Irrigation of ornamental plants nurseries because of the diversity of species grown there, requires considerable water supplies. The using of inappropriate intensity of irrigation in relation to water needs of plants is the cause of the deterioration of their quality and requires a significant investment of work related to control of their growth. Suitable irrigation enables the control of plant growth and development and also the reduction of water resources used and the costs associated with the labour. As a consequence, it may affect significantly the improvement of the competitiveness of the nursery and the reduction of the environment hazard caused by unreasonably high use of natural water resources. Regulated Deficit Irrigation (RDI) is a method consists in limitation or in complete cessation of irrigation during the appropriate plant development phase, in a way that it does not cause damage, deterioration of quality, flowering, crop yield and post-harvest stability. The periodic water deficit applied at the appropriate time and with suitable intensity allows to control plant growth and development, and also reduces water using during their growing significantly. This method has proved to be effective in reducing water using and improving yield in many species of fruit plants. The ...
The effect of deficit irrigation imposed in July-August period on shoot growth and flower formation in container grown rhododendron in commercial nursery were assessed. Plants were exposed to three irrigation regimes based on potential evapotranspiration rates (100% ET0 - well-watered control plants, 75% ET0 - moderate drought and 50% ET0 - severe drought). The values of evapotranspiration were calculated using the Penman-Monteith model. The degree of drought had significant effect on the plant growth and water status of plants. Severe drought inhibited secondary shoot elongation compared to less stressful regime but did not affect flower formation. ‘Catawbiense Boursault', ‘Nova Zembla' and ‘Pearce's American Beauty' plants exposed to severe drought were shorter, respectively by 39, 45 and 86% than well-irrigated plants and two of the three cultivars ‘Catawbiense Boursault' and ‘Pearce's American Beauty' produced fewer secondary branches (5.9 and 0.3) compared to control plants (9.2 and 1.7, respectively). Moderate drought did not affect plant growth but resulted in flower bud formation in ‘Nova Zembla' and ‘Pearce's American Beauty's cultivars. Estimated water consumption by rhododendrons throughout the whole growing season was reduced by 15% for moderate and 25% for severe drought compared to control, well-watered plants. The results have significant implications ...
