الفهرس Only 14 pages are availabe for public view
 |  | from | 92 |  |  |
| | | from | 92 | | |
Abstract
SUMMARY
The present work was designed to study the effect of planting dates, nitrogen fertilization and mineral fertilization (phosphorus and potassium) with or without bio- fertilization (mycorrhizae) on growth, seed yield, its components and chemical composition of oil lettuce (Lactuca scariola L. var. oleifera). Two field experiments were carried out in Mariut Experimental Farm of Desert Research Center, Alexandria Governorate, at Western Coast of Egypt, during 2005-2006 and 2006-2007 seasons. Each experiment included four planting dates (First October, Mid October, First November and Mid November), three nitrogen fertilization rates i.e. without nitrogen fertilization, 40 kg N/fed., and 80 kg N/fed. and mineral fertilizer with or without mycorrhizae levels (without mineral fertilizer and mycorrhizae added), (15,5 kg P2O5/fed. + 24 kg K2O/fed. without mycorrhizae, 15,5 kg P2O5/fed. + 24 kg K2O/fed. with mycorrhizae, 31 kg P2O5/fed. + 48 kg K2O/fed. without mycorrhizae and 31 kg P2O5/fed. + 48 kg K2O/fed. with mycorrhizae). Treatments were arranged in a split-split plot design with three replications. The main plots were devoted four planting dates, the N levels were allocated in sub-plots and the other five treatments (P, K, with and without mycorrhizae bio-fertilizer) were distributed in sub-sub plots.
The results obtained in this respect could be summarized as follows:
5.1. Effect of Planting Dates:
5.1.1. Growth characters:
a. Plant characters:
1. The four planting dates (First October, Mid October, First November and Mid November) showed significant differences in all plant characters i.e. Plant height, plant fresh weight, plant dry weight, stem fresh weight, stem dry weight. These were true at 90, 111 and 132 (DAS) in both successive seasons. The first planting date (First October) was significantly surpassed the other planting dates in all plant characters, but at age 132 (DAS) the differences between First and Mid October was not reach at 5 % of significance.
2. Stem / plant ratio was affected significantly by different planting dates only at ages 90 and 132 (DAS) in the second season.
b. Leaf characters:
1. The four planting dates (First October, Mid October, First November and Mid November) showed significant differences in leaf characters i.e. Leaves fresh weight, leaves dry weight, leaf area and leaf area index. These were true at 90, 111 and 132 (DAS) in both successive seasons. The first planting date (First October) was significantly surpassed the other planting dates in these characters.
2. Specific leaf weight (SLW) was significantly affected by different planting dates only at age 132 (DAS) in the first season.
3. Leaves/ plant ratio was affected significantly by different planting dates only at ages 90 and 111 (DAS) in the first season and at age 111 days in the second one.
4. Specific leaf area (SLA) was not affected significantly by the four planting dates at all ages for both seasons.
5.1.2. Seed yield and its components:
1. First November planting date recorded high values of 1000-seed weight, seed yield/plant seed yield kg/fed. biological yield , harvest index and crop index in the two successive seasons as compared with the other planting dates, but the differences between Firs and Mid November in 1000-seed weight and seed yield/plant were not significance.
2. Mid October planting date recorded height value of straw yield and the differences between planting dates were significant in both seasons.
5.1.3. Oil yield and some chemical contents:
1. There were significant differences between the four planting dates (First October, Mid October, First November and Mid November) on protein percentage, oil percentage, and oil yield for both seasons, but the differences between First and Mid November on protein percentage and oil percentage were not reaching at 5 % of significance.
2. Phosphorus and potassium percentage were not significantly affected by the four planting dates in both seasons.
5.2. Effect of Nitrogen Fertilizer:
5.2.1. Growth characters:
a. Plant characters:
1. Plant height, plant fresh weight, plant dry weight, stem fresh weight and stem dry weight were significantly affected by nitrogen fertilizer treatments at ages 90, 111 and 132 (DAS) in both seasons. Whereas these characters increased significantly by increasing nitrogen fertilizer from zero to 80 kg N/fed.
2. Stem / plant ratio was decreased by increasing nitrogen fertilizer from zero to 80 kg N/fed. at 90 and 111 (DAS) for both seasons, but at 132 days, this character was not significantly affected by nitrogen fertilizer treatments.
b. Leaf characters:
1. Leaves fresh weight, leaves dry weight, leaf area, leaf area index and specific leaf weight (SLW) were significantly affected by nitrogen fertilizer treatments at ages 90, 111 and 132 (DAS) in both seasons. Whereas these characters increased significantly by increasing nitrogen fertilizer from zero to 80 kg N/fed.
2. Leaves / plant ratio was decreased by increasing nitrogen fertilizer from zero to 80 kg N/fed. at 90 and 111 (DAS) for both seasons, but at 132 (DAS), this character was not significantly affected by nitrogen fertilizer treatments.
3. Specific leaf area (SLW) was not affected by the different nitrogen fertilizer treatments at all ages after sowing in both seasons.
5.2.2. Seed yield and its components:
1. The three nitrogen fertilizer treatments showed significant differences in 1000-seed weight, seed yield/plant seed yield/fed., harvest index and crop index, The highest values of these characters were obtained when plants were fertilized by 40 kg N/fed. for both successive seasons, but The differences between 40 and 80 kg /fed. on 1000-seed weight and seed yield/plant did not reach at 5 % of significance. These results were true for both successive seasons.