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  • Author or Editor: Hermann Restrepo-Díaz x
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The bean crop is of great importance for human consumption as a source of protein. One of the most limiting insect pests of this crop in Colombia is the whitefly, Trialeurodes vaporariorum (Westwood). Currently, various nonchemical pest control alternatives for cleaner production are being sought. This study aimed to determine the influence of kaolin on the development of populations of whitefly in greenhouses, and its effect on the physiological characteristics of the bean crop [Phaseolus vulgaris (L.)]. This work was conducted in the greenhouses of the Universidad Nacional de Colombia, in Bogotá. Three experiments were carried out and four treatments were evaluated: 1) control (without any insecticide), 2) synthetic chemical insecticides, and foliar applications of kaolin at 3) 2.5%, and 4) 5% (W/V). Generally, the results showed a high percentage of efficacy (≈91%) on whitefly control in plants treated with 5% kaolin, compared with the plants not treated with insecticides in the three different experiments. In addition, foliar applications of kaolin decreased transpiration by 40% and enhanced by 43% the contents of leaf chlorophyll without affecting bean yield. In conclusion, the use of kaolin particle can be considered as an alternative tool in a program of agricultural management on the bean crop since it can control a high percentage of whitefly and it may help the plant physiology, especially under conditions of abiotic stress such as drought stress.

Free access

Physalis peruviana L. crops are exposed to different stress conditions that limit their productivity. Within these conditions, abiotic stress caused by water and biotic stress by Fusarium oxysporum f. sp. physali (Foph) are frequent at commercial levels. The foliar application of synthetic elicitors can be a tool to mitigate the negative impacts of these stresses. The objective of this study was to evaluate the interaction between Foph inoculation and three foliar applications of brassinosteroids (BR), salicylic acid (SA), and a commercial elicitor based on botanical extracts (BE) of Echinacea purpurea, Potentilla erecta, and Aloe vera on the physiological [stomatal conductance (g S), leaf water potential (Ψwf), chlorophyll fluorescence, and growth] and biochemical [photosynthetic pigments, malondialdehyde (MDA) production, and proline content] responses of cape gooseberry plants subjected to a 6-day waterlogging period. The established treatments were as follows: 1) waterlogged plants without Foph; 2) waterlogged plants with Foph; 3) waterlogged, noninoculated (Foph) plants treated foliarly with BR, SA, or BE; and 4) waterlogged, inoculated (Foph+) plants treated foliarly with BR, SA, or BE. The results showed that the foliar application of BR or SA reduced vascular wilt development in plants subjected to a hypoxia period. In addition, three applications of BR, SA, or BE favored g S, Ψwf, growth, and chlorophyll fluorescence parameters in cape gooseberry plants under the interaction between Foph and oxygen deficit in the soil. Also, higher photosynthetic pigment and proline contents were observed in plants treated with elicitors under stress combination, whereas a lower MDA production was evidenced in this group of plants. In conclusion, BR, SA, or BE can help mitigate the negative effects of the simultaneous occurrence of Foph and a waterlogging condition for 6 days in cape gooseberry plants.

Open Access

Bean crops can be displaced to marginal areas or face abiotic stresses such as water deficit. Physiological responses allow the identification of tolerant genotypes and lead to more precise breeding strategies. The objective of this research was to evaluate the physiological (leaf gas exchange properties, leaf water content, and leaf thickness) and biochemical [proline and malondialdehyde (MDA)] responses of five common bush bean (Phaseolus vulgaris L.) cultivars (ICA-Cerinza, ICA-Bachue, NUA35, Bianca, and Bacatá) under a water shortage period by irrigation suspension (15 days) at two different phenological stages [vegetative: 40–55 days after seed emergence (DAE) or reproductive: (50–65 DAE)]. A completely randomized block design was carried out with a factorial arrangement (the phenological stage as the main factor and the cultivars as the secondary factor) for a total of 10 treatments with four repetitions per treatment. Leaf photosynthesis (P n ) showed equal photosynthesis values in control plants of all cultivars (≈20 μmol·m−2·s−1). The water deficit period reduced P n close to 55% (≈12 μmol·m−2·s−1) at both, vegetative, or reproductive stage in all cases. Similar results were also observed on leaf thickness, with a reduction of ≈10% in water-stressed plants at either vegetative or reproductive stage in all evaluated cultivars. A higher MDA and proline production were observed in plants affected by a 15-day water deficit period, mainly at the vegetative stage. The obtained results suggest that the vegetative stage presented a more negative impact on the evaluated physiological variables in most of the cultivars used. Cultivar Bachue showed lower gas exchange properties affectation and higher proline content, which may indicate that this cultivar can be tolerant to water deficit stress conditions. This study allows suggesting that proline and MDA estimation are simple, fast, and low-cost techniques to screen cultivars to obtain more precise breeding selection in common bean. Finally, common bean cultivar selection through the use of biochemical markers can be complemented by the estimation of leaf gas exchange parameters at different phenological stages.

