Coordination of leaf hydraulic, anatomical, and economical traits in tomato seedlings acclimation to long-term drought

Background Leaf hydraulic and economics traits are critical for balancing plant water and CO2 exchange, and their relationship has been widely studied. Leaf anatomical traits determine the efficiency of CO2 diffusion within mesophyll structure. However, it remains unclear whether leaf anatomical traits are associated with leaf hydraulic and economics traits acclimation to long-term drought. Results To address this knowledge gap, eight hydraulic traits, including stomatal and venation structures, four economics traits, including leaf dry mass per area (LMA) and the ratio between palisade and spongy mesophyll thickness (PT/ST), and four anatomical traits related to CO2 diffusion were measured in tomato seedlings under the long-term drought conditions. Redundancy analysis indicated that the long-term drought decreased stomatal conductance (gs) mainly due to a synchronized reduction in hydraulic structure such as leaf hydraulic conductance (Kleaf) and major vein width. Simultaneously, stomatal aperture on the adaxial surface and minor vein density (VDminor) also contributed a lot to this reduction. The decreases in mesophyll thickness (Tmes) and chlorophyll surface area exposed to leaf intercellular air spaces (Sc/S) were primarily responsible for the decline of mesophyll conductance (gm) thereby affecting photosynthesis. Drought increased leaf density (LD) thus limited CO2 diffusion. In addition, LMA may not be important in regulating gm in tomato under drought. Principal component analysis revealed that main anatomical traits such as Tmes and Sc/S were positively correlated to Kleaf, VDminor and leaf thickness (LT), while negatively associated with PT/ST. Conclusions These findings indicated that leaf anatomy plays an important role in maintaining the balance between water supply and CO2 diffusion responses to drought. There was a strong coordination between leaf hydraulic, anatomical, and economical traits in tomato seedlings acclimation to long-term drought.

Smarter Robotic Sprayer System for Precision Agriculture

The automation of agricultural processes is expected to positively impact the environment by reducing waste and increasing food security, maximising resource use. Precision spraying is a method used to reduce the losses during pesticides application, reducing chemical residues in the soil. In this work, we developed a smart and novel electric sprayer that can be assembled on a robot. The sprayer has a crop perception system that calculates the leaf density based on a support vector machine (SVM) classifier using image histograms (local binary pattern (LBP), vegetation index, average, and hue). This density can then be used as a reference value to feed a controller that determines the air flow, the water rate, and the water density of the sprayer. This perception system was developed and tested with a created dataset available to the scientific community and represents a significant contribution. The results of the leaf density classifier show an accuracy score that varies between 80% and 85%. The conducted tests prove that the solution has the potential to increase the spraying accuracy and precision.

Physical structure and biological composition of canopies in tropical secondary and old-growth forests

The area of tropical secondary forests is increasing rapidly, but data on the physical and biological structure of the canopies of these forests are limited. To obtain such data and to measure the ontogeny of canopy structure during tropical rainforest succession, we studied patch-scale (5 m2) canopy structure in three areas of 18–36 year-old secondary forest in Costa Rica, and compared the results to data from old-growth forest at the same site. All stands were sampled with a stratified random design with complete harvest from ground level to the top of the canopy from a modular portable tower. All canopies were organized into distinct high- and low-leaf-density layers (strata), and multiple strata developed quickly with increasing patch height. The relation of total Leaf Area Index (LAI, leaf area per area of ground) to patch canopy height, the existence of distinct high and low leaf- density layers (strata and free air spaces), the depth and LAI of the canopy strata and free air spaces, and the relation of the number of strata to patch canopy height were remarkably constant across the entire successional gradient. Trees were the most important contributor to LAI at all stages, while contribution of palm LAI increased through succession. We hypothesize that canopy physical structure at the patch scale is driven by light competition and discuss how this hypothesis could be tested. That canopy physical structure was relatively independent of the identity of the species present suggests that canopy physical structure may be conserved even as canopy floristics shift due to changing climate.

How Do Soil Resources Affect Herbivory in Tropical Plants Along Environmental Gradients? A Test Using Contrasting Congeneric Species

Plants adapted to different habitats exhibit differences in functional traits and these characteristics are influenced by soil properties. We tested the hypothesis that soil resource availability influences the functional traits of plants, affecting therefore herbivory levels. We examined three Byrsonima plant species with different life forms that occurred across a distinct edaphic habitat along the Doce River Basin, South-eastern Brazil. We characterize habitats according to soil nutrient concentration and measured functional characteristics of crown architecture, leaf nutrients, sclerophylly, leaf area and leaf density. In addition, we evaluated how these variables influenced herbivory levels of congeneric plants. Our data have shown that species along a gradient of soil nutrients have functional characteristics influenced by habitat, which in turn affected herbivory levels. By comparing species from different life forms but within the same genus along a stress-gradient of continuous habitats, we described a corresponding gradient of plant functional traits and tissue consumption by herbivorous insects.

