Leaf Growth Rate Research Articles

Effect of almond shell addition to substrates in Phaseolus vulgaris L. (cv. Saxa) growth, and physiological and biochemical characteristics

PurposeIn the almond industry, the major by-product is the shell, the woody outer layer of the almond fruits. The goal of this research was to study the consequence of the incorporation of almond shell to cultivation substrates on green bean plant grown in a growth chamber.MethodsAlmond shell was mixed with peat (20%:80%) (AS), or used as mulch (AM) on top of the control (C) substrate (33.3%:66.6% vermiculite and peat). Evaluated parameters included green bean pod production and characteristics and their biochemical parameters, namely pigments, total phenolics and antioxidant activity, and soluble sugars and proteins, but also leaf gas exchange parameters.ResultsThe use of almond shell as a mulch resulted in unexpected higher crop growth rate, relative leaf growth rate, and leaf area index, with similar production and dimension of pods, when compared to the control assay, with comparable amounts of phenolic compounds, antioxidant capacity, and soluble sugars and proteins, even if gas exchange parameters were negatively affected. By other hand, the data from the almond shell:peat mixture indicate important increase of carotenoid content, contrasting to the control substrate.ConclusionThese results indicate that almond shell has some potential as growing medium for green bean cultivation, when mixed with peat or used as a mulch.

Spatio-temporal variation in leaf morphofunctional attributes and relation to growth and survival of young woody plants

Leaves present adjustments in response to reducing the availability of environmental resources, which may reflect in the plant development. The study investigated the interannual variation in the morphofunctional foliar attributes of seedlings and juveniles of Myracrodruon urundeuva Allemao and Cenostigma pyramidale (Tul.) Gagnom & G.P. Lewis, besides the survival time and growth rates of individuals from two forests of different ages. We analyzed the relationships of the leaf characteristics with plant growth rate and survival time. In two forests, young (24 years) and mature (> 55 years), from the Brazilian semiarid, data sampling of the specific leaf area, specific leaf mass, leaf water content, and mean number of leaves was conducted for 2 years; the growth rate in diameter and height was evaluated during the rainy season of 2016 and the survival time. Most leaf characteristics, growth, and survival rates presented higher values in the young forest, besides more relationships between the leaf attributes and the survival time, according to the species and ontogenetic stage.

The Role of Abscisic Acid Signaling in Maintaining the Metabolic Balance Required for Arabidopsis Growth under Nonstress Conditions.

Abscisic acid (ABA) is a plant hormone that regulates a diverse range of cellular and molecular processes during development and in response to osmotic stress. In Arabidopsis (Arabidopsis thaliana), three Suc nonfermenting-1-related protein kinase2s (SnRK2s), SRK2D, SRK2E, and SRK2I, are key positive regulators involved in ABA signaling whose substrates have been well studied. Besides reduced drought-stress tolerance, the srk2d srk2e srk2i mutant shows abnormal growth phenotypes, such as an increased number of leaves, under nonstress conditions. However, it remains unclear whether, and if so how, SnRK2-mediated ABA signaling regulates growth and development. Here, we show that the primary metabolite profile of srk2d srk2e srk2i grown under nonstress conditions was considerably different from that of wild-type plants. The metabolic changes observed in the srk2d srk2e srk2i were similar to those in an ABA-biosynthesis mutant, aba2-1, and both mutants showed a higher leaf emergence rate than wild type. Consistent with the increased amounts of citrate, isotope-labeling experiments revealed that respiration through the tricarboxylic acid cycle was enhanced in srk2d srk2e srk2i These results, together with transcriptome data, indicate that the SnRK2s involved in ABA signaling modulate metabolism and leaf growth under nonstress conditions by fine-tuning flux through the tricarboxylic acid cycle.

