Stem anatomy of Lycopersicon esculentum Mill. treated with different plant growth regulators

The effects of plant growth regulators GA(3) 50 mg. L-1, NAA 100 mg. L-1, CCC 1500 mg.L-1 and SADH 3000 mg.L-1 on stem anatomy of Lycopersicon esculentum Mill cv. Angela Gigante were studied. Two sets of experiments were carried out in greenhouse during two separte periods. Anatomical studies,revealed that growth promoters induced increased xylem thickness and increased the number of tracheary elements while the growth retardants decreased xylem thickness and induced fiber formation.

Desiccation tolerance in seeds of Annona emarginata (Schldtl.) H. Rainer and action of plant growth regulators on germination

Annona emarginata (Schldtl.) H. Rainer (araticum-de-terra-fria) is used as a rootstock for several species of Annonaceae. It is suggested that these seeds should be sown immediately after extraction and, therefore, they could be intolerant to desiccation. There are several mechanisms involved with desiccation tolerance. Soluble sugars, for example, can accumulate and act as osmoprotectants for the membrane system during desiccation. The aim of this study is to assess desiccation tolerance in A. emarginata seeds. In addition, we examined the soluble sugars involved in desiccation tolerance. Finally, we determined the effect of gibberellic acid (GA4+7) and N-(phenylmethyl)-aminopurine in promoting the germination of seeds with different water contents. The experiment consisted of a randomized 4×5 factorial design (desiccation levels × concentration of growth regulators). After drying, seeds containing 31 (control), 19, 12 and 5% water were incubated in different concentrations of GA4+7 N-(phenylmethyl)-aminopurine (0, 250, 500, 750 and 1000 mg L-1) for 60 hours. The experiment was conducted in a germination chamber with alternating temperature and photoperiod of 20oC for 18 hours of darkness and 30oC for 6 hours of light. We analyzed electrical conductivity, germination rate, mean germination time, germination speed, frequency and uniformity of germination, percentage of dormant seeds and soluble sugar profile in intact seeds through high-performance liquid chromatography (HPLC). The data were subjected to analysis of variance, and the means were compared using Tukey's test at a threshold of p<0.05. The results showed that seeds of A. emarginata appears to be desiccation tolerant and, also, that sucrose increases when seed water content is reduced to values as low as 12%, exogenous GA4+7+N-(phenylmethyl)-aminopurine improves its germinability.

Plant growth regulator losses in cotton as affected by adjuvants and rain

Nas maiores regiões algodoeiras no Brasil, chove mais de 1.500mm anuais, existindo risco de ocorrer lavagem de reguladores de crescimento aplicados às folhas do algodoeiro, antes que sejam absorvidos. O objetivo deste trabalho foi avaliar a lavagem dos reguladores de crescimento cloreto de mepiquat e cloreto de chlormequat de folhas de algodoeiro por chuva, ocorrendo em diferentes momentos após a aplicação. O trabalho foi realizado em casa de vegetação. Ambos os reguladores foram aplicados no aparecimento do primeiro botão floral, na dose de 15g ha-1 de i.a. com e sem adjuvante siliconado, e chuva simulada foi aplicada aos 0, 0,75; 1,5; 3,0; 6,0; 12,0 e 24 horas após a aplicação dos reguladores, mais um tratamento sem chuva. A adição de adjuvante siliconado melhorou a absorção dos produtos. A ocorrência de chuva até mesmo 24 horas após a aplicação dos reguladores pode lavar parte dos produtos das plantas de algodoeiro, com maior intensidade para o tratamento sem adjuvante. A redução da absorção do produto leva à necessidade de reaplicá-lo para que possa haver a sua ação, sem comprometer sua função.

Design of fuzzy regulators with optimal initial conditions compensation

In almost all cases, the goal of the design of automatic control systems is to obtain the parameters of the controllers, which are described by differential equations. In general, the controller is artificially built and it is possible to update its initial conditions. In the design of optimal quadratic regulators, the initial conditions of the controller can be changed in an optimal way and they can improve the performance of the controlled system. Following this idea, a LNU-based design procedure to update the initial conditions of PI controllers, considering the nonlinear plant described by Takagi-Sugeno fuzzy models, is presented. The importance of the proposed method is that it also allows other specifications, such as, the decay rate and constraints on control input and output. The application in the control of an inverted pendulum illustrates the effectively of proposed method.

Growth Regulators and KNO3 on Seed Germination of Angelonia salicariifolia

Angelonia salicariifolia is an herbaceous perennial native to Brazil with ornamental potential as garden plant, cut-flower and potted plant. It has blue flowers 1.0 to 1.4 cm long, in 10-30 cm long terminal racemes. In previous studies seeds of A. salicariifolia showed a positive photoblastic behavior under constant temperatures of 10, 15, 20, 25, 30 and 35 degrees C. The present study evaluated the effects of growth regulators (100, 200, 300, 400, 500 mg L-1 of gibberellic acid and 2.25, 11.3, 22.5 mg L-1 of 6-benzylamino-purine) and potassium nitrate (0.2 and 1.0 %) on promoting its seed germination. The experiment was conducted in a completely randomized design with six replications of 25 seeds, for each treatment. Seeds from dehiscent capsules were sown on one layer of filter paper and moistened with growth regulators or KNO3 solutions. Germination was carried out at 25 degrees C +/- 1 degrees C, under continuous light or darkness. Germination (protusion of the radicle) was observed daily for 20 days. In the dark, only gibberellic acid promoted seed germination. The percentage of germination and the speed of germination index at 400 mg L-1 (47.3%; 0.86) and 500 mg L-1 (52.0%; 0.95) were significantly higher compared to 100 mg L-1 (27.8%; 0.38) and 200 mg L-1 (32.3%; 0.49). The mean germination time at 500 mg L-1 (10.0 days) was significantly smaller compared to 100 mg L-1 (11.9 days) and 200 mg L-1 (11.5 days). Under light, treatments did not differ among each other or from the control, except for 22.5 mg L-1 of 6-benzylamino-purine and potassium nitrate (1.0%), which decreased the percentage of germination and the speed of germination index compared to control. The application of growth regulators or potassium nitrate under light condition is not necessary, since these treatments did not improve germination percentage or the speed of germination index.