Effects of spatial heterogeneity of leaf density and crown spacing of canopy patches on dry deposition rates

<p>Trees have a large role in improving urban air quality, among other mechanisms, through dry deposition of scalars and aerosols on leaf surfaces. We tested the role of leaf density and canopy structure in modulating the rate of dry deposition. We simulated the interactions between a virtual forest patch and deposition rate of an arbitrary scalar using the Parallelized Large Eddy Simulation Model (PALM). Two canopy structures were considered: a homogenous canopy; and canopy stripes perpendicular to the wind direction. For each canopy stripe scenario, we considered thin, intermediate, and wide stripes, while the space between stripes equals the stripes’ width. Four leaf area densities were considered for each case. The results showed that stripes perpendicular to the wind direction had a larger deposition per leaf area than homogeneous canopies, and denser canopies had more total deposition, but lower per-leaf area rate. Our results can be explained by canopy-induced turbulence structures that couple the air within and above the canopy and lead to more effective leaf area where this coupling is stronger. We aggregate our results to the whole-patch scale and suggest a canopy-structure and leaf-area dependent correction to the canopy resistance parameter so to be used in coarse models that resolve dry deposition. </p>

Morphometry of leaf and shoot variables to assess aboveground biomass structure and carbon sequestration by different varieties of white mulberry (Morus alba L.)

Mulberry is economically important and can also play a pivotal role in mitigating greenhouse gases. Leaf and shoot traits were measured for Morus alba var. Kanmasi, M. alba var. Karyansuban, M. alba var. Latifolia, and M. alba var. PFI-1 to assess aboveground biomass (AGB) and carbon sequestration. Variety-specific and multivariety allometric AGB models were developed using the equivalent diameter at breast height (EDBH) and plant height (H). The complete-harvest method was used to measure leaf and shoot traits and biomass, and the ash method was used to measure organic carbon content. The results showed significant (p < 0.01) varietal differences in leaf and shoot traits, AGB and carbon sequestration. PFI-1 variety had the greatest leaf density (mean ± SE: 1828.3 ± 0.3 leaves tree−1), Karyansuban had the largest mean leaf area (185.94 ± 8.95 cm2). A diminishing return was found between leaf area and leaf density. Latifolia had the highest shoot density per tree (46.6 ± 1.83 shoots tree−1), total shoot length (264.1 ± 2.32 m), dry biomass (16.69 ± 0.58 kg tree−1), carbon sequestration (9.99 ± 0.32 kg tree−1) and CO2 mitigation (36.67 ± 1.16 kg). The variety-specific AGB models b(EDBH) and b(EDBH)2 showed good fit and reasonable accuracy with a coefficient of determination (R2) = 0.98–0.99, standard error of estimates (SEE) = 0.1125–0.3130 and root mean square error (RMSE) = 0.1084–0.3017. The multivariety models bln(EDBH) and (EDBH)0.756 showed good-fitness and accuracy with R2 = 0.85–0.86, SEE = 1.6231–1.6445 and RMSE = 1.609–1.630. On the basis of these findings, variety Latifolia has good potential for biomass production, and allometric equations based on EDBH can be used to estimate AGB with a reasonable accuracy.

Determination of the relatedness, ease of hybridization and gene exchange among members of the genus Capsicum in Nigeria

The fruit of Capsicum plants have a variety of names depending on place and type. This research was focused at studying the exchange of genes amongst members of the genus Capsicum in Nigeria. The process of interspecific and intervarietal hybridization of two (2) species of the genus Capsicum; C. annuum and C. frutasense were carried out and the results show that most of the studied attributes like arrangement of leaves, shape of leaves, leaf density were undetermined while majority with distinct changes follow maternal inheritance. There were less successes among the interspecific crosses and high successes between varietal crosses ranging from 19.5% to 2.4% for the inter-varietal cross and 9.3% to 2.4% for interspecific crosses. This indicates that there are more hybridization barriers among interspecific hybridization than inter-varietal hybridization. The closely related species and varieties had higher percentage success of hybridization and vice versa. Characters such as Hypocotyl colour had partial dominance. Erect flower position is dominant in W and hybrid T*W while pendant is recessive. Red fruit colour at maturity, green fruit stalk colour was dominant while yellow was recessive. A good knowledge of how related species of the genus Capsicum are, the easier it will enable researchers to hybridize and improve the genus.