PARAMETERS OF MULTIFRACTAL SPECTRUM FOR DESCRIBING GROWTH STATE OF SOYBEAN LEAVES

We studied soybean leaves of the main soybean cultivars and their mutants from Shanxi Province, China, using multifractal spectrum analysis of transmission scanned gray scale images of excised leaves. We demonstrate that the parameters of multifractal spectra correlate with the biological status of the plant. The width [Formula: see text] of the multifractal spectrum, a parameter of the transmission scanned gray scale image, is a good indicator of the metabolic state and growth rate of a soybean leaf. In general, the larger the value of [Formula: see text], the more exuberant the metabolism and the faster the growth rate of the leaf. [Formula: see text] is a parameter related with the distribution of chlorophyll in leaf, it reflects the concentration degree of chlorophyll; the smaller the value of [Formula: see text], the higher the concentration degree of chlorophyll in the leaf. [Formula: see text] is a parameter related with the distribution of water in the leaf, it reflects the concentration degree of water; the larger the value of [Formula: see text], the higher the concentration degree of water in the leaf. In order to reduce the impact of errors in the calculation of [Formula: see text], [Formula: see text] and [Formula: see text], we introduced three new parameters — the characteristic width [Formula: see text], the characteristic [Formula: see text] and the characteristic [Formula: see text]. We compare the values of [Formula: see text], [Formula: see text] and [Formula: see text] among the different leaves qualitatively by replacing [Formula: see text], [Formula: see text] and [Formula: see text] with [Formula: see text], [Formula: see text] and [Formula: see text], respectively. In research of soybean leaf growth, stress resistance of soybean cultivars and the breeding of excellent varietals, [Formula: see text] is shown here to be a new and useful indicator for analysis.

The passion fruit liana (Passiflora edulis Sims, Passifloraceae) is tolerant to ozone

Passiflora edulis Sims is a liana species of high economic interest and is an interesting model plant for understanding ozone action on disturbed vegetation. In this work we hypothesized that P. edulis has adaptive responses to oxidative stress that enable it to tolerate ozone damage based on its capacity to grow under a diversity of environmental conditions and to dominate disturbed areas. We exposed seedlings to three levels of ozone in a Free-Air Controlled Exposure (FACE) system (22, 41 and 58 ppb h AOT40 and 13.52, 17.24 and 20.62 mmol m−2 POD0, over 97 days) for identifying its tolerance mechanisms. Anatomical (leaf blade structure and fluorescence emission of chloroplast metabolites), physiological (leaf gas exchange, growth rate and biomass production) and biochemical (pigments, total sugars, starch, enzymatic and non-enzymatic antioxidant metabolites, reactive oxygen species and lipid peroxidation derivatives) responses were assessed. Ozone caused decreased total number of leaves, hyperplasia and hypertrophy of the mesophyll cells, and accelerated leaf senescence. However, O3 did not affect carbohydrates content, net photosynthetic rate, or total biomass production, indicating that the carboxylation efficiency and associated physiological processes were not affected. In addition, P. edulis showed higher leaf contents of ascorbic acid, glutathione (as well high ratio between their reduced and total forms), carotenoids, and flavonoids located in the chloroplast outer envelope membrane. Our results indicate that P. edulis is an O3-tolerant species due to morphological acclimation responses and an effective antioxidant defense system represented by non-enzymatic antioxidants, which maintained the cellular redox balance under ozone.

Effects of LED Light Quality of Urban Agricultural Plant Factories on the Growth of Daughter Plants of ‘Seolhyang’ Strawberry

This study was conducted to examine the influence of Light-Emitting Diode (LED) light quality in urban agricultural plant factories on the growth and development of Seolhyang strawberry daughter plants in order to improve the efficiency of daughter plant growth and urban agriculture. LED light quality by demonstrated that above-ground growth and development were greatest for daughter plant 2. Daughter plant 1 showed the next highest growth and development, followed by daughter plant 3. Among the different qualities of LED light, the stem was thickest and growth rate of leaves was highest for R + B III (LED quality: red 660 nm + blue 450 nm/photosynthetic photon flux density (PPFD): 241–243 μmol·m-2·s-1) and lowest for R (red 660 nm/115–117 μ mol·m-2·s-1). Plant height, leaf width, petiole length, and the leaf growth rate were highest for W (white fluorescent lamp/241–243 μ mol·m-2·s-1) and lowest for R + B Ⅰ (red 660 nm + blue 450 nm/80–82 μ㏖·m-2·s-1). For above-ground growth and development, as the plants surpassed the seedling age, mixed light (red + blue), rather than monochromatic light (red or blue), and higher PPFD values tended to increase development. Regarding the quality of the LED light, daughter plant 2 showed the highest chlorophyll content, followed by daughter plant 1, and daughter plant 3 showed the least chlorophyll content. When the wavelength was monochromatic, chlorophyll content increased, compared to that when PPFD values were increased. Mixed light vitality was highest in daughter plant 2, followed by 1, and 3, showed increased photosynthesis when PPFD values were high with mixed light, in contrast to the results observed for chlorophyll content.

