EFFECT OF DIFFERENT NITROGEN FERTILIZER RATES AND SOURCES ON LEAF CHEMICAL COMPOSITIONS AND YIELD OF QUINOA PLANT AS A NEW LEAFY VEGETABLE CROP

Quinoa (Chenopodium quinoa Willd.) has gained increased a worldwide attention since 1970s when it has been revived as a new food crop, due to the attractive nutritive value and potential health benefits as well as to its exceptional tolerance to several environmental stresses. It is considered as a new non-traditional leafy vegetable crop newly introduced to Egypt. Nitrogen requirements for quinoa plants are not clarified yet and the numbers of studies is still quite limited. The present study was conducted to evaluate the effect of nitrogen sources as ammonium sulfate 20.6% or calcium nitrate 15.5% used at rates of 40, 60 or 80 kg N/feddan on leaf chemical compositions and yield of two quinoa cultivars of Cica and Hualhuas harvested after 40 days from sowing date. A field experiment was carried out at the Experimental Farm of the Horticulture Dept., the Faculty of Agriculture, Ain Shams University, Shoubra El-Kheima, Cairo, Egypt, during the two winter seasons of 2015 and 2016. The treatments were laid out in a split plot design, with three replicates. The obtained results revealed that Cica cultivar was superior to Hualhuas concerning all measured chemical parameters of leaves and leaf yield during both seasons, except for leaf contents of chlorophyll a, b and total chlorophyll, ash, fats, Ca and Fe, where Hualhuas cultivar was superior to Cica in these parameters. However, no significant differences were detected between both cultivars regarding leaf carbohydrates content in both seasons. Re garding nitrogen rates and sources, quinoa plants received 80 kg N/feddan as calcium nitrate gave the highest significant values of carotenoids, nitrate, proteins, ash, N, K and Fe contents in both seasons of the study. Whereas, nitrogen treatment of 80 kg N/feddan from ammonium sulfate gave the highest values of leaf contents of Ca and leaf yield in both seasons. Nitrogen treatment of 60 kg N/feddan from calcium nitrate showed the highest significant values of chlorophyll a, b and total chlorophyll contents during both seasons. No significant differences were realized among all nitrogen treatments (rates and sources) on P content in both seasons. In relation to the interaction effect, the results clearly revealed that leaves of Cica plants received 80 kg N/feddan either from ammonium sulfate or calcium nitrate recorded significant increases in carotenoids, nitrate, proteins, ash, N, P, K and Na contents as well as yield without significant differences between them. On the other hand, the best values of chlorophyll a, b, total chlorophyll in both seasons were attained when Hualhuas plants received 60 kg N/feddan from calcium nitrate. Moreover, there were no significant differences noticed among nitrogen treatments applied to Cica plants in both seasons on Na. Furthermore, the best values of Zn content were obtained when Cica plants treated with 40 kg N/feddan from ammonium sulfate or 60 kg N/feddan from calcium nitrate without significant differences between them in both seasons of the study.  Given the experimental conditions of this study, it is concluded that Cica plants received 80 kg N/feddan either from ammonium sulfate or calcium nitrate gave the highest yield of leaves with acceptable quality attributes.