No abstract

The objective of this study was to assess the influence of different foliar gibberellic acid (GA3) levels (0, 10, 50, and 200 mg L-1) and application timing on the growth, physiology (chlorophyll and gas exchange) and flower quality of gerbera (Gerbera jamesonii cvs. Beaudine and Palm Beach) and Asiatic lily (Lilium × elegans cvs. Fangio and Eldivo). The application of GA3 (50 mg L-1) increased (p < 0.05) gerbera shoot height (30%), pedicel length (20%), and vase life (12.5%) and decreased the number of days to flowering (7%) compared to the control. GA3 application at the seedling stage increased pedicel length and flower diameter compared to GA3 treatment at the flower initiation stage. However, the chlorophyll content index, photosynthesis (Pn), stomatal conductance (gs) and transpiration (E) were similar across the study period. For Asiatic lily, 10 and 50 mg L-1 were the best GA3 levels in terms of leaf gs, E and flower diameter. Compared to 0, 10 and 50 mg L-1-GA3, 200 mg L-1-GA3 decreased the number of days to flowering. Overall, the application of 50 mg L-1-GA3 to gerbera and lily cultivars at the seedling stage can potentially improve flower quality and shorten the number of days to flowering.

Abstract:In extensive green roof settings, plant communities can be more robust than monocultures. In addition, native plants might be hardier and more ecologically sound choices than non-native plants in green roof systems. The objectives of this research were to (1) compare the performance of plant communities with that of monocultures and (2) compare the growth of natives to non-natives in a simulated green roof setting. We conducted a two-year experiment at an outdoor site in a desert environment using four plant morphological types (groundcover, forb, succulent and grass). Native plants selected were Chrysactinia mexicana, Melampodium leucanthum, Euphorbia antisyphilitica, and Nassella tenuissima, and non-natives were Delosperma nubigenum, Stachys byzantina, Sedum kamtschiaticum and Festuca glauca. Plants were assigned randomly to either monoculture or community and grown in 1 m × 1 m custom-built trays filled with 15 cm of a proprietary blend of 50/20/30 lightweight aggregate/sand/compost (by volume). Native forb, Melampodium, in community had greater coverage for four of the five measurements in the first year over native forb in monoculture and non-native forb regardless of setting. Native forb coverage was also greater than non-native forb for three of the four measurements in year 2, regardless of setting. Coverage of native grass was significantly greater than non-native grasses throughout the experiment. Coverage was also greater for eight of nine measurements for native succulent over non-natives succulent. However, non-native groundcover coverage was significantly greater than native groundcover for seven of nine measurements. On 1 November 2016, relative water content (RWC) for succulents (p = 0.0424) was greatest for native Euphorbia in monoculture at 88%. Native Euphorbia also had greater RWC than non-native Sedum on 4 April 2017 (78%) and 4 July 2017 (80%). However, non-native Sedum had greater root length (6548 cm), root dry weight (12.1 g), and root-to-shoot dry weight ratio (0.45) than native Euphorbia. At the end of year 2, the relative growth rate (RGR) of native Euphorbia of 0.15 g·g −1 ·d −1 was greater than that of Sedum. While the native succulent had a smaller root biomass, its greater RWC and RGR would indicate it had better plant water status and grew faster than the non-native. The lack of differences in plant performance regardless of assignment to monoculture or community would imply that communities and monocultures are equally suitable for arid region green roofs.

This research was aimed at assessing the impact of different doses of nutrients on growth and flower quality of the Asiatic hybrid Lilium ((Lilium × elegans Thunb.) cv. 'Fangio') under the soilless culture. Five nutrient (fertigation) regimes were applied (T1: daily, T2: twice a week, T3: weekly, T4: twice a month and T5: control). Increasing the nutrient supply increased chlorophyll content index (SPAD, 45-93%), leaf area (30-55%), number of flowers per plant (25-67%) and substrate electrical conductivity (EC: 28-300%) compared to control. Although T3 (weekly nutrient supply) had lower shoot N, P, K + and Ca +2 concentrations than T1, this regimen increased the number of flower buds by 20% and flower longevity by 56% compared to T1. Overall, weekly nutrient application is effective at maintaining flower quality and yield in the 'Fangio' lily, and compares favourably with programs in which fertigation is more frequent and the level of total applied nutrients is higher.

No abstract