Growth, yield and yield components of wheat as affected by crop sequences, seeding rates and nitrogen fertilizer levels

Two field experiments were carried out in Kafr El-Hamam Agriculture Research Station, Sharkia Governorates, ARC, during 2013/2014 and 2014/2015 seasons to study the effect of five crop sequences (maize/wheat (CS1), intercropping potatoes with maize/wheat (CS2), maize/fahlberseem/wheat (CS3), maize/peas/wheat (CS4), maize/fodder maize/wheat (CS5)) and four combination treatments between seeding rates and nitrogen fertilizer levels were as follows 50 kg seeds+60 kg N/fed (SN1),  50 kg seeds+75 kg N/fed (SN2),  60 kg seeds+60 kg N/fed (SN3),  60 kg seeds+75 kg N /fed (SN4) on growth, yield and its components of wheat (cv. Sakha 94). The treatments were arranged in a split plot design with three replications. The main plots were occupied by crop sequences and seeding rates with N fertilizer levels were assigned to the sup plots. The results revealed that:
Crop sequences had significant effect on plant height, number of tillers and spikes/m², spike length, weight of spike and grains/spike, 1000-grain weight, grain yield, cereal units, total income and total net income of wheat in both seasons as well as straw yield/fed in 1^st season only. Legume as preceding crops for wheat gave significantly higher grain yield compared with fodder maize. Whereas, the highest grain yield and net income after fahlberseem, (2.959, 2.980 ton/fed and 5422, 5414 L.E/fed), was at par with grain yield and net income obtained after peas, being (2.886 and 2.939 ton/fed as well as 5191 and 5071 L.E/fed), with an ignored differences in the 1^st and 2^nd seasons, respectively.
Increasing seeding rates from 50 to 60 kg/fed caused a significant increase in number of tillers and spikes/m², grain and straw yields/fed. On the other hand, increasing seeding rates caused a reduction in spike length, number of spikelets/spike, weight of spike and grains/spike as well as 1000-grain weight.
All characters gradually increased by increasing N fertilizer levels from 60 to 75 kg N/fed. Maximum grain yield was 2.801 and 2.888 ton/fed obtained from SN4 (60 kg seeds+75 kg N /fed) followed by SN2 (50 kg seeds+75 kg N/fed) being, 2.757 and 2.825 ton/fed in 1^st and 2^nd seasons, respectively. Similarly, the highest cereal units, total income and net income were detected with SN4 (60 kg seeds+75 kg N /fed) followed by SN2 (50 kg seeds+75 kg N/fed). It is worth to noting that under the same level of N fertilizer differences among seeding rates did not reach level of significance.
The interaction effect of crop sequences and seeding rates and N fertilizer levels showed significant differences in plant height, spike length, spike weight and 1000-grain weight.
Multiple cropping had significantly increased total cereal units, net incomes,land use efficiency (multiple cropping index(MCI) and cultivated land utilization index (CLUI)).