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Resistance (R) to preloaded gas diffusion was used to follow the evolution of R during cherimoya fruit maturation and senescence. Cherimoya ethane diffusion was linear and gave an R value of 2048 ± 167 s·cm-1 for preclimacteric fruit. R increased linearly during maturation, and significant differences were noted between fruit in which diffusion through the stem scar was or was not blocked with petroleum ielly.
Commercial production of pecan [Carya illinoinensis (Wangenh.) K. Koch.] generates significant woody biomass from hedge prunings with little economic value. Value-added uses could aid pecan growers, and one possible use is wood chips for potting substrates to lessen dependence on peatmoss, thereby aiding greenhouse growers. We evaluated vegetative growth and leaf nutrient responses of ‘Carpino’ garden chrysanthemum (Dendranthema ×grandiflorum) over a 60-day period. Plants were grown in five pecan wood chip substrate levels that substituted 0%, 25%, 50%, 75%, and 100% of peatmoss by volume. Three water soluble fertilizer (WSF) rates—N at 0, 200, or 400 mg·L−1 (0–N, 200–N, and 400–N, respectively)—were applied with each irrigation and to each of the wood substitution treatments. The WSF and wood substitution treatments interacted strongly. In the presence of wood, (25−100% substitution levels), increasing WSF to 400–N increased cumulative evapotranspiration (ET), crop height, total leaf number and area, total leaf and stem dry weight, and leaf N and P concentrations. However, with 0% wood substitution, 400−N provided little or no such enhancements. With 25% to 50% wood substitution, root dry weight increased by 61% to 91% from 0–N to 200–N, which may be an adaptive response to nutrient-limiting conditions at 200–N. Appearance of a white rot fungal species in and atop pecan wood-supplemented substrate supports the likelihood that microbial activity was, at least in part, responsible for the nutrient limitations. High WSF at 400–N in combination with 25% pecan wood substitution maintained adequate fertility and shoot growth that was comparable to the conventional peat-only substrate at 200–N. With low to moderate amounts of pecan wood, further adjustments to WSF rate and irrigation volume would support sustainable fertigation practices, reduce dependence on peatmoss by greenhouse industry, and provide a value-added recycling option for pecan growers.
Vanilla planifolia Jacks. is a species of great economic importance, since vanillin, a compound highly valued in the food and pharmaceutical industry, is extracted from its pods. This species is in the category of special protection, so it is important to take actions for its conservation and to maintain the genetic stability of the conserved germplasm. An adequate way to achieve this is through the minimal growth in vitro conservation techniques. The present work aimed to establish an in vitro conservation protocol for vanilla germplasm that allows the genetic stability of the conserved material. For the establishment of the minimal growth in vitro conservation protocol: two concentrations of basal Murashige and Skoog (MS) medium (50% and 100%), two incubation temperatures (4 and 22 °C) and two concentrations of abscisic acid (ABA) (3 and 5 mg⋅L−1) were evaluated. To evaluate the genetic stability of the germplasms used in this study (cultivated, wild, and V. insignis morphotypes) by analyzing the profiles of molecular markers SSR (simple sequence repeats) and ISSR (inter simple sequence repeats). The MS medium (100%) supplemented with 3 mg⋅L−1 of ABA and incubated at 22 °C, was the best treatment for the in vitro conservation of Vanilla spp. Compared with the control treatment, it allowed us to obtain smaller shoots (1.17 × 0.17 cm), which showed high genetic stability, given by the low percentages of polymorphism detected in morphotypes cultivated and wild (SSR 0%, ISSR 2%) and V. insignis (SSR 0%, ISSR 0%). We conclude the usefulness of the established protocol to conserve the genetic variation of the evaluated Vanilla germplasm.
The dendrometer has been proposed as a sensitive plant water indicator based on stem growth. However, studies including dendrometers have been mainly focused on fruit trees and less attention has been paid to ornamental shrubs (small plants). In the study described here, stem dendrometers were used to ascertain whether there is any relationship between water status and dendrometric indices in potted ornamental shrubs (1 to 2 cm diameter). For this purpose, three Mediterranean shrubs (Pittosporum tobira, Callistemon citrinus, and Rhamnus alaternus) were studied under water stress recovery conditions in winter, spring, and early summer. At the end of the experiment, an extreme water stress treatment, which resulted in plant death (August) was also studied. Stem diameter variations [maximum and minimum daily stem values (MXDS and MNDS, respectively), maximum daily shrinkage (MDS), and stem growth rate (SGR)], daily evapotranspiration (daily plant ET), and leaf water potential (Ψleaf) parameters were considered throughout the experiment. A regression analysis between dendrometric indices and daily plant ET showed that MXDS and MNDS were sensitive under water stress recovery conditions, especially in severe environmental conditions (spring and summer). The SGR in C. citrinus, the MDS in P. tobira, and both indices in R. alaternus were seen to be sensitive during the stress to death period. Although more studies are needed, the results confirm that the use of dendrometers in small plants may be useful to provide continuous and automated registers of the plant water status under different substrate water content and climatic conditions. However, the response of these indices may imply moderate water stress.