Luís Eduardo Panozzo

Desempenho individual e de populações de plantas de arroz híbrido em função da qualidade fisiológica das sementes

The work had the objective of evaluating the individual behavior of plants originated from seeds of high and low vigor of hybrid rice, inside of populations and behavior of populations of hybrid rice plants that were constituted by different ratio of plants derived from seeds of high and low physiological quality. The experiment was conducted in the experimental area of the agronomy school. It was used seeds of hybrid rice of the cultivar Avaxi, which belongs to the Ricetec®, consisting 5 treatments ( ratio of 0, 25, 50, 75 and 100% plants originated from seeds of high vigor in the population) including two lots characterized as low and high vigor. After the emergence of the plants in the trays, a looping was proceeded in order to remove the undesirable plants, removing the precocious plants in the low vigor lot and the delayed plants in the high vigor lot, intending to use the emerged plants of the day with higher frequencies of emergency on each one of the vigor levels. The transplant was carried out 20 days after sowing. The experiment was developed by a randomized complete block design, with 3 repetitions. It was evaluated: the plants height at 60 DAT, number of panicles per plant at 115 DAT, number of tiller at 60 DAT, leaf area, number of grains per panicle, number of grains per plant, weight of 1000 seeds and plant yield. Seeds of high vigor originated plants with better performance on all evaluations, independing ong the seedline distribuition. The use of high vigor seeds on the establishment of hybrid rice populations provided increases over than 30% on the yield.

Desempenho em campo de plantas isoladas de arroz híbrido em função da qualidade fisiológica das sementes

The work had the objective of evaluating the effects of seed vigor over several agronomic characteristics of hybrid rice plants. The experiment was conducted in the didactic experimental area of the Federal University of Pelotas (UFPEL). It was used two seed lots, which belong to the Ricetec®, characterized by presenting low and high vigor. The sowing was conducted directly on the field, in hollows distant 50 cm from each other, in order to isolate the plants. It was sowed 10 seed per hollow to allow posterior looping, leaving one plant per hollow at the end. The experiment was developed by a randomized completely block design, with 20 repetitions. Two treatments were tested; plants which were originated from low and high vigor seeds, formatting parcels constituted by only one plant. The soil fertility correction was accomplished by analyzing the soil, and the weed control was accomplished manually. The following parameters were evaluated: plant height at 60 and 115 days after plants emergence number of panicles per plant, leaf area, dry matter of the aerial part, number of grains per panicle, number of grains per plant, weight of 1000 seeds and plant yield. It was concluded that the seed physiological quality used for the plants establishment affected the performance of the adult plants. Seeds of high vigor originated plants with higher physiological potential which reflected on a higher growing and yield per plant.

Métodos de manejo de Cyperus esculentus na lavoura de arroz irrigado

The Cyperaceae family include the most important weeds found in the state of Rio Grande do Sul rice fields. The objective of this work was to evaluate Cyperus esculentus control and rice cv. Qualimax 1 selectivity and grain yield in function of the irrigation starting times, application times and penoxsulam rates. The trial was set up under field conditions in the agricultural year of 2005/2006 and was arranged in a completely randomized block design with split plots and four replications. Treatments were in a factorial scheme (2 x 3 x 5) and consisted of two herbicide application times (early and late), three irrigation starting times (1, 15 and 30 days after treatment), and herbicide rates (0, 24, 36, 48 and 60 g ha-1 ). The herbicide penoxsulam showed selectivity to the rice culture regardless of the association between the evaluated treatments. The application of penoxsulam, combined with irrigation starting 15 days after herbicide application promoted efficient control of C. esculentus. Highest grain yield was obtained by applying penoxsulam at the rates of 36 g ha-1 or above, regardless of the application time, and when early irrigation was carried out.

Physiological quality of castor bean seeds classified by size.

Seed size in many species may be an indication of their physiological quality. The objective of this study was to evaluate the physiological performance of castor bean seeds sorted by size. The experiment was conducted at the Seed Research Laboratory of the Department of Plant Science at the Federal University of Vicosa. Seeds of four castor bean cultivars, IAC 226, IAC 80, Al Guarany 2002 and BRS 188 Paraguacu were used. The seeds were harvested from all the plant racemes and classified into three different seed sizes for each cultivar. Tests were conducted to evaluate germination and vigor: germination at the 4th day, germination at the 7th day, accelerated ageing, seedling length of roots and shoots and fresh and dry weights of the seedlings. Based on the results for IAC 226 and BRS 188 Paraguacu there is a tendency for smaller seeds to show higher speeds and final percentage of germination but this was not the case for the IAC and 80 Al Guarany 2002.

Influence of Boron on Sunflower Yield and Nutritional Status

ABSTRACT Sunflower has been mentioned in the literature as a plant that requires large amounts of boron (B) to achieve a successful crop. This study aimed at evaluating the influence of sunflower fertilization with boron on the soil nutrient concentration, index leaf, seed yield, fatty acids’ composition of sunflower oil, and oil content. Cultivar M734 was selected for boron fertilization at 0, 3, 6, 9, and 12 kg ha−1 rates. The maximum economic return was obtained with 3.13 kg ha−1. Neither oil content nor fatty acid composition was affected by boron. With proper irrigation, the M734 cultivar was able to absorb boron in the 0 − 40-cm layer, ultimately producing about 3000 kg ha−1 of seeds in soils with only 0.30 mg kg−1 of boron. Based on these results, it is suggested that the boron fertilization program be expanded to include the soil strata at 0−20 cm and 20−40 cm.

