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Humidity and Plants
Abstract
Humidity levels control directly the rate of transpirational water loss and stomatal aperture of plants. Thus, humidity regulates photosynthetic rates, tissue temperatures, plant water potentials, and concentrations of Ca in certain tissues. Humidity also controls water taken in by tissues through condensation and direct vapor uptake.
... Similarly, relative humidity has a direct impact on plant growth and development. It signi cantly in uences plant photosynthesis, tissue temperature, plant water potential, and calcium concentration in various tissues (Tibbitts 1979 these parameters were within the optimal range for djulis growth (Fig. 1-3) and contributed to the successful growth and yield of both the red and yellow lines, especially with the application of PNSB as a biofertilizer. ...
Background:
Djulis is a nutrient-rich plant with potential health benefits, but its intensive fertilization hinders its yield, raising environmental concerns. Biofertilizers like purple non-sulfur bacteria (PNSB) offer an eco-friendly alternative to enhance growth and yield, yet limited research has investigated their efficacy on different djulis lines. Therefore, the current study aimed to investigate PNSB's effectiveness on two djulis lines in two fields, one control and the other inoculated with PNSB.
Methods:
Data on the growth and yield of djulis lines were collected and the results were statistically analyzed using independent sample t-tests and Duncan's multiple-range test.
Results:
The results showed that PNSB inoculation in the red line led to a significant increase in plant height (24%), leaf chlorophyll content (15%), spike length (35%), spike fresh weight (94%), shoot dry weight (207%), grain yield (86%), root length (119%), root volume (100%), and root dry weight (23%). As in the yellow line, PNSB inoculation significantly increased plant height (14%), spike length (26%), spike fresh weight (43%), shoot dry weight (53%), root length (36%), root volume (72%), and root dry weight (24%). Inoculation of PNSB had opposite effects on the maturity period of red and yellow djulis lines. It significantly improved the yield of the low-performing red line but had only minor effects on the high-performing yellow line, indicating the importance of selecting suitable lines.
Conclusion:
This study highlights PNSB's potential as a sustainable and cost-effective biofertilizer for djulis production and encourages further research to explore its applications in other crops and environments.
Climate models predict that everwet western Amazonian forests will face warmer and wetter atmospheric conditions, and increased cloud cover. It remains unclear how these changes will impact plant reproductive performance, such as flowering, which plays a central role in sustaining food webs and forest regeneration. Warmer and wetter nights may cause reduced flower production, via increased dark respiration rates or alteration in the reliability of flowering cue‐based processes. Additionally, more persistent cloud cover should reduce the amounts of solar irradiance, which could limit flower production.
We tested whether interannual variation in flower production has changed in response to fluctuations in irradiance, rainfall, temperature, and relative humidity over 18 yrs in an everwet forest in Ecuador.
Analyses of 184 plant species showed that flower production declined as nighttime temperature and relative humidity increased, suggesting that warmer nights and greater atmospheric water saturation negatively impacted reproduction. Species varied in their flowering responses to climatic variables but this variation was not explained by life form or phylogeny.
Our results shed light on how plant communities will respond to climatic changes in this everwet region, in which the impacts of these changes have been poorly studied compared with more seasonal Neotropical areas.
Background: Djulis (Chenopodium formosanum Koidz.) is a nutrient-rich plant with potential health benefits, but its intensive fertilization hinders its yield, raising environmental concerns. Biofertilizers like purple non-sulfur bacteria (PNSB) offer an eco-friendly alternative to enhance growth and yield, yet limited research has investigated their efficacy on different crop lines or varieties. Therefore, the current study aimed to investigate PNSB's effectiveness on two djulis lines in two fields, one control and the other inoculated with PNSB.
Methods: Data on the growth and yield of djulis lines were collected, and the results were statistically analyzed using independent sample t-tests and Duncan's multiple-range test.
Results: The results showed that PNSB inoculation in the red line led to a significant increase in plant height (24%), leaf chlorophyll content (15%), spike length (35%), spike fresh weight (94%), shoot dry weight (207%), grain yield (86%), root length (119%), root volume (100%), and root dry weight (23%). As in the yellow line, PNSB inoculation significantly increased plant height (14%), spike length (26%), spike fresh weight (43%), shoot dry weight (53%), root length (36%), root volume (72%), and root dry weight (24%). Inoculation of PNSB had opposite effects on the maturity period of red and yellow djulis lines. It significantly improved the yield of the low-performing red line but had only minor effects on the high-performing yellow line, indicating the importance of selecting suitable lines.
