Leaf Growth Patterns Research Articles

Leaf growth pattern and morphology of Sauropus androgynus (L.) Merr. in tropical lowland

Chikurmanis or katuk (Sauropus androgynus (L.) Merr.) is a traditional leafy vegetable that is consumed widely in Indonesia. The leaf is rich in vitamins, minerals, nutrients, and dietary fiber. The study aimed to investigate the leaf growth pattern and morphological characteristics of the chikurmanis cultivated in the tropical lowland ecosystem. The research was conducted on local farmland in Marga Sakti Sebelat, Bengkulu, Indonesia on December 2023 by survey method. The results showed that the leaf of chikurmanis grew in the daytime and continued to grow at nighttime as indicated in midrib length, leaf width, and foliole number. It is likely that nighttime growth become predominant in chikurmanis. The plant was a type of shrub with complete organs of stem, branch, root, flower, and leaf. The leaf was arranged as a compound leaf with many folioles in opposite positions. Midrib length (M) x leaf width (W) with a zero intercept of linear regression was the most reliable predictor of leaf area with the formula Y = 0.4964MxW (R2 = 0.9677). Keywords: chikurmanis plant; katuk; leaf area estimation; morphological trait; traditional leafy vegetable

Unveiling intra-population functional variability patterns in a European beech (Fagus sylvatica L.) population from the southern range edge: drought resistance, post-drought recovery and phenotypic plasticity.

Understanding covariation patterns of drought resistance, post-drought recovery and phenotypic plasticity, and their variability at the intra-population level are crucial for predicting forest vulnerability to increasing aridity. This knowledge is particularly urgent at the trailing range edge since, in these areas, tree species are proximal to their ecological niche boundaries. While this proximity increases their susceptibility, these populations are recognized as valuable genetic reservoirs against environmental stressors. The conservation of this genetic variability is critical for the adaptive capacity of the species in the current context of climate change. Here we examined intra-population patterns of stem basal growth, gas exchange and other leaf functional traits in response to an experimental drought in seedlings of 16 open-pollinated families within a marginal population of European beech (Fagus sylvatica L.) from its southern range edge. We found a high degree of intra-population variation in leaf functional traits, photosynthetic performance, growth patterns and phenotypic plasticity in response to water availability. Low phenotypic plasticity was associated with higher resistance to drought. Both drought resistance and post-drought recovery of photosynthetic performance varied between maternal lines. However, drought resistance and post-drought recovery exhibited independent variation. We also found intra-population variation in stomatal sensitivity to soil drying, but it was not associated with either drought resistance or post-drought recovery. We conclude that an inverse relationship between phenotypic plasticity and drought resistance is not necessarily a sign of maladaptive plasticity, but rather it may reflect stability of functional performance and hence adaptation to withstand drought. The independent variation found between drought resistance and post-drought recovery should facilitate to some extent microevolution and adaption to increasing aridity. The observed variability in stomatal sensitivity to soil drying was consistent with previous findings at other scales (e.g., inter-specific variation, inter-population variation) that challenge the iso-anisohydric concept as a reliable surrogate of drought tolerance.

Agro-morphological Growth Response of Acha (FONIO) (Digitaria exilis and Digitaria iburua [Kippist] Stapf.) Exposed to Colchicine: Germination, Plant Height and Leaf Number