Control of Echinochloa sp. in the Irrigated Rice Crop

The species of Echinochloa (barnyardgrass) stand out among major weeds infesting rice cropping and damages are variable depending on the weed population, rice cultivar, and management practices adopted by rice farmers. The objective of this work was to measure the control of barnyardgrass in rice cropping, cultivar Qualimax 1, due to the early times of flood irrigation, application times, and doses of penoxsulam. The experiment was conducted in the field, where the experimental design used a randomized block design with a split plot design with four replications. The treatments consisted of two application periods (early and late) of penoxsulam three times of irrigation start (1, 15 and 30 days after treatment application—(DAT)) and herbicide doses (0, 24, 36, 48 and 60 g ha−1). The herbicide penoxsulam revealed that combined with irrigation starting 15 days after herbicide application promoted efficient control of barnyardgrass.

Curva de embebição e condutividade elétrica de sementes de mamona classificadas por tamanho

The soaking period is very important for standardizing the electrical conductivity test since it directly influences the test results. The objective of this study was to evaluate the curves of absorption and electrical conductivity for different-sized castor bean seeds. Seeds of four castor bean varieties, IAC 80, IAC 226, BRS 188 Paraguacu and Al Guarany 2002, were studied. Seeds were collected from all racemes of the castor bean plants and classified by weight and shape. Subsequently, the seeds were classified by size using screens according to the cultivar. The curves of the absorption and electrical conductivity values were obtained by the weighing and systematic reading of four replications of 50 castor bean seeds until the end of the soaking process. Seeds of the IAC 80, BRS 188 Paraguacu and Al Guarany 2002 cultivars with a greater thickness and width had a higher moisture content, and this may increase solute leaching during soaking. In the IAC 226 cultivar, the seed moisture content and solute leaching from seeds with different thicknesses is related to their quality.

Diversidade e sensibilidade de Cyperus ferax ao herbicida Penoxsulam

The species of the genus Cyperus, Cyperaceae family, are the major weeds in the rice producing regions of the state of Rio Grande do Sul (RS). The objective of this study was to evaluate the diversity of Cyperus ferax in these regions and the sensitivity levels of this species to the herbicide penoxsulam. Thus, an experiment was conducted under greenhouse conditions in the Faculdade de Agronomia Eliseu Maciel. The experimental design was completely randomized, with four replications. Each experimental unit (plot) was composed of vases with a capacity of 0.55 dm3 of soil, with seven plants. Treatments were arranged in a factorial design.Factor A evaluated the places of collection (origin) of the seeds of C. ferax, a weed in RS irrigated rice fields; and factor B evaluated susceptibility to the herbicide penoxsulam (125 g ha-1), compared to a control without application. Differences were verified between the accessions of C. ferax regarding sensitivity to the herbicide penoxsulam. The biotypes from the irrigated rice fields at Depressao Central show, in general, higher shoot dry mass accumulation and leaf area. The C. ferax biotypes at the RS rice fields can be divided into two groups, according to their morphological characteristics.

Alelopatia de plantas de cobertura na superfície ou incorporadas ao solo no controle de Digitaria spp.

Os aleloquimicos podem sofrer modificacoes em diversos tipos de substrato, tanto incorporados quanto na superficie do solo. O objetivo deste estudo foi investigar os efeitos de diferentes niveis de palha de culturas de cobertura, quando incorporadas ou mantidas na superficie do solo, sobre a emergencia e o desenvolvimento inicial de Digitaria spp. (milha, capim-colchao e capim-de-roca). O delineamento experimental utilizado foi em bloco ao acaso, com quatro repeticoes. Os tratamentos foram arranjados em esquema fatorial com os seguintes fatores: (A) - manejo das coberturas (incorporado e na superficie do solo); (B) culturas de cobertura de solo (canola, nabo forrageiro, trevo-vesiculoso e azevem); e (C) niveis de palha (0, 1, 2, 4, 6 e 10 t ha-1). Com o aumento dos niveis de palha de canola e nabo forrageiro incorporados ao solo, ha em geral aumento na reducao das variaveis IVE e porcentagem de emergencia de milha. A presenca de palha de azevem na superficie do solo reduz o crescimento de milha, comparativamente a incorporacao, sendo necessario ao menos 6 t ha-1 de palha.

Épocas de aplicação de penoxsulam e de início da irrigação no arroz irrigado

Irrigated rice is subject to interference caused by biotic and abiotic factors. Among the former, weeds are the main causes of decreased productivity, directly interfering in rice yield. The objective of this study was to evaluate the effect of irrigation starting times, application times and penoxsulam rates on the yield components of irrigated rice, cultivar Qualimax 1. The experiment was installed in the field, in a randomized block design with split plots and four replications. The plots allocated application dates (early and late) of Penoxsulam, and the subplots the starting times of irrigation (1, 15 and 30 days after herbicide application - DAT) and the split-split herbicide doses (0, 24, 36, 48 and 60 g ha-1). The highest grain yield was obtained by applying penoxsulam at the rates of 36 g ha-1 or above, regardless of the application time, and when early irrigation was carried out. The anticipation of irrigation generally increases the yield components of rice cultivar Qualimax 1. The application of penoxsulam at equal doses or higher than 36 g ha-1, regardless of application dates or flood, do not change the yield components of irrigated rice.