دراسة تغيرالكثافة النباتيةتحت مستويات مختلفةمن التسميد النيتروجيني لمحصول الذرة الشامية في منطقتي مراوة والوسيطة بالجبل الاخضر

Abstract

Summary and conclusions. Two field experiments were conducted at two sites, namely Al-Wesaita that situated between latitude ˚ ˊ N and longitude ˚ ˊ E ( ) meter above the sea level, and Marawa which located which between latitude ˚ ˊ N and longitude ˚ ˊ E ( ) meter above the sea level. The two experiments carried out during 2016 growing season to investigate the impact of different nitrogen fertilizer levels (0-300-360) Kg / N / ha- in the form of Urea (46%N) on the growth, yield, and yield components of maize plants (Zea mays L.) (Hybrid Corn,352). Density treatments include three different rates of seed ( 50- 150- 250) Kg /ha- . The two experiments laid out as split-plot design with three replications, using plant densities as main plots and nitrogen fertilizer levels as sub plots. The experimental unit was 2×3 m (6m ) , planting method was on rows, the date of planting was the last week of April,2016 for both sites. Measurements of the growth characters were performed on Eight samples chosen randomly from each experimental unit, these agronomic characters included plant height, number of leaves /plant, stem girth, ear length, ear girth, ear weight, weight of 100-grain, weight of grains per ear, leaf area, leaf area index, number of rows / ear, number of grains / row, number of grains /ear, straw yield, grain yield, biological yield, harvest index, and chlorophyll A,B and total chlorophyll. Data of each agronomic character analyzed separately .using Gen-stat program and the Least Significant Difference (L.S.D) method was used for the comparison among means. The results obtained from the two experiments summarized as follow : 81 A- The effect of plant density : Results in Tables ( 3,6,11,16 and 22) showed a significant effect of plant density on the plant height, stem girth, ear length, ear girth ,ear weight, leaf area, leaf area index, weight of 100-grains, number of rows /ear, number of grains / row , number of grains / ear , straw yield and biological yield at Marawa site, however, number of leaves / plant , grain yield , harvest index and chlorophyll A,B and total chlorophyll in leaves did not show significant differences Tables (3, 22 and 29). At Al-Wesaita site , the precedent agronomic characters show significant differences as affected by different plant density, except the number of leaves / plant , straw yield, biological yield and chlorophyll A,B and total in leaves Tables (3,22 and ). B- The effect of nitrogen fertilizer levels : Results showed that nitrogen fertilizer had a significant effect on all agronomic characters tested in this investigation for the both sites ( Marawa and Al-Wesaita) as shown in Tables (3,6,11,16,and 22). However, nitrogen fertilizer levels had no significant effect on weight of 100-grain in Al Wesaita only and chlorophyll A,B and total chlorophyll in leaves in both experiments sites, Table (11 and 29). The interaction between density and nitrogen fertilizer had a significant effect on number of leaves / plant, ear length, ear girth, weight of grains per ear , weight of 100-grain, number of rows / ear, number of grains / row, number of grains / ear, grain yield, harvest index and total chlorophyll for Marawa site, in contrast the differences for the other agronomic characters did not reach the level of significant. Interaction between the two factors at Al-Wesaita site showed effect on stem girth, ear length, ear weight, weight of grains per ear, weight of 100- grain, leaf area, number of grains / row, number of grains / ear, grain yield and harvest index. In contrast, plant height, number of leaves / plant, ear 81 girth, leaf area index , number of rows / ear, straw yield, biological yield and chlorophyll A,B, and total showed no significant effect by the interaction between the two factors, that indicated each factor act separately on agronomic characters and did not depend on the other factor in this study at the two sites.