scholarly journals Uso da subirrigação para imposição de estresse hídrico em sistema semi-contínuo para medição de CO2

2015 ◽  
Vol 21 (2) ◽  
pp. 235 ◽  
Author(s):  
Rhuanito Soranz Ferrarezi ◽  
Marc W. Van Iersel ◽  
Roberto Testezlaf
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Plant Growth ◽  
Net Photosynthesis ◽  
Dry Mass ◽  
Co2 Exchange ◽  
Carbon Gain ◽  
Growth Responses ◽  
Shoot Height ◽  
Soil Moisture Sensors

The objectives of this work were to evaluate the effects of distinct moisture contents to trigger subirrigation on salvia photosynthesis and plant growth, and to verify the feasibility of subirrigation use in water stress imposition research in this crop. We evaluated two substrate volumetric water contents (VWC) as treatments (0.2 and 0.4 m3 m-3) to trigger subirrigation, with 4 replications. Each replication was composed of 10 plants. An automated semi-continuous multi-chamber crop CO2-exchange system was used, with capacitance soil moisture sensors for continuous moisture monitoring. Manual subirrigation with nutrient solution was performed when VWC dropped below the thresholds. In both treatments, the values of net photosynthesis, daily carbon gain and carbon use efficiency reduced over time, from 2 to 1.1 μmol s-1 from 2.2 to 1 μmol d-1 from 0.7 to 0.45 mol mol-1, respectively, in both soil moisture treatments. Total shoot dry mass (p=0.0129), shoot height in the tip of the highest flower (p<0.0001) and total leaf area (p=0.0007) were statistically higher at 0.4 m3 m-3 treatment. The subirrigation system was not efficient to impose water stress, due to excessive variation on VWC values after each irrigation event in both treatments. Higher soil moisture promoted positive plant growth responses in salvia cultivated by subirrigation.

Effect of Spray Components on Glyphosate Toxicity to Annual Grasses

Weed Science ◽  
1983 ◽  
Vol 31 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Douglas D. Buhler ◽  
Orvin C. Burnside
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Plant Growth ◽  
Surfactant Concentration ◽  
Growth Stage ◽  
Annual Grass ◽  
Spray Solution ◽  
Annual Grasses ◽  
Small Grains ◽  
Carrier Volume

Field and greenhouse research was conducted during 1980 and 1981 to evaluate the effects of carrier volume, surfactant concentration, and treatment date on glyphosate [N- (phosphonomethyl)glycine] toxicity to annual-grass weeds and volunteer small grains. Glyphosate phytotoxicity increased as carrier volume was decreased from 190 to 24 L/ha. The presence of a surfactant in the spray solution did not influence grass control when glyphosate was applied in a carrier volume of 24 L/ha. When glyphosate was applied in 48 or 95 L/ha, the presence of surfactant resulted in better grass control than glyphosate without surfactant. When applied in 190 L/ha, glyphosate with 0.5% (v/v) surfactant gave better grass control than glyphosate alone or commercially formulated glyphosate. When glyphosate was applied to plants under water stress, little control was achieved regardless of plant growth stage. Glyphosate application to grass after head initiation also resulted in reduced control. Maximum weed control with glyphosate was attained when applications were made to seedlings growing actively because of adequate soil moisture and favorable temperatures.

scholarly journals Growth of sweet pepper plants submitted to water tensions in soil and potassium silicate doses

2019 ◽  
Vol 37 (1) ◽  
pp. 82-88
Author(s):  
Alexandre Igor A Pereira ◽  
João de Jesus Guimarães ◽  
João Victor Costa ◽  
Fernando S de Cantuário ◽  
Leandro C Salomão ◽  
...  
Keyword(s):  
Water Stress ◽  
Plant Growth ◽  
Soil Water ◽  
Leaf Area ◽  
Capsicum Annuum ◽  
Sweet Pepper ◽  
Potassium Silicate ◽  
Growth Responses ◽  
Resistance Inducers ◽  
Pepper Plants

ABSTRACT Water stress compromises plant growth. Resistance inducers, such as potassium silicate (K2SiO3), can reduce negative effects of this stress on Solanaceae, Capsicum annuum. Plant height, stem diameter and leaf area may indicate the efficiency of potassium silicate foliarsprayagainst water stress. The aim of this study was to evaluate the growth of sweet pepper plants under water stress and K2SiO3 doses. The experiment was conducted in randomized blocks in a split-plot scheme in space. The treatments consisted of four soil water stresses: 15 kPa (field capacity), 25 (intermediate value), 35 and 45 kPa (water stress) and three doses of potassium silicate (0, 0.4 and 0.8 L 100 L-1 water), acting as resistance inducers to water stress. The resistance inducer maintained greater heights of the sweet pepper plants, under water stress (35 and 45 kPa) at the initial stage [(20 days after transplanting (DAT)]. Smaller plant diameters were observed at 80 and 100 DAT at 35 and 45 kPa. Sprays using K2SiO3 maintained sweet pepper leaf area with higher values, even under stress condition. The soil water tension from 35 kPa limited, in general, the plant growth. Growth responses in Capsicum annuum to K2SiO3, via foliar spraying, varied according to plant age, as well as the growth parameter considered in this experiment.

