Derek Brito Chaim Jardim Rosa

Gas exchange and antioxidant activity in seedlings of C opaifera langsdorffii Desf. under different water conditions

The aim of this study was to evaluate gas exchange, efficiency of the photosynthetic apparatus, and antioxidant activity in Copaifera langsdorffii Desf. The seedlings were cultivated under different conditions of water availability, in order to improve the utilization efficiency of available water resources. The seedlings were cultivated in four different water retention capacities (WRC- 25%, 50%, 75%, and 100%), and evaluated at four different time (T- 30, 60, 90, and 120 days). During the experimental period, seedlings presented the highest values for carboxylation efficiency of Rubisco (A/Ci), intrinsic water use efficiency (IWUE = A/gs), chlorophyll index, and stomatal opening, when grown in the substrate with 75% WRC, but the stomatal index (SI) was less the 25% WRC. The efficiency of photosystem II was not significantly altered by the treatments. Comparison between the extreme treatments in terms of water availability, represented by 25% and 100% WRC, represent stress conditions for the species. Water availability causes a high activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) in the plant.

APLICAÇÃO FOLIAR DE GA3 NO CRESCIMENTO E DESENVOLVIMENTO DE Passiflora edulis Sims f. flavicarpa Degener

With the knowledge that the exogenous application of gibberellins can alter physiological processes modifying the growth and development of plants as they function asregulator of cell division and elongation, the aim of this study was to evaluate the growth and development of Passiflora edulis Sims f. flavicarpa Degener grown under light of 650 µmol m-2 s-1 for nine months andsubjected to weekly sprays with GA3. The experimental design was completely randomized with five treatments (0.0, 1.5, 3.0, 15.0 and 30.0 mg L-1 GA3) and ten repetitions. The substrate used was composed of a mixture (1:1:1 by volume) of washed coarse sand, chaff of washed coal and dystroferric red latosol organized in pots with a capacity of 5L. The concentrations of GA3 influenced (p<0.05) most of the variables except the length of the main stem to the insertion of the first lateral stem, the number of lateral stems, the number of nodes of the main stem to the insertion of the first stem side, the number of nodes of the main stem to the insertion of the first tendril and the first three-lobed leaf, at the beginning of flowering, the number of lateral stems issued by the plant at the beginning of flowering and the number of nodes from the base of the main stem up the insertion of the first flower buds. Concentration of around 15 mg L-1 caused higher plant length, greater length, greater number of nodes of the plant, and higher fresh and dry weight of plants. The use of 30 mg L-1 GA3 anticipated the issuance of the first tendril and the first three-lobed leaf and produced a greater number of flower buds. Exogenous use of GA3 at concentrations of 30 mg L-1 was more effective in inducing floral that the evocation of Passiflora edulis Sims f. flavicarpa Degener.

Growth and development of Hemerocallis fulva subjected to doses of nitrogen and phosphorus

The objective was to evaluate the effect of different doses of nitrogen and phosphorus on growth and development of Hemerocallis fulva variety Flore Full, herbaceous perennial widely used in landscaping. The experimental design was randomized blocks with 25 treatments, arranged in a factorial 5 x 5 (0; 75; 150; 225 and 300 kg ha-1 N and 0, 100, 200, 300 and 400 kg ha-1 P), with 4 replicates. The phosphorus fertilization was carried out 15 days after planting (DAP) and nitrogen was applied in coverage divided in three equal applications at 15, 120 and 240 DAP. There were evaluated the plant height, number of tillers per plant, soil coverage area, the fresh mass of plant, root system and shoot; and the dry mass of plant, root system and aerial part, and calculated the ratio of root dry mass and plant dry mass. It was also obtained the nutrient content of the leaf tissue and root system. The highest tillering was gained with the use of 150 kg ha-1 N combined with 400 kg ha-1 of P. Intermediate doses of N (75-170 kg ha-1 of N) showed higher production of plant fresh and dry mass and root dry mass. Doses of N and P influenced the N and P content in plant tissues of roots and leaves of Hemerocallis. Plants fertilized with 300 kg ha-1 of N and 273 kg ha -1 of P lead to the highest levels of N in the leaves and doses of 80 kg ha-1 of N and 68 kg ha-1 P, the highest content of P in the leaves of H. fulva. Already, in the roots, the highest N content was obtained with application of 300 kg ha-1 N in the presence of P and doses of 225 kg N ha-1 combined with 300 ha-1 P provided the highest P content in the roots

LUMINOSITY AND WATER IMMERSION IN THE INTERMEDIATE ACCLIMATIZATION FOR Dendrobium phalaenopsis Deang Suree

Dendrobium phalaenopsis Deang Suree has good germination and development in asymbiotic culture medium, however his ex vitro adaptation still requires studies, because it causes dehydration of plants, delay their growth and development. The objective of this work was to study the combined effect of the immersion time in distilled water plant and two luminosity conditions in the treatment of intermediate acclimatization to D. phalaenopsis . Plants were divided into sets of 40, being subjected to immersion for 0, 12, 24, 36, 48, 60, 72 or 84 hours. After each immersion period the plants were transferred for containers containing the substrate planting and later allocated in growth room for intermediate acclimatization for 30 days. A set of 20 plants from each period of immersion and from the control remained under white fluorescent light (18.9 µmol m -2 s -1 ) and the other 20 plants remained under white fluorescent light + red fluorescent light (14.85 µmol m -2 s -1 ). After this period, the plants were subjected to acclimatization in greenhouse for 10 months. While immersion time increased the increments of fresh weight, pseudobulbs number and the roots number of plants grown under white light + red light decreased, while plants grown under white light did not show response with respect to immersion time. Absence of immersion in distilled water independently of luminosity condition is beneficial to plants of D. phalaenopsis Deang Suree.

Adubação fosfatada no desenvolvimento de Hemerocallis fulva L.

In clayey Oxisol from the Brazilian Cerrado, where there is high P fixation, the phosphorus fertilization is necessary to increase the growth and flowering of ornamental plants. Thus, the objective of this study was to analyze the development of Hemerocallis as affected by phosphorus application in clayey Oxisol (Typic Haplustox). The experiment was conducted at the Gardening area of University Federal of Grande Dourados (UFGD) in Dourados-MS, Brazil. The experimental design was a randomized block with four replications. The treatments consisted of four P2O5 rates (0, 250, 500, 1000 kg ha-1) using simple superphosphate as source. The experimental unit was composed of one Hemerocallis fulva ‘Flore Pleno’ plant, grown in a plastic pot (5 liters). Phosphorus fertilization increased linearly the concentration of phosphorus in the soil; the plant had maximum absorption (5.26 g kg-1) with the calculated dose of 727 kg ha-1 P2O5. H. fulva has a root system that develops best under high availability of P, however, for aerial part, the maximum of shoots fresh mass (451.1 g) was obtained with 427 kg ha-1 of P2O5. Number of flower buds, flower diameter and height flower stalks were higher in the presence of phosphorus.