Evaluation of effects of ammonium, calcium and potassium amounts on yield and quality of rose(Rosa hybrida L.) and susceptibility of them against gray mold diseases.

In order to investigate effect of nitrogen form (NH4, NO3), potassium and calcium levels in nutrient solution on quantitives and qualitive yield and susceptibility to gray mold (Botrytis cinerea),in soilless media with greenhouse condition on rose(Rosa hybrida L.) cut flower the variety Vendenta, tow separate experiments was conducted in The National ornamental plants research station of Mahallat. First experiment was carried out as factorial in randomized complete block design, with tow factors; 1)amonium three levels 0, 2.5 and 5 mM(from 10 mM total nitrogen and residue as nitrate), 2) calcium two levels 1.6 and 4.8 mM, with four replication in first year. The second experiment was peformed like first one but with two factors; 1) potassium three levels 1, 5 and 10 mM, 2) calcium two levels 1.6 and 4.8 mM in second year. Cut flowers in different treatments after harvesting in two experiments, were inoculated with the conidial suspension of Botrytis cinerea (104 spore/ml). Amount of diseases progress was daily evaluated and used area under diseases progress curve (AUDPC) as index of treatments comparison. Results of first experiment were showed that with increasing ammonium concentration in nutrition solution, Ca and K amount reduced, and P, Zn, Mn, Fe and B enhanced in leaf significantly. Increasing calcium concentration in nutrient solution resulted significant enhanced N, Ca, Mn and B and reduced K, Zn and Cu in leaf. To study quantitives and qualitive yield index of rose showed with increasing ammonium from 0 to 2.5 mM, caused enhancement peduncle length, fresh weight and number of cut flowers, whereas 5 mM ammonium decreased flower diameter, peduncle lenght, fresh weight of cut flowers and vaselif significantly. Increasing calcium concentration enhanced flower diameter, and fresh weight of cut flowers significantly. Increasing of ammonium concentration in nutrition solution, caused significant increase of diseases in cut flowers. In the other hand with increasing of calcium concentration from 1.6 to 4.8mM, diseases significantly decreased. Minimum amount of diseases was observed in treatment with 0mm ammonium and 4.8mM calcium. According results of this experiment are recommended 2.5 mM nitrogen as ammonium and the residue as nitrate with 4.8 mM calcium in soilless media. The results of second experiment showed effect of potassium and calcium interaction on height, vaselife, fresh weight and excellent cut flower percent was significant. The most percent of excellent and height of cut flower was ovserved at 5 and 1.6 mM K and Ca respectively. 10 and 1.6 mM potassium and calcium treatment showed the greatest vaselife and fresh weight of cut flower that did not have deferent significant with 5 and 1.6 mM. Increasing calcium concentration in nutrient solution did not have effect on improving quantitives and qualitive characteristics of cut flower and reduced P, Fe and B in leaf significantly. Therefore, the optimum potassium and calcium concenteration in nutrient solution are recommended at 5 and 1.6 mM respectively. On the other hand with increasing of potassium concentration in nutrition solution, from 1 to 5mM, diseases increasing 2.5 times. Also was observed that increasing calcium concentration in nutrient solution caused decreasing of gray mold in rose cut flower significantly. Minimum amount disease in cut flowers in this experiment was observed in treatment with 1mM potassium and 4.8mM calcium. Key words : Rose, Rosa hybrida L, Nitrogen, Potassium, Calcium, Gray mold, Botrytis cinerea, Soilless media.