Change in photosynthesis and water relations with age and season in Abiesamabilis

1984 ◽  
Vol 14 (1) ◽  
pp. 77-84 ◽  
Author(s):  
R. O. Teskey ◽  
C. C. Grier ◽  
T. M. Hinckley
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Relations ◽  
Net Photosynthesis ◽  
Carbon Gain ◽  
Xylem Water Potential ◽  
Needle Age ◽  
Stressful Environment ◽  
Competitive Success ◽  
One Year

Seasonal changes in water relations and net photosynthesis were measured over a year in current and 1-year-old foliage of Abiesamabilis (Dougl.) Forbes, a subalpine conifer. Responses were compared with maximum rates achieved in older foliage. Current-year foliage developed slowly during the growing season. Although growth began on 22 June, highest rates of stomatal conductance and net photosynthesis did not occur until September and October. One-year-old foliage had the highest rates of net photosynthesis (12.9 mg CO2•dm−2•h−1) and stomatal conductance (3.1 mm•s−1) during the summer. Net photosynthesis decreased with needle age, but foliage as old as 7 years had rates of net photosynthesis as high as 5.0 mg CO2•dm−2•h−1. There was no evidence of photosynthetic adjustment to seasonal change in temperature. The optimum temperature for photosynthesis remained at 15 ± 1.5 °C throughout the year. No water stress was observed during the summer. Xylem water potential never decreased below −1.65 MPa and was always well above the turgor loss point. The lack of any apparent water stress, combined with photosynthetic characteristics, indicated that summer was the most important season for carbon gain. These results also suggested that a strategy for competitive success by Abiesamabilis in this cold, stressful environment is minimum dependence on the carbon gain of any individual age-class of foliage. Instead trees rely on the combined photosynthetic capacity of many years of foliage.

scholarly journals Cuttings of Lippia alba with emphasis on time for seedling formation, substrates and plant growth regulators

2015 ◽  
Vol 33 (2) ◽  
pp. 230-235 ◽  
Author(s):  
Cristina B Lima ◽  
Ana C Boaventura ◽  
Marli M Gomes
Keyword(s):  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Dry Mass ◽  
Mineral Fertilizers ◽  
Shoot Height ◽  
Lippia Alba ◽  
Statistical Designs ◽  
Time Required ◽  
The Relationship

We aimed to establish the period of time required for seedlings formation, as well as to evaluate the effect of substrates and plant growth regulators in cuttings of L. alba. Three experiments were performed, with statistical designs chosen according to each test objectives. Rooting (%), shoot height (cm), longest root length (cm), leaves number, fresh and dry matter masses (g), were analyzed. The absolute rate of shoot and root system growth, together with the relationship between dry mass of roots and shoots were efficient in predicting the period of greatest speed and accumulation of organic matter in plants. The plant growth regulators favored the vegetative performance of seedlings, with better development 30 days after the cuttings containing mineral fertilizers, vermicompost, clay soil and sand commercially known as 'medium sand'.

Field evaluation of asparagus crowns and germinating seeds inoculated with plant growth-promoting rhizobacteria

2009 ◽  
Vol 89 (6) ◽  
pp. 1133-1138
Author(s):  
S M Liddycoat ◽  
D J Wolyn
Keyword(s):  
Water Stress ◽  
Plant Growth ◽  
Field Evaluation ◽  
Dry Weight ◽  
Plant Growth Promoting Rhizobacteria ◽  
Asparagus Officinalis ◽  
Shoot Height ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Germinating Seeds

Plant growth-promoting rhizobacteria (PGPR) have the ability to enhance growth and establishment by reducing stress ethylene, or providing exogenous indol-3-acetic acid (IAA), nitrogen, iron, or phosphorus. In previous greenhouse studies, PGPR inoculation of asparagus seeds or seedlings enhanced growth under optimal and water stress conditions. Experiments were conducted in this study to determine if PGPR could provide benefits to transplanted crowns and germinating seeds in the field. Plant growth-promoting rhizobacteria did not positively affect shoot height, count, or diameter of inoculated crowns, or percent germination and seedling dry weight of inoculated seeds. The limitations of using PGPR in the field and potential for future success are discussed.Key words: Asparagus officinalis, Pseudomonas , water stress, drought, irrigation

scholarly journals Physiological Responses of Cowpea (Vigna unguiculata) Under Irrigation With Saline Water and Biostimulant Treatment

