Two field experiments were carried out during both successive winter seasons of 2008/2009 and 2009/2010 in a private farm near Gamasa city, Dakahlia Governorate to evaluate the effect of Nitrogen fertilization forms (NH4 : NO3) and Potassium fertilization levels on plant growth, chemical composition, yield and quality of radish plants (Raphanus sativus, L., cv. Radish early 40 days).
Factorial experiment in a randomized complete block design was used. The experiment included 15 treatments: First factor: 5 treatments of N-forms (NH4 : NO3), i., N1=100% NH4, N2=75% NH4+25% NO3, N3=50% NH4 + 50% NO3, N4=25% NH4+75% NO3 and N5=100% NO3. Second factor 3 treatments of K-levels: K1 = 40, K2 = 70 and K3 = 100 Kg K2O/fed.
The results obtained from this work could be summarized as follow:
The maximum values of vegetative growth parameters, total chlorophyll, N%, K%, yield and its components and quality parameters were recorded for the plants supplied with N-forms as N3 treatment (50%NH4 + 50%NO3) and N4 treatment (25% NH4 + 75% NO3). Whereas, the lowest one were produced when 100% NH4 was the only N-form. This trend was true in the two seasons.
The highest values of these parameters were realized for the treatments of K2 (70 kg K2O/fed) or K3 (100 kg K2O/fed).
With regard to the effect of interaction between N-forms and K-levels, it can be observed that the best vegetative growth parameters, chemical constituents, yield and quality parameters were documented for the plants received the N forms as N3 (50%NH4 + 50%NO3) followed by N4 (25% NH4 + 75% NO3) of N-fertilizers at the rate of 100 kg N/fed combination with K2 level (70kg K2O/fed). Whereas, the lowest one were produced when 100% NH4 was the only N-form with all levels of potassium during the both seasons under the conditions of new sand cultivated area of Dakahlia Governorate, Egypt.