A drought-tolerant clone of Tagetes minuta L. (Asteraceae) was selected in vitro on a medium containing 60 mM mannitol. In the greenhouse, a decrease in soil field capacity (FC) from 100 to 40 % reduced oil yield by 49, 71 and 71 % for drought-tolerant, non-drought tolerant cloned and seed-grown plants, respectively. In soil at 40 % FC, the drought-tolerant clone had the highest leaf dry weight and oil yield. At 100 % FC, there was no significant difference in leaf dry weight, but the drought-tolerant clone had a significantly higher percentage oil content and yield than seed-grown plants. The main components of the oil were monoterpenes of which trans- and cis-tagetone together were 52.3 % - 64.2 %. Drought significantly altered the content of some oil components.

Seeds of the aromatic plant fennel (Foeniculum vulgare Mill) were sown in sandy soil with 0 or 2.5 kg m⁻² of organic fertilizer (OF); chicken manure, cattle manure or plant compost. Plants were irrigated two, three, four, five or six times at 21-day intervals commencing 21 days after sowing and continuing until harvest. Increasing the number of irrigations and application of organic fertilizers significantly delayed harvesting. Water stress imposed by restricting the number of irrigations significantly decreased plant height, branch number, and fruit and oil yield, whereas it increased the percentage volatile oils. All organic fertilizers increased plant growth and yield parameters. With or without organic fertilization, the increase in fruit yield with irrigation outweighed the decrease in volatile oil percentage, so volatile oil yield increased with irrigation. However, there was no significant difference in volatile oil yield between five and six times irrigated plants under any type of fertilization. By increasing both fruit yield and volatile oil percentage, organic fertilizers considerably increased oil yield. Chicken manure fertilized plants irrigated five or six times gave the highest volatile oil yields of 2.08 and 2.09 ml plant⁻¹, respectively, followed by cattle manure fertilized plants irrigated five times (1.98 ml plant⁻¹).

Leaves from 14-d-old Capsicum annuum L. cv. Anaheim seedlings were cultured on Murashige and Skoog (MS) medium containing different combinations of indole-3-acetic acid (IAA) and 6-benzyladenine (BA). After 3 months, cultures were transferred to new medium where BA was replaced with 9 μM isopentenyladenine (2iP) to enhance the growth of shoot buds. Developing shoots were elongated and rooted on MS medium enriched with 9 μM indole-3-butyric acid (IBA). All cultures were maintained in 250 cm³ baby jars covered with a clear polypropylene lid with or without microporous polypropylene membrane. Vessel type and plant growth regulators significantly affected callus morphogenic appearance, organogenesis and in vitro plantlet growth. Ventilated vessels supported photomixotrophic culture and improved regeneration and growth of plantlets. Higher plantlet dry mass and content of photosynthetic pigments, and lower stomatal density of plantlets grown in ventilated than in non-ventilated vessels facilitated ex vitro acclimation and growth.