Miguel Dall'Agnol

Análise de trilha para rendimento de sementes em trevo vermelho (Trifolium pratense L.)

Red clover is a temperate legume species that shows good dry matter yield potential and forage quality, being indicated to supplement livestock animals during the cool season in the Southern part of Brazil. The objective of this experiment was to study seed yield in red clover through the use of path analysis, aiming to generate basic information to be used on breeding program or in management strategies, which lead to an increase on seed yield, natural reseeding and thus to a greater pasture persistence. The following variables were analyzed: seed yield, number of stems per plant, number of seed head per plant, number of seed head per stem and weight of one thousand seeds. The number of seed head per plant was the variable with the greatest correlation with seed yield (r = .710), basically through its direct effect on seed yield. The other variables showed smaller correlation coefficients with seed yield (r values from .175 to .578) as well as presented negative or small direct effects on it. Therefore, the number of seed head per plant showed to be the main characteristic to be considered when an increase in the red clover seed yield is required.

Cytogenetic data for Paspalum notatum Flügge accessions

Several species of the genus Paspalum L. are important forages, due to quality, productivity and tolerance to environmental stresses. Chromosome numbers, meiotic configurations and pollen fertility were evaluated in a collection of 85 accessions of Paspalum notatum Flugge and in seven accessions of Pensacola (P. notatum var saurae). All P. notatum accessions were tetraploid, with 2n = 4x = 40, except one diploid accession, considered as an escape of Pensacola. All Pensacola plants had 2n = 2x = 20. Meiotic configurations at diakinesis and metaphase I varied among tetraploid accessions, from plants with only bivalents to plants with high frequency of quadrivalents. Pollen fertility varied from 82.5 to 95.9% among diploid accessions and from 72.4 to 97.9% among the tetraploid. Due to the apomictic mode of reproduction of tetraploid P. notatum, meiotic irregularities can be maintained by the plants without harming their propagation. At the same time, pollen fertility should be high enough to assure endosperm development, since the species is pseudogamous. Wild diploid P. notatum populations, apart from the endemic P. notatum var saurae are very rare. From a plant breeding point of view, all the examined tetraploid accessions are potentially male-fertile and could be used as males in crosses.

Produção de forragem de capim-elefante sob clima frio: curva de crescimento e valor nutritivo

This work aimed to quantify the yield and nutritive value of elephantgrass (cv. Cameroon), in Lages, Santa Catarina, with the objective to identify possible limitations to its production and to show its viability in the region. The trial was carried out from 1982 to 1985, when the elephantgrass was established in plots in a complete block design. The treatments were the sum of growing days up to the evaluation day, in order to establish a growth curve. The accumulated dry matter (DM) started 42 days after an uniformization cut and the plots were cut in sequence every 21 days, up to complete 210 days of growth, always leaving a 50 cm stubble. The regrowth ability in each period was also evaluated every 21 days. Data were submitted to variance and regression analyses. The elephantgrass dry matter accumulation was significantly dependent of days of growth, showing growth rates of 185 and 65 kg DM/ha/day on 1983/84 and 1984/85, respectively. In the first growing period, it was obtained 31,132 kg DM/ha with 210 days of growth and 3,310 kg DM/ha in the first 63 days of growth. In 1984/85, the plants accumulated about one-third of that obtained in the previous year, probably due to nutritional problems and to a drought spell. In the regrowth evaluations, the highest yields were obtained with plants growing for 42 (1,149 kg DM/ha) and 63 days (1,259 kg DM/ha). The two years average of crude protein and in vitro dry matter digestibility was 20% and 65%, respectively. Although the cold climate, the elephantgrass is a viable alternative for the Santa Catarina highlands.

