INFLUENCE OF SOME SEEDING AND NITROGEN RATES ON GRAIN YIELD AND INSECT NATURAL INFESTATION OF SOME WHEAT CULTIVARS

Abstract

A Field experiment was performed on Bahteem Agric. Res. Station Farm Qalubia Governorate , during the two growing seasons 2009/10 and 2010/11 to study the effect of three seeding rates i.e. 300, 350 and 400 grains /m2 and two nitrogen fertilizer levels i.e. 75 and 90 kg N/fed on yield and yield components as well as grain crude protein and total carbohydrate percentages . In addition the intensity of natural infestation with cereal aphids and leafminer on six wheat cultivars i.e. Sakha 93, Sakha 94, Gemmeiza 10 and Sids 12 (bread wheat); Beni-Sweif 4 and Beni-Sweif 5 (durum wheat) was also investigated. Results indicated that Beni-Sweif 4 cultivar exhibited longer period to heading (89.5 days) and to maturity (140.5 days). On the other hand, Beni-Sweif 5 exhibited taller plants (101.2 cm) followed by Beni-Sweif 4 (99.9 cm) and Sids 12 (97.5 cm). While Beni-Sweif 5 and Sids 12 cultivars gave more spikes (518.5 and 516.1 spikes/ m2, respectively), but highest number of grains /spike was shown by Beni-Sweif 5 and Beni-Sweif 4 (67.4 and 66.0 grains/spike, respectively).The highest values of 1000-grain weight and grain yield were in Beni-Sweif 4 and Sids 12 (48.6 and 48.5 g & 16.2 and 16.3 ardab/fed., respectively). While Beni-Sweif 4 gave the highest value of straw yield (3.6 ton/fed.).On the other hand, Beni-Sweif 5 and Beni-Sweif 4 cultivars gave the highest values of grain crude protein and total carbohydrate percentages (12.2 and 11.9 % & 76.7 and 75.8%, respectively). As seeding rate increased caused a significant increase in period to heading (90 days) and to maturity (138 days), number of spikes/m2 (522.1 spikes /m2 ) and straw yield (3.5 ton /fed.) and caused a significant decrease in plant height (89.6 cm), number of grains/spike (56.6 grains/spike), 1000-grain weight (42.9 g), grain yield (15.5 ardab/fed.) and also decrease in grain crude protein and total carbohydrate percentages (11 and 71.3%,respectively). Seeding rate of 300 grains/m2 was caused a significant increase in plant height (101.4 cm), number of grains /spike (64.8 grains/spike), 1000-grain weight (49.2 g), grain yield (16.2 ardab /fed.) and also caused increase in grain crude protein and total carbohydrate percentages (11.8 and 73.2%,respectively). Increasing nitrogen rate from 75 to 90 Kg /fed caused a significant increase in plant height (97.3 cm), number of spikes /m2 (514.7 spikes /m2 ), number of grains /spike (61.5 grains/spike),1000-grain weight (46.8 g), grain yield (16.2 ardab /fed.), straw yield (3.4 ton /fed.) and also caused increase in grain crude protein and total carbohydrate percentages (11.5 and 72.6%,respectively). For insect infestation, results revealed that Beni-Sweif 4 and Sids 12 cultivars were significantly effective in decreasing number of cereal aphids (62.1 and 83.3 aphids /10 plants, respectively). On the other hand, Beni-Sweif 4 and Beni-Sweif 5 showed the least number of leafminer (2.4 and 3.4 mines & 1.5 and 2.2 larvae /100 leaves, respectively). Increasing seeding rate from 300 grains/m2 to 400 grains /m2 caused a significant increase in number of cereal aphids (159.5 aphids /10 plants) and leafminer (9.2 mines and 6.7 larvae /100 leaves). The least number of cereal aphids (82.1 aphids /10 plants) and leafminer (3.7 mines and 2.5 larvae /100 leaves) were obtained at a seeding rate of 300 grains /m2. Increasing nitrogen rate from 75 to 90 Kg /fed caused a significant increase in number of cereal aphids (133.3 aphids /10 plants) and leafminer (7.9 mines and 5.6 larvae /100 leaves). From these results, it could be concluded that sowing Sids 12 cultivar (bread wheat) or Beni-Sweif 4 cultivar (durum wheat) under seeding rate of 300 grains/m2 and applying 90 KgN/fed gave the highest grain yield/fed and least infestation by cereal aphids and leafminer.