الفهرس 
INTRODUCTION
. Effect of weed competition on maize productivity and quality.Only 14 pages are availabe for public view
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Abstract
Four field experiments were carried out in Mallawy Agricultural Research Station, Agricultural Research Center, El-Minia Governorate, during 2015 and 2016 seasons to: 1. Estimate the reduction in maize yield due to weeds competition and the best appropriate method to control these weeds. 2. Evaluate the efficacy of certain single herbicides at full rate and their mixtures at reduced rate (50 % of full rate) with mineral oil on weed control, productivity and quality of maize. The treatments of each two trials were distributed in a Randomized Complete Block Design with four replications. The normal cultural practices for maize in the experimental were followed. Part I:- The first two experiments included nine treatments to estimate the reduction in maize yield due to weeds competition and the best appropriate method to control these weeds as follows: 1. Grassy weeds control by hand weeding twice at 20 and 40 DAS and allow broad–leaved weeds to dominate. 2. Grassy weeds control by pendimethalin known commercially as ”Stomp extra 45.5 % SC” used at the rate of 682.5 g a.i./fed. applied post sowing before irrigation as pre-emergence (PRE), and allow broad – leaved weeds to dominate. 3. Broad-leaved weeds control by hand weeding twice at 20 and 40 DAS and allow grassy weeds to dominate 4. Broad-leaved weeds control by bromoxynil octanoate known commercially as ”Brominal 24 % EC” used at the rate of 240 g a.i./fed. applied at 15 day post maize crop emergence (4-6 leaves stage of maize) as post–emergence (POST) and allow grassy weeds to dominate. 5. Total weeds control by hand weeding twice at 20 and 40 DAS. 6. Total weeds control by foramsulfuron sodium 3.35 % + iodosulfuron – methyl sodium 0.11 % + thiencarbazone – methyl 1.07 % % known commercially as ”Maister power 4.53 % OD” used at the rate of 22.65 g a.i. / fed. applied as POST. 7. Total weeds control by hand weeding twice at 20 and 40 DAS except Euphorbia geniculata, Ortega. was used in the study as model weed species, which are the most common broad-leaved weeds of maize fields in the region. 8. Total weeds control by hand weeding twice at 20 and 40 DAS except Brachiaria reptans, L. was used in the study as model weed species, which are the most common grassy weeds of maize fields in the region. 9. Untreated check allow to naturally established populations of total weeds to dominate. Resulted can be summarized as follow: 1. Hand weeding twice at 20 and 40 DAS, for controlling broadleaved weeds, hand weeding twice at 20 and 40 DAS, for controlling total weeds, hand weeding twice at 20 and 40 DAS for controlling all total weeds, except Brachiaria reptans, and foramsulfuron sodium + iodosulfuron–methyl sodium + thiencarbazone–methyl gave the highest reduction in the dry weight of broad-leaved weeds without significant difference between them. These treatments significantly reduced the dry weight of broad-leaved weeds by 98.17, 98.11, 97.03 and 93.99 and by 98.56, 98.51, 97.72 and 86.50 % controlling effect as compared with untreated check in the first and second seasons, respectively. The same trend was found concerning control of Euphorbia geniculata, alone as the most predominated broadleaved weeds. 2. Hand weeding twice at 20 and 40 DAS, for controlling grassy weeds, hand weeding twice at 20 and 40 DAS, for controlling total weeds, hand weeding twice at 20 and 40 DAS for controlling all total weeds, except Euphorbia geniculata, and pendimethalin at 682.5 g a.i./fed. were the best treatments in controlling grassy weeds without significant difference between them. These treatments significantly reduced the dry weight of grassy weeds by 95.72, 94.34, 94.16 and 90.80 in the first season and by 97.65, 94.34, 95.25 and 95.32 % controlling effect in the second season as compared with untreated check. The same trend was found concerning control of Brachiaria reptans, alone as the most predominated grassy weeds. 