2018 ◽  
Vol 10 (12) ◽  
pp. 24
Author(s):  
Leonardo Vieira de Sousa ◽  
Rayanne Maria Paula Ribeiro ◽  
Manoel Galdino dos Santos ◽  
Fernando Sarmento de Oliveira ◽  
Hugo Ferreira ◽  
...  
Keyword(s):  
Vigna Unguiculata ◽  
Saline Water ◽  
Net Photosynthesis ◽  
Co2 Concentration ◽  
Dry Mass ◽  
Saline Stress ◽  
Stress Effect ◽  
Negative Effects ◽  
Shoot Height ◽  
Cowpea Cultivars

Cowpea (Vigna unguiculata) is one of the world’s main crops, and it is a fundamental source of protein for semiarid regions population. In these regions, the use of high salts concentration water in irrigation systems is one of the major factors that contributes to reduced cowpea yield. One way to alleviate the negative effects of salinity is through the biostimulants application, which is a product that has beneficial substances to the plants metabolism. The aim of this study was to evaluate the application of biostimulant in cowpea cultivars under irrigation with saline water. The study was carried out in the Agrarian Sciences Center, of the Department of Agronomic and Forest Sciences of the Federal Rural University of the Semi-Arid, in the city of Mossoró, RN. The experimental design was completely randomized, with four replications. The treatments were arranged in 5 × 2 × 2 factorial scheme, with five doses of biostimulant (0, 15, 30, 45 and 60 mL L-1), two electrical conductivities of the irrigation water (0.5 and 5.0 dS m-1), and two cowpea cultivars (IPA-206 and BRS Guariba). The evaluated characteristics were: chlorophyll content index, stomatal conductance, net photosynthesis, internal CO2 concentration, transpiration rate, shoot height, stem diameter and shoot dry mass. The biostimulant application was not efficient in attenuating the salinity stress effect on the development of cowpea cultivars. The higher biostimulant concentrations along with the use of saline water increased the negative effects of salinity on the cowpea plants physiology. There was no difference between the cultivars regarding the tolerance to saline stress and the application of biostimulant.

Evaluating Effect of Degree of Water Stress on Growth and Fecundity of Palmer amaranth (Amaranthus palmeri) Using Soil Moisture Sensors

Weed Science ◽  
2018 ◽  
Vol 66 (6) ◽  
pp. 738-745 ◽  
Author(s):  
Parminder S. Chahal ◽  
Suat Irmak ◽  
Mithila Jugulam ◽  
Amit J. Jhala
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Seed Germination ◽  
Crop Production ◽  
Growth Index ◽  
The United States ◽  
Palmer Amaranth ◽  
Maximum Height ◽  
Amaranthus Palmeri ◽  
Soil Moisture Sensors

AbstractPalmer amaranth (Amaranthus palmeriS. Watson) is the most problematic weed in agronomic crop production fields in the United States. The objective of this study was to determine the effect of degree of water stress on the growth and fecundity ofA. palmeriusing soil moisture sensors under greenhouse conditions. TwoA. palmeribiotypes collected from Nebraska were grown in loam soil maintained at 100%, 75%, 50%, 25%, and 12.5% soil field capacity (FC) corresponding to no, light, moderate, high, and severe water stress levels, respectively. Water was regularly added to pots based on soil moisture levels detected by Watermark or Decagon 5TM sensors to maintain the desired water stress level.Amaranthus palmeriplants maintained at ≤25% FC did not survive more than 35 d after transplanting.Amaranthus palmeriat 100%, 75%, and 50% FC produced similar numbers of leaves (588 to 670 plant−1) based on model estimates; however, plants at 100% FC achieved a maximum height of 178 cm compared with 124 and 88 cm at 75% and 50% FC, respectively. The growth index (1.1×105to 1.4×105cm3plant−1) and total leaf area (571 to 693 cm2plant−1) were also similar at 100%, 75%, and 50% FC.Amaranthus palmeriproduced similar root biomass (2.3 to 3 g plant−1) at 100%, 75%, and 50% FC compared with 0.6 to 0.7 g plant−1at 25% and 12.5% FC, respectively. Seed production was greatest (42,000 seeds plant−1) at 100% FC compared with 75% and 50% FC (14,000 to 19,000 seeds plant−1); however, the cumulative seed germination was similar (38% to 46%) when mother plants were exposed to ≥50% FC. The results of this study show thatA. palmerican survive ≥50% FC continuous water stress conditions and can produce a significant number of seeds with no effect of on seed germination.

