Made available in DSpace on 2016-08-17T17:11:02Z (GMT). No. of bitstreams: 1 DISSERTACAO_ANTONIA DE LIMA DA SILVA.pdf: 596277 bytes, checksum: 87785a3c189c598f2fcb892036144118 (MD5) Previous issue date: 2015-05-07 / FUNDAÇÃO DE AMPARO À PESQUISA E AO DESENVOLVIMENTO CIENTIFICO E TECNOLÓGICO DO MARANHÃO / In the humid tropics, construction and soil fertility maintenance represent a challenge for farmers and also for the researchers who are dedicated to the implementation of sustainable farming systems. The objective was to evaluate the influence of ground cover use of inorganic nitrogen and increase efficiency of water use on the soil mechanical resistance to penetration, chlorophyll content and productive corn parameters in the agri-environmental conditions of the humid tropics. The treatments were: soil cover with corn + inorganic nitrogen (Ninorg) + shift watering every 4 days (4CN); Corn with ground cover + shift watering every 4 days (4C); Without mulching corn + shift + Ninorg watering every 4 days (4SN); Corn without soil cover + shift watering every 4 days (4); Corn with ground cover + shift + Ninorg watering every 8 days (8CN); Corn with ground cover + shift watering every 8 days (8C); Without mulching corn + Ninorg + shift watering every 8 days (8SN); Corn without cover soil + shift watering every 8 days (8S). In reading I to relative chlorophyll content (CRT I) 4CN treatment differed from all the other treatments being similar only with the 4SN treatment. Soil moisture levels differ between treatments in the evaluations performed at 4 and 8 days after irrigation, the evaluation performed at 4 days after irrigation, the 4CN treatments, 4C and 8C with higher percentages differ from 4SN treatments, 4S and 8SN . Regarding the soil penetration resistance (RP), in assessing four days after irrigation was found that there were no differences between treatments in the superficial layers of 0-5 cm, as in the layer 6-10 cm, the 8S treatment differed from other treatments, with higher PR of 1.53 MPa. With respect to the evaluation performed on the 8th day after the irrigation, it was found differences between treatments within each depth and maximum penetration resistance (PMAX). Most productivity components 4CN demonstrates that treatment promoted significant differences when compared to treatments with irrigation every 8 days. Regarding the efficiency of water use, treatment with 8-day irrigation schedule, proved to be more efficient, with the maximum value of 17.28 kg / m3. In view of the foregoing, it is concluded that the efficiency of water usage was higher than in treatments with high turn independently of the presence or non-watering of the soil cover. / No trópico úmido, a construção e manutenção da fertilidade dos solos representam grande desafio para os agricultores e também para os pesquisadores que se dedicam à implantação de sistemas agrícolas sustentáveis. Objetivou-se avaliar a influência do uso de cobertura do solo, do incremento de nitrogênio inorgânico e eficiência do uso da água sobre a resistência mecânica do solo à penetração, conteúdo de clorofila e os parâmetros produtivos do milho nas condições agroambientais do trópico úmido. Os tratamentos avaliados foram: Milho com cobertura do solo + nitrogênio inorgânico (Ninorg) + turno de rega a cada 4 dias (4CN); Milho com cobertura do solo + turno de rega a cada 4 dias (4C); Milho sem cobertura do solo + Ninorg + turno de rega a cada 4 dias (4SN); Milho sem cobertura do solo + turno de rega a cada 4 dias (4S); Milho com cobertura do solo + Ninorg + turno de rega a cada 8 dias (8CN); Milho com cobertura do solo + turno de rega a cada 8 dias (8C); Milho sem cobertura do solo + Ninorg + turno de rega a cada 8 dias (8SN); Milho sem cobertura o solo + turno de rega a cada 8 dias (8S). Na leitura I do Teor Relativo de Clorofila (TRC I), o tratamento 4CN diferiu de todos os outros tratamentos, sendo semelhante apenas com o tratamento 4SN. Os teores de umidade do solo diferiram entre os tratamentos nas avaliações realizadas aos 4 e 8 dias após a irrigação, na avaliação realizada aos 4 dias após a irrigação, os tratamentos 4CN, 4C e 8C com maiores porcentagens diferiram dos tratamentos 4SN, 4S e 8SN. Com relação a resistência do solo à penetração (RP), na avaliação 4 dias após a irrigação foi constatado que não houve diferenças entre os tratamentos nas camadas superficiais de 0-5 cm, já na camada 6-10 cm, o tratamento 8S diferiu dos demais tratamentos, apresentando maior RP de 1,53 MPa. Com relação à avaliação realizada aos 8 dias após a irrigação, verificou-se diferenças entre os tratamentos dentro de cada profundidade e resistência máxima à penetração (PMAX). A maioria dos componentes de produtividade demonstra que o tratamento 4CN promoveu diferenças significativas quando comparado aos tratamentos que receberam turno de rega de 8 dias. Em relação a eficiência do uso da água, os tratamentos com turno de rega de 8 dias, mostraram-se mais eficientes, apresentando o valor máximo de 17,28 kg/m3. Diante o exposto, conclui-se que a eficiência do uso da água foi superior nos tratamentos com maior turno de rega independente da presença ou não de cobertura do solo.

