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The derivatives of aloe plant leave [Aloe vera (L.) Burm. f.], such as gel, juice, and powder, are highly appreciated in the industrial sector. This study evaluated the effect of different soil moisture contents on the growth, production, and gel quality of aloe grown in an arid region of Mexico. The study was conducted in a randomized complete block design with three replicates. Base on the percentage of field capacity (FC), three irrigation treatments were tested: 42%, 72%, and 100% of FC corresponding, on average (± standard deviation), to 0.12 ± 0.02 m³ m-3 (as control), 0.18 ± 0.02 m³ m-3, and 0.24 ± 0.02 m3 m-3 of soil water content, respectively. Aloe plants watered with 72% of FC had greater plant height and leaf width than plants watered at 42% of field capacity, while plants with 100% of FC treatment had the longest (56.1 cm) and thickest (1.5 cm) leaves. Aloe plants irrigated at either 72% or 100% of field capacity produced the freshest leaf biomass and gel. In contrast, plants grown at 42% of field capacity treatments had the highest pH (4.94), total soluble solids (1.77 °Brix), ash content (0.62%), methanolprecipitated solids (1.24%), and total solids (1.88%) of aloe gel. Even though the lowest soil moisture content (42% of field capacity) reduced plant and leaf growth and leaf and gel yields, gel quality was enhanced, meeting the gel quality standards demanded by the international market. [ABSTRACT FROM AUTHOR]

The quality of yield prediction is linked to that of leaf area. We first analysed the consequences of flowering time and environmental conditions on the area of individual leaves in 127 genotypes presenting contrasting flowering times in fields of Europe, Mexico, and Kenya. Flowering time was the strongest determinant of leaf area. Combined with a detailed field experiment, this experiment showed a large effect of flowering time on the final leaf number and on the distribution of leaf growth rate and growth duration along leaf ranks, in terms of both length and width. Equations with a limited number of genetic parameters predicted the beginning, end, and maximum growth rate (length and width) for each leaf rank. The genotype-specific environmental effects were analysed with datasets in phenotyping platforms that assessed the effects (i) of the amount of intercepted light on leaf width, and (ii) of temperature, evaporative demand, and soil water potential on leaf elongation rate. The resulting model was successfully tested for 31 hybrids in 15 European and Mexican fields. It potentially allows prediction of the vertical distribution of leaf area of a large number of genotypes in contrasting field conditions, based on phenomics and on sensor networks. [ABSTRACT FROM AUTHOR]

Introduction: Defoliation and light competition are ubiquitous stressors that can strongly limit plant performance. Tolerance to defoliation is often associated with compensatory growth, which could be positively or negatively related to plant growth. Genetic variation in growth, tolerance and compensation, in turn, plays an important role in the evolutionary adaptation of plants to changing disturbance regimes but this issue has been poorly investigated for long-lived woody species. We quantified genetic variation in plant growth and growth parameters, tolerance to defoliation and compensation for a population of the understorey palm Chamaedorea elegans. In addition, we evaluated genetic correlations between growth and tolerance/compensation. Methods: We performed a greenhouse experiment with 711 seedlings from 43 families with twelve or more individuals of C. elegans. Seeds were collected in southeast Mexico within a 0.7 ha natural forest area. A two-third defoliation treatment (repeated every two months) was applied to half of the individuals to simulate leaf loss. Compensatory responses in specific leaf area, biomass allocation to leaves and growth per unit leaf area were quantified using iterative growth models. Results: We found that growth rate was highly heritable and that plants compensated strongly for leaf loss. However, genetic variation in tolerance, compensation, and the individual compensatory responses was low. We found strong correlations between family mean growth rates in control and defoliation treatments. We did not find indications for growth-tolerance/compensation trade-offs: genetic correlation between tolerance/compensation and growth rate were not significant. Implications: The high genetic variation in growth rate, but low genetic variation in tolerance and compensation observed here suggest high ability to adapt to changes in environment that require different growth rates, but a low potential for evolutionary adaptation to changes in damage or herbivory. The strong correlations between family mean growth rates in control and defoliation treatments suggest that performance differences among families are also maintained under stress of disturbance. [ABSTRACT FROM AUTHOR]

This study aimed to elucidate for the first time the combined effects of marine heatwaves (MHWs) and light limitation simulated in mesocosm on critical physiological descriptors of the surfgrass Phyllospadix torreyi , which constitutes highly productive meadows along the intertidal and subtidal rocky shores of the Pacific coast of North America. Our results revealed that short-term exposure (~7 days) to extreme thermal anomalies of + 9 °C had positive effects on the photosynthetic capacities of P. torreyi , as indicated by increments in maximum photosynthetic rates, photosynthetic efficiency (α), maximum electron transport rate, and effective quantum yield. Despite that its photosynthetic performance was enhanced, exposure to warming caused a decrease in its internal carbon reserves (i.e. energy status), likely as a consequence of carbon mobilization/utilization to activate heat-stress responses. Plants exposed to light limitation (i.e. sub-saturating irradiance of 30 μmol photon m−2 s−1) generally exhibited an increase in α and/or a decrease in respiration, which ultimately allowed for a reduction in plant compensation irradiance. The combination of low light and seawater warming resulted in a decrease in non-structural carbohydrates content, daily net-productivity, and leaf growth rates. Gross photosynthetic rates at control saturating irradiance exhibited higher activation energy and, thus, greater responsiveness to seawater warming than plants kept under light limitation. While our results indicated that unusual warming events might favor the photosynthetic performance of P. torreyi, combining this condition with a drastic light reduction can lead to internal carbon depletion and potentially compromise plant survival in the long term. • First study to assess physiological responses of surfgrass to warming and low light. • Unexpectedly, warming can favor photosynthetic performance of P. torreyi. • Phyllospadix torreyi can partially photoacclimate under light limitation. • Productivity and growth decreased under the combination of low light and warming. • Marine heatwaves combined with low irradiance could compromise P. torreyi survival. [ABSTRACT FROM AUTHOR]

Seagrass beds provide much of the primary production in estuaries; host many fishes and fish larvae, and abate erosion. The present study presents original analytical methods for estimating mean leaf-growth rates of eelgrass (Zostera marina). The method was calibrated by using data collected in a Z. marina meadow at Punta Banda estuary in Baja California, Mexico. The analytical assessments were based on measurements of leaf length and standard regression procedures. We present a detailed explanation of the formal procedures involved in the derivation of these analytical methods. The measured daily leaf-growth rate was 10.9 mm d-1 leaf-1. The corresponding value projected by our method was 10.2 mm d-1 leaf-1. The associated standard errors were of 0.53 and 0.56 mm d-1 leaf-1 respectively. The method was validated by projecting leaf-growth rates from an independent data set, which gave consistent results. The use of the method to obtain the mean leaf growth rate of a transplanted plot is also illustrated. Comparison of our leaf-growth data with previously reported assessments show the significant forcing of sea-surface temperature on eelgrass leaf dynamics. The formal constructs provided here are of general scope and can be applied to equivalent eelgrass data sets in a straightforward manner. [ABSTRACT FROM AUTHOR]