Requirement ◽  
Red Light ◽  
Continuous Light ◽  
Leaf Expansion ◽  
Minimal Amount ◽  
Light Intensities ◽  
Bean Plants ◽  
Effect Of Light

The effect of light intensity on primary bean leaf unfolding and elongation was studied with intact and excised 10-day-old plants grown under red light. Continuous light of 40 μmol; m−2S−1 was enough to induce maximal leaf expansion both on intact and excised bean plants. Lower light intensities had a partial effect. The growth rate during the first 24 h in light was linearly related to light intensity up to 130 μmol; m−2S−1, although this light intensity was already supra-optimal for final leaf size. The minimal amount of light energy needed for full leaf expansion was about 15 mol photons m−2. The mode of light application, level of intensity, and irradiance duration were not critical when the total energy requirement was fulfilled. Under insufficient light applications for full leaf expansion, interrupted irradiance and longer low light intensity application induced leaf elongation more efficiently. Generally, the effect of different white light intensities on primary bean leaf expansion was the same on both intact and excised red-light-grown plants.

scholarly journals Environment and Sporulation in Phytopathogenic Fungi IV. The Effect of Light on the- Formation of Conidia of Peronospora Tabacina Adam

1963 ◽  
Vol 16 (1) ◽  
pp. 88 ◽  
Author(s):  
IAM Cruickshank
Keyword(s):  
Light Source ◽  
Monochromatic Light ◽  
Continuous Light ◽  
Visible Spectrum ◽  
Phytopathogenic Fungi ◽  
Time Of Day ◽  
Light Conditions ◽  
Low Light ◽  
Maximal Inhibition ◽  
Effect Of Light

Using a leaf�disk technique, an analysis of the effect of light on the sporulation intensity of P. tabacina was carried out. The following points were demonstrated: (I) Under conditions of continuous light, sporulation of P. tabacina is sensitive to very low light intensities. ED5!1 for inhibition of sporulation was 16 ftvV cm- 2 for incandescent light (4 f,c.), and 0�58 p.W cm-2 for a monochromatic light source (469 mpo) in the region of maximum effectiveness. (2) Dark treatments induced sporulation under otherwise continuous light conditions. The response was directly proportional to the length of the exposure to darkness over the period 1�5-7 hr. (3) The time of day at which sporulation occurred could be modified by adjustment of the time of day at which darkness was initiated. (4) Within the visible spectrum, the region exerting maximal inhibition on sporulation occurred at 450-525 mJL.

scholarly journals Back to the basics: Integrating weed biology into weed management plans

2017 ◽  
Author(s):  
Jared Goplen ◽  
Lisa Behnken ◽  
Ryan Miller ◽  
Liz Stahl
Keyword(s):  
Weed Management ◽  
Weed Biology ◽  
Management Plans

scholarly journals The Effect of Light Exposures on the Content of Harmful Substances in Edible Potato Tuber

Agriculture ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 139
Author(s):  
Katarzyna Rymuza ◽  
Marek Gugała ◽  
Krystyna Zarzecka ◽  
Anna Sikorska ◽  
Pavol Findura ◽  
...  
Keyword(s):  
Laboratory Tests ◽  
Light Exposure ◽  
Continuous Light ◽  
Potato Tubers ◽  
Potato Varieties ◽  
Harmful Substances ◽  
Total Glycoalkaloids ◽  
The Impact ◽  
Linear Manner ◽  
Effect Of Light