Thesis (M. Sc. Agric.(Plant Production)) -- University of Limpopo, 2019 / Nightshade (Solanum retroflexum Dun.) is among the most important indigenous leafy vegetables in Vhembe District, Limpopo Province, South Africa, due to its high values of beta-carotene, vitamin E, folic acid, ascorbic acid, calcium, iron and protein. Vhembe District occurs in the tropical regions of Limpopo Province and the production of vegetables is dependent upon the availability of irrigation water. An Integrated Drip Irrigation System (IDIS) and a 3S planter were developed to save water by planting several plants/hole of drip irrigation system. The subsystems in IDIS allow for the production of different crops with different water requirements, whereas the 3S planter can be used for planting from one to nine plants/hole of drip irrigation system. Also, the subsystems could be used in assessing irrigation interval for crops under various planting densities. The interaction of irrigation interval and planting density of S. retroflexum had not been documented. The objective of this study, therefore, was to determine the interactive effects of irrigation interval and planting density on biomass yield and chemical nutrient elements (summer harvest only) of S. retroflexum under field conditions. The irrigation interval and planting density/hole were arranged in a split-plot experimental design, with eight replications. The main plot was irrigation interval and the subplot was the planting densities. Harvesting was done twice for both summer and winter experiments. The first harvest (H1) was done at 6 weeks after transplanting, with the second harvest (H2) being done at six weeks after the first harvest. Fresh shoots were oven-dried at 60°C for 72 h for the determination of dry matter. Mature leaves were powdered and analysed for mineral content (Ca, P, K, Mg, Na, Fe, Zn, Mn and Cu) using the ICPE-9000. Data were subjected to analysis of variance using SAS software. In the summer experiment, the interaction was significant (P ≤ 0.05) for dry shoot mass at H1 and H2. However, the contribution of xv the interaction in the total treatment variation (TTV) of the variable was negligent and therefore, only single factors were reported. Irrigation interval and planting density had highly significant (P ≤ 0.01) effects on plant variables during H1 and H2 in summer and winter. However, irrigation interval effects for dry shoot mass were not significant for summer H2. Interaction effects were significant for Ca, P, K, Mg, Mn and Cu in leaf tissues during summer H1, but were not significant for Na, Fe and Zn. Also, irrigation interval was significant for Ca, Mg, P, K, Na, Fe, Zn, Mn and Cu during summer H1, whereas planting density had no significant effects for all chemical nutrients except for Ca, P and K during summer H1. Dry shoot mass of S. retroflexum increased linearly with increasing irrigation interval and planting density. Results suggested that most nutrient elements increased with deficit irrigation water and higher planting density, whilst P decreased under high planting density. The study showed that there is a high potential for saving water through longer irrigation intervals and produce good high yields at a higher planting density. In conclusion, the use of IDIS and 3S planter to promote growth and accumulation of essential nutrient elements on S. retroflexum demonstrated that longer irrigation interval and higher plant density per drip irrigation hole could be suitable for cultivation of this indigenous vegetable. The recommendation of this study is that higher planting density and longer irrigation intervals are key determinants of higher biomass yield and water saving strategies for large-scale production of the crop. Further, the mineral composition of the crop was under the influence of higher planting density and irrigation intervals.

