Thiago Schmitz Marques da Rocha

Contribuição das ramificações e a evolução do índice de área foliar em cultivares modernas de soja

The purposes of this study were to quantify the branches contribution and the leaf area index evolution in modern cultivars of soybean with different maturity groups, stem termination, sowing in different dates and producing regions of soybean in Rio Grande do Sul. Field experiments were conducted during the growing season 2013/2014 in Santa Maria, Julio de Castilhos and in three soybean crops on the municipalities of Restinga Seca, Tupancireta and Agua Santa. It were carried out analysis (occurrence date) of reproductive stages and determination total, maximum, of main stem and of branches of leaf area index in thirteen cultivars of soybean. The leaf area index on the branches contributes with about 31%, 12.3% and 11% of the total leaf area index on the determinate cultivars and with 20.2%, 11.8% and 9% of the total leaf area index on the indeterminate cultivars sowing in September, November and February, respectively, in Santa Maria. Most cultivars showed a reduction on total leaf area index, maximum, of main stem and of branches with the delay on planting date, independently of the maturity group and stem termination.

Desenvolvimento de cultivares de soja em função do grupo de maturação e tipo de crescimento em terras altas e terras baixas

O objetivo deste trabalho foi caracterizar o desenvolvimento de cultivares de soja com diferentes grupos de maturacao e tipos de crescimento em terras altas e terras baixas no Rio Grande do Sul. Foram conduzidas nove epocas de semeadura em Santa Maria (ambiente de terras altas) e uma epoca de semeadura em Capao do Leao (ambiente de terras baixas) durante os anos agricolas 2010/2011, 2011/2012 e 2012/2013, com 11 cultivares de soja. O delineamento experimental em todos os experimentos foi blocos ao acaso, em parcelas subdivididas. Foi quantificada a duracao, em oC dia, do ciclo de desenvolvimento, da fase vegetativa e reprodutiva, e do periodo entre a data que ocorreu o inicio do florescimento e o numero final de nos para todas as epocas e locais de semeadura. Houve reducao da duracao da fase reprodutiva, do ciclo total de desenvolvimento (exceto algumas cultivares semeadas em setembro), com o atraso da data de semeadura independentemente do grupo de maturacao e tipo de crescimento. As semeaduras de setembro, janeiro e fevereiro promovem uma reducao da fase vegetativa na maioria das cultivares quando comparadas com a epoca recomendada (novembro e dezembro). Cultivares indeterminadas apresentam um maior periodo de sobreposicao das fases vegetativa e reprodutiva do que as cultivares determinadas em todas as epocas e locais de cultivo. O desenvolvimento da soja e similar quando cultivada em terras altas e terras baixas.

Transpiration and leaf growth of potato clones in response to soil water deficit

Potato (Solanum tuberosum ssp. Tuberosum) crop is particularly susceptible to water deficit because of its small and shallow root system. The fraction of transpirable soil water (FTSW) approach has been widely used in the evaluation of plant responses to water deficit in different crops. The FTSW 34 threshold (when stomatal closure starts) is a trait of particular interest because it is an indicator of tolerance to water deficit. The FTSW threshold for decline in transpiration and leaf growth was evaluated in a drying soil to identify potato clones tolerant to water deficit. Two greenhouse experiments were carried out in pots, with three advanced clones and the cultivar Asterix. The FTSW, transpiration and leaf growth were measured on a daily basis, during the period of soil drying. FTSW was an efficient method to separate potato clones with regard to their response to water deficit. The advancedclones SMINIA 02106-11 and SMINIA 00017-6 are more tolerant to soil water deficit than the cultivar Asterix, and the clone SMINIA 793101-3 is more tolerant only under high solar radiation.

Efeito do espaçamento de plantio no crescimento, desenvolvimento e produtividade da mandioca em ambiente subtropical

The objective of this study was to analyze the effect of different planting spacings on the growth, development and stems and roots yield in a subtropical environment of Rio Grande do Sul, Brazil. Treatments consisted of four spacings: 0.8x0.8 m, 1.0x1.0 m, 1.2x1.2 m, 1.5x1.5 m, corresponding to densities of 15,625 plants ha -1 -1 , respectively. The cultivar used was Fepagro - RS 13. The variables of growth and development analyzed were green leaf area, plant height, number of senesced leaves, internode lenght, final leaf (FLN), number of lateral shoots, final size of leaves, phyllochron and stem and root fresh and dry weight yield. The maximum leaf area index and phyllochron increases as plant density increases. The final leaf size and number of lateral shoots increases as plant density decreases. The FLN differed only for the second sympodial branching, with the largest number of leaves in the 1.5x1.5m plant spacing. The stems yield of cultivar Fepagro - RS 13 does not vary with the planting spacing, but tuber root yield per area is higher at higher densities, while yield per plant and per root is higher in lower densities.

Efeito do tipo de crescimento no desenvolvimento de cultivares modernas de soja após o início do florescimento no Rio Grande do Sul

There was a change in the genetics of soybeans grown in southern Brazil from the 2000s, which requires investment in basic and detailed studies about growth and development. The purpose in this paper was to characterize the overlap period of vegetative and reproductive phases, growth in height and the emission of nodes after the beginning of flowering in determinate and indeterminate cultivars in different sowing dates and soybean regions in Rio Grande do Sul. Field experiments were conducted during the growing seasons of 2012/2013 and 2013/2014, in Santa Maria, Itaqui, Frederico Westphalen, Capao do Leao, Julio de Castilhos and in 3 commercial soybean crops in Restinga Seca, Tupancireta and Agua Santa. Overlap determination (in days) of vegetative and reproductive phases, difference in the number of nodes and height in R8 and R1 were estimated. The cultivars with indeterminate growth had higher overlap period of vegetative and reproductive phases, height growth and emission of nodes after the beginning of flowering in comparison with the determinate cultivars. The magnitude of the overlap values of vegetative and reproductive phases and of the increase in height and number of nodes after R1 ranged with the type of growth, maturity group, location, and sowing date.

Dano por Granizo na Cultura da Soja em Condições de Lavoura: Um Estudo de Caso

The objective of this study was to quantify the damages caused by a hail event on a soybean farm. The hail event happened at Agua Santa County, Rio Grande do Sul State, Brazil, during the 2013/2014 growing season. Were conducted dry matter evaluations of leaf, petiolate, pod and leaf area index. Such measurements were obtained before and also after of the hail event occurred on 08/02/2014. By using satellite and radar images it was possible to identify the hail event intensity. The hail event damage on the soybean crop were reduction dry matter on leaf blade (0.13 Mg ha−1), on petiolate (0.01 Mg ha−1) and on pods (0.002 Mg ha−1), also were observed a decrease in leaf area index that varying from 7 to 34% and breaking off the growth apex in 32% of plants on the experiment. Therewith, the satellite and radar images can be a tool to help the extension on determination of hail damage on soybean farms.

COMPARAÇÃO DA PRODUTIVIDADE DE SOJA OBSERVADA E SIMULADA PELO MODELO SOYSIM PARA SEIS MUNICÍPIOS DO RIO GRANDE DO SUL

A produtividade da cultura da soja foi simulada por um modelo ecofisiologico e comparada com dados de produtividade observada de seis municipios do Rio Grande do Sul – RS. As simulacoes foram realizadas atraves do modelo SoySim, com quatro datas de semeadura, tres grupos de maturacao e tres niveis tecnologicos distintos.