الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 119 |  |  |
| | | from | 119 | | |
Abstract
Objectives: Study the effect of nitrogen form ratio, to determine the optimum level of potassium and their interaction effect on growth, chemical composition, yield and quality of radish plants. Methods & Results: 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 and Potassium fertilization levels on plant growth, chemical composition, yield and quality of radish plants (Raphanus sativus, L.) cv. Early radish 40 days. Factorial experiment in a randomized complete block design was used with four replicates for each treatment. First factor (N-forms): N1=100% NH4, N2= 75%NH4 +25%NO3, N3= 50% NH4 + 50% NO3 , N4= 25%NH4 +75% NO3 , N5= 100% NO3. Second factor (K-levels): K1 = 40 Kg K2O /fed, K2 = 70 Kg K2O/fed, K3 = 100 Kg K2O/fed The obtained results could be summarized as follows: 1-Vegetative growth characteristics: With regard to the effect of interaction between N-forms and K-levels, it can be observed that plants fertilized by of N3 treatment (50%NH4+50%NO3) followed by N4 treatment (25%NH4+75%NO3) combined with K2 level (70kg K2O/fed) had the highest values of all aforementioned traits. Whereas, the lowest once were produced when 100% NH4 was the only N-form used with all levels of potassium at different growth periods during the both seasons. 2- Chemical composition: The maximum values of chlorophyll a, b and total chlorophyll and nitrogen percentage in leaves and roots were realized by using the treatment of N3 (50%NH4+50%NO3) followed by N4 treatment (50%NH4+50%NO3) combined with K2 (70 kg K2O/fed) treatment. In this connection, it can be observed that plants fertilized with N3, N4 and N5 treatments combined with K3 level (100kg K2O/fed) had the highest values of potassium contents in leaves and roots at the most growth periods during both seasons 3- Yield and its components: The highest mean values of root length, shoulder, middle diameter of radish root, fresh, dry weight of root and yield were documented for the plants received the N3 treatment (50%NH4+50%NO3) followed by N4 treatment (25%NH4 + 75%NO3) combined with K2 level (70kg K2O/fed). Whereas, the results of these parameters, stated that with 100%NH4 were less than the other combinations of NH4 and NO3 or 100%NO3. 4- Quality parameters: - The lowest accumulation of NO2-N and NO3-N were recorded for the plants supplied with N-form as N1, N2 and N3 * K3 treatments (100kg K2O/fed) followed by N4 level with the same level of K. It is also observed that, plants fertilized with N-form as N1 (100%NH4) combined with K3 (100kg K2O/fed), followed by N2 or N3 treatments with same level of potassium, had the highest mean values of total sugars. Whereas, the highest mean values of T.S.S. were recorded for the treatments N3 (50%NH4+50%NO3) followed by N4 (25%NH4+75%NO3) combined with K2 (70 kg K2O/fed) treatment during both seasons. Conclusion: Generally, this investigation suggested that, the best vegetative growth, chemical constituents, yield and quality parameters were documented for the plants received the N-forms as N3 treatment (50%NH4 + 50%NO3) followed by N4 treatment (25%NH4 + 75%NO3) of N-fertilizer at the rate of 100 kg N/fed combined with K2-level (70 kg K2O/fed.) under the conditions of new sandy cultivated area of Dakahlia Governorate, Egypt.