The Tissue Flow in Brachiaria brizantha Pasture Under Intermittent Stocking

The present work aims to evaluate the morphological and structural characteristics of Brachiaria brizantha cultivars in the system of grazing in the intermittent stocking. The experiment was conducted at EMBRAPA - Beef Cattle. The experimental delineation used was a randomized block with three treatments and three repetitions. The treatments were constituted by grasses of the same species (Brachiaria brizantha) composed by cv. Xaraés, BRS Paiaguás, and the ecotype B4. On the heights of post-grazing, it was observed an interaction between seasons of the year and cultivars. It was observed that the leaf appearance rate (LAR) was higher in the cv. BRS Paiaguás, in relation to the other pastures. The leaf elongation rate (LER) was higher in perforations of the ecotype B4. In the winter, it was registered the lowest values of leaf area index (LAI), LAR, and LER, and, as a consequence, impact in a higher leaf life duration. Although there were some structural variations between tropical climate pastures, it was possible to verify that the phenotypic plasticity of these pastures presented the same behavior, once it suffered a higher influence of abiotic factors. Therefore, all the pastures of B. brizantha converged to the same LAI indicating high phenotypic plasticity.

GROWTH AND DEVELOPMENT OF MOMBASSA GRASS GROWN IN FULL SUN AND SHADE UNDER NITROGEN LEVELS

The objective of this work was to evaluate the effects promoted by full sun and natural shading (25%) enviroemnts , under the productive components of Panicum maximum cv. Mombasa grown in diferent levels of nitrogen (0, 25, 50, 100 kg ha-1 cycle-1 ). Urea was used as nitrogen source, applied on the surface. This study evaluated the following variables: number of total leaves (NTL), number of green leaves (NGL), number of dead leaves (NDL), leaf lifespan (LLS), sheath length (SL), stem elongation rate (SER), Phyllochron (PHYL), leaf appearance rate (LApR), leaf elongation rate (LElR), leaf senescence rate (LSR), average length of leaf blade (ALLB), leaf area index (LAI) and tiller population density (TPP). The shaded environment provided better conditions for sheath length and leaf elongation rate, however in full sun the tiller density was higher.

leafkin—An R package for automated kinematic data analysis of monocot leaves

Growth is one of the most studied plant responses. At the cellular level, plant growth is driven by cell division and cell expansion. A means to quantify these two cellular processes is through kinematic analysis, a methodology that has been developed and perfected over the past decades, with in-depth descriptions of the methodology available. Unfortunately, after performing the lab work, researchers are required to perform time-consuming, repetitive and error-prone calculations. To lower the barrier towards this final step in the analysis and to aid researchers currently applying this technique, we have created leafkin, an R-package to perform all the calculations involved in the kinematic analysis of monocot leaves using only four functions. These functions support leaf elongation rate calculations, fitting of cell length profiles, extraction of fitted cell lengths and execution of kinematic equations. With the leafkin package, kinematic analysis of monocot leaves becomes more accessible than before.

Containerized Onion Transplants: A Management System to Enhance Growth, Yield, and Quality

In the United States, most short-day onions are direct seeded. With this method, plant stands can be reduced because of extreme temperatures, weed pressure, and soil-borne diseases. Containerized transplants offer an alternative method of stand establishment with less seedling losses while producing uniform bulb sizes and high marketable yield. However, the use of transplants is not a widespread commercial practice because of the high cost of production. This study aims to select the best transplant strategies to improve onion crop performance in semiarid regions of southwest Texas or similar environments. Three sequential transplanting dates of early, mid, and late season (14 Nov., 8 Dec., and 9 Jan.) and two seedling densities of one seed per cell (T1) and three seeds per cell (T3) were evaluated on growth, yield, bulb quality, and phytonutrient content of three onion cultivars, two yellow (‘Caramelo’ and ‘Don Victor’), and one red (‘Lambada’). During early development, late-transplanted onions had an increase in plant height and greater leaf elongation rate than early and midtransplanted onions, whereas early plantings required more days to reach maturity than mid and late plantings. Overall, early and midtransplanting dates resulted in higher yields than late plantings. Although increasing seedling density (T3 vs. T1) did not significantly reduce marketable yield in early plantings, T1 produced a higher number of jumbo and colossal bulb sizes than T3. Onion quality was mostly affected by cultivar and not by transplant strategies. The technique of establishing onions from transplants grown from one plant per cell (T1) or multiple plants (T3) from early November to early December provides a practical and economical alternative to achieve earlier crops, while reducing the length of the production season, as planting date is delayed.

