Das Ziel der vorliegenden Arbeit bestand darin, in Modellversuchen in Wasserkultur und im Festsubstrat sowohl elementspezifische (Mg-, Fe-, Mn- oder Zn-Mangel) als auch komplexe N hrstoffmangelsituationen (gleichzeitiger Mangel an Fe, Mn und Zn) zu simulieren und die Wirkung pr ventiver resp. kurativer Blattapplikationen auf Wachstum und Ertrag von Buschbohnenpflanzen zu untersuchen. Zusammengefaát wurden folgende Ergebnisse erzielt. Bei unzureichendem Mg- und Fe-Angebot sowie bei gleichzeitigem Mangel an Fe, Mn und Zn wurden das Wachstum und die Ertragsbildung hochsignifikant vermindert. Die Auswirkungen des Mg-Mangels auf Wachstum und Ertrag wurden durch die pr ventive Blattapplikation erfolgreich ausgeglichen. Die verwendeten Mikron hrstoff-Formulierungen waren bei Fe-Mangel bzw. bei multipler Mikron hrstoff-Unterversorgung, im Gegensatz zu Mn- bzw. Zn-Mangel, weniger wirksam. Aufgrund des N hrstoffmangels w hrend der generativen Phase wurden die gebildeten Bl ten und H lsen abgeworfen. Den Mangelpflanzen erm glichte die Blattapplikation erst die H lsenbildung. Ausschlaggebend f r die H he des H lsenertrages war die Anzahl der gebildeten H lsen, da das H lsengewicht nicht wesentlich beeinfluát wurde. Aufgrund des verminderten N hrstoffangebotes im N hrmedium nahm die Konzentration der betroffenen N hrstoffe im Blatt bis in den kritischen Grenzwertbereich ab. Mit Ausnahme der Fe-Mangelvarianten wirkte die Blattd ngung dieser Abnahme der N hrstoffkonzentration erfolgreich entgegen. Hinsichtlich Wachstum Ertragsbildung und N hrstoffaufnahme wurden, sowohl bei den Mg- als auch bei den Mikron hrstoff-Blattd ngern keine von der Zusammensetzung abh ngigen Wirksamkeitsunterschiede festgestellt. Bez glich der untersuchten Parameter des Wachstums und der Ertragsbildung erwies sich die pr ventive Mg-Blattapplikation der kurativen gegen ber als hochsignifikant berlegen. Derart deutliche Wirksamkeitsunterschiede in Abh ngigkeit vom Applikationszeitpunkt blieben bei den Mikron hrstoff-Blattd ngern aus. Ein Mg- und Mikron hrstoffangebot von 10% im Jugendstadium konnte ein ungest rtes vegetatives Wachstum der Pflanzen gew hrleisten. Eine Mg- bzw. Mikron hrstoff-Unterversorgung der Pflanzen w hrend der generativen Phase bewirkte einen R ckgang des Samenertrages von ber 60% bis 80%. Mit Hilfe der Blattapplikationen w hrend der generativen Phase wurde der Abwurf der reproduktiven Organe hochsignifikant vermindert. Dadurch konnten ber 90% des Samenertrages der Kontrolle erreicht werden. Ungeachtet einer erfolgreichen Impfung mit Rhizobium blieben die Pflanzen ohne N-Startd ngung im Vergleich zu einer Startd ngung mit einer quivalentmenge von 40 kg N/ha bei Wachstum und Ertragsbildung hochsignifikant zur ck. Gemessen am Samenertrag konnten die Auswirkungen des N-Mangels im Jugendstadium durch eine Nachd ngung zu Bl hbeginn nicht mehr ausgeglichen werden. Durch die Kombination Nachd ngung zu Bl hbeginn und Blattapplikation w hrend der Kornf llungsphase wurde die Abscission von reproduktiven Organen signifikant vermindert und die h chste Ertragswirksamkeit erzielt. Unabh ngig von den Behandlungen lag der Rohproteingehalt der Samen bei 20%. Auch die anderen N hrstoffe der Samen lagen im normalen Konzentrationsbereich f r Buschbohne. / The aim of this study was to simulate as well specific (Mg-, Fe-, Mn- and Zn-deficiency) as complex nutrient deficiency situations in model systems using either nutrient solution or solid substrates and to investigate the effect of preventive or curative applications of foliar fertilizers on growth and yield of bean plants. Results may be summarized as follows: Insufficient supply of magnesium and iron or simultaneous deficiency in Fe, Mn and Zn resulted in highly significant reduction of growth and yield of bean plants. Effect of magnesium deficiency on growth and yield could be successfully compensated by preventive foliar fertilization. The applied micronutrient compounds were less successful in the case of iron deficiency or multiple micronutrient deficiency situations as compared to manganese or zinc deficiency. Nutrient deficiency during the generative phase resulted in dropping of flowers and pods. In deficient plants foliar fertilizer