Effect of nitrogen and calcium stock plant nutrition on Petunia × hybrida leaf and anther explant growth in vitro

Petunia × hybrida Hort. Vilm.-Andr. ‘Coral Sea’ stock plants were grown with a modified Hoagland's solution to determine the effect of stock plant N and Ca nutrition on subsequent leaf explant and anther growth in vitro. In separate experiments, N was 0, 75, 150 or applied at 0, 100, 200 or 400 mg 1⁻¹ as nitrate-N, and Ca was applied at 300 mg 1⁻¹. Leaf explants from plants grown with 100 mg 1⁻¹ N produced the greatest amount of callus, while those from plants grown with 200 and 400 mg 1⁻¹ N produced the highest number of shoots. Nitrogen treatments increased the anther fresh weight and the number of shoots per culture compared to anthers derived from stock plants that did not receive N.The fresh weight of shoots produced by leaf explants decreased with increasing Ca concentrations applied to stock plants. Anthers derived from stock plants treated with 0 mg 1⁻¹ Ca produced the highest number of shoots per culture.Anatomically, both filament and anther wall tissue produced callus, but no callus production from microspores was observed. Organs produced by anthers were diploid.     

Day and night temperatures,daily light integral,and CO2 enrichment affect growth and flower development of Campanula carpatica ‘Blue Clips’

Campanula carpatica Jacq. ‘Blue Clips’ plants were grown in a greenhouse under nine combinations of day and night temperatures created by moving plants every 12 h among three day/night temperatures (15, 20, and 25°C). At each temperature, there were three daily light integrals (DLI; 4.2, 10.8, and 15.8 mol m⁻² per day, averaged over the experimental period) created with varying supplemental light, and ambient (≈400 μmol mol⁻¹) and enriched (≈600 μmol mol⁻¹) CO₂ concentrations. Time to flower was closely related to average daily temperature (ADT), and was not significantly affected by the day or night temperatures delivered to achieve a specific ADT. Time to flower was not largely affected by DLI or CO₂ enrichment. As plant ADT increased between 15 and 25°C, flower diameter decreased about 1 mm per degree and was not related to the difference between day and night temperatures (DIF). Flower diameter was smallest and least sensitive to changes in temperature at lower DLI and at ambient CO₂ levels. There were 10 less flower buds and 0.3 g less dry mass per plant at first flower for every 1° increase in plant ADT at high and medium DLIs. Flower bud number and dry mass were relatively low and less sensitive to changes in ADT at low DLI, and increased slightly with CO₂ enrichment at medium and high but not at low DLI. Plant height was not related to ADT, but increased linearly as DIF increased from −6 to 12°C at all DLIs, but the response was stronger under low DLI than high and medium DLIs. Flower bud number and dry mass were correlated closely with the ratio of DLI to daily thermal time (base temperature of 0°C). Flower bud number and dry mass were highest when C. carpatica plants were grown at 15°C with a DLI of 10–15 mol m⁻² per day.     

The effect of thermal environment,planting date and crown size on growth,development and yield of Fragaria × ananassa Duch. cv. Elsanta

Summary

The effects of environmental conditions, planting date and crown size on the timing, intensity and duration of cropping in the strawberry Fragaria × ananassa cv. Elsanta were investigated. Temperature was positively correlated with the rate of progress to fruiting whereas crown size had no effect. The first fruit reached harvest maturity after an estimated 891 day-degrees had elapsed above a base temperature of 2.9°C for waiting bed plants and 831 day-degrees above a base temperature of 2.4°C for cold stored plants. Temperature was negatively correlated with total yield, berry number and average berry weight for both waiting bed and cold stored plants of different crown sizes. Yield, berry number and average berry weight were positively correlated with crown size. The effect of temperature on the yield components appeared to be due to its effect on vegetative growth of the plants: canopy development was more limited at warmer temperatures. These results can be used to generate models to predict the effect of growth environment on cropping in strawberry.     

The long-term effects of pre-planting soil fumigation on the growth and cropping of cvs Laxton’s Fortune and Cox’s Orange Pippin on M.2 rootstock,planted on land affected with a replant disease of apple

Soil fumigation of land affected by apple replant disease, using chloropicrin at 281 1 ha^-1 before planting-out, caused increases in shoot numbers, trunk girth and of 35% in total crop accumulated over 10 years for cv Cox’s Orange Pippin on M.2 rootstock. Chloropicrin at 1121 ha^-1 gave rise to a smaller response, and DD at 5621 ha^-1 was ineffective. Cv Laxton’s Fortune on M.2 showed little response to any treatment.