Controlling Powdery Mildew; Use of Arbuscular Mycorrhizal Fungi as Biocontrol Agent instead of Chemical Fungicides

Plant protection based solely on modern fungicides could lead to genetic changes in neurons of animal and humans that contribute to cases of autism and Alzheimer disease, unless the bio control agents is applied or replaced. Most researches is focused on the strongest chemical fungicides, dangerous to human health, for effective plant disease control and we believe that non-chemical control methods such as biological agents like AMF are of great importance. The aim of study was to investigate whether the soil inoculation with Glomus isolates of arbuscular mycorrhizal fungi (AMF) affected control of powdery mildew disease of apple MM111 and its survival and growth instead of use of chemical fungicides such as Flint and Stroby. Twenty apple seedlings were randomly arranged to 4 treatments, each with 5 replicates (T1, control = no AMF, no fungicide, T2= Flint fungicide, T3= Stroby fungicide and T4 = only AMF mixture) and were monitored throughout 9 weeks. All seedlings were exposed to powdery mildew on week 6 and only T2 and T3 plants treated by fungicides after developing mildew colonies on the leaves. Results showed that, seedling length in plants cultivated in AMF-inoculated-soil was significantly higher than other treatments especially in weeks 1-4 and weeks 6-9. Leaf growth rate of all plants during the experimental growth period non-significantly increased between treatments with the exception of first week that did show a significant increase in leaf growth rate of group 4 plants, even after exposure to disease. T4 samples showed a high average of leaves numbers (P < 0.05) in compared to other groups followed by T3 samples during the experimental growth period. The data from this study confirmed the response of seedling and leaf growth rates of apple seedlings to mycorrhizal colonization. It was concluded that plants cultivated in soil inoculated to AMF throughout 6 weeks had higher resistance and growth rates against Podosphaera leucotricha fungi as an agent of powdery mildew disease in apple seedling and it can be considered as an applicable strategy in biocontrol measures against pathogens when most researches is focused on chemical fungicides.

Bedrock geology affects foliar nutrient status but has minor influence on leaf carbon isotope discrimination across altitudinal gradients.

Carbon isotope discrimination (Δ13C) in plant leaves generally decreases with increasing altitude in mountains. Lower foliar Δ13C at high elevation usually is associated with higher leaf mass per area (LMA) in thicker leaves. However, it is unclear if lower foliar Δ13C in high-altitude plants is caused by improved photosynthetic capacity as an effect of higher nutrient, especially nitrogen, content in thicker leaves. We investigated trends of foliar Δ13C in four species, each belonging to a different plant functional type (PFT), across two altitudinal gradients, each on a different bedrock type (carbonate and silicate bedrock, respectively) in a region of the southern Alps (Italy) where the foliar Δ13C was not affected by water limitation. Our objective was to assess whether the altitudinal patterns of foliar Δ13C in relation to leaf morphology and foliar nutrients were conditioned by indirect control of bedrock geology on soil nutrient availability. The foliar Δ13C of the four species was mainly affected by LMA and, secondarily, by stomatal density (SD) but the relative importance of these foliar traits varied among species. Area-based nutrient contents had overall minor importance in controlling C discrimination. Relationships among foliar Δ13C, foliar nutrient content and leaf growth rate strongly depended on soil nutrient availability varying differently across the two gradients. In the absence of water limitation, the foliar Δ13C was primarily controlled by irradiance which can shape anatomical leaf traits, especially LMA and/or SD, whose relative importance in determining C isotope discrimination differed among species and/or PFT. Decreasing foliar Δ13C across altitudinal gradients need not be determined by improved photosynthetic capacity deriving from higher nutrient content in thicker leaves.

