<p> A micrometeorological investigation was conducted over and within a crop of corn (Zea mays, var. Seneca Chief). The purpose of the experiment was to observe net radiation profiles within the canopy and to determine their behavior with respect to crop density. Discussion of the construction and evaluation of linear net radiometers for use in this study is included. The net radiation profiles are examined and compared with existing theoretical models. The form of the profiles is studied and a new model of net global radiation profiles based on micrometeorological data and crop parameters is discussed. </p> / Thesis / Master of Science (MSc)

Investigation of soil bioactivity and weed infestation in spring oilseed rape agrocoenosis of different density Aušra Grybaitė Field experiments were carried out in 2004 and 2005 at the Experimental Station of Lithuanian University of Agriculture to study the influence of different spring oilseed rape (Brassica napus L.) ‘Sponsor’ densities (50.1-100, 100.1-150, 150.1-200, 200.1-250, 250.1-300, 300.1-350, 350.1-400, 400.1-450 plants m-2) on soil bioactivity and weed infestation. Soil - Calc(ar)i-Endohypogleyic Luvisol. By increasing of spring oilseed rape crop urease activity in the soil didn’t chage significantly. The saccharase activity in the rape agrocoenosis with density more than 150.1 plants m-2 significantly increased in comparison with saccharase activity in the thinest rape agrocoenosis. The content of humus (r = 0.73, P < 0.05) and available phosphorus (r = 0.71, P < 0.05) influenced the saccharase activity. Spring oilseed rape crop density had no influence on number of weed species, weed sprouts and weed density before harvest. Efficiency of weed suppressing increased when weed density in crop at 3-4 leaves stage increased. This proved the small similarity indexes of weed density in crop at 3-4 leaves stage and before harvest. Rape crop density had no influence on weed species change. Significant negative relationship was found between weed air-dry biomass and rape crop density (r = -0.82, P < 0.01). Most of weeds in rape crop were therophytes. Most of them... [to full text]

The experimental objective. The study was designed to establish the effects of crop stand density and fertilization on spring rape productivity. Statements to be defended: 1. Crop stand density and plant supply with nutrients affect the penetration of photosynthetically active radiation to the soil surface and various heights of crop canopy. 2. Under favourable nutritional conditions, spring rape reaches the maximum photosynthetic productivity at flowering in a crop with a lower stand density; while under less favourable conditions, the maximum photosynthetic productivity at flowering is achieved in a crop with a higher stand density. 3. Under favourable nutritional conditions, at optimal crop stand density, spring rape accumulates the highest content of nutrients in the above-ground plant part at flowering stage. 4. In differently fertilized spring rape crops weed occurrence is determined by plant number per unit area, light regime and meteorological conditions. 5. Under favourable nutritional conditions, having formed an optimal spring rape crop, the plants become more resistant to the dark leaf and pod spot, verticillium wilt, sclerotrinia stem rot and rape stem pests; however, the crop remains susceptible to phoma stem canker. 6. Diverse photosynthetic conditions in differently fertilized spring rape crops differing in stand density determine formation of the above-ground and root mass of spring rape plants. 7. Spring rape yield formation depends on the number of... [to full text] / Tyrimų tikslas – nustatyti pasėlio tankumo ir tręšimo įtaką vasarinių rapsų pasėlio produktyvumui. Ginamieji disertacijos teiginiai: 1. Pasėlio tankumas ir augalų aprūpinimas maisto medžiagomis daro įtaką fotosintetiškai aktyvios radiacijos prasiskverbimui į dirvos paviršių ir įvairius vasarinių rapsų pasėlio ardus. 2. Palankiomis mitybos sąlygomis vasariniai rapsai fotosintezės produktyvumo maksimumą žydėjimo tarpsniu pasiekia retesniame pasėlyje, o augdami mažiau palankiomis – tankesniame pasėlyje. 