Conclusion: This study highlights PNSB's potential as a sustainable and cost-effective biofertilizer for djulis production, bolstering both food security and agricultural productivity.
Botanical gardens or public gardens are popular destinations for people seeking to enjoy the beauty and diversity of plant life and have an important role for biodiversity conservation. Biodiversity is defined as taxonomic, phylogenetic, or functional variability among living organisms and variability within and between ecosystems. A product of ecosystem functioning, the biodiversity is an element of human well-being and an environmental commodity, like clean air or water [1]. However, the visitors of botanical garden or public garden often view plants as static objects, rather than living organisms with their own needs and wellbeing. This perception can be changed by using monitoring technology to provide visitors with real-time data about the health and wellbeing of the plants in the garden.
Rising temperatures are influencing forests on many scales, with potentially strong variation vertically across forest strata. Using published research and new analyses, we evaluate how microclimate and leaf temperatures, traits, and gas exchange vary vertically in forests, shaping tree and ecosystem ecology. In closed-canopy forests, upper-canopy leaves are exposed to the highest solar radiation and evaporative demand, which can elevate leaf temperature (Tleaf ), particularly when transpirational cooling is curtailed by limited stomatal conductance. However, foliar traits also vary across height or light gradients, partially mitigating and protecting against the elevation of upper-canopy Tleaf . Leaf metabolism generally increases with height across the vertical gradient, yet differences in thermal sensitivity across the gradient appear modest. Scaling from leaves to trees, canopy trees have higher absolute metabolic capacity and growth, yet are more vulnerable to drought and damaging Tleaf than their smaller counterparts, particularly under climate change. In contrast, understory trees experience fewer extreme high Tleaf 's but have fewer cooling mechanisms and thus may be strongly impacted by warming under some conditions, particularly when exposed to a harsher microenvironment through canopy disturbance. As the climate changes, integrating the patterns and mechanisms reviewed here into models will be critical to forecasting forest-climate feedbacks.
Greenhouse climate is a highly complex system that contains nonlinearity and dependencies between each system state. This paper proposes a novel nonlinear model predictive control (NMPC) framework for greenhouse climate control to minimize the total control cost mainly coming from energy use. A nonlinear dynamic model of the greenhouse climate, including temperature, humidity, CO2 level, and light intensity, is first constructed based on developed mass balances and energy transport phenomena. Real-world greenhouse climate data and outdoor weather data are gathered to systematically identify the system parameters for the nonlinear greenhouse climate model. The nonlinear dynamic model is then integrated into the proposed NMPC framework which iteratively solves a nonlinear programming problem to obtain the optimal control inputs of fan airflow rate, pad cooling air velocity, heating pipe flow rate, CO2 injection rate, fogging rate, supplemental light intensity, and shade curtain coverage. The stability and feasibility issues of the proposed NMPC framework on a semi-closed greenhouse are explicitly discussed in this work. Case studies on controlling a greenhouse located in Cornell University campus are simulated to demonstrate the performance of the proposed NMPC framework. The results show the NMPC framework could efficiently minimize total control cost and constraint violation. Humidity, CO2 level, and light intensity can be controlled with nearly no violation on the predetermined constraints over different seasons and climate conditions. As for temperature, it is almost always maintained within the acceptable region in winter and spring. On extreme days of summer, there are some temperature violations due to the limited cooling capacity.
Several investigations have shown that enhanced mixing brought about by wind turbines alters near-surface meteorological conditions within and downstream of a wind farm. When scalar meteorological parameters have been considered, the focus has most often centered on temperature changes. A subset of these works has also considered humidity to various extents. These limited investigations are complemented by just a few studies dedicated to analyzing humidity changes. With onshore wind turbines often sited in agricultural areas, any changes to the microclimate surrounding a turbine can impact plant health and the length of the growing season; any changes to the environment around an offshore wind farm can change cloud and fog formation and dissipation, among other impacts. This article provides a review of observational field campaigns and numerical investigations examining changes to humidity within wind turbine array boundary layers. Across the range of empirical observations and numerical simulations, changes to humidity were observed in stably stratified conditions. In addition to the role of atmospheric stability, this review reveals that the nature of the change depends on the upstream moisture profile; robustness of the mixing; turbine array layout; distance from the turbine, in all three directions; and vertical temperature profile.
