Rose yield, dry matter partitioning and nutrient status responses to rootstock selection

Yield, dry matter partitioning and leaf nutrient status of 'Bridal White' rose (Rosa x hybrida) plants grafted on the rootstocks R. manetti, R. x odorata, R. x 'Natal Briar' and R. x 'Dr. Huey', were evaluated under greenhouse conditions. Plants were grown in 161 containers filled with a peat:bark:sand growing medium and fertigated with a complete nutrient solution. Flower and dry biomass yield data collected over four flushes of growth and flowering did not show significant differences between rootstocks. Foliage quality or greenness, as expressed in chlorophyll readings, was the highest in R. manetti plants, and lowest in 'Natal Briar' and 'Dr. Huey' plants. Whole plant harvests produced similar total dry matter in all rootstocks, but revealed significant differences in allocation patterns. 'Natal Briar'-grafted plants allocated significantly less biomass to leaves, but more biomass to roots, producing a shoot-to-root ratio of 3.5. This ratio was significantly lower than the 4.6, 7.1 and 7.3 ratios observed in 'Dr. Huey', R. x odorata and R. manetti, respectively. Tissue analyses pointed to significant differences in nutrient status, with 'Natal Briar' plants having the most distinctive leaf nutrient profile which included the lowest concentrations of P, K and Fe, and the highest concentrations of Mg, Cl, B and Na. The foliage on R. x manetti and R. x odorata plants presented the lowest B and Mn concentrations, respectively, while 'Dr. Huey' had the highest P and Zn concentrations. (C) 2002 Elsevier Science B.V. All rights reserved.