Free access

Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is the most serious threat to the global citrus industry, and its management has mainly depended on the application of chemical insecticides. The use of biopesticides can play an important role in regulating this pest. In a first test, two separate experiments were conducted in two different municipalities (Apulo and Jerusalen, Cundinamarca, Colombia) to evaluate the effect of foliar Beauveria bassiana and imidacloprid sprays on ACP populations in 2015 and 2016, respectively. In a second test, two separate tests were carried out in commercial Tahiti lime orchards to evaluate the efficacy of three different commercial biopesticides (Beauveria bassiana and extracts of Sophora sp. and garlic-chili pepper). In test 1, imidacloprid-treated trees showed a reduction (60% and 80%) in cumulative ACP adults in 2016. ACP cumulative nymphs were also diminished by foliar imidacloprid and B. bassiana application, between 40% and 65% in 2015 and 2016, respectively. ACP cumulative eggs showed lower individuals in imidacloprid-treated flushes at 3 and 4 weeks after treatment 9 (WAT) in 2016. In test 2, the results obtained showed ACP adults and eggs unaffected by biopesticide treatments; nymphs were reduced 50% to 75% in trees treated with the three biopesticides in comparison with control trees. All three biopesticides tested can be considered useful tools in integrated pest management (IPM) programs for ACP, since these products reduced immature ACP individuals between 50% and 75% under field conditions.

Free access

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is the most serious threat to the global citrus industry, and its management has depended mainly on the application of chemical insecticides. The application of plant elicitors can contribute to the insect management and also enhance plant physiology. A set of three different experiments was carried out to evaluate the efficacy of foliar applications of synthetic elicitors [salicylic acid (SA), brassinosteroids (Br), chitosan, or thiamine] on the population dynamics of D. citri and their effects on the physiology of Tahiti lime trees. The treatments were as follows: trees were sprayed separately with thiamine, SA, or chitosan at a dose of 100 ppm, respectively; trees were treated with foliar brassinosteroid applications at a dose of 1 ppm; and untreated trees (control). By the end of the experiment, the elicitors reduced (75%) the number of adult psyllids compared with the control, where trees treated with chitosan had ≈0.5 adult individuals accumulated per flush shoot, whereas the control showed around two individuals. Salicylic acid and thiamine also reduced the number of nymphs compared with the control in the 4 weeks after treatment (WAT) (5.5 vs. 10.08 nymphs, respectively). Treatment with synthetic elicitors also caused a 30% reduction in oviposition by D. citri. The foliar applications with Br promoted a greater relative growth rate (RGR) (44 mm·cm−1·d−1) compared with the control treatment and chitosan (24 and 26 mm·cm−1·d−1, respectively). Chitosan sprays favored proline synthesis in both flush shoots and leaves. These results suggest that the use of synthetic elicitors can be considered as a tool to reduce the number of applications of chemical insecticides and decrease the development of resistances by D. citri because these synthetic elicitors showed an efficacy between 40% and 60% in all its stages in field conditions.

Free access

Vascular wilt caused by Fusarium oxysporum f. sp. physali is the most limiting disease in cape gooseberry crops. The use of natural products such as organic additives is a promising alternative for management of this disease. The present study sought to evaluate the physiological response of cape gooseberry plants infected with this pathogen and treated with the organic additives chitosan, burned rice husks, or their mixture. The test was conducted under greenhouse conditions and soil was inoculated with F. oxysporum f. sp. physali strain Map5. Chitosan was applied to seeds and seedlings at the time of transplantation, whereas burned rice husk was incorporated into the soil in a 1:3 ratio. Plants inoculated and not inoculated with the pathogen were used as controls. The following variables were evaluated: area under the disease progress curve (AUDPC), leaf water potential, stomatal conductance (g S), leaf area (LA), dry matter accumulation, photosynthetic pigment contents, proline synthesis, and lipid peroxidation estimation [malondialdehyde (MDA)]. The results showed that cape gooseberry plants with vascular wilt and treated with chitosan had higher g S, leaf water potential, LA, dry matter accumulation, and proline content values. In addition, the levels of vascular wilt severity decreased in comparison with pathogen-inoculated controls. The results suggest that chitosan applications on cape gooseberry plants may be considered as an alternative in the integrated management of the disease in producing areas, because they can mitigate the negative effect of the pathogen on plant physiology.

Open Access