Productivity and Quality of Two Broccoli Cultivars as Affected by Different Levels of Nitrogen Fertilizers

Two field experiments were conducted in newly reclaimed soil for two winter seasons during 2006/2007 to 2007/2008 at El- Nobaria region, Beheira Governorate, Egypt, to study the effect of different levels of nitrogen sources on vegetative growth, yield and quality of two broccoli cultivars (cvs. Broccoli Calabrese and Hybrid Southern Star) which was combined with five treatments of two nitrogen sources. Poultry manure and nitrogen mineral fertilizer (ammonium nitrate, 33.5 % N), each supplying 100 units of nitrogen per fed., i.e. (I) 100% organic manure alone; (II) 75% organic manure + 25% mineral fertilizer; (III) 50% organic manure + 50% mineral fertilizer; (IV) 25% organic manure + 75% mineral fertilizer and (IIV) 100 % mineral fertilizer alone. Results indicate that plants of Southern Star cultivar showed higher vegetative growth parameters (fresh weight of leaves, stems and total plant; yield and its components; heads physical quality (weight, diameter and height); total phenols, N, P and K in tissues of broccoli leaves and heads compared with cv. Calabrese. Plants of Calabrese cultivar gave the tallest plants; high values of dry weight (leaves, stems and spears) and higher content of total soluble solids and ascorbic acid. Nitrogen sources differed statistically in their effect on the vegetative growth of broccoli plants. The highest vegetative growth was obtained when all nitrogen requirements were supplemented as 75% organic + 25% mineral treatment. Lower values of plant growth, higher content of ascorbic acid and total phenols were obtained by applying 100% mineral nitrogen. Treatments where all nitrogen was applied as organic manure showed significant increases in the vegetative growth, yield and quality of heads and reduced total phenols and ascorbic acid, with the highest total soluble solids. The results indicated that combined effect of cultivars and nitrogen sources caused significant increases in vegetative growth, yield and chemical contents. The highest vegetative growth, yield and chemical contents were obtained by growing southern Star cultivar combined with 75% organic + 25% mineral treatment.