Physiology and morphology of rice plants with silicon supplementation and Dietholate seed treatment under water deficit

Silicon is an enzyme stimulator that promotes signaling for the production of antioxidant, osmoprotective compounds and attenuates interference in photosynthesis in rice plants subjected to water deficit. The aim of this study was to evaluate the possible effects of silicon as a stress reliever in rice plants grown from seeds treated with dietholate under of water deficit conditions. The experimental design was fully randomized with three replicates, 144 experimental units consisting of pots containing 4.4 pounds soil, and a 3x2x2x4 factorial arrangement: three soil water conditions (50% and 100% of soil water retention capacity and water blade of 5.0 cm); two cultivars (IRGA 424 RI and Guri INTA CL); two sources of Si (sodium and potassium metasilicate); and four Si rates (0; 4.0; 8.0 and 16 g L-1). Silicon boosted stomatal density; induced an increase in the maximum photochemical efficiency of photosystem II (PSII) under both water deficit and optimal conditions, boosting photosynthesis; and increased effective quantum yield of PSII and levels of total dry mass. Thus, silicon attenuated the effects of water deficit in plants grown from seeds treated with dietholate

Anatomical changes in Urochloa Plantaginea and Urochloa Platyphylla under different soil moisture conditions

Urochloa plantaginea and Urochloa platyphylla are common weeds in the highland area. However, in recent years, they have been found in wetlands and poorly drained soils, but the biology and behavior of the species in these conditions are not known. Thus, the objective was to assess anatomical changes in plants of Urochloa plantaginea and Urochloa platyphylla grown under different soil moisture conditions, as well as the adaptive structures generated as a result of each environment. A completely randomized experimental design in the form of a 2x2 factorial design was used, with factor A being two species of Urochloa (U. plantaginea and U. platyphylla), and species B being three soil moisture conditions (50 and 100% FC and 5 cm water depth), with four repetitions. The assessments were performed by means of anatomical cuts, observing the number and diameter (micrometers - μm) of aerenchymas in stems, roots and leaves; total diameter and the central root cylinder (μm); diameter of the fistula medulla and cortex (μm) in stems; mesophyll thickness and leaf midrib (μm). It was found that, for the two species of Urochloa, the water depth condition induced an increase in the number and diameter of aerenchymas in roots and leaves and provided a larger diameter of the fistulous pith in stems. The diameter of the central cylinder and the thickness of the leaf mesophyll midrib were more compact at 50% FC, also, for both species. Therefore, the adaptive structures generated vary as a result of the field capacity of the soil

Silicon In the Growth of Rice Seedlings Pretreated with Dietholate and Subjected to Cold Stress

Silicon (Si) is an enzyme stimulator that can promote signaling for the production of antioxidant compounds, important in cellular detoxification of excess ROS accumulated during stress. The aim of the study was to evaluate the effects of Si on post-germination rice seeds in the mitigation of cold stress combined with stress induced by seed treatment with the dietholate protector. The experimental design was fully randomized with three replicates and a 3x2x2x4x2 factorial arrangement: three temperatures (5, 10 and 20 °C), two cultivars (IRGA 424 RI and Guri INTA CL), two seed pretreatments (with and without dietholate), four rates of Si (0; 4.0; 8.0 and 16 mg.L-1) and two sources of Si (sodium and potassium metasilicate). Seed pretreatment with dietholate reduced shoot and radicle length, especially at the lower temperatures of 5 and 10 °C. Sodium metasilicate as the source of Si was more efficient in boosting shoot and radicle length, both with and without pretreatment, regardless of temperature. Si was found to attenuate low-temperature stress and the impairment of shoot and radicle growth in rice seedlings grown from seeds pretreated with dietholate

CONTROL OF Cyperus difformis BY ALS HERBICIDES AND AUXIN MIMICS

A ocorrência de biótipos de Cyperus difformis L. com característica de resistência à aplicação de herbicidas no setor da orizicultura é uma preocupação mundial. Nesse sentido, objetivou-se avaliar a eficiência do controle de C. difformis por herbicidas inibidores da acetolactato sintase (ALS) e mimetizador de auxina. O delineamento experimental foi inteiramente casualizado, com quatro repetições, totalizando 252 unidades experimentais compostas por vasos com 12 quilogramas de solo e os tratamentos arranjados em esquema fatorial 3x7x2x2: três herbicidas (dois inibidores da ALS pirazossulfurom-etílico e bispiribaque-sódico e um mimetizador de auxina triclopir-butotílico); sete doses dos herbicidas (0.0x, 0.5x, 1x, 2x, 4x, 8x e 16x a dose de registro); dois biótipos de C. difformis (Santa Rosa do Sul e Meleiro, Santa Catarina (SC)); e duas umidades de solo (100% saturado e lâmina d’água de 5,0 cm). O biótipo C. difformis de Meleiro-SC é 8x (320 g. i.a. ha-1) mais resistente a dose de registro do bispiribaque-sódico, já o biótipo de Santa Rosa do Sul-SC é mais sucetivel, reduzindo 50% da massa seca da parte aérea com 0.5x da dose de registro (20 g i.a. ha-1). O pirazossulfurom-etílico demostrou-se ineficiente na redução da massa seca da parte aérea em ambos os biótipos. Os biótipo C. difformis de Santa Rosa do Sul-SC e Meleiro-SC, nas duas condições de umidade do solo são suscetíveis ao triclopir-butotílico, reduzindo 50% da massa seca da parte aérea com 0.5x (166 g. i.a. ha-1) a dose de registro.The occurrence of Cyperus difformis L. biotypes with characteristics of resistance to herbicide application in the rice sector is a worldwide concern. In this sense, the objective was to evaluate the efficiency of the control of C. difformis by acetolactate synthase (ALS) inhibitors and auxin mimic. The experimental design was completely randomized, with four replications, totaling 252 experimental units composed of pots with 12 kilograms of soil and the treatments arranged in a 3x7x2x2 factorial scheme: three herbicides (two ALS inhibitors pyrazosulfuromethyl and bispiribaque-sodium and a mimetic of triclopyr-butotyl auxin); seven doses of the herbicides (0.0x, 0.5x, 1x, 2x, 4x, 8x and 16x the registration dose); two biotypes of C. difformis (Santa Rosa do Sul and Meleiro, Santa Catarina (SC)); and two soil moisture (100% saturated and 5,0 cm water depth). The C. difformis biotype of Meleiro-SC is 8x (320 g. i.a. ha-1) more resistant to the registration dose of bispiribaque-sodium, whereas the biotype of Santa Rosa do Sul-SC is more susceptible, reducing 50% of the dry mass of the aerial part with 0.5x of the registration dose (20 g. i.a. ha-1). Pyrazosulfuromethyl proved to be inefficient in reducing the dry mass of the aerial part in both biotypes. The biotypes C. difformis of Santa Rosa do Sul-SC and Meleiro-SC, in both soil moisture conditions, are susceptible to triclopyr-butotyl, reducing 50% of the dry mass of the aerial part with 0.5x (166 g. i.a. ha-1) the registration dose