Growth and Flowering of Zantedeschia elliottiana and Z. rehmannii in Response to Environmental Factors

The influences of irradiance level, day length, temperature, and leaf area on growth and flowering of Zantedeschia elliottiana Engl. W. Wats (yellow calla lily) and Z. rehmannii (pink calla lily) were determined. Plants grown with 45% or 15% of natural irradiance were taller than those grown under full natural irradiance but flowered at the same time and produced a similar number of flowers. Leaf removal treatments had no effect on any characteristic measured. Plants grown with a night interruption (NI; 2200 hr to 0200 hr) were taller than those under short days (SD = 8 hours), but flowered at the same time and produced a similar number of flowers. Plants were grown with air at 15 or 20C in combination with medium temperatures at ambient level (1C less than air temperature) or a constant 20 or 25C. Z. rehmannii grown with the medium at 20 or 25C and air at 1.5 or 20C flowered faster and were taller than plants grown with air at 15C and with the medium at ambient temperature, but plants from all temperatures produced the same number of flowers over a 120-day cycle. When plants grown with a NI in the first cycle were replanted and grown through a second cycle, they were taller than plants grown from SD treatment first-cycle plants. No first growth-cycle treatment influenced flowering in the second growth cycle.

INFLUENCE DU NIVEAU D’IRRADIANCE D’APPOINT (HPS) EN PEPINIERE SUR LA CROISSANCE ET LA PRODUCTIVITE D’UNE CULTURE DE TOMATE DE SERRE.

Tomato plants (Lycopersicon esculentum Mill. ’Vendor’) were seeded at three different dates between 23 Jan. and 17 Feb. 1984. Young tomato plants received the following supplementary lighting treatments: natural light only, and natural irradiance supplemented by 10, 20 or 30 W m−2 (PAR) for a photoperiod of 17 h. Twenty-nine days after the first seeding date, shoot dry weight of plants grown under 10, 20 or 30 W m−2 was, respectively, 311, 378 and 458% of the control. Shoot dry weight of the third seeding was 159, 181 and 207% of the control for the 10-, 20- or 30-W m−2 treatments, respectively. Early yields were increased by 19,4, 31,2 and 42% when tomato transplants received 10, 20 or 30 W m−2. Total yields were not significantly affected by supplementary lighting provided in the nursery period.Key words: Tomato, supplementary light, growth, productivity, HPS, Lycopersicon esculentum Mill.

Winter Survival and Growth of Chondrus crispus in Onshore Culture Tanks

Commercial aquaculture of Chondrus crispus in eastern Canada required the development of reliable methods for ensuring the winter survival of a healthy, vegetative inoculum. Two procedures were investigated. Agitated cultures of C. crispus (stocking density <6 kg∙m−2) in running seawater grew at average rates of 0.21–0.34 kg∙m−2∙wk−1 during two winters under natural irradiance. Cultures maintained in undisturbed, outdoor tanks of seawater over three winters showed little or no net production; however, survival was excellent provided that the stocking density remained below approximately 10 kg∙m−2. The plants were capable of resuming growth when environmental conditions improved. We found no difference in the responses of the several haploid and diploid isolates examined. Large vegetative inocula required for commercial aquaculture can be maintained simply and reliably in tanks of clean seawater if they are undisturbed and an ice cover is allowed to form.