Alexandra Augusti Boligon

Wheat seedling emergence estimated from seed analysis

There are various vigor tests for the evaluation of seeds physiological quality, however, few studies correlate this tests with plants emergency. This study aimed at identifying wheat (Triticum aestivum L.) seed analysis variables that best predict seedling emergence. Wheat seeds (CEP 30 cultivar) were divided into two batches, one initially subjected to the accelerated ageing process and forming the low-quality batch, and the other, without application of the accelerated ageing process, to compose a high-quality batch. The following seed test variables were evaluated: (i) percentage of normal seedlings in the germination tests, (ii) initial germination counting, (iii) accelerated ageing, (iv) cold test without soil, (v) germination speed index, and (vi) emergence of seedlings in sand after seven and 15 days. The following seedling characteristics were evaluated: root and shoot lengths, total length, and dry mass of the root and shoot. The characteristics evaluated for the seedlings were subjected to path analysis and the seed tests variables to stepwise multiple regression analysis, taking seedling emergence at seven days as the response variable. Factor analysis was also carried out on all variables. Dry mass of the shoot and root length presented the best correlation with seedling emergence for the high-quality batch, but this behavior was not observed for any variable in the low-quality batch. Accelerated ageing was the best seedling emergence estimator for both batches of the used cultivar.

Genetic progress in sunflower crop in Rio Grande do Sul State, Brazil

The sunflower has adaptability to growing regions with different climatic and soil characteristics, showing drought tolerance and high-quality oil production. The State of Rio Grande do Sul is the third largest sunflower producer in Brazil, with research related to the sunflower breeding initiated after the decade of 1950. The aim of this study was to evaluate the genetic progress for grain yield, oil content, and oil yield of sunflower (Helianthus annuus L.) in the State of Rio Grande do Sul. Data of grain yield, oil content, and oil yield obtained from 58 sunflower cultivar yield trials in 19 municipalities in Rio Grande do Sul during the period from 2005 to 2014 were used. Genetic progress was studied according to the methodology proposed by Vencovsky and data from sunflower cultivar yield trials were used. Annual genetic progress of sunflower during the period of 10 years (2005-2014) was 132.46 kg⋅ha-1⋅year-1 for grain yield, -0.17%/year for oil content, and 48.11 kg⋅ha-1⋅year-1 for oil yield. The sunflower-breeding programs in the State of Rio Grande do Sul were efficient for the traits grain yield and oil yield and presented no efficiency for oil content.

Tamanho e forma da unidade amostral para quantificação da serapilheira em fragmento de Floresta Estacional Subtropical

Para o estudo do ciclo de nutrientes em uma floresta, e necessaria a estimacao precisa da quantidade de serapilheira depositada e de suas fracoes. Entre as formas reconhecidas para minimizar a variabilidade entre amostras esta o uso do tamanho otimo de unidades amostrais para a coleta da serapilheira. Entretanto, existem poucas recomendacoes nesse sentido, o que gera variacao no tamanho da unidade amostral utilizada em experimentos similares. Assim, o objetivo deste trabalho foi determinar o tamanho e a forma otimos da unidade amostral para quantificacao de serapilheira em Floresta Estacional Subtropical. Para isso, foram alocadas, aleatoriamente, na area cinco parcelas de dimensoes 3,0 x 2,0 m em cada uma das quatro estacoes do ano, subdivididas em 96 unidades basicas de 0,25 x 0,25 m. Em cada unidade basica foi coletada toda a materia orgânica acima do solo, sendo esta separada nas fracoes folhas, galhos finos, residuo. A estimativa do tamanho otimo da unidade basica foi obtida por dois metodos distintos. Observou-se que o coeficiente de variacao diminui a medida que aumenta o tamanho da unidade amostral; ha diferencas na variabilidade da producao de serapilheira entre as parcelas na mesma estacao de coleta; unidades amostrais retangulares sao mais homogeneas entre si que as quadradas; recomenda-se a utilizacao de unidades amostrais de 0,40 m2 (1,5 m x 0,25 m) para a coleta de serapilheira em fragmento de Floresta Estacional Subtropical.