Reliable values of relative humidity are basic inputs for modelling in many disciplines and in the most disparate scientific fields. Unfortunately, humidity variables remain less focused than other meteorological parameters and generally suffer from considerable uncertainty mainly due to the fact that their observations are not widely available, fostering the use of the observations of other meteorological quantities to estimate them. The aim of this work is to assess the loss in daily maximum and minimum relative humidity accuracy when sampling interval becomes coarser than one hour. For this purpose, meteorological data from the ERA5 dataset, the most advanced reanalysis product released by the European Centre for Medium-Range Weather Forecasts (ECMWF), are used. Among the many advantages of ERA5 over the previous release ERA-Interim are the finer temporal resolution and data archived at the hourly time step. Near-surface relative humidity is derived using 1- and 3-hourly reanalysis data of 2-m temperature, 2-m dew-point temperature and surface pressure. Deviations from the actual values, as obtained from reference measures acquired at 15 minute intervals, are evaluated. Results show that the biases of the ERA5-based values are consistently reduced compared to its predecessor and that the performance of the calculated 1-hourly time resolution relative humidity data is almost equivalent to using observations. Reducing the sampling interval from three to one hour provides a significant improvement in data quality. The results indicate significant increases in errors in the estimates when the temporal resolution of the meteorological inputs becomes coarser than one hour, exceeding also the numerical and approximation errors due to simplifying assumptions in the theoretical and empirical formulas used. The positive impact of improving temporal resolution from ERA-Interim to ERA5 reanalysis is also quantified by the number of the correct relative humidity extremes increasing by 50%.
The humidity of the atmosphere profoundly affects every aspect of morphogenesis and the practical importance of this has provided the impetus for extensive research, particularly in agriculture. Maximov’s (13) excellent monograph delineates the effects of various moisture regimes on growth, structure and composition of crop plants, and Wangerman’s (23) review focuses on effects of water supply and humidity on plants which can regulate their water content and those which cannot. These and other reviewers have been quick to point out that effects of relative humidity are frequently confounded by interrelationships with other factors, including particularly temperature, light and soil moisture. Thus the analysis of morphological and histochemical effects of atmospheric humidity per se is frequently difficult.
Calcium is the fifth most abundant element in the earth’s crust, accounting for more than 3% of its composition. The exchangeable Ca content of a “normal” soil ranges from 65 to 85% of its total exchange capacity (12). Leaves of dicotyledonous plants generally contain from 0.5 to 5.5% Ca on a dry weight basis (44). The aboveground woody portions of trees in a 36-year-old apple orchard (35 trees per acre) contain about 200 lb. of Ca/acre as compared to about 175 lb. of all other nutrient elements combined (98). Recognizable foliar symptoms of Ca deficiency are seldom observed on field-grown fruit or vegetable crops. Despite these facts, serious economic losses occur annually from physiological disorders resulting from an inadequate level of Ca in the fruits, storage roots, or tubers of many plants or to the heart leaves of cabbage, lettuce, and other compact leafy vegetables.
Foliar sprays of Ca(NO 3 ) 2 or CaCl 2 completely controlled lettuce tipburn in the variety ‘Meikoningen’ when directed to susceptible immature leaves. Analysis of treated and untreated plants showed that treatment markedly increased the Ca content of tipburn susceptible leaves and revealed a 5-fold increase in Ca content as one progressed from immature heart leaves to mature basal leaves in untreated plants. Foliar sprays of organic acid salts, particularly oxalate, accelerated the development of tipburn and increased its severity. When Ca and oxalate treatments were alternated, application of Ca at the beginning of the dark period and oxalate in the morning resulted in markedly less tipburn than application of these sprays in the reverse order.
‘Thaxter’ and ‘Fordhook 242’ lima bean ( Phaseolus lunatus L.) cultivars were subjected to climatic variables in controlled-environment cabinets to determine conditions which were adverse to their reproduction. High night temperature promoted flower opening but was deleterious to pod set and retention. High humidity increased pod set and retention, apparently by promoting good pollen germination. High humidity, however, was unfavorable when it was combined with high temperature. Low night temperature was unfavorable when it was combined with low humidity. The most favorable environment for pod set and retention consisted of high humidity, low night temperature, and high soil moisture. ‘Fordhook 242’ set and retained fewer pods under environmental stress than ‘Thaxter’.