Produção agronômica de uma coleção de acessos de Paspalum nicorae Parodi

This study was carried out to evaluate a collection of 53 accessions of Paspalum nicorae, introduced in two physiographically distinct regions over two years, with the objective of characterizing production and quality of forage of access for subsequent phases of a forage plant breeding program. The accessions were established in lines in randomized block design with three replications and the evaluations were performed from October 2007 to February 2009 by using cuts. There was variation of forage production among access over time and among sites. The majority of the accessions of P. nicorae presented high forage yield when compared with the control (P. notatum cv. Pensacola) and some accessions presented very expressive performances. The percentages of crude protein obtained from accessions in the collection were similar to the ones found in the control access. The accessions 28B and 26A of P. nicorae are indicated for subsequent stages in a program of forage plant breeding.

Variabilidade genética de caracteres forrageiros em Paspalum

The objective of this work was to determine the genetic variability and the expression of traits of interest for forage production in species of Paspalum. The experiments were carried out in different locations and crop years in randomized block design with three replicates. Five accessions of P. nicorae and two of P. guenoarum were evaluated, besides the cultivar Pensacola (P. notatum), used as a control. The following traits were determined: leaf/stalk ratio; harvest index; and total, leaf, and stalk dray matter. Both main effects (genotype, years, and locations) and the interactions among factors had significant influence on the evaluated traits. The evaluated accessions showed genetic variability in traits of interest for forage production, and their performance varied according to the location and year of cultivation. Total and leaf dry matter production are the traits that most contribute to the detection of the observed genetic variability, regardless of the year of evaluation.

Mode of reproduction of Brazilian species of Adesmia (Leguminosae).

Mode of reproduction was studied in 15 species of Adesmia DC. (Leguminosae). In six species, three treatments were used: mutual pollination, mechanical stimulation and control. Fifty-four plants of these six species were grown in a greenhouse, individually isolated in nylon screen boxes. Flowers were labelled and submitted to the different treatments. In addition, the frequency of spontaneous self-pollination in the absence of pollinators was studied in 200 plants of nine other species. These 200 plants were kept in a greenhouse, which avoided contact with any possible pollinator. Adesmia bicolor, A. muricata, A. punctata and A. riograndensis produced seed both by cross- and self-pollination. Adesmia punctata and A. riograndensis need mechanical stimulation for self-pollination. Adesmia incana reproduced by self-pollination; however, the possibility of cross-pollination cannot be totally ruled out. Adesmia tristis reproduced mainly by cross-pollination and a mechanism of self-incompatibility is suggested. Among the nine species that were not exposed to pollinators, A. securigerifolia produced a large amount of seed, indicating that it is a self-pollinating species. Adesmia arillata, A. araujoi, A. ciliata, A. psoraleoides, A. rocinhensis, A. reitziana, A. sulina and A. vallsii did not produce any seed under the experimental conditions, suggesting that they are cross-pollinated or that they need mechanical stimulation to reproduce.

Variabilidade genética em populações naturais de Bromus auleticus Trin. ex Nees (Poaceae) com base em isoenzimas e marcadores RAPD

Bromus auleticus is a perennial, native species of the state of Rio Grande do Sul, which has demonstrated adaptability, potential yield of good quality forage as well as high morphological diversity. This work has analyzed band patterns from enzymatic systems and RAPD markers, with the objective to access the genetic variability in 16 accessions of Bromus auleticus from Rio Grande do Sul. The variability was evaluated using Jaccard similarity index. The method of grouping based on the average (UPGMA) was used in cluster analyses. The similarity index ranged from 0.0 to 0.50 using isozumes and from 0.15 to 0.71 using RAPD markers. The data have been efficient for the formation of different groups, indicating the genetic variability of the accession analyzed. However, these groupings have little relationship with the respective collecting places. The genetic variability of the accessions is important to the genetic improvement, allowing future genotype selection based on their respective performances. The simultaneous utilization of isozymes and RAPD was efficient in characterizing the genetic diversity of the accessions evaluated.

Caracterização morfofisiológica de genótipos de cornichão (Lotus corniculatus L.)