scholarly journals Auxin Applications Affect Posttransplant CO2 Exchange Rate and Growth of Bare-rooted Vinca [Catharanthus roseus (L.) G. Don] Seedlings

1999 ◽  
Vol 124 (3) ◽  
pp. 234-238 ◽  
Author(s):  
Marc van Iersel
Keyword(s):  
Exchange Rate ◽  
Catharanthus Roseus ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Mass ◽  
Co2 Exchange ◽  
Naphthaleneacetic Acid ◽  
Negative Effects ◽  
Transplant Shock ◽  
Whole Plant

Uprooting and transplanting seedlings can cause root damage, which may reduce water and nutrient uptake. Initiation of new roots and rapid elongation of existing roots may help minimize the negative effects of transplant shock. In this study, seedlings with four true leaves were transplanted into diatomaceous earth and the plants were transferred to a growth chamber, where they were treated with NAA (0, 0.025, 0.25, and 2.5 mg·L-1; 36 mL/plant). The effects of drenches with various amounts of 1-naphthaleneacetic acid (NAA) on the posttransplant CO2 exchange rate of vinca [Catharanthus roseus (L.) G. Don] were quantified. Whole-plant CO2 exchange rate of the plants was measured once every 20 minutes for a 28 day period. Seedlings treated with 0.025 or 0.25 mg·L-1 recovered from transplant shock more quickly than plants in the 0 and 2.5 mg·L-1 treatments. Naphthaleneacetic acid drenches containing 0.025 or 0.25 mg·L-1 increased whole-plant net photosynthesis (Pnet) from 10 days, dark respiration (Rdark) from 12 days, and carbon use efficiency (CUE) from 11 days after transplanting until the end of the experiment. The increase in CUE seems to have been the result of the larger size of the plants in these two treatments, and thus an indirect effect of the NAA applications. These differences in CO2 metabolism among the treatments resulted in a 46% dry mass increase in the 0.025 mg·L-1 treatment compared to the control, but shoot-root ratio was not affected. The highest rate of NAA (2.5 mg·L-1) was slightly phytotoxic and reduced the growth rate of the plants.

scholarly journals Subirrigation automated by capacitance sensors for salvia production

2014 ◽  
Vol 32 (3) ◽  
pp. 314-320 ◽  
Author(s):  
Rhuanito S Ferrarezi ◽  
Marc W van Iersel ◽  
Roberto Testezlaf
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Irrigation Schedule ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Experimental Unit ◽  
Data Logger ◽  
Shoot Height ◽  
Randomized Design ◽  
Substrate Moisture

Subirrigation is typically controlled using timers to periodically irrigate plants based on a pre-determined schedule. The objective of this study was to evaluate the usefulness of capacitance-type sensors to monitor substrate water content and to control subirrigation automatically for salvia production in greenhouse. Additionally, we quantified the effect of different substrate volumetric water content (VWC) on growth of plants cultivated in 15-cm diameter × 13.75-cm height pots. Automation was performed using three EC-5 capacitance soil moisture sensors per experimental unit, connected to a system with a CR10X data logger, AM16/32 multiplexer, SDM-CD16AC relay driver and NK-2 submersible pumps. Substrate moisture readings were taken every 15 minutes, and plants were irrigated only if the readings dropped below pre-set VWC thresholds. We evaluated five levels of substrate VWC (0.1, 0.2, 0.3, 0.4 and 0.5 m3 m-3), with two replications, in a completely randomized design. The system effectively monitored and recorded VWC, and controlled irrigation accordingly. Substrate VWC ranged from 0.1 to 0.41, 0.2 to 0.39, 0.3 to 0.41, 0.4 to 0.43 and 0.5 to 0.53 m3 m-3, in ascending order of the treatments, with the highest values recorded after irrigation events. The number of irrigation events, total volume of nutrient solution applied, net photosynthesis, dry weight, number of branches and leaves, shoot height, leaf area, canopy light interception, and leaf chlorophyll content all increased significantly with the increase in VWC (p<0.0001). The VWC of 0.5 m3m-3 provided the highest plant growth (p<0.0001). Capacitance sensors can be used to both monitor soil moisture and control subirrigation for salvia production in soilless substrate, reducing the possibility of water stress caused by daily irrigation schedule using timers.

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