3. Palankiomis mitybos sąlygomis esant optimaliam pasėlio tankumui vasariniai rapsai žydėjimo tarpsniu antžeminėje dalyje sukaupia didžiausią maisto medžiagų kiekį. 4. Skirtingai tręštuose vasarinių rapsų pasėliuose piktžolių plitimą lemia augalų skaičius ploto vienete, šviesos režimas ir meteorologinės sąlygos. 5. Palankiomis mitybos sąlygomis suformavus optimalų vasarinių rapsų pasėlį augalai tampa atsparesni juodosios dėmėtligės, verticiliozės, baltojo puvinio ir rapsų stiebų kenkėjų pažeidimams, tačiau išlieka jautrūs fomozės pažeidimams. 6. Nevienodos fotosintezės sąlygos skirtingai tręštuose, nevienodo tankumo vasarinių rapsų pasėliuose lemia vasarinių rapsų antžeminės ir šaknų masės formavimąsi. 7. Vasarinių rapsų derliaus formavimąsis priklauso nuo augalų skaičius ploto vienete bei jų aprūpinimo maisto medžiagomis. 8. Palankiomis mitybos sąlygomis didžiausias energetinis efektyvumas gaunamas retesniame vasarinių rapsų pasėlyje, o nepalankiomis – tankesniame.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Moringa oleifera is a three of the Moringacea family, native of India, drought tolerant, introduced to Brazil in the 1950s aiming to treat water by its purifying power. It is also widely used as an herbal medicine in human heath in the treatment and prevention of diseases. It has a high amount of protein in the leaves and is well accepted by animals as a forage. The objective of this work was to evaluate the productivity and the quality of the Moringa accumulated forage mass, cultivated in different crop densities in the coastal tableland region of Sergipe State. A trial was carried out in the Jorge do Prado Sobral Experimental Station of Embrapa Tabuleiros Costeiros located in the county of Nossa Senhora das Dores - Sergipe. A randomized block design with eight replicates was used to test the effect of the densities 250,000 (0,20 m x 0,20 m), 500,000 (0,10 m x 0,20 m) and 1,000,000 (0,10 m x 0, 10 m) plants / ha in plots of 3,0 x 3,0 m. Six cuts were carried out from November 23, 2015 to November 23, 2016. The parameters of green biomass production, dry matter production (DM), survival rate (TS), stems and leaves ratio in green and dry matter were evaluated. No significant differences (p <0.05) were observed among means for all the parameters, except for the survival rate that was higher in the treatment of the lower density (81.64%) in relation to the other two (61.31%) and (45.54%). It was concluded that there is no benefit in increasing crop density above 250,000 plants / ha. / A Moringa oleifera é uma árvore da família moringácea, originária da Índia, tolerante a seca que foi introduzida no Brasil na década de 1950 e se apresenta como importante fonte de alimentos volumosos para de ruminantes. Ela proporciona elevada quantidade de proteína nas folhas e é bem aceita pelos animais. O objetivo deste trabalho foi avaliar a produtividade e a qualidade da massa de forragem acumulada de moringa cultivada em sistema adensado na região dos tabuleiros costeiros de Sergipe. O experimento foi instalado no Campo Experimental Jorge do Prado Sobral pertencente a Embrapa Tabuleiros Costeiros, localizado no município de Nossa Senhora das Dores – Sergipe. Foi utilizado um delineamento em blocos casualizados com oito repetições visando testar o efeito das densidades em 250.000 (0,20 m x 0,20 m), 500.000 (0,10 m x 0,20 m) e 1.000.000 (0,10 m x 0,10 m) plantas/ha e parcelas de 3,0 X 3,0 m, com 8 repetições por tratamento. Foram realizados 6 cortes ao longo de um ano, em um período de avaliação de 23 de novembro de 2015 e término em 23 de novembro de 2016. Os parâmetros produtivos avaliados foram os seguintes: produção de biomassa verde, matéria seca (MS), taxa de sobrevivência (TS), proporção de caule e folhas na matéria verde e seca. Quanto aos parâmetros bromatológicos, foram avaliados os teores de matéria seca, cinzas, extrato etéreo, proteína bruta, FDN e FDA. Os resultados encontrados demonstraram não haver diferença significativa (p>0,05) entre os parâmetros estudados, exceto para a taxa de sobrevivência que foi maior no tratamento de menor adensamento (81,64%) em relação aos outros dois (61,31%) e (45,54%). Concluiu-se que não existe beneficio em aumentar o adensamento acima de 250.000 plantas/ha. / São Cristóvão, SE