Effects of rice-husk biochar on sand-based rootzone amendment and creeping bentgrass growth

Turf provides an irreplaceable surface for recreational and sport activities in urban landscape. Sand-based rootzone is recommended for turf establishment because of its excellent compaction resistance. It is necessary to improve the water and nutrient retention of sand-based rootzone by soil amendments in maintaining healthy turf. The objective of this research was to evaluate the effects of rice-husk biochar on sand-based rootzone amendment and creeping bentgrass (Agrostsis stolonifera) establishment. The results showed that bulk density was linearly decreased in proportion to rice-husk biochar. Total porosity and capillary porosity, water retention, and saturated hydraulic conductivity were significantly increased in proportion to rice-husk biochar. Sand-based rootzone amended with 10% of rice-husk biochar promoted the seed germination and young seedling growth with the significantly higher growth rate, leaf emergence rate, shoot and root biomass, and turf coverage than the control. These results indicate that rice-husk biochar had superior characteristics to previous reported biochars in the sand-based rootzone amendment and could be used to improve soil physical properties and turf healthy in sports and recreation playgrounds.

Features of Prooxidant and Antioxidant Systems of Greater Plantain Plantago major Growing for a Long Time under Conditions of Radioactive Contamination

The viability and state of the prooxidant and antioxidant systems of Plantago major seed progeny from cenopopulations growing for a long time at the East-Ural Radioactive Trace (EURT) has been estimated. Radiation doses of maternal plants have been calculated using our empirical data in ERICA Tool. The absorbed dose rates for plantain in the EURT zone varied from 19 to 157 μGy/h, which is 178–1455 times higher than the background values. These relatively low levels of chronic irradiation did not cause a significant decrease in the survival rate of P. major seed progeny; the rate of root and leaf growth decreased only in seedlings from the most polluted cenopopulation. A prooxidant shift was revealed in seedlings from the EURT zone. Given the same regime of enzyme protection (SOD, CAT, and POX) against active oxygen forms, the average rate of accumulation of secondary products of lipid peroxidation (MDA) was 3.3 times higher in impact samples than in background samples. The level of prooxidant shift in impact samples is not linearly related to dose rates that are classified as low doses.

Projected drought effects on the demography of Ashe juniper populations inferred from remote measurements of tree canopies

Tree mortality from drought is anticipated to increase as climate change promotes more frequent or severe water limitation. Ecosystem impacts of woody mortality depend on both the number and sizes of trees that die, but a limited capacity to predict mortality risk for individual trees hinders the capacity to forecast drought effects on tree population demography and ecosystem processes. We remotely measured leaf area of living Ashe juniper trees at three savanna sites in central Texas, USA to characterize the frequency-size distribution (FSD) of juniper populations and evaluate mortality risk from drought as a function of tree size. Mortality risk of individuals was assessed from the deviation in leaf area per tree from that of a similarly sized individual with near maximal leaf area using correlations among leaf area, growth rate, and mortality measured during a prior drought. We found that the FSD of juniper trees is bell-shaped at each site. Mortality risk from drought exceeded 25% of emergent (> 4 m height) trees in savanna juniper populations, but was highest for largest trees. Mortality risk was greatest at a grazed savanna, exceeding 50% of trees with projected canopy area > 20 m2. Results imply that severe drought could kill a large fraction (18–85%) of intermediate- to large-sized Ashe juniper trees in central Texas savannas. Our analysis demonstrates a novel use of remote measurements of canopy foliation to link mortality risk from drought to the demography of Ashe juniper populations through properties of individual trees.

