Potted Pepper Plants Research Articles

Inibidor da biossíntese de giberelinas em pimenteiras ornamentais

ABSTRACT The objective of this study was to evaluate whether the inhibition of gibberellin biosynthesis affects the morphophysiological traits of potted ornamental Capsicum baccatum and Capsicum annuum growing under shade house conditions. Plants maintained in 2.7 L pots were arranged in a completely randomized design in a 2x4 factorial consisting of two pepper cultivars Chapéu-de-frade (C. baccatum) and Vulcão (C. annuum) and four paclobutrazol (PBZ) concentrations (0, 25, 50, and 75 mg L-1) with four replicates. At 30, 45, and 60 days after treatment, the plants were analyzed, and data were submitted to the analysis of general and regression variance. Gibberellin biosynthesis inhibition affected the morphophysiological and biochemical evaluations. For most evaluated traits, no interaction between factors was observed, suggesting that both pepper cultivars had a similar response to the growth regulator. PBZ-induced inhibition of gibberellin biosynthesis improved plant water status, which enhanced the vigor of potted pepper plants. The dramatic reduction of upper leaves promoted by plant growth regulators compared to basal ones negatively impacted the visual ornamental aspect of Chapéu-de-frade peppers.

Sensitivity of ornamental pepper to ethylene

ABSTRACT The genus Capsicum has varying levels of sensitivity to ethylene. Variability knowledge allows planning post-production methodologies of potted pepper plants and can be used in breeding programs. The objective of this study was to evaluate the ethylene sensitivity of three ornamental pepper genotypes of the germplasm bank of Universidade Federal de Viçosa. Pepper plants were exposed to 10 μL L-1 ethylene during 48 hours. The flowers were highly sensitive to exogenous ethylene in all genotypes except Pimenta colorida which was moderately sensitive. Regarding leaf abscission, Pimenta colorida and Pimentão ornamental are classified as highly sensitive to ethylene application. Already the fruits responded with the early appearance of the typical coloration when ripe, except for Pimenta laranja. When fruits fell, the highest rates were observed for green fruits, followed by ripe green and ripe fruits.

Baseline sensitivity of Phytophthora capsici to the strobilurin fungicide benzothiostrobin and the efficacy of this fungicide

Phytophthora capsici Leonian is a destructive oomycete plant pathogen that causes diseases in a wide range of crops worldwide. Benzothiostrobin is a broad-spectrum strobilurin fungicide that may control pepper Phytophthora blight. In the current study, the sensitivities of 90 P. capsici isolates collected from different regions in southern China to benzothiostrobin were measured. The curative and protective effects of benzothiostrobin against pepper Phytophthora blight were also determined. The formation of sporangia was inhibited by lower concentrations of benzothiostrobin, approximately 1 μg mL−1 on V8 media, than was necessary to inhibit zoospore discharge. The frequency distribution curve for the benzothiostrobin sensitivity was unimodal with mean EC50 values of 1.84 ± 0.24, 0.60 ± 0.10 and 4.44 ± 0.27 for inhibiting mycelial growth, sporangia formation and zoospore discharge, respectively. The P. capsici isolates used in this study exhibited decreased sensitivity to several commonly used effective fungicides, including mefenoxam, cyazofamid, fluazinam and propamocarb. Furthermore, benzothiostrobin had no cross-resistance with azoxystrobin, pyraclostrobin or famoxadone. The disease severity of pepper Phytophthora blight on pepper leaves and plants was dramatically reduced by benzothiostrobin application of 150 μg mL−1. Benzothiostrobin provided both curative and protective properties against pepper Phytophthora blight on detached pepper leaves and potted pepper plants, with greater protective activity than curative activity. These results suggested that benzothiostrobin may be used for the management of P. capsici.

Feeding History Affects Intraguild Interactions between Harmonia axyridis (Coleoptera: Coccinellidae) and Episyrphus balteatus (Diptera: Syrphidae).