Acha (Fonio) Digitaria sp. is a valuable cereal crop widely cultivated in several African countries. The genetic improvement of Acha through induced mutagenesis has gained attention for enhancing desirable traits. Colchicine, a mitotic inhibitor, is commonly used to induce polyploidy, which can lead to alterations in plant characteristics. This study aimed to investigate the effects of colchicine treatment on germination, plant height, and leaf count of two Acha species. Seeds from two Digitaria species, Digitaria exilis, and Digitaria iburua, were subjected to colchicine treatment using different concentrations (0.05, 0.10, 0.15, and 0.20g/dL). The control group was treated with distilled water. Germination rates were assessed by measuring the percentage of seeds that successfully sprouted. Plant height and leaf number were measured at maturity and analyzed using ANOVA on SPSS Version 26. The results indicated that colchicine treatment significantly affected germination, plant height, and leaf number in both Digitaria species. Germination rates varied depending on the concentration, with lower germination observed at higher concentrations (70.70% and 74.3% for 0.20g/dL treatment in both species). In terms of plant height, colchicine-treated Acha plants exhibited significant differences compared to the control group. The majority of treated plants showed increased growth (57.00 cm to 60.70 cm in D. exilis and 114.10 to 122.40 cm in D. iburua) compared to the control. Variability in plant height was observed among the treated plants, suggesting that colchicine-induced polyploidy had varying effects on height across different genotypes. Similarly, the number of leaves was affected by colchicine treatment. Treated plants exhibited an increase in leaf number (56.70 to 60.7 for D exilis and 32.60 to 36.30 for D. iburua), compared to the control group (49.7 and 29.7 respectively). This variability suggests that colchicine-induced polyploidy may have influenced leaf development and growth patterns in Acha. Colchicine treatment had significant effects on germination, plant height, and leaf count in both varieties of Acha. The results suggest that colchicine-induced polyploidy can alter these plant characteristics. These findings provide insights into the potential use of colchicine treatment for inducing desirable traits in Acha through polyploidization, which may have implications for crop improvement and breeding programs. Further research is warranted to explore the underlying mechanisms and assess the impact of these alterations on overall agronomic performance and yield potential.

Anatomical Mechanisms of Leaf Blade Morphogenesis in Sasaella kogasensis 'Aureostriatus'.

There are limited studies on the cytology of bamboo leaf development from primordium to maturity. This study delves into the leaf morphological characteristics and growth patterns of Sasaella kogasensis 'Aureostriatus' and provides a three-dimensional anatomical analysis of cell division, expansion, and degradation. Leaves on the same branch develop bottom-up, while individual leaves develop the other way around. Like bamboo shoots and culms, the leaves follow a "slow-fast-slow" growth pattern, with longitudinal growth being predominant during their development. The growth zones of individual leaves included division, elongation, and maturation zones based on the distribution of growth space. By measuring 13,303 epidermal long cells and 3293 mesophyll cells in longitudinal sections of rapidly elongating leaves, we observed that in the rapid elongation phase (S4-S5), the division zone was located in the 1-2 cm segment at the bottom of the leaf blade and maintained a constant size, continuously providing new cells for leaf elongation, whereas in the late rapid elongation phase (S6), when the length of the leaf blade was approaching that of a mature leaf, its cells at the bottom of the blade no longer divided and were replaced by the ability to elongate. Furthermore, to gain an insight into the dynamic changes in the growth of the S. kogasensis 'Aureostriatus' leaves in the lateral and periclinal directions, the width and thickness of 1459 epidermal and 2719 mesophyll cells were counted in the mid-cross section of leaves at different developmental stages. The results showed that during the early stages of development (S1-S3), young leaves maintained vigorous division in the lateral direction, while periplasmic division gradually expanded from the bottom to the top of the leaf blade and the number of cell layers stabilized at S4. The meristematic tissues on both sides of the leaf were still able to divide at S4 but the frequency of the division gradually decreased, while cell division and expansion occurred simultaneously between the veins. At S6, the cells at the leaf margins and between the veins were completely differentiated and the width of the leaf blade no longer expanded. These findings revealed changes in cell growth anisotropically during the leaf development of S. kogasensis 'Aureostriatus' and demonstrated that leaf elongation was closely related to the longitudinal expansion of epidermal cells and proliferative growth of mesophyll cells, whereas the cell division of meristematic tissues and expansion of post-divisional cells contributed to the increases in blade width and thickness. The presented framework will facilitate a further exploration of the molecular regulatory mechanisms of leaf development in S. kogasensis 'Aureostriatus' and provide relevant information for developmental and taxonomic studies of bamboo plants.