3. Hand weeding twice at 20 and 40 DAS, for controlling total weeds, foramsulfuron sodium + iodosulfuron–methyl sodium + thiencarbazone–methyl, hand weeding twice at 20 and 40 DAS, for controlling broad-leaved weeds and hand weeding twice at 20 and 40 DAS for controlling all total weeds, except Brachiaria reptans, weed were the superior treatments in controlling total weeds. These treatments significantly reduced the dry weight of total weeds by 97.66, 91.07, 88.49 and 86.30 in 2015 season and by 97.43, 87.26, 78.25 and 82.04 % controlling effect in 2016 season as compared with untreated check. 4. All weed control treatments significantly increased grain yield and its components as compared with untreated check exception of grassy weeds control by hand weeding twice at 20 and 40 DAS treatment. 5. Hand weeding twice at 20 and 40 DAS for controlling all total weeds, foramsulfuron sodium + iodosulfuron – methyl sodium + thiencarbazone – methyl, hand weeding twice at 20 and 40 DAS for controlling broad-leaved weeds, hand weeding twice at 20 and 40 DAS for controlling all total weeds except Brachiaria reptans gave the highest grain yield, its components i.e. plant height, ear height, ear length, ear diameter, number of rows/ear, number of grains/row, ear weight, ear grains weight, 100-grain weight and grains quality as compared with other treatments and untreated check. 6. Leaving the total weeds (untreated check), leaving the broadleaved weeds and controlling grassy weeds by hand weeding and herbicide, leaving the grassy weeds and controlling broad-leaved weeds by herbicide, leaving Euphorbia geniculata, as the most predominated broad-leaved weed and leaving Brachiaria reptans, as the most predominated grassy weed reduced the grain yield, its components i.e. plant height, ear height, ear length, ear diameter, number of rows/ear, number of grains/row, ear weight, ear grains weight, 100-grain weight and grains quality in both seasons as compared to the treatment which total weeds controlled mechanical with hand weeding twice at 20 and 40 DAS. 7. Hand weeding twice at 20 and 40 DAS for controlling all total weeds, foramsulfuron sodium + iodosulfuron – methyl sodium + thiencarbazone – methyl, hand weeding twice at 20 and 40 DAS for controlling broad-leaved weeds, hand weeding twice at 20 and 40 DAS for controlling all total weeds except Brachiaria reptans gave the highest significant values in grain yield of maize (ardab/fed.) in both seasons. The previous treatments gave (28.45, 25.43, 23.59 and 23.72 ardab/fed.) in 2015 season and (26.95, 23.15, 22.76 and 22.6 ardab/fed.) in 2016 season as compared with untreated check which gave the lowest value in grain yield (7.72 and 7.81 ardab/fed.) in the both seasons, respectively. 8. The reduction in maize yield due to broad-leaved weeds competition was 69.30 and 63.06 % in the both seasons, respectively, when grassy weeds were controlled by hand weeding. The reduction in maize yield due to grassy weeds competition was 29.99 and 33.46 % in the both seasons, respectively, when broadleaved weeds were controlled by herbicide. The reduction in maize yield due to Euphorbia geniculata, as the most predominated broad-leaved weed when total weeds controlled by hand weeding twice was 39.75 and 43.51 % in the both seasons, respectively. While, the reduction in maize yield due to Brachiaria reptans, as the most predominated grassy weed when total weeds controlled by hand weeding twice was 16.64 and 16.15 % in the both seasons, respectively. Whereas the reduction in maize yield due to total weeds was 72.88 and 71.03 % in the two seasons, respectively, as compared to the treatment of hand weeding twice at 20 and 40 DAS for controlling total weeds. 9. Hand weeding twice at 20 and 40 DAS for controlling total weeds, foramsulfuron sodium + iodosulfuron – methyl sodium + thiencarbazone – methyl were the superior treatments in increasing protein percentage and carbohydrate percentage of maize grain. These treatments significantly increased protein percentage of maize grains by 50 and 34.48 in 2015 season and by 70.48 and 55.71 % in 2016 season, while the increase in carbohydrate percentage of maize grain was 20.68 and 18.98 in 2015 season and by 19.92 and 17.22 % in 2016 season, as compared with untreated check.