Effects of Light and Relative Humidity in In Vitro Conditioning of Asparagus Plantlet Before Transplanting

Abstract

Asparagus shoots, in experiment 1, were cultured on an MS medium supplemented with 0.04 mg/l IBA and 60 g/l sucrose under white light of 28, 37 and 44 μmol/m²/s photosynthetic photon flux density (PPFD), blue light of 21,29 and 40 μmol/m²/s PPFD and red light of 12, 16 and 25 μmol/m²/s PPFD. The best condition for root induction was under 25 μmol/m²/s PPFD of red light. After transplanting for 6 weeks, all rooted plants survived.
The tallest plantlets and the longest root length were recorded from those previously under white light of 37 and 28 μmol/m²/s PPFD, respectively. The number of shoot/clump and the whole plant fresh weight were unaffected by light conditions. In another experiment, asparagus shoots were cultured on an MS medium supplemented with 0.04 mg/l IBA and 60 g/l sucrose in the close chamber inwhich relative humidity (RH) was controlled at 32, 56 and 90% Each culture vessel had a hole either 0, 0.5 or 1.0 cm diameter on its closure. After transplanting for 6 weeks, the tallest plantlets of 22.83 cm were obtained from those previously in the culture vessels with no hole on their closures under 32% RH. The highest fresh weight of 4.81 gm were recorded from those previously in the culture vessel with a 0.5 cm hole on its closure under 32% RH. The highest fresh weight of plantects of 4.81 gm was recorded from those previously in the culture vesses with a 0.5 cm hole on their closures under 32% RH. The root length and the numder of shoot/clump and the whole plant fresh weight of the plantlets were not affected by the RH and the vessel closure conditions.