Hemp Disease Detection and Classification using Machine Learning

The project aims to create an efficient and effective method for the identification and isolation of diseases affecting cannabis plants. Marijuana is a versatile plant with commercial and medicinal uses. The plant is easy to grow and care for and is suitable for all climates. But like other plants, cannabis disease can affect the plant's growth and have a significant financial impact on cannabis production. The project aims to use the power of machine learning to increase the accuracy and speed of disease diagnosis by identifying characteristics such as leaf changes, growth patterns, texture or softness or squishiness. This research aims to improve early detection and management of these diseases in cannabis cultivation by creating a robust model learned from different datasets of cannabis plant images, good models learned from many different cannabis plants.

Mapping understory plant communities in deciduous forests from Sentinel-2 time series

Understory plant communities are an integral component of deciduous forests, playing a vital role in the overall health of the ecosystem. However, remote sensing of understory plant communities is challenging due to the obstruction by the forest canopy. In this study, we proposed an automated dense Sentinel-2 time series-based approach for understory plant communities and created maps of four understory classes (i.e., native shrubs of greenbrier and mountain laurel, and invasive shrubs of barberry and the assemblage of mixed invasive) at 10 m resolution in Connecticut's deciduous forests in 2020. A harmonic time series model and three years of Sentinel-2 time series from 2019 to 2021 were used to classify understory species based on their unique, intra-annual phenology characteristics. The time series model coefficients captured the subtle phenology differences and created synthetic cloud-free images within a short temporal window in the spring prior to canopy leaf-on (hereafter called “observation window”). During the observation window, Sentinel-2 data penetrated the deciduous overstory canopy and observed the unique trajectories of different understory species due to their phenology differences. We also calculated spatial texture features (i.e., mean, second moment, and contrast from gray level co-occurrence matrix) based on the synthetic images created within the observation window to capture the different conditions of leaf growth and distinct spatial patterns within deciduous forests. By using the spectral, temporal, and spatial features as input variables from dense Sentinel-2 data, auxiliary data (i.e., LiDAR and soil drainage layer), a random forest classifier, and a new strategy to iteratively select representative sample (namely ISRS), understory species maps were created with an overall accuracy of approximately 93%, and the user's and producer's accuracies varied from 39% to 99% for the three mapped understory species and one assemblage of species. The proposed method created an accurate binary map of understory presence with an overall accuracy of 95%, a producer's accuracy of 84%, and a user's accuracy of 68%. Additionally, we separated the invasive (i.e. barberry and mixed invasive of multi-flora rose, oriental bittersweet, honeysuckle, winged euonymus, and autumn olive) and native (greenbrier and mountain laurel) species with an overall accuracy of 94%. We estimated that the invasive species cover an area of 649.33 ± 140.59 km2, which occupied a large proportion (∼53%) of the shrub understory in Connecticut's deciduous forests.

Model-based reconstruction of whole organ growth dynamics reveals invariant patterns in leaf morphogenesis.

Plant organ morphogenesis spans several orders of magnitude in time and space. Because of limitations in live-imaging, analysing whole organ growth from initiation to mature stages typically rely on static data sampled from different timepoints and individuals. We introduce a new model-based strategy for dating organs and for reconstructing morphogenetic trajectories over unlimited time windows based on static data. Using this approach, we show that Arabidopsis thaliana leaves are initiated at regular 1-day intervals. Despite contrasted adult morphologies, leaves of different ranks exhibited shared growth dynamics, with linear gradations of growth parameters according to leaf rank. At the sub-organ scale, successive serrations from same or different leaves also followed shared growth dynamics, suggesting that global and local leaf growth patterns are decoupled. Analysing mutants leaves with altered morphology highlighted the decorrelation between adult shapes and morphogenetic trajectories, thus stressing the benefits of our approach in identifying determinants and critical timepoints during organ morphogenesis.

Beilschmiedia weii (Lauraceae), a new species from Dayaoshan Mountain of Guangxi, China

Beilschmiedia weii, a new species of Lauraceae from Dayaoshan Mountain of Guangxi, China, is described and illustrated. It is morphologically most similar to B. wangii and B. rufohirtella in having ferruginous pubescent terminal buds, branchlets, abaxial leaf blades, panicles and fruiting pedicels, but can be easily distinguished from them by the leaf growth pattern, the color of flowers, the length of panicles and fruiting pedicels, the shape and size of fruits, and the phenology. A table to distinguish the new species from other morphologically similar Beilschmiedia species is provided, as well as a color plate.

