الفهرس 
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Abstract
Two field experiments were conducted at Ras-sudr Experimental Station, South of Sinai Governorate, in two successive summer seasons, 2011 and 2012 to study the effect of saline water irrigation levels, sowing dates and soil mulching treatments, on some growth characters and forage yield of pearl millet (Pennisetum glaucum (L.) R.Br.) cv. Shandaweel 1. Each experiment included twenty four treatments, which were the combination between two levels of saline water irrigation, i.e. 4500 and 8000 ppm, three sowing dates, i.e. 1 May as 1st, 15 May as 2nd and 1 June as 3rd dates of sowing and four soil mulching treatments, i.e. without, plastic sheet, one and two ton rice straw/fed. The experimental design was laid out in a split-split plot design with three replicates for each experiment. Saline water irrigation levels were arranged in the main plots, sowing dates were allocated in the sub plots, and soil mulching treatments were assigned in the sub-sub plots.
The results showed that plant dry wt./fed.(ton/fed.) was reduced with increasing saline water irrigation levels from 4500 to 8000 ppm by 32.7, 52.7 and 100.0% in the 1st season; 42.9, 69.6 and 100.0% in the 2nd one at 1st, 2nd and 3rd cuts, respectively. These results may be due to reducing the most growth characters, i.e. plant height, number of tillers/m2, leaves and stems dry weights per fed. in two seasons, number of leaves/plant, leaves area/plant and leaf area index in the 2nd season.
Results indicated that the two earlier sowing dates, i.e. 1st May and 15th May, gave three cuts, whereas the latest one, 1st June, produced only two cuts in two seasons. At 1st cut, plant dry weight per fed. was increased significantly with delaying sowing dates from the 1st to 2nd and the 3rd sowing date by 23.7 and 17.0%, respectively, in the 1st season. However, in the 2nd one, the reverse was true. At 2nd cut, the most growth characters were reduced significantly with delaying sowing dates in two seasons. Moreover, at 3rd cut, these results was more pronounced until the 2nd sowing date and hence, at 3rd cut, did not produced any growth in two seasons.
Soil mulching with plastic had a significant increase in the most growth traits at the 1st cut in two growing seasons, as well as at the 2nd cut in the 1st season only. Moreover, soil mulching with 2 ton rice straw/fed. produced a significant increase in the most growth characters at the 2nd cut in the 2nd season and at the 3rd cut in the two growing seasons.
At the 1st cut, in the 1st season, the most growth characters except No. of tillers, were increased significantly with delaying sowing dates up to the latest date, at the lowest saline water irrigation level, and to the middle sowing date, at the highest one. No. of tillers/m2 was decreased significantly with delaying sowing dates, whereas, the reverse was true for plant ht. However, at the 2nd cut, delaying sowing dates decreased significantly the most growth traits, at the lowest saline level. While, the earlier sowing dates of 1st and 15 May did not differ significantly in the most cases, at the highest saline one. Furthermore, the latest sowing date of the 1st June did not gave any growth at the highest saline water irrigation. At the 3rd cut, all growth traits, except No. of tillers/m2 and leaf/stem ratio, decreased significantly with delaying sowing dates from the 1st to 15 May at the lowest saline level. Whereas, the latest sowing date of the 1st June, at the lowest saline water irrigation, as well as the 3rd cut, all sowing dates, at the highest one, did not produce any growth. It is noticeable that there are a tendency the most of growth traits to increase at the lowest saline level than that the highest one at the three cuts. In the 2nd growing season, significant interaction between saline water irrigation levels and sowing dates indicates that the lowest level gave a positive effect for the most growth traits of pearl millet crop at any planting date in the three cuts. At any cut, a significant or insignificant reduction in the most growth characters were shown with delaying sowing dates from 1st May to 1st June, at any saline water irrigation level. Furthermore, the latest sowing date of 1st June did not produce any growth at the 2nd cut, with the highest saline water irrigation and at the 3rd cut, with the lowest one. While, the highest saline water irrigation, at any sowing date, did not gave any growth at the 3rd cut.
Regarding the effect of the interaction between saline water irrigation levels and soil mulching, results revealed that, at 1st cut, in two growing seasons, soil mulching with plastic under the lowest saline water irrigation level produced maximum values of plant dry weight (ton/fed.). These results may be attributed to the significant increase in the most of growth traits, except leaf/stem ratio. Whereas, the minimum values of dry weight was obtained from the interaction between the highest saline water irrigation level and soil mulching with 2 ton rice straw/fed. With advanced growth development of pearl millet crop, at the 2nd cut, in two seasons, mulched soil with 2 ton rice straw/fed.at the lowest salinity level gave the highest values of the most growth characters. The reverse was true for the highest saline level with without soil mulching. Furthermore, with more advanced growth, at 3rd cut, in two growing seasons, the highest saline water irrigation did not produce any growth at any soil mulching treatments.
Concerning the effect of the interaction between sowing dates and soil mulching treatments at three cuts in two growing seasons, results indicated that, at 1st cut, mulched soil with plastic sheet at later sowing dates, i.e. 15 May and 1st June, produced the maximum value of dry forage yield in 1st season. While, in the 2nd growing season, the maximum value of dry forage yield was obtained from mulched soil with plastic sheet at the earliest sowing date (1st May). At 2nd cut, mulched soil with two ton rice straw/fed., at middle sowing date (15 May), in the 1st season, and at the 1st sowing date, in the 2nd one, gave the highest value of dry forage yields. Moreover, at the 3rd cut, soil mulching with two ton rice straw at the earliest sowing date of the 1st May produced the highest value of dry forage yield in two growing seasons.
At 1st cut, in two growing seasons, soil mulching with plastic sheet at latest sowing date (1st June) of the lowest saline water irrigation level, gave the highest value of dry forage yield. On the other hand, at the 2nd cut, mulched soil with two tons rice straw/fed. at 1st sowing date produced higher values of plant ht., No. of tillers/m2 and dry forage yield under the lowest saline water irrigation level in two seasons. While, unmulching soil surface either at 1st or 2nd sowing dates, in two seasons, produced the minimum values of the most growth traits and consequently dry forage yield under the highest saline water irrigation level. At the 3rd cut, the earliest sowing date (1stMay), at the lowest saline level, mulched soil surface with 2 ton rice straw/fed in two growth seasons, produced maximum values of the most growth traits and consequently dry forage yield. Whereas, mulched soil surface with plastic sheet, in the 1st season; and without mulching in the 2nd one, at the 2nd sowing date gave the lowest values of the most growth characters under the lowest saline water irrigation level.