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Produção e qualidade de sementes de arroz (Oryza sativa L.) sob diferentes doses de fósforo aplicadas ao soloOliveira, João Carlos Pinto 08 April 2011 (has links)
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Previous issue date: 2011-04-08 / The objective of this work was to evaluate the quality and the yield compounds of
seed of rice when different levels of phosphorus are applied to the soil. The utilization
of rock phosphates as source of phosphorus on rice crop has been a growing
recommendation, considering the low availability of phosphorus in the system.
Besides the majority of bibliographies do not report any effect on grain yield with
higher levels of phosphorus in the soil, there is no information on how the seeds of
flooding rice behave with respect to the quality and components of production under
these conditions. The soil was prepared in the conventional method and fertilized
before sowing according the analysis recommendation of soil (55kg.ha-1 of K2O in
form of KCl) and phosphorus in form of rock phosphate in the levels: zero, 30, 45, 60,
75 and 90kg.ha-1 of P2O5 and 90kg.ha-1 of nitrogen in surface dressing in form of
urea in two times. It was used cv. BRS Querência in sowing density of 90kg.ha-1 of
viable seeds, sowed on November, 23, 2007. The experiment was carried out in
Estação de Terras Baixas of Embrapa Clima Temperado and at the Laboratory of
Seed Analysis Flávio Farias Rocha of Agronomy College at the Universidade Federal
de Pelotas. The analysis of flag leaf was carried out in Plant Nutrition Laboratory of
Embrapa Clima Temperado. The experimental design was with randomized complete
blocks design with four repetitions. The seeds were harvest on April, 2, 2008 and
presented 23% of moisture, and they dried in a forced-air stationary dryer at 40oC
until 15% of moisture. It was evaluated for seed yield per hectare, yield compounds
and the levels of phosphorus in a flag leaf, collected at the flowering stage. Two
germination tests were carried out 90 and 450 days after the harvest. The last one
was considered as a vigor test in seeds harvested and stored. The seed yield per
hectare and the percent of germination in vigor test showed fit quadratic regression
models. The percent of perfect grains and the levels of phosphorus and magnesium
in flag leaves fit linear regression models. A significant correlation was found
(P<0.05%) between phosphorus and magnesium levels in flag leaves and the
percentage of germination in vigor test. The use of Arad rock phosphate affected the
yield and quality of rice seeds on Planossoil of Coastal Plain of Rio Grande do Sul. / O objetivo do presente trabalho foi avaliar a qualidade e a produção de sementes de
arroz irrigado, quando diferentes doses de fósforo são aplicadas ao solo. A utilização
de fosfato natural como fonte de fósforo na cultura do arroz irrigado vem sendo uma
recomendação crescente, considerando a baixa disponibilidade do fósforo no
sistema. Além da maioria das bibliografias não relatarem algum efeito sobre a
produção de grãos quando se elevam os níveis de fósforo no solo, não se têm
informações sobre como se comportam as sementes de arroz irrigado com relação a
sua qualidade e aos componentes da produção nestas condições. O preparo do solo
foi convencional, adubado antes da semeadura conforme recomendação da análise
de solo (55kg.ha-1 de K2O na forma de KCl) e fósforo na forma de fosfato natural
variando segundo os tratamentos: zero, 30, 45, 60, 75 e 90kg.ha-1 de P2O5 e
90kg.ha-1 de nitrogênio na forma de ureia em cobertura, em duas vezes. Utilizou-se
a cv. BRS Querência na densidade de 90kg.ha-1 de sementes viáveis, semeada em
23 de novembro de 2007. O experimento foi conduzido na Estação de Terras Baixas
da Embrapa Clima Temperado e no Laboratório de Análise de Sementes Flávio
Farias Rocha, da Faculdade de Agronomia Eliseu Maciel da Universidade Federal de
Pelotas. As análises das folhas bandeira foram realizadas no Laboratório de Nutrição
Vegetal da Embrapa Clima Temperado. O delineamento experimental foi o de blocos
completos ao acaso, com quatro repetições. As sementes foram colhidas em dois de
abril de 2008 quando apresentavam 23% de umidade, sendo secadas em secador
estacionário com ar forçado a 40oC até 13% de umidade. Foi avaliado o rendimento
de sementes por hectare, os componentes da produção de sementes e os teores de
fósforo na folha bandeira coletada na fase do florescimento. Foram realizados dois
testes de germinação. O primeiro, 90 dias após a colheita das sementes, e o
segundo, 450 dias após a colheita. Este último foi considerado como avaliação do
vigor nas sementes colhidas e armazenadas. O rendimento de sementes por hectare
e a percentagem de germinação no teste de vigor apresentaram respostas que se
ajustaram a modelos de regressão quadráticos. Já a percentagem de grãos inteiros
e quebrados e os teores de fósforo e de magnésio nas folhas bandeira se ajustam a
modelos de regressão linear. Também se encontrou uma correlação significativa e
positiva (P<0,05%) entre os teores de fósforo e de magnésio nas folhas bandeira e a
percentagem de germinação no teste de vigor. O uso do fosfato natural de Arad teve
influência na produção e qualidade de sementes de arroz irrigado em Planossolos
da Planície Costeira do Rio grande do Sul.
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Elucidating and Mapping Heat Tolerance in Wild Tetraploid Wheat (Triticum turgidum L.)Ali, Mohamed Badry Mohamed 2010 December 1900 (has links)
Identifying reliable screening tools and characterizing tolerant germplasm sources is essential for developing wheat (Triticum aestivum L.) varieties suited for the hot areas of the world. Our objective was to evaluate heat tolerance of promising wild tetraploid wheat (Triticum turgidum L.) accessions that could be used as sources of heat tolerance in common- and durum-wheat (Triticum durum) breeding programs.
We screened 109 wild tetraploid wheat accessions collected by the International Center for Agriculture Research in the Dry Areas (ICARDA) from the hottest wheat growing areas in Africa and Asia, as well as, two common wheat checks for their response to heat stress by measuring damage to the thylakoid membranes, flag leaf temperature depression (FLTD), and spike temperature depression (STD) during exposure to heat stress for 16 beginning at anthesis. Measurements were taken on the day of anthesis then 4, 8, 12, and 16 days post anthesis (DPA) under controlled optimum and heat-stress conditions. Individual kernel weight (IKW) and heat susceptibility index (HSI) measurements were also obtained. Prolonged exposure to heat stress was associated with increased damage to thylakoid membranes, as indicated by the high ratio of constant fluorescence (O) to peak variable fluorescence (P).
A positive and significant correlation was found between O/P ratio and both FLTD and STD under heat-stress conditions. A negative and significant correlation was found between FLTD and HSI and between STD and HSI based on the second and third measurements (4 and 8 DPA). Correlations obtained after the third measurement were not significant because heat-stress accelerated maturity and senescence.
For a pedigree-based mapping strategy a family approach was then developed by crossing and back-crossing heat-tolerant and heat-susceptible germplasm. A set of 800 lines resulting from the pedigree-based family approach was phenotyped using FLTD, chlorophyll content and yield and its components under heat stress. Genotyping of these lines was accomplished using simple sequence repeat (SSRs) markers. Some QTLs associated with heat stress tolerance were identified. This study identified potential heat-tolerant wild tetraploid wheat germplasm and QTL conditioning heat tolerance that can be incorporated into wheat breeding programs to improve cultivated common and durum wheat.
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