RESUMEN El cultivo de tomate presenta un alto potencial productivo pero puede afectarse debido al estrés biótico y abiótico. Se ha informado un aumento de la resistencia de la planta a las condiciones de estrés con la aplicación foliar de compuestos minerales del suelo, sin embargo, aún es necesario comprender mejor cómo reacciona la planta al uso de este compuesto. Por lo tanto, este estudio evaluó el efecto de la aplicación foliar del compuesto mineral del suelo sobre los atributos fisiológicos y de crecimiento de las plantas de tomate. Este experimento se llevó a cabo en Lagoa Formosa / MG durante 2016. Se usaron diferentes tasas del compuesto mineral del suelo durante el ciclo del cultivo, lo que constituye cuatro manejos distintos. El manejo consistió en diferentes dosis del compuesto mineral en cuatro etapas después del trasplante de las plántulas de tomate. El diseño experimental utilizado fue de bloques al azar. Se realizaron las siguientes evaluaciones fisiológicas: proteína soluble total, peróxido de hidrógeno, actividad de la enzima nitrato reductasa, ureasa, superóxido dismutasa (SOD), peroxidasa, fenilalanina amoniaco liasa y peroxidación lipídica (LP). Las evaluaciones de crecimiento fueron biomasa vegetal y rendimiento. La aplicación foliar del compuesto mineral del suelo aumentó la actividad de la enzima SOD en 4,17 y 6,25%. El uso del compuesto mineral del suelo también aumentó la actividad de LP y redujo la actividad de las enzimas antioxidantes. La aplicación foliar de compost mineral del suelo a dosis de 0,5; 0,750; 1,0 y 1.0 kg ha-1 a los 15, 25, 40 y 60 días después del trasplante, respectivamente, aumentó el rendimiento de tomates de mesa al 20%.

ABSTRACT The tomato crop has a high productive potential that can be depleted by biotic and abiotic stresses. Increased plant resilience to stress conditions has been reported with foliar applications of soil-mineral compounds; however, it is necessary to better understand how plants react to the use of this compound. Thus, this study evaluated the effect of foliar applications of a soil-mineral compound on the physiological and growth attributes of tomato plants. This experiment was carried out in Lagoa Formosa/MG during 2016. Different rates of the soil-mineral compound were used during the crop cycle, forming four distinct managements. The management consisted of different doses of the mineral compound in four stages after transplanting the tomato seedlings. The experiment design used randomized blocks. The following physiological evaluations were performed: total soluble protein, hydrogen peroxide, nitrate reductase enzyme activity, urease, superoxide dismutase (SOD), peroxidase, phenylalanine ammonia lyase, and lipid peroxidation (LP). The growth assessments were plant biomass and yield. Foliar applications of the soil-mineral compound increased the activity of the SOD enzyme by 4.17 and 6.25%. The use of the soil-mineral compound also increased the LP activity and reduced the antioxidant enzyme activity. The foliar application of the soil-mineral compost at doses of 0.5, 0.750, 1.0 and 1.0 kg ha-1 at 15, 25, 40 and 60 days after transplanting, respectively, increased the yield of the table tomatoes by 20%.

RESUMO Nos últimos anos, houve rápido crescimento na utilização de substâncias que buscam aumentar a produtividade de soja, como as citocininas, seja por alterações fisiológicas ou morfológicas. Objetivou-se avaliar o efeito da época de aplicação de citocinina na forma de cinetina, na cultura da soja. O experimento foi realizado em condições de campo, utilizando-se quatro tratamentos (controle e cinetina nos estágios vegetativos V4, V6 e V4 + V6), com cinco repetições, em blocos inteiramente casualizados. Foram realizadas avaliações fisiológicas (atividade de nitrato redutase e peroxidase, teor de H2O2 e peroxidação de lipídios) e fenométricas (massa de matéria seca de raiz e folhas), além da produtividade. A aplicação de cinetina em V4, V6 ou V4 + V6 proporcionou incremento na atividade da enzima nitrato redutase, redução do estresse (avaliado por meio da peroxidação lipídica e teor de peróxido de hidrogênio) e aumento no teor de massa de matéria seca. Todas essas características repercutiram no aumento da produtividade. Contudo, os efeitos mais expressivos foram causados pela aplicação de cinetina em V6, que proporcionou incremento de 20 % na produtividade, em relação ao controle.

ABSTRACT A fast growth in the use of substances that increase soybean yield through physiological or morphological changes, such as cytokinin, has taken place in recent years. This study aimed at assessing the effect of the application time of cytokinin as kinetin on soybean crops. The experiment was carried out under field conditions, using four treatments (control and kinetin at the vegetative stages V4, V6 and V4 + V6), with five replications, in completely randomized blocks. Physiological (nitrate reductase and peroxidase activity, H2O2 content and lipid peroxidation) and phenometric parameters (leaf and root dry mass), as well as yield, were evaluated. The application of kinetin at V4, V6 or V4 + V6 increased the activity of the nitrate reductase enzyme and reduced stress (evaluated via lipid peroxidation and hydrogen peroxide content), in addition to raising the dry matter content. All these characteristics resulted in increased yield. However, the most significant effects were caused by the application of kinetin at V6, which increased yield in 20 %, in relation to the control.