Effect of different nitrogen to potassium ratios on some quantitative and qualitative indices of Rosa hybrida L. Dolce Vita

Rose is the most important cut flower in the world and the most of its production is as hydroponics in the greenhouse. Nutrition is one of the most important requirements for high quality rose production in greenhouse conditions. Nitrogen and potassium are the most important nutrient elements in rose nutrition, and the balance of these two elements has a significant effect on vegetative and reproductive growth. In order to determine the proper nitrogen to potassium ratio in rose plant nutrition, a completely randomized design with 6 replications was conducted on commercial rose rootstocks cv. Dolce Vita in greenhouse conditions. Grafted rootstocks were purchased at the transplant stage and were cultivated in a greenhouse with a night/day temperature regimes of 16 /22-24°C in 10 liters pot in peat moss, cocopeat and perlite substrates with a ratio of 5:35:65. After establishment and reaching the plants to reproductive stage, they were nourished with commercial nutrition formula with three ratios of nitrogen to potassium (1 to 1.25, (1 to 1.5) as a control and a common ratio in commercial rose nutrition formulas) 1 to 1.75 and 1 to 2). During the growth period, common cultivation practices such as branches bending, green pruning, budding and etc. were carried out and traits including number of leaves, leaf area, flowering stem length, chlorophyll index and nitrogen (nitrate form), potassium and phosphorus content were measured. The results of analysis of variance showed that leaf area trait at 5% level and flowering stem length, chlorophyll index, and potassium and phosphorus content were significantly different at 1% level. The highest leaf number and area, flowering shoot length and phosphorus in the N/K ratio of 1 to 1.75, the highest chlorophyll index and NO3 content in the control and N/K ratio of 1 to 1.25, and the highest potassium content in the N/K ratio of 1 to 2 were obtained. The results of this experiment showed positive effects of increasing the potassium to nitrogen ratio (1/1.75) of nutrient solution on quantitative and qualitative traits of rose cv. Dulce Vita.

Keywords:

Nutrition , Rose , Potassium , Leaf area , Chlorophyll index