Disruption of tomato TGS machinery by ToLCNDV causes reprogramming of vascular tissue-specific TORNADO1 gene expression.

Vascular development-related TRN1 transcription is suppressed by cytosine methylation in fully developed leaves of tomato. ToLCNDV infection disrupts methylation machinery and reactivates TRN1 expression - likely causing abnormal leaf growth pattern. Leaf curl disease of tomato caused by tomato leaf curl New Delhi virus (ToLCNDV) inflicts huge economical loss. Disease symptoms resemble leaf developmental defects including abnormal vein architecture. Leaf vein patterning-relatedTORNADO1gene's (SlTRN1) transcript level is augmented in virus-infected leaves. To elucidate the molecular mechanism of the upregulation ofSlTRN1in vivo, we have deployedSlTRN1promoter-reporter transgenic tomato plants and investigated the gene's dynamic expression pattern in leaf growth stages and infection. Expression of the gene was delimited in the vascular tissues and suppressed in fully developed leaves. WRKY16 transcription factor readily activated SlTRN1 promoter in varied sized leaves and upon virus infection, while silencing of WRKY16 gene resulted in dampened promoter activity. Methylation-sensitive PCR analyses confirmed the accumulation of CHH methylation at multiple locations in theSlTRN1promoter in older leaves. However, ToLCNDV infection reverses the methylation status and restores expression level in the leaf vascular bundle. The virus dampens the level of key maintenance and de novo DNA methyltransferases SlDRM5, SlMET1, SlCMT2 with concomitant augmentation of two DNA demethylases, SlDML1 and SlDML2 levels inSlTRN1promoter-reporter transgenics. Transient overexpression of SlDML2 mimics the virus-induced hypomethylation state of theSlTRN1promoter in mature leaves, while silencing of SlDML2 lessens promoter activity. Furthermore, in line with the previous studies, we confirm the crucial role of viral suppressors of RNA silencing AC2 and AC4 proteins in promoting DNA demethylation and directing it to restore activated transcription ofSlTRN1. Unusually elevated expression of SlTRN1 may negatively impact normal growth of leaves.

In Vitro plant regeneration from leaf explants of Tagetes erecta L.

Regeneration of multiple shoots via callus induction and organogenesis was obtained from young leaf explants of the field grown marigold (Tagetes erecta L.). Callus induction and shoot regeneration at various frequencies were observed using different concentrations and combinations of growth regulators. Highest percentage (90%) of callus formation was observed within two weeks on MS medium supplemented with 5.0 mg/l BAP with 2.5 mg/l NAA. The maximum percentage (80%) of shoot bud formation (10±0.5/callus) was obtained from MS medium containing 1.0 mg/l BAP with 0.5 mg/l kinetin. The regenerated shoots developed highest percentages (90%) of roots on half strength MS medium supplemented with 1.0 mg/l IBA. The plantlets when transferred into potsoil 80% survived. Regenerated plants were morphologically uniform with normal leaf shape and growth pattern.
 Bangladesh J. Sci. Ind. Res.56(2), 69-74, 2021

Functional traits, growth patterns, and litter dynamics of invasive alien and co-occurring native shrub species of chir pine forest in the central Himalaya, India

Across the continents, plant invasion is identified as one of the main threats to ecosystem functioning and stability. The main objective of this research was to evaluate the differences in the functional traits between invasive alien (Ageratina adenophora (Spreng.) and Lantana camara L.) and native (Berberis asiatica Roxb. Ex DC., Pyracantha crenulata (D. Don.) M. Roemer and Rubus ellipticus Sm.) shrub species of chir pine (Pinus roxburghii Sarg.) forest in the central Himalaya. Three 0.5 hectare chir pine forest stands were selected and individuals of similar diameter were tagged for comparative studies of leaf traits, growth pattern, and biomass accumulation in structural organs of each invasive alien and native species. Our one-way ANOVA and Tukey’s post hoc test results showed that both the invasive alien species have significantly (p < 0.05) higher SLA, LWC, total chlorophyll content, foliar nutrient (N and P), RGR, LMR, SMR, nutrient uptake, and nutrient use efficiencies than native species. Leaf litter decomposition rate and nutrient release were also significantly (p < 0.05) higher in both the invasive alien species. Native species, R. ellipticus, shared some of the traits, such as leaf area, chlorophyll content, RGR, LAR, LMR, and nutrient uptake efficiency with invasive alien species. The majority of traits differed among invasive alien and native species, implying that the success of invasive alien species is best described by being functionally distinct from native species. These findings indicate that invasive alien species had advanced functional traits which may be playing an important role in a rapid spread in the central Himalaya.