The influence of atmospheric moisture levels of 85% and 50% relative humidity (RH) (3.5 and 11.6 mb saturation vapor deficit respectively) at 20°C for 16:8 long day (LD) cycle on butterhead lettuce, ( Lactuca sativa L. cv. Meikoningen), during a growth period of 4 weeks from seeding, was studied in organic soil and liquid cultures. Significantly faster growth rates were evident on plants developing under 85% RH than under 50% in both soil and liquid culture with the largest increases occurring with plants grown in soil culture. The higher humidity level increased leaf number 15%, leaf size 30%, dry weights 62%, and leaf water contents from 93% to 94%. The differences in leaf number and dry weight equalled about 2 days growth difference at 4 weeks after seeding. The density of stomata was greater on plants grown under 50% RH but the total number of stomata per leaf under the 2 humidity levels was the same. The leaf resistance was significantly higher on plants grown under 50% than under 85% RH. The principle significance of high humidity level during growth of lettuce is the production of larger marketable heads with a higher water content in a slighly reduced period of time.
Experiments with Prunus armeniaca were carried out under conditions of constant temperature but varying air humidity. Experiments were also contucted with a constant water vapor difference between the evaporating sites in a leaf and the air, but with varying leaf temperature. These served as a basis for predicting the daily course of total diffusion resistance under the natural climatic conditions of a desert. For the simulation, the rsults of the experiments at constant conditions with only one variable factor are fitted with empirical equations which serve as "calibration curves" to predict the change in diffusion resistance caused by a change in humidity and temperature calculated from the meteorological data of a desert day. The simulation shows that for P. armeniaca humidity and temperature are the dominating factors in controlling the daily course of diffusion resistance. For meteorologically very different days the simulation allows the increase in diffusion resistance in the morning to be predicted with an accuracy of 90%-105% as compared to directly observed measurements. In the afternoon, especially after extreme climatic conditions during the morning, the deviation between predicted and observed values of diffusion resistance may be greater, but not more than -20% to -30%. This possibly indicates the existence of an additional factor of significance which was not included in the simulation. The two peaked curves of net photosynthesis and transpiration characteristic of plants living under arid conditions can be explained in this species by the humidity-and temperature-controlled stomatal response. This stomatal regulation leads to a decreasing total daily transpirational water loss on a dry day as compared to a moist one. The significance of this controlling mechanism for the primary production and the water relations of P. armeniaca is discussed.
Many investigations have been made on transpiration and photosynthesis of plants. However, the relationship between transpiration and photosynthesis has not been completely estabilished. The study reported here was planned to elucidate the effect of transpiration on the apparent photosynthesis and the relation of temperature and photosynthesis in several crops: sweet potato, rice, soybean and peanut. 1) Experiments were conducted outdoors under full sunlight using an apparatus which has a humidity-controlling system (Fig. 1). In early growth stage, photosynthesis was not affected by restraint of the transpiration caused by increasing humidity in the chamber, but in late growth stage a marked increase of photosynthetic rates occurred by restraining the transpiration (Figs. 2-5). These results suggest that water supply from root to the photosynthetic organ turns insufficient in the late growth stage. 2) Fig. 6 and Fig. 7 indicate the relation of leaf temperature and photosynthesis in sweet potato and soybean plant at various growth stages. In early growth stage, apparent photosynthesis was insensible of high temperature from 30 to 40°C. In late growth stage, however, apparent photosynthetic rates showed a rapid decrease at high-temperature range. These phenomena were also recognized in other crops, e.g., rice and peanut. From results of the investigation for the stomatal opening and fluctuation of water level in sweet potato leaves under various temperature condition, it may be concluded that depression of photosynthetic rate at high-temperature range was due to a deficit of water content and high stomatal resistance in leaf. 3) In the series of experiments as shown in Figs. 2-5, water vapour transfer coefficient (D) was calculated for several crops from the equation presented in the note of Fig. 9. There was a close relationship between the transpiration and the ‘D’ value. The ‘D’ values, selected under approximately constant conditions with leaf temperature of 35°C and air volume passing through a chamber of 8-11 m³/hr, showed high correlations to photosynthetic rates in three crops except soybean plant (Fig. 10). The ‘D’ value is a reciprocal of diffusion resistance(r) which can be divided into two components: (i) resistance in external air during diffusion away from leaf(ra), and (ii) resistance through the stomata(rs). It is considered that the ‘D’ mainly depends on 1/rs in the case of Fig. 10. Accordingly, when photosynthetic rate is high at high leaf temperature, stomata are widely open. 4) Two factors, total sugar content in root and the ratio of root dry weight (R) to leaf area (F), must be concerned with the water supply from root to photosynthetic organ. Therefore, both factors, whose changes with time are shown in Fig. 14, would be correlated to the ‘D’ values of each growth stage.