Growth and Development of Potted Rhododendron Cultivars ‘Catawbiense Boursault’ and ‘Old Port’ in Response to Regulated Deficit Irrigation

Abstract

The aim of this study was to analyse the effect of regulated deficit irrigation (RDI) on growth and development of potted rhododendron ‘Catawbiense Boursault’ and ‘Old Port’ plants and to evaluate the usefulness of this technique for saving water in nursery production and promoting flowering. Plants were grown in 1.9 litre plastic containers in unheated greenhouse and were subjected to six irrigation treatments lasting for 14 weeks from June to mid-September. A drip irrigation system with one 2 dm3·h-1 emitter per container was used. Six treatments of irrigation were applied: T1) 1 ETp (evapotranspiration) (control, well watered plants); T2) 0.75 ETp (moderate deficit irrigation); T3) 0.5 ETp (strong deficit irrigation) during the entire period of the experiment and the others three were: T4) 1 ETp for 5 weeks followed by 0.5 ETp for 4 weeks and 1 ETp for 5 weeks (strong deficit irrigation in phase II); T5) 1 ETp for 5 weeks followed by 0.25 ETp for 4 weeks and 1 ETp for 5 weeks (very strong deficit irrigation in phase II) and T6) 0.5 ETp for 5 weeks followed by 1 ETp for 4 weeks and 0.5 ETp for 5 weeks (strong deficit irrigation in phases I and III and well watered plants in phase II). The results showed that exposing plants to moderate water deficit (0.75 ETp) for 14 weeks had the best effect on quality of Rhododendron ‘Old Port’ plants. In this cultivar the application of very strong water deficit (0.25 ETp) for 4 weeks during floral buds initiation improved significantly floral bud set. Reduction of water supply by 50% during 14 weeks of Rhododendron ‘Catawbiense Boursault’ cultivation resulted in both the enhanced plant quality and increased number of floral buds set. Rhododendrons has adapted to reduced water supplies through stomatal control. At the end of the experiment, chlorophyll fluorescence parameter Fv/Fm (quantum efficiency of photosystem II) did not indicate damage to photosynthetic apparatus and relative chlorophyll content in leaves of plants subjected to all irrigation regimes did not differ significantly between each other.

Elongation of Hibiscus acetosella Under Well-watered and Drought-stressed Conditions

“…Leaf area and number of leaves were 36% lower for drought-stressed than for well-watered plants (P = 0.012 and P = 0.016, respectively; Table 1), but the average leaf size was unaffected by drought (Table 1). Reduced leaf area with drought stress has been reported for G. lindheimeri (Burnett and van Iersel, 2008), Rhododendron 'Catawbiense Boursault' and Rhododendron 'Old Port' (Koniarski and Matysiak, 2013), S. splendens (Burnett et al, 2005), and T. erecta (van Iersel and Nemali, 2004). Leaf size of H. acetosella 'Panama Red' was reduced with decreasing substrate volumetric water content (Bayer et al, 2013).…”

“…Drought stress has been used to reduce elongation in many species including Gaura lindheimeri Engelm. & Gray 'Siskiyou Pink' (Burnett and van Iersel, 2008), Rhododendron 'Catawbiense Boursault' and Rhododendron 'Old Port' (Koniarski and Matysiak, 2013), Tagetes erecta L. 'Queen Sophia' (van Iersel and Nemali, 2004), Salvia splendens F. Sellow. Ex Roem.…”

Fertilizer Rate and Substrate Water Content Effect on Growth and Flowering of Beardtongue

“…Plant appearance is important to consumers, with consumers associating appearance with overall plant health [5] and poor plant form or uniformity resulting in reduced sales [6]. Uneven plant growth can be the result of irrigation practices, pruning, or plant growth regulation applications.…”

Effects of Continuous and Periodic Water Stress on Cold Hardiness of Rhododendron Cultivars

“…After the end of this experimental part of the study, shrubs were left in an unheated greenhouse and each container with plant was irrigated with 300 ml of water. The methodology concerned this stage of study was the same as in study of Koniarski and Matysiak [2013] and this is the continuation of that research.…”

“…In 2012, experiments were conducted whose aim was to analyse the effect of regulated deficit irrigation (RDI) on growth and development of potted rhododendron 'Catawbiense Boursault' and 'Old Port' plants [ Koniarski and Matysiak 2013]. Those studies found that moderate and severe water deficit maintained throughout the 14-week period of growing of shrubs Rhododendron 'Catawbiense Boursault' and 'Old Port' as well as severe water deficit applied only during the vegetative growth limits the elongation growth of shoots, improves plant habit and quality.…”