Investigating cellular stress response to heat stress in the seagrass Posidonia oceanica in a global change scenario

Posidonia oceanica meadows are facing global threats mainly due to episodic heat waves. In a mesocosm experiment, we aimed at disentangling the molecular response of P. oceanica under increasing temperature (20 °C–32 °C). The experiment was carried out in spring, when heat waves can potentially occur and plants are putatively more sensitive to heat stress, since they are deprived in carbohydrates reserves after the cold winter months. We aimed to identify the activation of different phases of the cellular stress response (CSR) reaction and the responsive genes activated or repressed in heated plants. A molecular traffic light was proposed as a response model including green (protein folding and membrane protection), yellow (ubiquitination and proteolysis) and red (DNA repair and apoptosis) categories. Additionally, we estimated phenological trait variations to complement the information obtained from the molecular proxies of stress. Despite reduced leaf growth rate, heated plants did not exhibit signs of irreversible damage, probably underlying species pre-adaptation to warm and fluctuating regimes. Gene expression analyses revealed that molecular chaperoning, DNA repair and apoptosis inhibition processes related genes were the ones that mostly responded to high thermal stress and will be target of further investigation and in situ proofing for assessing their use as indicators of P. oceanica performance under sub-lethal heat stress.

Leaf growth rate and nitrogen content determine respiratory costs during leaf expansion in grapevines

Respiration processes are well recognized as fundamental for the plant carbon balance, but little attention has been paid to the relationships among respiration rates, environment and genetic variability. This can be of particular interest to understand the differences in net carbon balances in crops as grapevines. Night respiration (Rn ) and its associated growth (Rg ) and maintenance (Rm ) components were evaluated during leaf expansion in two grapevine cultivars (Tempranillo cv. and Garnacha cv.) that differ in their plant growth pattern and carbon balance. Simultaneously, leaf traits as leaf mass area, nitrogen (N) and carbon (C) content were evaluated in order to relate to the respiratory processes and the leaf growth. The results showed the differences in respiration rates associated with the leaf expansion pattern. Tempranillo developed leaves with higher leaf area and lower dry weight per leaf unit than Garnacha. Although differences between cultivars were observed in terms of growth costs in expanding leaves, the maintenance costs were similar for both cultivars. Also, a significant linear regression was found between respiration rates and N content in expanding and mature leaves. The results indicate that differences in structure and nitrogen content of expanding leaves may lead to respiratory differences between cultivars. These results also demonstrate the importance of respiratory cost components in carbon balance calculations in grapevines.

Mapping and Predicting Non-Linear Brassica rapa Growth Phenotypes Based on Bayesian and Frequentist Complex Trait Estimation.

Predicting phenotypes based on genotypes and understanding the effects of complex multi-locus traits on plant performance requires a description of the underlying developmental processes, growth trajectories, and their genomic architecture. Using data from Brassica rapa genotypes grown in multiple density settings and seasons, we applied a hierarchical Bayesian Function-Valued Trait (FVT) approach to fit logistic growth curves to leaf phenotypic data (length and width) and characterize leaf development. We found evidence of genetic variation in phenotypic plasticity of rate and duration of leaf growth to growing season. In contrast, the magnitude of the plastic response for maximum leaf size was relatively small, suggesting that growth dynamics vs. final leaf sizes have distinct patterns of environmental sensitivity. Consistent with patterns of phenotypic plasticity, several QTL-by-year interactions were significant for parameters describing leaf growth rates and durations but not leaf size. In comparison to frequentist approaches for estimating leaf FVT, Bayesian trait estimation resulted in more mapped QTL that tended to have greater average LOD scores and to explain a greater proportion of trait variance. We then constructed QTL-based predictive models for leaf growth rate and final size using data from one treatment (uncrowded plants in one growing season). Models successfully predicted non-linear developmental phenotypes for genotypes not used in model construction and, due to a lack of QTL-by-treatment interactions, predicted phenotypes across sites differing in plant density.