While the effect of several factors such as predator and prey size, morphology and developmental stage on intraguild predation (IGP) is widely investigated, little is known about the influence of diet on the occurrence and outcome of IGP. In the present study, the effect of the diet experienced during larval development on IGP between the ladybird Harmonia axyridis and the syrphid Episyrphus balteatus is investigated. Four diets were tested for H. axyridis: eggs of the Mediterranean flour moth Ephestia kuehniella, pea aphids, Acyrthosiphon pisum, in an ad libitum amount, pea aphids in a limited amount, and honey bee pollen. For E. balteatus only the two aphid diets were tested. First, experiments were performed to determine the quality of the various diets for development of both predators. Second, IGP experiments between H. axyridis and E. balteatus were performed both in Petri dishes and on potted pepper plants. The diet of both species influenced the incidence of IGP between H. axyridis and E. balteatus both in Petri dishes and on potted plants. In general, smaller larvae of H. axyridis (those fed on poor or restricted diet) fed more on hoverflies than large (well-nourished) ladybird larvae. Further, poorly nourished (smaller) larvae of E. balteatus were more susceptible to predation than well-fed (larger) hoverfly larvae. The observed effects were not only due to the lower fitness of larvae of both predators reared on an inferior quality diet but also to changes in predator behaviour. The results from this study show that IGP interactions are influenced by a multitude of factors, including feeding history of the organisms involved, and emphasize the importance of taking these factors into account in order to fully understand the ecological relevance of IGP.

Biocontrol of Late Blight Disease (Phytophthora capsici) of Pepper and the Plant Growth Promotion byPaenibacillus ehimensisKWN38

AbstractFor field application of a bacterial strain used to controlPhythophthora capsici, we will need a biologically and economically efficient carrier medium. The known antagonistPaenibacillus ehimensisKWN38 was grown in a grass medium where it showed high antifungal and lytic enzyme activities. To demonstrate the potential ofP. ehimensisKWN38 for biocontrol of late blight disease in pepper, pot trials were conducted by treating the 1‐month‐old plants with water (W), a selected grass medium (G3),GplusP. ehimensisKWN38 inoculation (G3P) or synthetic fungicide (F). The shoot dry weight inG3Pwas higher than that inWandFtreatments at 15 days after zoospore infection (DZI). The root dry weight inG3Pwas also higher than that inW. The root mortality ofG3 andWincreased over 58 and 80% at 15 DZI, and some plants in those treatments wilted due to the failure of root physiology. The plants inG3PandFsurvived well because of their better root health conditions. Soil cellulase activity ofG3Pwas consistently higher than that ofWandFat earlier observation times (0, 2 and 6 DZI). The rootβ‐1,3‐glucanase activity ofG3Ppromptly increased to maximum shortly after zoospore infection and reached the maximum value of 51.12 unit g−1of fresh weight at 2 DZI. All these results indicate that inoculation ofP. ehimensisKWN38 to the root zone of potted pepper plants increases plant growth, root and soil enzyme activities and alleviates the root death caused by infection withP. capsicizoospores.

Influence of Sub- Versus Top-irrigation and Surfactants in a Recirculating System on Disease Incidence Caused by Phytophthora spp. in Potted Pepper Plants

Zoospores of Phytophthora capsici spread from inoculated source plants to healthy potted pepper plants located on separate ebb-and-flow benches when the recycled nutrient solution originated from a common reservoir. Amending the recirculating nutrient solution with a surfactant, which selectively kills zoospores, resulted in 100% control of the spread of the pathogen in an ebb-and-flow and a top-irrigated cultural system. Without a surfactant in the recirculating nutrient solution, all plants in an ebb-and-flow cultural system died within 6 weeks. In contrast, all plants in a top-irrigated cultural system died within 2 weeks after inoculation of source plants. These results suggest that the use of recycled irrigation water in an ebb-and-flow cultural system is less conducive to pathogen spread than its use in a top-irrigated cultural system, but may still serve as efficient means of inoculum movement in the absence of control measures.