Reginaldo Teodoro de Souza

Glyphosate applied at low doses can stimulate plant growth

BACKGROUND Glyphosate blocks the shikimic acid pathway, inhibiting the production of aromatic amino acids and several secondary compounds derived from these amino acids. Non-target plants can be exposed to low doses of glyphosate by herbicide drift of spray droplets and contact with treated weeds. Previous studies have reported that low doses of glyphosate stimulate growth, although these data are very limited. The objective of this study was to determine the effects of low glyphosate doses on growth of a range of plant species. RESULTS Growth of maize, conventional soybean, Eucalyptus grandis Hill ex Maiden, Pinus caribea L. and Commelia benghalensis L. was enhanced by 1.8-36 g glyphosate ha(-1). Growth of glyphosate-resistant soybean was unaffected by any glyphosate dose from 1.8 to 720 g AE ha(-1). The optimum doses for growth stimulation were distinct for plant species and tissue evaluated. The greatest stimulation of growth was observed for C. benghalensis and P. caribea. Shikimic acid levels in tissues of glyphosate-treated soybean and maize were measured and found to be elevated at growth-stimulating doses. CONCLUSION Subtoxic doses of glyphosate stimulate the growth of a range of plant species, as measured in several plant organs. This hormesis effect is likely to be related to the molecular target of glyphosate, since the effect was not seen in glyphosate-resistant plants, and shikimate levels were enhanced in plants with stimulated growth.

Aspectos metodológicos para análise de depósitos de pulverizações pela determinação dos depósitos pontuais

The objective of this research was to study the variability of individual tracer deposits (simulating herbicides applied in post-emergence) on Brachiaria plantaginea and Commelina benghalensis infesting soybeans crop. The tracer deposits were evaluated also on the crop. A boom sprayer was used, equipped with 110-SF-03 nozzles and 250 L ha-1 of a solution was applied containing 0.18% of each of the following dyes: FDC-1 and Satur-Yellow; 150 soybean plants; 141 and 150 Brachiaria plantaginea plants were used as targets located in the rows and between the rows of the crop, respectively; 50 Commelina benghalensis plants located between the rows and 125 glass plates of 19.76 cm2 (25 in the rows; 50 and 50 at 12.25 cm and 22.5 from the rows). The spray deposits (mL per plant or plate and mL cm-2) were individually estimated in each of the 566 targets by washing them in de-ionized water and measuring the concentration of dye FDC-1 in the solutions by spectrophotometry. The results for each target type and position were expressed in an increasing order and associated to accumulated frequencies from 0 to 100%. Regression analysis was performed according to the Gompertz model and using the individual deposits and the accumulated frequencies as independent and dependent variables, respectively. The values for ratio maximum deposit/minimum deposit were 7, 4, 10 and 6 for soybean, Commelina benghalensis and Bachiaria plantaginea in the rows and between the rows, respectively. The average deposits were 34% superior in the plants of Brachiaria plantaginea located in the rows, compared to the plants between the rows.

Depósito de pulverização com diferentes padrões de gotas em aplicações na cultura do algodoeiro

The experiment was carried out to evaluate the leaf deposition and the efficiency of different drop pattern by spraying cotton plants at the end of the growing season, under adverse air temperature and humidity conditions. The sprays, applied at the same pressure, were made with a JACTO UNIPORT speed-sprayer equipped with the nozzles JA3 (hollow cone), AD-IA/D 11003 (double flat fan), and AD-IA 11003 (flat fan) for 150 L ha-1 spray volume, and the nozzle AD-IA 11004 (flat fan) for 200 L ha-1 spray volume. It was applied the FDC 35.08; 47.60 and 39.25% for the nozzles JA3, AD-IA/D 11003, AD-IA 11003, and AD-IA 11004, respectively.

Efeitos de doses e formas de aplicação de reguladores de crescimento em uvas sem sementes, cv. BRS Clara, em região tropical

O objetivo deste trabalho foi avaliar o efeito do uso dos reguladores vegetais, acido giberelico e tidiazuron, no tamanho de bagas da cultivar BRS Clara em Regiao Tropical. Os experimentos foram conduzidos em 2006 e 2007, na Estacao Experimental de Viticultura Tropical, em Jales-SP, regiao noroeste do Estado de Sao Paulo, em plantas da cv. BRS Clara. Foram testadas diferentes concentracoes de GA3 aplicadas isoladamente, combinadas com Crop Set ou tidiazuron, em aplicacoes unicas ou sequenciais (2 e 4 vezes). As avaliacoes foram feitas por ocasiao da maturacao das uvas, considerando-se a massa fresca dos cachos, dos engacos e das bagas, determinadas por meio de balanca analitica; o comprimento e o diâmetro medio das bagas, utilizando-se de paquimetro; e o teor de solidos soluveis (SS), por meio de refratometro manual. Os experimentos foram conduzidos em delineamento experimental de blocos casualizados, representados por uma planta, com 15 repeticoes, no ano de 2006, e 10 repeticoes, no ano de 2007. Os dados foram submetidos a analise de variância e, para a comparacao das medias dos tratamentos, foi utilizado o teste Skott Nott, ao nivel de 5% de probabilidade. Observou-se que o uso dos reguladores promoveu o crescimento das bagas na cultivar BRS Clara em todos os tratamentos, diferindo da testemunha.The purpose of this study was to evaluate the effect of the use of plant growth regulators, gibberellic acid and thidiazuron about the size of the berries BRS Clara in Tropical Region. The experiments were conducted in 2006 and 2007, in the Experimental Station of Tropical Viticulture in Jales, SP, northwestern state of Sao Paulo. Were tested different concentrations of GA3 applied in isolation, combined with Crop set and thidiazuron, in single or sequential applications (2 and 4 times). The assessments were made during the ripening of the grapes, considering the masses of fresh bunch of rachis and berry, determined by analytical balance, the average length and diameter of the berries, using caliper and the content of soluble solids (TSS), through manual refractometer. The experiments were conducted on experimental design in randomized blocks, represented by a plant, with 15 repetitions in 2006 and 10 repetitions in the year 2007. The data were subjected to analysis of variance and for comparison of the average number of treatments, was used to test Skott Nott at the level of 5% probability. It was observed that the use of plant growth regulators promoted the growth of berries in BRS Clara, with all treatments differing of the control.

