Tow field experiments were carried out during the two successive summer seasons of 2010 and 2011 at the Agric. Res. and Exp. Center of Fac. Of Agric. Moshtohor to study the effect of five plant population densities (20, 22, 24, 26 and 28 thousand maize plants per fed.) and seven periods for weed control [un-weeded control (treatment 1), weed control at 20 (treatment 2), 20+35 (treatment 3), 20+35+50 (treatment 4), 20+35+50+65 (treatment 5), 20+35+65+80 (treatment 6) and 20+35+80+95 days after sowing (treatment 7)] on growth, yield and its components of maize, associated weeds as well as the net economic return of maize. The obvious results of this investigation can be summarized as follows:
Increasing plant population density from 20 to 28 thousand plants /fed. significantly decreased total number and fresh weight of removed weeds and number of removed grassy weeds at periods of weed control in the first season, fresh and dry weights of total and broad-leaved weeds at maize harvest, as well as maize stem diameter, area of topmost ear, plant leaf area at 100 days from sowing , number of plants carried two ears, ear length, number of grains per row, number and weight of grains per ear, 100-grain weight, ear weight, shelling percentage and grains yield per plant in both seasons. On the other hand, plant height, ear height, leaf area index at 100 days from planting, number of plants per fed. at harvest, number of ears per fed., number of days from sowing to 50 % tasseling and silking and stover yield per feddan. in both seasons were significantly increased. Generally, the greatest ear, grain and biological yields / fed. were results from maize planting by 26000 plants / fed. This was true in the two growing seasons.
Un-weeded check significantly decreased all these characters except fresh and dry weights of broad-leaved, grassy and total weeds at maize harvest compared with weed removal even once after maize emergence. The maximum grain and biological yields/ fed. were produced from planting maize under weed control at 20, 35, 50 and 65 days from sowing. The critical period of weed control (CPWC) in maize crop based on 5% acceptable yield loss was 20 - 35 days after sowing.
The highest values of leaf area index and stover yield / fed. were recorded from planting maize at the highest density under weed control by treatment 5. While, the lowest plant density under the same weed control gave the maximum values for leaf area / plant, ear length, No. of grains per row, No. and weight of grains /ear, 100-grain weight, ear weight and grain yield / plant in the two growing seasons. Meanwhile, the greatest maize grain and biological yields / fed. were resulted from maize planting by 26000 plants / fed. under the same weed control (weed control at 20 +35 + 50 + 65 days from sowing).
-Economic return
The best treatment was that planting 26000 maize plants / fed. under weed control by treatment 3 in the first season and treatment 5 in the second season, where the net farm return valued 1979.0 and 2990.5 L.E. / fed. in the first and second seasons respectively. |