The diel rhythm of leaf growth and cell proliferation in capsicum (Capsicum annuum L.)

Relationship between the diel leaf growth of capsicum and proliferative activity of cells has been investigated using a computer-aided image analysis. It has been established the leaf growth pattern observed in this species allows to refer it to the second type of growth of dicotyledons, which is characterized by the maximum growth rate in the evening or at the beginning of the night. A DNA cytometry study of leaf cells shows that their proliferative activity is also higher at night than during the day. This suggests that the diel rhythm of capsicum leaf growth is due to the synchronization of cell cycle with a lighting.

Spatiotemporal coordination of cell division and growth during organ morphogenesis.

A developing plant organ exhibits complex spatiotemporal patterns of growth, cell division, cell size, cell shape, and organ shape. Explaining these patterns presents a challenge because of their dynamics and cross-correlations, which can make it difficult to disentangle causes from effects. To address these problems, we used live imaging to determine the spatiotemporal patterns of leaf growth and division in different genetic and tissue contexts. In the simplifying background of the speechless (spch) mutant, which lacks stomatal lineages, the epidermal cell layer exhibits defined patterns of division, cell size, cell shape, and growth along the proximodistal and mediolateral axes. The patterns and correlations are distinctive from those observed in the connected subepidermal layer and also different from the epidermal layer of wild type. Through computational modelling we show that the results can be accounted for by a dual control model in which spatiotemporal control operates on both growth and cell division, with cross-connections between them. The interactions between resulting growth and division patterns lead to a dynamic distributions of cell sizes and shapes within a deforming leaf. By modulating parameters of the model, we illustrate how phenotypes with correlated changes in cell size, cell number, and organ size may be generated. The model thus provides an integrated view of growth and division that can act as a framework for further experimental study.

Water relations determine short time leaf growth patterns in the mangrove Avicennia marina (Forssk.) Vierh.

High-resolution leaf growth is rarely studied despite its importance as a metric for plant performance and resource use efficiency. This is in part due to methodological challenges. Here, we present a method for in situ leaf growth measurements in a natural environment. We measured instantaneous leaf growth on a mature Avicennia marina subsp. australasica tree over several weeks. We measured leaf expansion by taking time-lapse images and analysing them using marker tracking software. A custom-made instrument was designed to enable long-term field studies. We detected a distinct diel growth pattern with leaf area shrinkage in the morning and leaf expansion in the afternoon and at night. On average, the observed daily shrinkage was 37% of the net growth. Most of the net growth occurred at night. Diel leaf area shrinkage and recovery continued after growth cessation. The amount of daily growth was negatively correlated with shrinkage, and instantaneous leaf growth and shrinkage were correlated with changes in leaf turgor. We conclude that, at least in this tree species, instantaneous leaf growth patterns are very strongly linked to, and most likely driven by, leaf water relations, suggesting decoupling of short-term growth patterns from carbon assimilation.

A Review of Visual Descriptors and Classification Techniques Used in Leaf Species Identification

Plants are fundamentally important to life. Key research areas in plant science include plant species identification, weed classification using hyper spectral images, monitoring plant health and tracing leaf growth, and the semantic interpretation of leaf information. Botanists easily identify plant species by discriminating between the shape of the leaf, tip, base, leaf margin and leaf vein, as well as the texture of the leaf and the arrangement of leaflets of compound leaves. Because of the increasing demand for experts and calls for biodiversity, there is a need for intelligent systems that recognize and characterize leaves so as to scrutinize a particular species, the diseases that affect them, the pattern of leaf growth, and so on. We review several image processing methods in the feature extraction of leaves, given that feature extraction is a crucial technique in computer vision. As computers cannot comprehend images, they are required to be converted into features by individually analysing image shapes, colours, textures and moments. Images that look the same may deviate in terms of geometric and photometric variations. In our study, we also discuss certain machine learning classifiers for an analysis of different species of leaves.