The birdsfoot trefoil cv. Sao Gabriel is an important winter-spring growing legume in the Southern Brazil, which main limitation is the low persistence under grazing. The objective of this work was to evaluate eight populations of this cultivar, selected under grazing or cut, comparing with one rhizomatous genotype (cv. ARS-2620) and a cultivar from Uruguay without rhizomes (cv. Trueno), with the purpose to evaluate the morphological variability and characters linked to grazing tolerance. Two assays were conducted in the greenhouse with plants grown in pots until the full flowering stage. It was observed morphological variability in the germplasm, with variation in the leaf, stem and crown morphology as well as in growth habit. Only in the cv. ARS-2620 was observed typical rhizomes, but all the genotypes showed subterraneous stems. The cv. ARS-2620 was susceptible to mites and two populations showed symptoms of anthracnose (Colletotrichum sp.). The morphophysiological variability of the cv. Sao Gabriel populations can be used in a birdsfoot trefoil breeding programs.

Disponibilidade e valor nutritivo de forragem de leguminosas nativas (Adesmia DC.) e exóticas (Lotus L.)

RESUMO - O genero Adesmia DC. possui 17 especies nativas no Brasil, distribuidas nos Estados do Sul, cuja importância esta vinculada a sua adaptacao ao solo e clima regionais, alem de ser de crescimento hibernal (temperadas). Este trabalho teve o obj etivo comparar o padrao de acumulo de materia seca (MS) e valor nutritivo de forragem de A. latifolia, A. punctata e A. tristis, tendo como padrao Lotus corniculatus (cornichao) e L. uliginosus. O ensaio foi realizado em casa de vegetacao durante 210 dias (4000 graus-dia). A disponibilidade de forragem (DF) foi similar entre A. latifolia (276 g MS/m 2 ) e cornichao (275 g MS/m 2 ) e entre A. tristis (201g MS/m 2 ) e L. uliginosus (192 g MS/m 2 ), sendo que A. punctata apresentou a menor DF (155 g MS/m 2 ). A. latifolia caracterizou-se pela maior precocidade na DF, devido ao crescimento mais rapido em relacao as demais especies, sugerindo seu potencial para utilizacao dur ante a estacao fria. Em relacao as analises de qualidade, o teor de proteina bruta (PB) nas folhas de A. latifolia foi de ate 21,6% e a DIVMO atingiu 72,3%. Os maiores conteudos de PB e DIVMO foram encontrados nas folhas de cornichao, 30,3 e 75,8%, respectivamente. A. tristis apresentou DIVMO muito baixa nos caules (34,9 a 44,7%), o que poderia limitar seu consumo por bovinos. Concluiu-se que, entre as especies de Adesmia estudadas, A. latifolia detem o maior potencial forrageiro, sugerindo a continuidade de estudos com a especie.

Morphological variation in Paspalum nicorae Parodi accessions, a promising forage

Paspalum nicorae Parodi is a perennial, apomictic tetraploid forage species, native in the state of Rio Grande do Sul, Brazil, with grazing tolerance and adapted to sandy soils and moderate droughts. As a first step to future breeding, a morphological characterization regarding leaf hairiness, sheath, leaf and central venation color, growing habit, plant height, raceme number and length, and leaf length and width was performed in 53 accessions from Rio Grande do Sul that are part of a Paspalum species breeding program. 35.84% of the accessions had completely hairy leaves, 73.58% had green sheath, 54.71% whitish central venation, 50.94% decumbent habit. Leaf color was estimated by two methods, color chart and colorimeter. The accessions were classified as 76.92% green, 13.45% greenish yellow and 9.62% as grayish green by the first, and 59.62% grayish, 32.69% grayish yellow, 5.77% yellow and 1.92% dark grayish by the second method. Raceme length ranged from 9.40 to 1.30 cm, number of racemes from one to six (48.73% of the accessions had four racemes), leaf length and width from 36.13 to 13.06 cm and 0.67 to 0.36 cm, respectively, and plant height from 115.70 to 29.00 cm. Therefore, a large morphological variation among accessions was detected, with no relation to geographical location but indicating a high potential use in plant breeding programs.