Tomato and lettuce are amongst the most important fresh vegetables used in South Africa. However, growth, yield and quality of tomato and lettuce are constrained by water shortage and poor productivity of sandy soil. In South Africa, large parts of the agricultural land are in a semi-arid region and water is becoming scarcer and more costly. Recognizing the fundamental importance of water-holding amendments like gel-polymers to enhance water use efficiency and soil physical properties, this study was carried out to investigate the effects of pure gel-polymer and fertiliser-fused gel-polymer soil amendments across five irrigation intervals on growth, yield and quality of tomato (Lycopersicon esculentum Mill.) and lettuce (Lactuca sativa L.). The response of tomato growth, yield and quality to irrigation interval and gel-polymer soil amendments (pure gel-polymer and fertiliser fused gel-polymer) was conducted in a tunnel. The gel-polymer treatments were: control (sandy soil), two pure gel-polymer levels (8 and 16 g-20 L-1 sandy soil, equivalent to 400 g and 800 g-m-3) and two fertiliser fused gel-polymer levels (20 and 40 g-20 L-1 sandy soil, equivalent to 1 kg and 2 kg-m-3). Irrigation was either applied once daily or every second, third, fourth or fifth day, equivalent to 0.8, 1.25, 1.45, 1.88 and 2.29 L of water per 20 L bag of sand. Fruit mass, fruit diameter, fruit number, plant height, stem diameter, number of trusses, root fresh and dry mass, total soluble solids, fruit juice pH and titratable acidity were determined. Neither irrigation interval nor gel-polymer amendments had an influence on tomato quality (total soluble solids, pH and titratable acidity). Generally, plant yield, height, stem diameter, number of trusses, and root fresh and dry mass were increased with gel-polymer amendments compared to pure sandy soil. Regardless of irrigation interval, both fertilizer-fused gel-polymer levels appeared to be effective in improving plant growth and yield compared to pure gel-polymer, which gave good results only at the higher level of application. The study revealed that gel-polymer amendments increased productivity of tomato on a sandy soil. Similarly, the response of lettuce growth, yield and quality to gel-polymers and irrigation intervals was investigated under a tunnel conditions. The gel-polymer treatments were: control, two pure gel-polymer levels (4 and 8 g-10 L-1 sandy soil, equivalent to 400 g and 800 g-m-3) and two fertilizer-fused gel-polymer levels (10 and 20 g-20 L-1 sandy soil, equivalent to 1 kg and 2 kg-m-3). Irrigation was either applied daily or every second, third, fourth or fifth day, equivalent to 0.63, 0.83, 1.04, 1.25 and 1.46 L per 10 L plastic bags. Measurements were made of fresh head mass, head height, head circumference, head diameter, stem diameter, fresh root mass, dry root mass and dry head mass. The dried head samples were analysed for percentage tissue calcium and nitrogen. Lettuce grown on sandy soil amended with higher level of pure gel-polymer (Stock 8) and both fertiliser fused gel-polymer levels (Aqua 10 and 20) resulted in significantly higher fresh and dry head mass, head circumference, head diameter, head height, stem diameter, and fresh and dry root mass as compared to low level of pure gel-polymer (Stock 4) and sandy soil without gel-polymer (control). All irrigation intervals did not have an effect on growth, yield and quality of lettuce except at irrigation interval of every third day, which significantly lowered head circumference. Gel-polymer did not have a significant effect on percentage calcium and nitrogen concentration in the leaf tissue. Growing lettuce in soil amended with higher pure gel-polymer (Stock 8) level and both fertiliser-fused gel-polymer (Aqua 20 and Aqua 40) would likely be economically advantageous for a grower due to improved growth and higher yield of good quality lettuce. / Dissertation (MSc (Horticulture))--University of Pretoria, 2005. / Plant Production and Soil Science / unrestricted