Different vegetative growth stages of Kimchi cabbage (Brassica rapa L.) exhibit specific glucosinolate composition and content

This study aimed to simultaneously investigate the changes in growth characteristics and glucosinolate (GL) content during different growth stages in Kimchi cabbage. Two Kimchi cabbage cultivars ‘Chuweol’ and ‘HwiparamGold’ were grown in the field and plant characteristics such as leaf length, number and fresh weight, and GL contents were measured weekly from 2 to 9 weeks after transplanting (WAT). The only significant difference between the two cultivars for either plant growth or GL content was observed for GL contents during 3 and 7 WAT. Leaf length increased until 4 WAT and then remained unchanged, exhibiting logarithmic growth. The fresh weight and number of leaves increased linearly until 9 WAT. Five GLs (two aliphatic GLs: progoitrin and gluconapin, two indole GSLs: glucobrassicin and neoglucobrassicin, and one aromatic GL: gluconasturtiin) of the nine GLs investigated in this study (glucoiberin, progoitrin, glucoraphanin, sinigrin, gluconapin, glucobrassicin, gluconasturtiin, 4-methoxy glucobrassicin and neoglucobrassin) were detected in the two cultivars. The contents of these five GLs were similar in the two cultivars during 2 WAT, but gluconapin and gluconasturtiin increased more dramatically than the others. The increasing pattern of total GL more closely resembled the leaf growth pattern than the fresh weight. Our results suggest that the change in total GL content positively correlates to leaf length, and the increase in total GL content is attributed to the increase in the amount of gluconasturtiin and gluconapin during the autumn growing season.

Nitrogen resorption efficiency of 13 tree species of a cool temperate deciduous forest in Central Japan

ABSTRACTThe nitrogen (N) concentration of green and senescent leaves, and the N resorption efficiency of 13 dominant species from three distribution patterns along a slope (Ridge, Valley, and Uniform types) and two types of leaf emergence pattern (determinate and indeterminate flush types) were examined in a cool temperate natural forest in central Japan. Ridge species tended to have lower N concentrations of green and senescent leaves and higher N resorption efficiency than those of Valley species, and those of Uniform species were intermediate to other types with some exceptions. Furthermore, indeterminate flush species tended to have higher N concentrations in green and senescent leaves and lower N resorption efficiency than those of the determinate type. The N concentration of senescent leaves, which is an index of leaf-level N use efficiency (NUE), was significantly correlated with N concentrations in green leaves and with N resorption efficiency. The concentration in green leaves was not correlated with N resorption efficiency, suggesting that interspecific variation in the N concentration was not a major determinate of the N resorption efficiency at this study site. Rather N resorption efficiency was positively correlated with the start date of leaf fall, suggesting that early leaf fall species, which tended to have intermediate leaf flush types (with some exceptions), were not proficient in N resorption. Thus, the patterns in NUE and N resorption efficiencies were affected not only by the distribution pattern along the slope but also by leaf phenology in this cool temperate deciduous forest.

Leaf mottling/variegation and shape in the Ledebouria revoluta complex – Development, stability and putative function

