الفهرس 
Effect of chemical fertilizationOnly 14 pages are availabe for public view
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Abstract
Two field experiments were executed at the Experimental Nursery of the Ornamental Horticulture Department, Faculty of Agriculture, Cairo University, Giza during 2006 and 2007 seasons. The first experiment aimed to study the effect of four nitrogen levels (0, 20, 40, and 60 kg N/fed), three potassium levels (0, 20 and 40 kg K2O/fed.) and three harvesting dates [105, 120 and 135 days after transplanting] on yield and chemical composition of Artemisia annua L. plant. While the second one aimed to study the effect of foliar application with Zn (0, 25, 50 mg/l) under the previously mentioned harvesting dates on yield and chemical composition of Artemisia annua L. plant.
Results indicated that delaying harvesting date up to 135 days after transplanting significantly increased herb dry yield by 2.43 ton fed-1 (30 %) in the first season, and 3.09 ton fed-1 (38 %) in the second one compared to earlier harvesting date. The essential oil yield significantly increased by 40.16 kg fed-1 (99 %) and 62.38 kg fed-1 (182 %) in the latest harvesting rather than earlier harvesting in the first and second seasons, respectively. Plants fertilized with 60 kg N and 40 kg K produced high herbage yield. Application of 20 kg N with 40 kg K was recommended for high essential oil yield in earlier harvesting dates, while application of 40 kg N with 40 kg K was recommended in the latest harvesting date.
During the vegetative growth stage (105 DAT); essential oil was rich in -pinene, -pinene, borneol and -caryophyllene. It was rich in linalool, camphore, borneol and -caryophyllene during the budding stage (120 DAT), while 1,8-cineole, artemisia keton, camphene and myrcene were predominant during the flowering stage (135 DAT).
Application of 40 kg N/fed with 40 kg K2O /fed resulted in the highest artemisinin content (0.19%) in the first season and (0.14%) in the second season. Harvesting artemisia plants after 120 days from transplanting produced the highest artemisinin yields (11.77 and 11.16 kg/fed in the first and second seasons, respectively). Application of 40 kg N/fed with 40 kg K2O/fed gave the highest artemisinin yields (19.0 and 14.22 kg /fed in the first and second seasons, respectively).
Chlorophyll b, carotenoid, total carbohydrate and element contents (P, K, Fe, Zn and Mn) except chlorophyll a and N contents increased with plant age. The highest contents of leaf pigments, total carbohydrates and studied elements were determined in plants fertilized with 60 kg N and 40 kg K at all harvesting dates in both seasons.
Spraying of artemisia plants with 50 mg/L of Zn and harvesting after 135 days resulted in the highly significant essential oil yields either per plant (7.59 and 9.22 g) or per feddan (127.61 and 154.84 kg) in the first and second seasons, respectively. Spraying of plants with Zn at the rate of 50 ppm resulted in the highest artemisinin yields (16.81 and 12.95 kg in the first and second seasons, respectively).
Spraying of plants with Zn at the rate of 50 mg/l resulted in the highest contents of chlorophyll a, chlorophyll b, carotenoids, total carbohydrates, Fe, Zn and Mn at all harvesting dates in both seasons.