Growth responses of Lantana (Lantana camara L.) varieties to varying water availability and light conditions

The Journal of the National Science Foundation of Sri Lanka publishes the results of research in all aspects of Science and Technology. The journal also has a website at http://www.nsf.gov.lk/. 2021 Impact Factor: 0.682The JNSF provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.Cover :Leatherback (a), green (b - adult & f - hatchling), hawksbill (c) and olive ridley (d) turtles who nest in Sri Lankan beaches, green turtle crawl marks (e) and by-catch of sea turtles in fisheries (c & d)Photo credits: SJ Perera (a & c), WPN Perera (b & e), K Ekaratne (d & f)

Responses of seminal wheat seedling roots to soil water deficits

The aims of this paper are to develop our understanding of the ways by which soil water deficits influence early wheat root growth responses, particularly how seminal roots respond to soil drying and the extent to which information on differences in soil water content are conveyed to the shoot and their impact on shoot behaviour. To achieve this, wheat seedlings have been grown, individually for around 25 days after germination in segmented soil columns within vertical plastic compartments. Roots were exposed to different soil volumetric moisture contents (SVMC) within the two compartments. Experiments where the soil in the lower compartment was allowed to dry to different extents, while the upper was maintained close to field capacity, showed that wheat seedlings allocated proportionally more root dry matter to the lower drier soil compartment. The total production of root, irrespective of the upper or lower SVMC, was similar and there were no detected effects on leaf growth rate or gas exchange. The response of seminal roots to proportionally increase their allocation of dry matter, to the drier soil was unexpected with such plasticity of roots system development traditionally linked to heterogeneous nutrient distribution than accessing soil water. In experiments where the upper soil compartment was allowed to dry, root growth slowed and leaf growth and gas exchange declined. Subsequent experiments used root growth rates to determine when seminal root tips first came into contact with drying soil, with the intentions of determining how the observed root growth rates were maintained as an explanation for the observed changes in root allocation. Measurements of seminal root ABA and ethylene from roots within the drying soil are interpreted with respect to what is known about the physiological control of root growth in drying soil.

Size and fitness responses of eelgrass (Zostera marina L.) following reciprocal transplant along an estuarine gradient

Eelgrass (Zostera marina) differs in shoot size, growth rate, and life history investment along a 30-km estuarine gradient in Willapa Bay, Washington (USA). In this study, reciprocal transplants were carried out among four sites in the estuary to test the roles of source population and outplant site for summer-season performance, a method that distinguishes any advantage of locally-tuned phenotypes and whether such trait differences are fixed or phenotypically-plastic. Shoots were measured after 2–3 months for size, leaf emergence rate (productivity) and shoot emergence rate (fitness), as well as simply finding them again (retrieval). Results generally did not support that best performance came from local shoots (few source x outplant site interactions). However, at one site, local shoots had higher fitness than other sources, and for one source, local retrieval exceeded that at other sites. Across all outplants, retrieval improved with rhizome length, suggesting that longer rhizomes provided better anchors. Fitness and productivity were both reduced for transplants into eelgrass relative to those in nearby bare areas at most sites, likely reflecting strong intraspecific competition for transplanted shoots. At this within-estuary scale in summer, morphology appeared entirely plastic, given convergence to local size, but annual vs. perennial life history was strictly a function of source population regardless of outplant site. This reciprocal transplant study supports many of the best practices for restoration, which include effective anchoring of shoots into locations with suitable environmental conditions. Matching donor populations for life history may be more important than for size, given differential phenotypic plasticity in these traits.

Growth patterns of Phragmites karka under saline conditions depend on the bulk elastic modulus

Salt stress is known to hamper steady-state water flow, which may reduce plant growth. This research was aimed to study the roles of leaf turgor, osmotic adjustment and cell wall elasticity under saline conditions which may reduce biomass production in Phragmites karka (Retz.) Trin, ex. Steud. (a marsh grass). Plants were grown in 0, 100 and 300 mM NaCl and harvested on 3, 7, 15 and 30 days to observe periodic changes in growth and water relations. Leaf number, relative growth rate, and relative elongation rates were higher in the non-saline control than in the plants grown under saline conditions. Plants showed a rapid decline in leaf growth rate (7–15 days) in 300 mM NaCl compared with a delayed response (15–30 days) in 100 mM NaCl. Leaf water potential decreased with increases in salinity after the third day of exposure whereas osmotic potential decreased after the fifteenth day. Low leaf turgor (Ψp) on the third day indicated an initial phase of osmotic stress under saline conditions. Plants maintained higher Ψp in 0 and 100 mM than in 300 mM NaCl. Differences between mid-day and pre-dawn water potential and water saturation deficit were higher in 300 mM NaCl than with other treatments. Water potential and hydraulic capacitance at turgor loss point decreased whereas bulk elastic modulus increased in 300 mM NaCl. Maintenance of turgor and growth at 100 mM NaCl could be related to efficient osmotic adjustment (use of K+ and Cl–), higher WUEi, and lower bulk elasticity whereas poor growth at 300 mM NaCl may have been a consequence of low turgor, decreased cell hydraulic capacitance and higher bulk elastic modulus.

