Trials were done on four Lachenalia cultivars (Romaud, Robyn, Rolina and Romelia) to improve flower quality and inflorescence stem length and to evaluate vase life, as these criteria are important for the cut flower grower. Flowering size bulbs were grown under five different shade nets (white 18%, green 40%, black 40%, black 55%, black 7O%) and in the open as a control. Under each shade net, bulbs were planted at a low planting density of two bulb diameters apart (56 bulbs/m2), as well as a high planting density of one bulb diameter apart (111 bulbs/m2). The effect (If the growth hormone gibberellic acid (GA3) on plant growth was investigated to determine if longer stems could be obtained. The plants were treated with gibberellic acid at 10 ppm and 0 ppm, which was applied as a foliar spray and as El bulb dip treatment. It is necessary to identify and describe specific flowering stages to be able to establish a standard rating system for Lachenalia vase life. The morphology of Lachenalia cultivar Romaud was described to determine the real succession of opening flowers on the inflorescence. The stages of 'first flower', 'full flower' and '50% wilt' were described. A high photosynthetically active radiation (PAR) measurement of 1250 µ.mol.m-2.s-1 in the control, resulted in the shortest inflorescence stem length of 13 cm for all four cultivars compared to the rest of the shade nets. The longest inflorescence stem length of 24 cm was produced for cultivars Rolina and Romelia by a low PAR of 400 µ.mol.m-2.s-1 under the black 70% shade net. The inflorescence stem length of all four Lachenalia cultivars tend to decrease to a minimum of 13 cm when average temperatures are 30oC and higher and to a maximum of 24 cm when temperatures are in the range from 24 to 27oC. A long vase life of 12 to 14 days for cultivar Rolina was observed under the green 40% and black 40% shade nets, compared to 10 to 11 days in the control. The green 40% shade produced a long vase life of 14 to 16 days for cultivar Romelia, compared to the 12 to 14 days in the control. Planting density significantly increased inflorescence stem length by about 2.5 cm and vase life by 2 days at the high planting density compared to the low planting density for all four cultivars. Inflorescence stem length for cultivars Romaud and Romelia increased significantly by 3 cm for both the GA3 foliar spray and bulb dip treatments. The number of flowers per inflorescence decreased significantly by about 3 to 5 flowers for cultivar Romaud and Romelia when GA3 was applied as a foliar spray or bulb dip treatment. A significant increase in vase life (2 days) of GA3 treated plants was observed. All four Lachenalia c:ultivars are suitable for cut flower production, as inflorescence stem lengths were either just below or above the 20 cm mark and vase life was longer than the five to six days required by the cut flower industry.
Dissertation (MSc (Agric): Horticulture)--University of Pretoria, 2006.