Effect of growth regulators in citral content in lemongrass in different seasons (in Portuguese)

The purpose of the present research was to evaluate the effect of plant growth regulators in yield citral content in lemongrass (Cymbopogon citratus (D.C.) Stapf), in different seasons. The field experiment was conducted on Sao Manuel Experimental Farm, Agronomical Science College, Paulista Estatal University, Botucatu, Brazil, which soil was classified in alic yellon red latosol (Haplorthox). Plants were randommly assigned blocks to treatments with three repetitions. The experimental groups consisted of GA3 (50 and 100 mg.l-1);Ethrel (100 and 200 mgl-1); CCC (500 and 1000 mg.l-1); Alar 85 (1000 and 2000 mg.l-1); Accel (20 and 40 mg.l-1) and control group. Five applications of plant growth regulators were realized every other three months. After 40 days of each foliar spray, the plants were cut and determined the citral yield. The essential oils were extracted from leaf tissue by hydrodistillation in a Clevenger apparatus. Samples of 250g of leaf and put in Clevenger apparatus with deionized water for 3h to determine the yield of essential oil. The citral content was analyzed by GC. In the present study the concentrations of plant growth regulators used did not increase citral content.

Growth regulators for in vitro propagation of Tillandsia gardneri (Bromeliaceae)

Tillandsia gardneri Lindi, is a herbaceous perennial with ornamental value. However, in Brazil there is no report about this species' cultivation on a commercial scale. The low multiplication rate of T. gardneri (in average one offshoot/plant/year) leads to illegal over-collection in the wild to meet commercial demands. The development of protocols for in vitro propagation of T. gardneri may be useful for increasing multiplication rate, producing enough plants to supply the ornamental market and also to reduce the pressure over plants collection in the wild. The present study evaluated the effect of growth regulators (6-benzylaminopurine-BA alone or in combinations with naphthaleneacetic acid-NAA) on shoots development from seedlings pre-established in vitro, from seed germination on 1/4 MS medium without growth regulators. Seedlings (with about 1.0 cm long) were re-cultured to solid 1/2 MS media supplemented with growth regulators. After 30 days on the induction medium seedlings were re-cultured to MS basal medium. The experiment was conducted in a complete randomized design with four replications and ten treatments: control (free of growth regulators), BA (0.5, 1.0 and 2.0 mg/L), BA (0.5 mg/L) + ANA (0.1 mg/L), BA (1.0 mg/L) + ANA (0.1 mg/L), BA (1.0 mg/L) + ANA (0.5 mg/L), BA (2.0 mg/L) + ANA (0.1 mg/L), BA (2.0 mg/L) + ANA (0.5 mg/L), and BA (2.0 mg/L) + ANA (1.0 mg/L). The outgrowth of shoots did not occur on medium devoid of growth regulators (control). Regression analysis for some evaluated parameters, such as percentage of seedlings responsive to shoot formation and number of shoots/seedling, and regulators concentrations (BA or ANA) were significant, allowing the establishment of the growth regulators concentration for obtaining the best multiplication rate. Some seedlings maintained in media with ANA (0.5 or 1.0 mg/L) were completely converted into callus masses that turned dark brown leading to seedlings death.

Tifton 419 Bermudagrass (Cynodon dactylon C. transvaaliensis) response to plant grow inhibitors

Tifton 419' bermudagrass cultivar [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] is the most preferred turfgrass for sportive, commercial and residential lawns. On similar species, such as Stenotaphrum secundatum and Zoysia japonica, gibberellic acid-inhibiting plant growth regulators (PGRs) are used to decrease mowing frequency. A very limited research has been reported yet on the PGRs regarding seasonal effects of single vs. multiple applications of these products on turfgrass quality and clipping production on South America. This study aimed to evaluate the effect of sequential applications of different plant growth inhibitors during re-growth and flower rachis emission of 'Tifton 419' Bermudagrass. The treatment pattern includes an initial application followed by one sequential application at 14 days intervals, according to the following: prohexadione-calcium at 100+100 or 200+200 g a.i. ha-1, bispyribac-sodium at 40+40 or 60+60 g a.i. ha-1, trinexapac-ethyl at 113+113, 226+113, 226+226, 452+113, 452+226, 452+452, 678+0 or 904+0 g a.i. ha-1, and untreated control. The treatment effect was evaluated based on measurements of visual injury, height of plants, height and number of flower rachis, and clipping total dry mass production. The results showed that only bispyribac-sodium provided visual injury on 'Tifton 419' Bermudagrass, but the symptoms quickly tend towards zero at 21 days after second application (DASA). 'Tifton 419' Bermudagrass greens could be better handle by sequential application of trinexapac-ethyl, or prohexadione-calcium or bispyribac-sodium, once the height of plants, seedhead emission and total clipping dry mass reduction were over than 37%, 91% and 88%, respectively, for a period up to 60 DASA.