ABSTRACT The effect of silicon (Si) on fitness and leaf consumption of the fall armyworm (FAW), Spodoptera frugiperda (Smith), has been observed in the laboratory, but the effects of Si on damage or defoliation reduction have not yet been determined under field conditions. Here, we evaluated the effects of amendment of soil with Si on defoliation by FAW and crop yield in maize. Two field experiments were carried out, with four doses of Si and a control (no Si amendment). Experiment #1 evaluated 150, 300, 450, and 600 kg of total Si·ha-1, with natural or manual infestation with FAW eggs, while Experiment #2 tested 600, 800, 1,000 and 1,200 kg of total Si·ha-1, with natural or manual infestation with FAW larvae. Defoliation reduction was observed with Si increasing in both Experiments #1 and #2. However, reduction was not observed in all evaluations, and it was dependent of infestation (natural and manual) and the time since manual infestation. Reduction in defoliation began at 600 kg Si·ha-1. In contrast, plant Si content increased linearly with increasing soil Si application. No effect of Si application was observed on maize kernel yield. The increase in leaf Si content reduced FAW defoliation, but it did not affect maize yield from 600 to 1,200 kg·ha-1 of Si. Amendment of soil with Si can be used as a strategy to optimize integrated pest management of FAW in maize.

ABSTRACT The objective of this study was to evaluate the germination process of lettuce (Lactuca sativa L.) and salad rocket (Eruca sativa L.) storead cypselae/seeds, both organic and conventional, to verify if one is more suited for seed production. The cypselae/seeds were stored in metal containers in a cold chamber. Then, they were placed inside Gerbox boxes in a Mangelsdorf germinator set at 20 °C, under continuous fluorescent white light. Germination capacity, time, rate, uniformity, and synchrony were then measured. The experimental design applied to lettuce was completely randomized with 2 varieties x 2 systems (organic, and conventional), with five repetitions of 25 seeds each. The design chosen for the salad rocket followed a similar rationale, with two systems (organic and conventional), comprised of ten repetitions of 25 seeds each. The assumptions were tested, followed by ANOVA, average tests, and charts as functions of time. Lettuce cypselae withstood storage for ten years, maintaining their viability and germination pattern over time. The cypselae in the conventionally-grown Rainha de Maio cultivar were more suitable, while for the Quatro Estagoes cultivar, the organically-grown ones which were proved to be more suitable. Both conventional and organic salad rocket seeds remained viable for more than nine years. The conventional seeds were faster, more uniform, and presented a greater synchronization index, nevertheless.

RESUMEN El objetivo del estudio evaluó el proceso germinativo de cipselas/semillas almacenadas de lechuga y rúcula de sistemas orgánicos y convencionales. El almacenamiento fue en envases de metal dentro de cámara fría, fueron acondicionadas en cajas Gerbox, en germinador Mangelsdorf a 20 °C, bajo luz blanca fluorescente continua. Se calcularon medidas de capacidad, tiempo, veloci dad, uniformidad y sincronización. El delineamiento para lechuga fue completamente casualizado con 2 cultivares x 2 sistemas (orgánico y convencional), con cinco repeticiones de 25 semillas. Para rúcula el delineamiento fue el mismo con dos sistemas (orgánico y convencional), con diez repeticiones de 25 semillas. Se probaron las presuposiciones, seguido del análisis de varianza, comparación de medias y gráficos en función al tiempo. Las cipcelas de lechuga toleran el almacenamiento durante diez años, manteniendo la viabilidad y el patrón de germinación a lo largo del tiempo. Sin embargo, la respuesta es particular por genotipo, las cipcelas de la cv. Rainha de Maio convencionales son más aptas, mientras que para la cv. Quatro Esta^oes las orgánicas se muestran viables. Las semillas de rúcula permanecen viables por más de nueve años, pero las semillas convencionales son más rápidas, uniformes y presentan mayor sincronía.

RESUMO O acúmulo de silício (Si) nas plantas pode reduzir perdas de produtividade, pela indução de resistência a estresses abióticos e bióticos. Avaliou-se o acúmulo de Si em sorgo lignocelulósico (Sorghum bicolor), em casa-de-vegetação, bem como o efeito da sua aplicação sobre as características agronômicas e indução de resistência à antracnose (Colletotrichum sublineolum), em experimento de campo. Dezesseis genótipos de sorgo foram avaliados em casa-de-vegetação, quanto à adubação com silicato, recebendo 0 kg ha-1 ou 261 kg ha-1 de Si, mensurando-se a concentração de Si na parte aérea do sorgo. Quatro genótipos que responderam à adubação com Si foram testados em campo, com 0 kg ha-1 ou 400 kg ha-1 de Si, avaliando-se a concentração de Si nas folhas, altura de planta, porcentagem de acamamento, severidade da doença antracnose, rendimento de grãos e matéria fresca e seca da planta. A resposta do sorgo à adubação com Si em casa-de-vegetação variou com o genótipo e, dos 16 genótipos avaliados, 12 foram responsivos, acumulando mais Si após a fertilização com este elemento. Os quatro genótipos testados em campo foram responsivos, mas não foi encontrado efeito do Si sobre a produtividade de grãos ou sobre a produção de matéria fresca e seca do sorgo. No entanto, a aplicação de Si ao solo reduziu o acamamento de plantas e a severidade da antracnose em sorgo.

ABSTRACT Silicon (Si) accumulation in plants may reduce yield losses by inducing resistance to both abiotic and biotic stresses. This study aimed to evaluate the Si accumulation by lignocellulosic sorghum (Sorghum bicolor) in a greenhouse experiment, as well as the effect of its application on agricultural traits and on the induction of resistance against anthracnose (Colletotrichum sublineolum) in a field experiment. Sixteen sorghum genotypes were evaluated in a greenhouse for their response to silicate fertilization, receiving either 0 kg ha-1 or 261 kg ha-1 of Si, measuring the Si concentration in the sorghum shoots. Four genotypes that were responsive to Si fertilization were tested in the field, receiving either 0 kg ha-1 or 400 kg ha-1 of Si, being evaluated the Si concentration on the leaves, plant height, lodging percentage, anthracnose disease severity, grain yield and plant fresh and dry matter. The response of sorghum to Si fertilization in the greenhouse varied with the genotype and, of the 16 genotypes evaluated, 12 were responsive, accumulating more Si after the fertilization with this element. All four genotypes tested in the field were responsive, but no effect of Si was observed on grain yield or on sorghum fresh and dry matter production. However, the soil Si application reduced the plant lodging and anthracnose severity ratings in sorghum.

A preliminary analyses of the possible contamination of surface and groundwater by the active ingredients of the pesticide products used in the areas with intensive agricultural activities of Alto Paranaíba region, MG, Brazil, was carried out. The active ingredients and formulated products most used in the region were identified and their characteristics of environmental importance were presented. The EPA screening criteria, the groundwater ubiquity score (GUS) and the criteria proposed by Goss were used to evaluate which pesticides might contaminate the local waters. Among the active ingredients studied, several present risks to the local aquatic environment.