EFFECT OF SOWING DATE AND SOIL MULCHING ON PEARL MILLET (Pennisetum glaucum, L) PRODUCTIVITY UNDER IRRIGATION WITH SALINE WATER

Abstract

The present study aimed to investigate the effect of three sowing dates and four soil surface mulching treatments under two saline water irrigation levels on some growth characters and forage yield of pearl millet crop in the two summer growing seasons of 2011 and 2012. Therefore, two field experiments were conducted at Ras-sudr Experimental Station, Sounth of Sinia 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, 15 May and 1 June 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 soil texture of this site was sandy loam containing calcium carbonate of 58.99 and 61.28%. in the 1st and 2nd season respectively. In two seasons, the lowest saline water irrigation level, 4500 ppm, gave three cuts at 1st and 2nd sowing dates, and two cuts at the 3rd sowing date of the 1st June. However, the highest saline water irrigation level, 8000 ppm, produced two cuts at 1st and 2nd sowing dates, as well as, one cut at the 3rd sowing date. The 1st cut was taken after 60 days from sowing dates, 2nd cut after 45 days from the 1st cut date as well as the 3rd cut was taken after 45 days from the 2nd cut date. At every cut, one squair meter as well as ten plants from each plot were chosen at random to estimate the following growth parameters; plant hight (cm), number of tillers/m2, number of leaves/plant leaf area index (LAI) and leaves/stem ratio, dry leaves weight (ton/fed), dry stem weight (ton/fed) and plant dry weight (ton /fed). All obtained data were subjected to the proper statistical analysis of variance according to the procedure outlined by Steel and Torrie (1960). The mean followed by the same alphabetical letters are not statistically different at the 0.05 level of significance according to Duncan multiple range test (1995). The obtained results can be summarized as follows: I- On growth characters : 1- Effect of saline water irrigation: Results indicated that the lowest saline water irrigation level gave three cuts, whereas the highest level produced only two cuts in two seasons. All growth parameters at three cuts in two seasons, except leaf/stem ratio at 1st cut in the 1st season, were decreased significantly with the highest saline water irrigation (8000 ppm). Furthermore, the hgihest level of saline water irrigation did not gave any growth with advanced growth development, at the 3rd cut in two growing seasons. Plant dry wt./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 decreasing plant ht., No. of tillers/m2, dry weights of leaves and stems per m2 in two seasons; leaf area and LAI in the 2nd season.

2- Effect of sowing dates: 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. were increased significantly with delayed sowing dates from the 1st to the the