Doctoral Degrees (Soil, Crop and Climate Sciences)
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Browsing Doctoral Degrees (Soil, Crop and Climate Sciences) by Subject "Bulbs (Plants) -- Fertilizers -- South Africa"
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Item Open Access The effect of nitrogen, phosphorus and potassium fertilisation on the growth, yield and quality of Lachenalia(University of the Free State, 2004-11) Engelbrecht, G. M.; Du Preez, C. C.; Spies, J. J.English: Very little is known about the response of Lachenalia to fertilisation when cultivated in soil. The objective of this study was therefore to quantify the effect of fertilisation on the growth, yield and quality of Lachenalia in both the nursery and pot plant phases. In order to achieve this two pot trials for the nursery phase and one pot trial for the pot plant phase were conducted in the glasshouse. For the first trial in the nursery phase the combined effect of nine nitrogen levels and three application times on the Lachenalia cultivars, Rupert and Ronina, were studied. The nitrogen was applied at levels equivalent to 0, 30, 70, 120, 180, 250, 330, 420 or 520 kg N ha -1 . Three different nitrogen application times were used namely: one third with planting and the rest 10 weeks after planting (T1); one third with planting and the other two thirds after planting (T 2) or one quarter with planting and the other three quarters after planting (T3). The leaf area of Ronina plants was larger than that of Rupert plants irrespective of nitrogen levels and application times. However, Ronina bulbs were larger and softer than Rupert bulbs. The nutrient (N, P, Ca and Mg) and carbohydrate (D-glucose, sucrose and starch) content of Rupert bulbs were higher than that of Ronina bulbs. Application of nitrogen had a positive influence on the leaf area, bulb fresh mass and circumference of both cultivars. Bulb firmness was negatively influenced by nitrogen application. The best results for most parameters were obtained when nitrogen was applied in four equal applications. In the second trial for the nursery phase the response of Rupert and Ronina to five nitrogen (0, 70, 180, 330 or 520 kg N ha -1 ) and five phosphorus (0, 10, 30, 50 or 80 kg N ha -1 ) or five potassium (0, 70, 180, 330 or 520 kg N ha -1 ) levels were studied. Neither the interaction between nitrogen and phosphorus levels nor the interaction between nitrogen and potassium levels had a large influenced on the growth and development of Lachenalia. Results obta ined in this trial with respect to the effect of nitrogen levels on the different parameters mainly confirm with the results obtained with the first trial. In the trial for the pot plant phase the effect of seven nitrogen levels (0, 30, 70, 120, 180, 250, 330, 420 or 520 kg N ha -1 ) on Lachenalia grown from 7-8 cm bulbs, whereof the fertilisation history in the nursery phase differed, was investigated. The fertilisation history of the bulbs in the nursery phase consisted of three nitrogen levels (0, 70, 250 or 520 kg N ha -1 ) combined with two nitrogen application times (T1, T2 or T3 as described earlier). The leaf area of Ronina plants was larger than that of Rupert plants. Nitrogen applied in the nursery phase promoted the leaf area of both Rupert and Ronina. Application of nitrogen in the nursery phase and in the pot plant phase increased the number of inflorescence per plant and the number of florets per inflorescence. The peduncle length increased with higher nitrogen levels in the nursery phase wherea s the peduncle diameter increased with higher nitrogen levels in the pot plant phase.