Frequency of fungicide application for controlling downy mildew in seedless grape plant ‘BRS Vitória’

Different application frequencies of metalaxyl + mancozeb were evaluated to control downy mildew in vine plants ?BRS Vitoria? in two experiments conducted in Jales, Sao Paulo, one in the production cycle and another in branches formation cycle. In experimental design of randomized blocks, five treatments were compared (1- two weekly applications; 2- one weekly application; 3- one application every 14 days; 4- one application every 21 days; 5- applications after sporulation) with four replications, each plot with three plants.

Exogenous Abscisic Acid Promotes Anthocyanin Biosynthesis and Increased Expression of Flavonoid Synthesis Genes in Vitis vinifera × Vitis labrusca Table Grapes in a Subtropical Region

Hybrid (Vitis vinifera ×Vitis labrusca) table grape cultivars grown in the subtropics often fail to accumulate sufficient anthocyanins to achieve good uniform berry color. Growers of V. vinifera table grapes in temperate regions generally use ethephon and, more recently, (S)-cis-abscisic acid (S-ABA) to overcome this problem. The objective of this study was to determine if S-ABA applications at different timings and concentrations have an effect on anthocyanin regulatory and biosynthetic genes, pigment accumulation, and berry color of the Selection 21 cultivar, a new V. vinifera ×V. labrusca hybrid seedless grape that presents lack of red color when grown in subtropical areas. Applications of S-ABA 400 mg/L resulted in a higher accumulation of total anthocyanins and of the individual anthocyaninsanthocyanins: delphinidin-3-glucoside, cyanidin-3-glucoside, peonidin-3-glucoside, and malvidin-3-glucoside in the berry skin and improved the color attributes of the berries. Treatment with two applications at 7 days after véraison (DAV) and 21 DAV of S-ABA 400 mg/L resulted in a higher accumulation of total anthocyanins in the skin of berries and increased the gene expression of CHI, F3H, DFR, and UFGT and of the VvMYBA1 and VvMYBA2 transcription factors in the seedless grape cultivar.

Effects of plant growth regulators for growth in seedless grape, cv. BRS Clara, in tropical region

O objetivo deste trabalho foi avaliar o efeito do uso dos reguladores vegetais, acido giberelico e tidiazuron, no tamanho de bagas da cultivar BRS Clara em Regiao Tropical. Os experimentos foram conduzidos em 2006 e 2007, na Estacao Experimental de Viticultura Tropical, em Jales-SP, regiao noroeste do Estado de Sao Paulo, em plantas da cv. BRS Clara. Foram testadas diferentes concentracoes de GA3 aplicadas isoladamente, combinadas com Crop Set ou tidiazuron, em aplicacoes unicas ou sequenciais (2 e 4 vezes). As avaliacoes foram feitas por ocasiao da maturacao das uvas, considerando-se a massa fresca dos cachos, dos engacos e das bagas, determinadas por meio de balanca analitica; o comprimento e o diâmetro medio das bagas, utilizando-se de paquimetro; e o teor de solidos soluveis (SS), por meio de refratometro manual. Os experimentos foram conduzidos em delineamento experimental de blocos casualizados, representados por uma planta, com 15 repeticoes, no ano de 2006, e 10 repeticoes, no ano de 2007. Os dados foram submetidos a analise de variância e, para a comparacao das medias dos tratamentos, foi utilizado o teste Skott Nott, ao nivel de 5% de probabilidade. Observou-se que o uso dos reguladores promoveu o crescimento das bagas na cultivar BRS Clara em todos os tratamentos, diferindo da testemunha.The purpose of this study was to evaluate the effect of the use of plant growth regulators, gibberellic acid and thidiazuron about the size of the berries BRS Clara in Tropical Region. The experiments were conducted in 2006 and 2007, in the Experimental Station of Tropical Viticulture in Jales, SP, northwestern state of Sao Paulo. Were tested different concentrations of GA3 applied in isolation, combined with Crop set and thidiazuron, in single or sequential applications (2 and 4 times). The assessments were made during the ripening of the grapes, considering the masses of fresh bunch of rachis and berry, determined by analytical balance, the average length and diameter of the berries, using caliper and the content of soluble solids (TSS), through manual refractometer. The experiments were conducted on experimental design in randomized blocks, represented by a plant, with 15 repetitions in 2006 and 10 repetitions in the year 2007. The data were subjected to analysis of variance and for comparison of the average number of treatments, was used to test Skott Nott at the level of 5% probability. It was observed that the use of plant growth regulators promoted the growth of berries in BRS Clara, with all treatments differing of the control.