Background: The impact of light on the content of undesirable substances is particularly important in the case of potatoes available in store where the tubers are exposed to continuous light access. Both washed and unwashed potatoes are available, hence the hypothesis that the amount of harmful substances stored in tubers depends not only on the time of their exposure to light, but also on whether they were washed or not. Methods: In order to verify the hypothesis, laboratory tests were carried out on the tubers of five potato varieties originating from a univariate field experiment. The aim of the study was to analyse the change in the content of total glycoalkaloids (TGA) and nitrates (V) in tubers of five potato varieties depending on the time of light exposition (0, 7, 14 days) and pretreatment of tubers. Results: It has been demonstrated that the content of glycoalkaloids and nitrates in potato tubers depended significantly on the variety, time of exposure to light and pretreatment. Most glycoalkaloids were accumulated in the tubers of the Lord (89.67 mg·kg−1) and Irga (89.05 mg·kg−1) varieties. The time of light exposure significantly influenced the increase in glycoalkaloids and nitrates in the studied potato tubers. The increase in TGA after 14 days ranged from 20.67 mg∙kg−1 for variety Vinieta to 54.67 mg∙kg−1 for variety Irga. The increase in nitrates ranged from 11.67 mg∙kg−1 for variety Bellarosa to 27.50 mg∙kg−1 for variety Irga. Exposure time affected the content of glycoalkaloids in a parabolic manner and the content of nitrates in a linear manner.

The effect of light environment during tillage on the recruitment of various summer annuals

Weed Science ◽  
1998 ◽  
Vol 46 (2) ◽  
pp. 214-216 ◽  
Author(s):  
Robert S. Gallagher ◽  
John Cardina
Keyword(s):  
Weed Management ◽  
Light Environment ◽  
Light Conditions ◽  
Agricultural Systems ◽  
Giant Foxtail ◽  
Viable Approach ◽  
High Degree ◽  
Weed Emergence ◽  
Tillage Operations ◽  
Effect Of Light

Weed seeds can require an exposure to light for induction of germination. Conducting tillage operations at night and thus preventing the photoinduction of germination has been proposed as a means to reduce weed emergence in agricultural systems. This research was conducted to evaluate night tillage as a weed management option and to determine which tillage operations have the greatest effect on light-mediated recruitment. Weed emergence was evaluated after conducting factorial combinations of day and night moldboard plowing and disking in the springtime from 1992 through 1995. The light environment during disking generally had a slightly greater effect on emergence than the light environment during plowing. Emergence of pigweed species and giant foxtail was, at most, 30 to 55% higher following day vs. night disking. Emergence of other weeds was not affected by the light environment during tillage. We conclude that night tillage may not be a viable approach to weed management due to insufficient reductions in weed emergence associated with night tillage and the high degree of variability in the recruitment response to light conditions during tillage.

scholarly journals New design universal working bodies of tillage and seeding equipment

2019 ◽  
pp. 73-76
Author(s):  
Yu. F. Lachuga ◽  
B. Kh. Akhalaya ◽  
Yu. Kh. Shogenov
Keyword(s):  
Vertical Axis ◽  
Planting Depth ◽  
Sowing Depth ◽  
Row Crops ◽  
Inner Surface ◽  
Seed Placement ◽  
Working Bodies ◽  
Final Operation ◽  
Working Processes

New designs of tillage and seeding equipment are presented. Technological and technical deficiencies of the existing working bodies for surface tillage and sowing techniques of row crops are noted. To eliminate the shortcomings, new universal working bodies of tillage and sowing units have been proposed, which provide for the mechanization and automation of working processes of tillage and seeding of various row crops. Their technological and technical advantages over the existing traditional working bodies are given. The technical characteristics of the new working bodies are presented, which allow to simultaneously perform four operations: cultivation, fissure, seeding and leveling the field surface. Execution of the sieve in the form of two discs with rollers on its inner surface allows cutting a slit along the sides from the vertical axis of seed placement, at a depth of almost twice the sowing depth to improve the water-air regime, with simultaneous compaction of the soil by the rollers. The final operation to level the soil across the entire width of the cultivator's paw grip is carried out by embedding a train. Also presented is the design of a modernized pneumatic sowing unit for various sowing methods, ensuring the simultaneous sowing of seeds of several types of row crops with their placement at different planting depth in accordance with agrotechnical requirements

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