The aims of this paper are three-fold: 1. To analyse the development and stability in vegetative traits such as leaf shape, growth and pigmentation patterns in three different morphotypes (defined by leaf shape and pigmentation) of the Ledebouria revoluta complex. 2. To discuss the putative function of leaf mottling/variegation. 3. To discuss plasticity in these traits in relation to taxonomy and species delimitation within the complex. Clones were analysed in a cultivation experiment with two nitrogen levels (N1 and N2), three morphotypes (A, B & C) and two light levels (L1 and L2). Anthocyanins were found in hypodermal cells, particularly in the proximal (i.e. young) parts of the leaf. The red pigmentation faded out in distal (i.e. more mature) parts of the leaf. Furthermore, older, outer leaves had more pigmentation than younger, inner leaves. Increased nitrogen availability had no effect on leaf pigmentation. Some plants developed significantly more red pigmentation adaxially at high light intensities, whereas abaxial pigmentation was unaffected by light intensity. The pigmentation of the two sides of a leaf therefore seems to be regulated independently and may accordingly serve different functions for the plants. Adaxial pigmentation (mainly in the form of mottling, pigmentation mainly in spots) may serve as photoprotection, whereas abaxial pigmentation (mainly in the form of variegation, pigmentation mainly in bands) may possibly be aposematic. In the field a high degree of intrapopulational variation in pigmentation patterns was observed. This might be due to local habitat heterogeneity and gene flow or frequency dependent selection. Characters relevant to taxonomy (leaf shape, pigmentation pattern) only changed to a limited extent, suggesting that the vegetative traits are genetically based. The three different morphotypes were easily recognized unrelated to the different treatments. Whether a formal taxonomic status is justified for the different morphotypes will need more plant material and genetic data and cannot be decided based on this study.

Microvine : A New Model to Study Grapevine Growth and Developmental Patterns and their Responses to Elevated Temperature

Growing standardized plant material in controlled environment can facilitate the disentangling of the many impacts of climate change on grapevine production and quality. Microvine is a natural gibberellic acid insensitive mutant showing dwarfism, early and continuous flowering along the vegetative axes. It was initially proposed as a model for genetics. In this study, we questioned its suitability to facilitate and hasten the characterization of grapevine vegetative and reproductive growth and development patterns as wells as their responses to temperature elevation. A series of experiments were performed in the greenhouse and in growth chambers under either ‘standard’ (25/15°C days/night) or contrasted (from 22/12°C up to 30/25°C) thermal treatments for several weeks. Under ‘standard’ thermal condition, measured temporal patterns of leaf and berry growth were similar among several phytomers along the main axis allowing us to estimate temporal growth patterns from spatial distribution of organ size. These patterns were stable between independent experiments under similar thermal and irradiance conditions. When plants were exposed to contrasted thermal treatments, leaf emergence rate was found linearly related to average daily temperature allowing us to derive a thermal time based model of development. Under cool thermal conditions (22/12°C), the temporal evolution of biochemical parameters was similar to that classically found for grapevine. However, exposing plants to a + 8°C thermal treatment for 450 °Cd revealed strong alterations of the thermal time based developmental program with either acceleration (leaf and internode growth) or delay (flowering, sugar accumulation in berries), as well as major uncoupling between growth and storage in internodes. These results reveal the potential of Microvine to study grapevine responses to the many facets of climate change.

Corn Response to Climate Stress Detected with Satellite-Based NDVI Time Series

Corn growth conditions and yield are closely dependent on climate variability. Leaf growth, measured as the leaf area index, can be used to identify changes in crop growth in response to climate stress. This research was conducted to capture patterns of spatial and temporal corn leaf growth under climate stress for the St. Joseph River watershed, in northeastern Indiana. Leaf growth is represented by the Normalized Difference Vegetative Index (NDVI) retrieved from multiple years (2000–2010) of Landsat 5 TM images. By comparing NDVI values for individual image dates with the derived normal curve, the response of crop growth to environmental factors is quantified as NDVI residuals. Regression analysis revealed a significant relationship between yield and NDVI residual during the pre-silking period, indicating that NDVI residuals reflect crop stress in the early growing period that impacts yield. Both the mean NDVI residuals and the percentage of image pixels where corn was under stress (risky pixel rate) are significantly correlated with water stress. Dry weather is prone to hamper potential crop growth, with stress affecting most of the observed corn pixels in the area. Oversupply of rainfall at the end of the growing season was not found to have a measurable effect on crop growth, while above normal precipitation earlier in the growing season reduces the risk of yield loss at the watershed scale. The spatial extent of stress is much lower when precipitation is above normal than under dry conditions, masking the impact of small areas of yield loss at the watershed scale.