application was a precondition for pod formation. Since pod weight was not substantially affected by plant nutrition pod number was the decisive factor for pod yield. As a result of reduced nutrient supply in the substrates leaf concentration of investigated nutrients declined below critical deficiency levels. With exception of the Fe-deficiency variants application of foliar fertilizers successfully compensated for the decrease in leaf nutrient concentrations. The composition of Mg and micronutrient foliar fertilizers did not affect significantly plant growth, yield and nutrient uptake. For the investigated parameters of growth and yield formation preventive foliar application of magnesium fertilizers was significantly more effective as compared to curative application. Such distinctive differences in fertilizer effects with time of application could not be found in micronutrient fertilizers. Mg and micronutrient supply of as low as 10% of optimal supply during juvenile growth phase could guarantee undisturbed vegetative growth. Drastic decrease of magnesium or micronutrient supply during the reproductive phase resulted in a reduction of pod yield up to 60 - 80%. Foliar fertilizer application during the reproductive development significantly reduced dropping of reproductive organs and thus seed yields of more than 90% of control were achieved. Nevertheless after a successful inoculation with Rhizobium plants without a nitrogen start dressing had significantly lower growth and yields than those with a starter fertilization of 40 kg N/ha. With regard to seed yield the effects of nitrogen deficiency during the juvenile phase could not be compensated by late fertilization at the flowering stage. The combination of a late fertilization at the flowering stage and leaf application during pod filling resulted in decreased pod abscission and therefore in highest yields. Independently of treatments the raw protein content of the bean seeds approximated to 20%. Also other nutrients in the seeds were in the adequate range for Phaseolus bean.

Orientador: Marcelo Carvalho Minhoto Teixeira Filho / Resumo: As deficiências de boro (B) e zinco (Zn) comumente ocorrem em solos de Cerrado. Por isso, para obtenção de maiores produtividades de milho é necessário entender melhor a interação desses elementos, como se existe efeito sinérgico ou antagônico na absorção destes micronutrientes do solo, tal como o modo de aplicação mais vantajoso (via solo ou foliar) e o efeito residual destas adubações. Sendo assim, objetivou-se avaliar o efeito de doses de B aplicadas via solo e via foliar, ambos com ou sem adubação com Zn no solo sobre o estado nutricional, componentes de produção e produtividade do milho primavera/verão e o residual destas adubações via solo no milho outonal, em solo de Cerrado com baixo teor de boro. O experimento foi desenvolvido em um Latossolo Vermelho distrófico em sistema plantio direto. O delineamento experimental dos dois experimentos foi em blocos ao acaso com quatro repetições, dispostos em esquema fatorial 2 x 5, sendo: com ou sem adubação via solo com 2 kg ha-1 de Zn, na forma de sulfato de zinco aplicados na ocasião da semeadura do milho primavera/verão; e 5 doses de B (0, 1, 2, 3 e 4 kg ha-1 na semeadura do milho primavera/verão (experimento 1) ou 0, 170, 340, 510 e 680 g ha-1, que correspondem respectivamente, 0; 0,25; 0,50; 0,75 e 1% de ácido bórico na calda de pulverização aplicada via foliar na fase de pré-pendoamento do milho (experimento II). Após a colheita do milho primavera/verão, avaliou-se o residual destes tratamentos aplicados via solo no cultiv... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Boron deficiencies (B) and zinc (Zn) commonly occur in Cerrado soils. Thus, for obtaining higher maize yields is necessary to better understand the interaction of these elements, as if exists synergistic or antagonistic effect on the absorption of these micronutrients in soil, such as the most advantageous mode of application (by soil or foliar) and the effect of these residual fertilizations. Therefore, it was aimed to evaluate the effect of B rates applied to soil (experiment I) and foliar application (experiment II), both with or without Zn fertilization in the soil on nutritional status, yield components and grains yield of spring/summer maize and the residual of these fertilizations in the soil in the autumnal maize, in Cerrado soil with low boron content. The experiment was conducted in an Oxisol under notillage system. The experimental design of the two experiments was a randomized block with four replications, in a factorial 2 x 5, being: with or without soil fertilization with 2 kg ha-1 Zn, in the form of zinc sulfate applied on the occasion of sowing of spring/summer maize; and 5 doses of B (0, 1, 2, 3 and 4 kg ha-1 applied at sowing of spring/summer maize (experiment 1) or 0, 170, 340, 510 and 680 g ha-1 , which correspond respectively, 0, 0.25, 0.50, 0.75 and 1% of boric acid in the spray solution applied by foliar in pre-tasseling of maize (experiment II)). After harvesting of the spring/summer maize was evaluated the residual of these treatments applied to the s... (Complete abstract click electronic access below) / Mestre

Os efeitos da aplicação foliar de fósforo (Pi) na condutância estomática (gs) e na fotossíntese (A), foram avaliados em genótipos de feijoeiro, A320, Carioca e Ouro Negro, cultivados em potes numa casa de vegetação. Este estudo foi feito durante o dia após a aplicação foliar de 10 g de Pi L-1, em plantas hidratadas, e durante um período de deficiência hídrica iniciada dois ou cinco dias após a aplicação. Durante o dia após a aplicação de Pi, não foi observado nenhuma diferença, entre os tratamentos com e sem Pi, nas trocas gasosas de ambas as cultivares. Durante a desidratação, a aplicação de Pi não causou aumento de gs, mas causou aumento de A, nas medições às 0900, 1200 e 1500 horas, nas cultivares (Carioca e Ouro Negro), mas com um efeito maior na cultivar Ouro Negro, principalmente às 1200 horas. A eficiência intrínseca do uso da água (EIUA) também foi superior nas plantas com suprimento foliar de Pi. Quanto aos componentes da produção, a aplicação de Pi causou aumento do número de vagens das plantas da cultivar Ouro Negro, sob desidratação. Portanto, a aplicação de Pi foliar pode reduzir o efeito de uma desidratação quando aplicado dois dias antes da suspensão da irrigação. Além disso, o potencial fotossintético (Ac) de Ouro Negro com Pi foi superior ao de A320, com e sem Pi, na seca máxima, e ao A320 sem Pi, na reidratação. A dissipação térmica, não fotoquímica (NPQ), do genótipo A320 sem Pi foi maior que com Pi e que a do Ouro Negro, com e sem Pi, na reidratação, provavelmente devido aos menores valores de A neste tratamento sem Pi. O uso de fosfato de amônio substituindo a uréia ou o sulfato de amônio, que são aplicados aos 25 DAE, é recomendável. / The effects of foliar Pi supplying (Pi) on stomatal conductance (gs) and photosynthesis (A) were measured in genotypes, A320, Carioca and Ouro Negro, grown under greenhouse condition. Measurements of gs and A were taken one day after Pi application (10 g L-1) on well-irrigated plants, and during drought stress period beginning two or five days after Pi supplying. During the day after Pi application, it was not observed any difference on gas exchange of genotypes (Carioca and Ouro Negro) due to the treatments with and without Pi. During water stress, the Pi supplying did not cause increase of gs, however, caused increase of A at 0900, 1200 and 1500 h in both genotypes. This effect was higher when considered Ouro Negro at 1200 h. The intrinsic water use efficiency (IWUE) was also increased in Pi-supplied plants. The Pi supplying caused increase on pod number of Ouro Negro plants under water deficit. These results suggest that the foliar Pi application may reduce the effect of water deficit on photosynthesis when supplied two days before the water withholding. In addition, the O2 evolution (Ac) on Ouro negro with extra Pi was higher than for A320, with or without Pi, at the last day of the mild water deficit, and it was higher than A 320 with extra Pi at rehydration. The non-photosynthetic quenching (NPQ), was higher for A320 without Pi at recovery, probably due to the smaller values of A at this treatment. The use of ammonium phosphate, instead of urea or ammonium sulphate to be applied as usual 25 DAS, is recommended.