Drought Response in Selected Tropical Inbred Maize Lines and Relative Expression of <i>PARP2</i> Gene under Limited Water Conditions

Drought is the leading single factor that limits maize production thus inhibiting the crops genetic potential. In response to drought, maize and other plants synthesize Poly ADP-Ribose (PAR) protein. This process is controlled by the Poly ADP-Ribose Polymerase (PARP) genes and consumes cellular energy, leading to plant death. This study evaluated four tropical inbred maize (<i>Zea mays L</i>.) lines; CML 216, CML 144, A04 and E04 for their response to growth limiting water stress and their relative expression of <i>PARP2</i> gene under drought and non-drought conditions. The leaf lengths and growth rates of the fourth leaf were monitored for 21days post emergence while fresh and dry weights of drought stressed and non-stressed seedlings were recorded a month after emergence of the fourth leaf. The relative expression of <i>PARP2</i> gene was determined using rtPCR after isolating RNA from drought stressed and non-stressed maize seedlings. There was no significant difference in the mature lengths of the fourth leaf in the four genotypes when the maize seedlings were not subjected to drought and when subjected to severe drought stress. However, subjecting maize seedlings to mild drought resulted in a significant difference in the mature leaf lengths based on the different genotypes (P= 0.0066). The growth rate of maize seedlings based on the fourth leaf was observed to be affected by drought, with a higher mean growth rate (1.74 cm day^-1) registered in seedlings which were not subjected to drought and those subjected to moderate drought (1.78 cm day^-1). A slower growth rate (1.37 cm day^-1) was observed in seedlings subjected to severe drought stress. Fresh and dry weights of maize seedlings were also observed to be significantly different based on the level of drought exerted (P = < 0.0001) and the genotype (P = < 0.0001). The expression of <i>PARP2</i> gene was found to be directly proportional to the level of drought stress exerted. Results from this study suggest how tropical maize genotypes respond to drought.

Measurement of Arabidopsis thaliana Plant Traits Using the PHENOPSIS Phenotyping Platform.

High-throughput phenotyping of plant traits is a powerful tool to further our understanding of plant growth and its underlying physiological, molecular, and genetic determinisms. This protocol describes the methodology of a standard phenotyping experiment in PHENOPSIS automated platform, which was engineered in INRA-LEPSE (https://www6.montpellier.inra.fr/lepse) and custom-made by Optimalog company. The seminal method was published by Granier et al. (2006). The platform is used to explore and test various ecophysiological hypotheses (Tisné et al., 2010; Baerenfaller et al., 2012; Vile et al., 2012; Bac-Molenaar et al., 2015; Rymaszewski et al., 2017). Here, the focus concerns the preparation and management of experiments, as well as measurements of growth-related traits (e.g., projected rosette area, total leaf area and growth rate), water status-related traits (e.g., leaf dry matter content and relative water content), and plant architecture-related traits (e.g., stomatal density and index and lamina/petiole ratio). Briefly, a completely randomized (block) design is set up in the growth chamber. Next, the substrate is prepared, its initial water content is measured and pots are filled. Seeds are sown onto the soil surface and germinated prior to the experiment. After germination, soil watering and image (visible, infra-red, fluorescence) acquisition are planned by the user and performed by the automaton. Destructive measurements may be performed during the experiment. Data extraction from images and estimation of growth-related trait values involves semi-automated procedures and statistical processing.