MORFOLOGIA FOLIAR DE SORGO SACARINO CULTIVADO EM DIFERENTES ESPAÇAMENTOS ENTRELINHAS E ÉPOCAS DE SEMEADURA

RESUMO - O objetivo deste trabalho foi avaliar as características morfogênicas do colmo principal de genótipos de sorgo sacarino, em diferentes espaçamentos entrelinhas e épocas de semeadura. O experimento foi conduzido em Santa Maria-RS, em delineamento experimental de blocos ao acaso em esquema trifatorial (2x2x3), com dois genótipos de sorgo sacarino (BRS 506 e Fepagro 19), dois espaçamentos entrelinhas (0,50 m e 0,70 m) e três épocas de semeadura (outubro, novembro e dezembro), quatro repetições e dois anos de cultivo. Foram avaliadas a taxa de alongamento das folhas, o número final de folhas no colmo, a taxa de surgimento de folha, filocrono e taxa de elongamento de colmo. As variáveis não apresentaram interação tripla significativa entre genótipo, espaçamento de entrelinhas e época de semeadura. O genótipo BRS 506 apresentou número de folhas acumuladas, taxa de alongamento de folhas nas épocas de semeaduras constante. O atraso na época de semeadura resulta em menor número de folhas acumuladas e taxa de elongação do colmo para o Fepagro 19. O filocrono para o espaçamento entrelinhas 0,70 m é inferior ao de 0,50 m. Os genótipos estudados estão aptos para a produção na região, desde que a semeadura ocorra no mês de outubro. Palavras-chave: alongamento foliar, filocrono, graus-dia, índice Haun, Sorghum bicolor. LEAF MORPHOLOGY OF SWEET SORGHUM CULTIVATED IN DIFFERENT ROW SPACINGS AND SOWING DATES ABSTRACT - The objective of this work was to evaluate the morphogenic characteristics of the main stem of sweet sorghum genotypes in different spacing between lines and sowing times. The experimental was carried out in a randomized complete block design in a trifactorial scheme (2x2x3), with two sweet sorghum (BRS 506 and Fepagro 19), two spacing between lines (0.50 m and 0.70 m) and three sowing seasons (October, November and December), four replications and two years of cultivation. The leaf elongation rate, the final number of leaves in the stem, the leaf appearance rate, phyllochron and shoot elongation rate were evaluated. The variables did not present significant triple interaction between genotype, spacing between rows and sowing time. The genotype BRS 506 presented a number of accumulated leaves, leaf elongation rate at constant sowing times. The delay in sowing seasons results in a lower number of accumulated leaves and the elongation rate of the stem for genotype Fepagro 19. The phyllochron for the 0.70 m line spacing is less than 0.50 m. The genotypes studied are suitable for production in the region, as long as sowing occurs in October.Keywords: leaf elongation, phyllochron, degree-days, Haun index, Sorghum bicolor.

Levels of defoliation and regrowth dynamics in elephant grass swards

The morphogenetic and structural characteristics of forage plants and the processes of growth and senescence in tissues may vary according to the grazing management strategies used. This research aimed to assess the process of regrowth in elephant grass swards Cv. 'Pioneiro' submitted to two pre-grazing heights (90 and 120cm) combined with two levels of defoliation (50 and 70%). A reduction of the leaf elongation rate (LER) was observed during the regrowth stages, in addition to a reduction in the rate of leaf appearance (LAR) and aerial tiller population density (ATPD). In contrast, an increase was observed in leaf senescence (LSR) and stem and pseudo stem elongation rates (SER). The severe defoliation (70%) combined with a pre-grazing height of 120cm compromised the regrowth of elephant grass cv. 'Pioneiro', which must be managed with a maximum height of 90cm and maximum level of defoliation of 50% of the initial height.

Morphogenetic characteristics of three Brachiaria brizantha cultivars submitted to nitrogen fertilization

This study aims to evaluate the morphogenetic characteristics of three cultivars of Brachiaria brizantha subjected to nitrogen fertilization. The design was a randomized block in factorial arrangement 4x3; three cultivars of B. brizantha - Marandu, Piatã, Xaraés and four nitrogen levels - 0, 80, 160 and 240 kg/ha, with three replications. The experimental units consisted of plastic pots filled with 5 dm3 of soil. Thereupon the establishment fertilization, varieties were sowed directly in the pots, leaving, after thinning, five plants per pot. Forty-five days after planting, it was done a standardization cut at 10 cm tall. Nitrogen levels were distributed according to the treatments, divided in three applications. The morphogenetic characteristics were evaluated in three tillers per sampling unit and data were submitted to analysis of variance and regression. For all evaluated characteristics there was no interaction between factors cultivar and nitrogen levels, verifying only the effects of nitrogen on the variables leaf appearance rate and phyllochron. The dose 240 kg/ha of N corresponds to the greater leaf appearance rate. Cultivar Marandu shows the higher leaf blade: pseudostem and ratio of leaf elongation rate and elongation pseudostem, which favors higher forage quality.