Hybrid Rice Seed Treatment with Pesticides Improves Its Physiological Quality and Performance

Pathogens in the soil or transmitted by seeds can reduce the stand of plants, affecting the yield of the crop. Furthermore, in the case of rice, the low temperature is a limiting factor in culture. The treatment of seeds with insecticides is an alternative to reduce the damage caused by pests incidents during the early stages of plant development and in some cases, may assist in the germination of seeds exposed to low temperatures. In this sense, the objective of this study was to evaluate the influence of seed treatment with insecticides in the physiological quality and yield of hybrid rice seeds, cv. Inov CL. For this, three experiments were conducted with treated seeds in different doses of thiamethoxam + lambda-cyhalothrin and fipronil totaling seven treatments, including the control (no product). In the first experiment, it was determined seed germination to 10°C, 13°C, 16°C, 20°C and 25°C. In the second experiment, it was assessed seed vigor through accelerated aging, cold test and emergency field. The third experiment was carried out into the field to observe the number of panicles m-2 and crop yield. It is concluded that treatment of hybrid rice seeds, cv. Inov CL with thiamethoxam + lambda-cyhalothrin and fipronil increases the germination percentage of seed and early seedling performance. Treatment of hybrid rice seeds, cv. Inov CL with thiamethoxam + lambda-cyhalothrin provides greater germination and early seedling performance compared to treatment with fipronil. Treatment of hybrid rice seeds, cv. Inov CL with thiamethoxam + lambda-cyhalothrin in dosages of 500 mL 100 kg-11 of seeds or 500 mL 45 kg-1 of seeds increases grain yield.

Physiological Performance of Rice Seeds Treated to Thiamethoxam and Placed under Storage

High-yielding crops can only achieve their potential when the appropriate technological tools are applied and weather conditions do not impose restrictions. One such technological tool is the treatment of seeds, in which different products are used and, in some cases, cause little-known effects capable of modifying the plant’s metabolism and/or its morphology. The insecticide thiamethoxam alters the plant’s physiology and morphology, accelerating its development, thus enhancing its vigor. The objective of this study was to evaluate the influence of thiamethoxam on the physiological performance of rice seeds during storage. The research was conducted in a green-house and at the laboratory of the Department of Plant Science, Faculty of Agronomy Eliseu Maciel —UFPel (Federal University of Pelotas). Rice seeds from cultivars INIA Olimar and El Paso L144 were treated to a commercial product containing 350 grams of active ingredient thiamethoxam at doses of 0, 100, 200, 300, 400 and 500 g per 100 kg of seed. Seeds were tested for physiological quality immediately after being treated (check treatment) and at 3, 6, 9 and 12 months under storage, through germination test, cold test, accelerated aging and greenhouse emergence test. The concentration range from 200 to 400 g a.i. 100 kg-1 seed yielded the highest germination and seed vigor values for both rice cultivars during the storage period.

Physiological Performance of Common Bean Seeds Treated with Bioactivator with and without Moisture Restriction

The commonbean (Phaseolus vulgaris L.) is an important agricultural crop due to its nutritional properties. Insecticides and fungicides employed to control pests and diseases in the common bean may cause as yet unknown effects on the plant’s morphology and metabolism. Bioactivators are complex organic substances, capable of exerting modification upon growth patterns, plant DNA transcription, gene expression, metabolic enzymes and mineral nutrition. Thiamethoxam insecticide has shown positive action on the enhancement of vigor expression, phytomass accretion and the promotion of deeper root systems. The aim of this work was to evaluate the effect of thiamethoxam on the physiological performance of common bean seeds. Seeds from cultivars Pérola and IAPAR Siriri were treated to thiamethoxam concentrations of 0, 100, 200, 300, 400 and 500 mL&middotkg-1 seed. Physiological quality was measured through tests for germination value, first count, cold test, accelerated aging and seedling shoot and root lengths, all undertaken in the presence and absence of moisture stress. Thiamethoxam stimulated the physiological performance of common bean seeds under moisture stress or in the absence of it, with levels varying according to cultivar and seed lot. The best physiological seed performance was obtained within the range of 200 mL&middotkg-1 seed to 400 mL&middotkg-1 seed.

Isoenzyme Expression in Bean Seed Germination Treated with Thiamethoxam with and without Drought Stress

The thiamethoxam acts as enhancer, allowing maximizing the expression of seed vigor. Isozymes are products of gene expression, highly influenced by the environment, because genes that control its expression are manifested in certain stages of development and in specific organs and tissues, or even under the action of certain stimulus. This study evaluated the isoenzyme expression in bean seedlings from seeds treated with thiamethoxam. Bean seeds were used, cultivar Pérola and IAPAR Siriri, submitted or not to drought stress. Seeds were treated at doses of thiamethoxam: 0, 1, 2, 3, 4 and 5 mL·kg-1 of seed. Isozymes were extracted from seedlings collected five days after sowing. We evaluated the expression of isoenzymes: Glutamate Oxalacetate transaminase (GOT), acid phosphatase (FAC), peroxidase (PO), Esterase (EST), malate dehydrogenase (MDH) and glutamate dehydrogenase (GTDH). Interpretation of the results was based on visual analysis of electrophoresis gels, considering the presence/absence and the intensity of each electrophoretic band. Bean seeds treated with thiamethoxam with doses up 3 mL·kg-1 of seed are higher germination untreated, even when submitted to drought stress. The expression of isozymes GOT, FAC, PO, EST, MDH and GTDH is not affected significantly in bean seedlings of Pérola and IPR Siriri under different doses of thiamethoxam with and without drought stress.