ABSTRACT Perennial ryegrass is one of the most important food sources in animal production. However, several pests affect this crop, and one of the primary control strategies is the symbiotic relationships between ryegrass endophyte fungi. This fungus produces alkaloids that exhibit toxic activity against arthropods. Furthermore, the effect of fungi may extend to higher trophic levels, including predators (spiders and/or insects), decreasing their abundance and diversity. Given the importance of spiders and insects as predators, whether the symbiotic interaction between perennial ryegrass and endophyte fungus reduces the abundance and diversity of predators pose an important question. To address this question, natural enemies in perennial ryegrass were collected and analyzed over a year, and the percentage of endophyte fungus was evaluated by the presence of hyphae from two ryegrass cultivars, Jumbo (E-) and Alto AR1 (E+). We observed an 80% endophyte infection rate for (E+) and 0% for (E-). Moreover, 222 individual spiders corresponding to 10 families were identified in both perennial ryegrasses, including 209 individuals for (E-) and 13 for (E+). The most abundant spider family was Lycosidae, representing 71.17% of the total spiders. In addition, 65 insects were collected, corresponding to 6 families, with Carabidae being the most abundant. Furthermore, the Simpson index indicated the dominance of the family Lycosidae. Overall, spider and insect abundance and diversity were reduced in (E+), suggesting a negative effect of the endophyte on predator populations.

Abstract Integrated Nutrition Management (INM) is a concept developed during the last decade in fruit agroecosystems based on the application of organic matter, biostimulants, and adjusted chemical fertilization to improve soil quality, plant rhizogenesis, and nutrition. Nevertheless, there are few studies on the application of the INM concept on the recovery of decayed orchards. The present study was focused on the evaluation of the effects of INM on soil and plant quality changes as recovery indicators of a decayed pear orchard. Two treatments (T1: conventional, T2: INM) were evaluated under three tree vigor levels, during two growing seasons. Old pear trees were used in a factorial experiment of two treatments (control and INM) x three vigor levels, based on a previous aerial Normalized Difference Vegetation Index (NDVI) image. Soil properties, nutrient leaf contents, and NDVI were evaluated. Soil chemical and biological properties and their spatial variability were determined after two and five years of treatment application, respectively. The INM improved β-glucosidase activity, reduced bulk density, and increased soil porosity. Furthermore, nutrient indices (NDVI x N, K, Ca, Mg, Cu, Fe, and B) were significantly increased under INM. After two years, soil chemical properties and root density were improved by INM. A significantly higher yield, soil organic matter, soluble C, and dehydrogenase activity was observed with INM after five growing seasons. The results indicated that INM is a sustainable alternative for recovering decayed orchards, through the inclusion of good-quality organic matter within the management program.

Abstract Microbial inoculant based on beneficial bacteria is a complementary management tool to increase vegetable production. However, its integration with chemical fertilization has been poorly studied. The present study evaluated the effects of microbial inoculant separately and in combination with chemical fertilization on lettuce under greenhouse conditions. An experiment was performed in pots using a completely randomized design. The microbial inoculant was applied at three fertilization levels. Soil response evaluated variables were: available N and P, total soil bacteria, soil enzymatic activities, and N leaching. Agronomic variables measured were: aerial biomass, chlorophyll content, and nutrient foliar contents. Microbial inoculant had a significant impact on soil total bacteria concentration. The application of reduced chemical fertilization and microbial inoculant had a similar effect in terms of soil nutrient availability and soil enzymatic activities as the complete fertilization. Nitrogen leaching was strongly dependent on chemical fertilization rate. Treatment application decreased chlorophyll concentration compared to the control. The application of microbial inoculant and chemical fertilization increased foliar N and P contents improving their uptake. The combined addition of microbial inoculant with chemical fertilization increases the bacteria concentration without altering enzymatic activities, maintaining similar soil nutrient levels and improving N and P uptake in lettuce. Future studies could be performed in lettuce to determine the impact under different growth stages and different soil conditions.

Abstract The application of different organic matter sources as soil amendments is a common practice to stimulate root development and soil quality to improve crop yield and quality. For evaluating the effect of organic amendments on soil quality indicators and agronomic variables in table grape (Vitis vitifera) var Thompson seedless, different treatments including compost from grape pomace, humic extract, microbial inoculant, and chemical NPK fertilization, were evaluated in a pot experiment using an Inceptisol soil. Organic materials were applied in four C rates: compost, 0, 125, 250 y 500 g C pot-1; humic extract, 0, 25, 50 and 100 g C pot-1; compost and humic extract at their maximum C rates were also evaluated in absence of chemical fertilization, and microbial inoculant as bio-stimulant. Results showed a stronger root development in plants with compost and inoculant application. Furthermore, organic matter mineralization increased nutrient availability; this was evidenced by an increment of enzymatic activities, particularly β-glucosidase, acid phosphatase, and alkaline phosphatase, in all treatments receiving compost. On the other hand, the application of humic extract produced a larger increment in WSC per carbon unit applied compared to compost, meaning that the former would be more efficient than the latter to provide C for soil microorganisms. This study showed that the joint application of compost, mineral fertilizer, and microbial inoculant should be considered to improve root development in Table grape (Vitis vinifera L.) and soil quality, under Integrated Nutrient Management (INM) programs.