Growth of three wheat cultivars and nitrogen use efficiency as affected by nitrogen fertilizer levels and seeding rates

الملخص EN

Two field experiments were carried out during ٢٠١٤/٢٠١٥ and ٢٠١٥/٢٠١٦ seasons at Agric.

Exp.

Res.

Sta.

at Giza, Fac.

Agric., Cairo Univ.

to study the influence of three nitrogen fertilizer levels (٧٥, ١٠٠ and ١٢٥ kg N/fad.), three seeding rates (٢٠٠, ٣٠٠ and ٤٠٠ grains/m٢ ), on growth of three wheat cultivars (Sakha-٩٤, Gemmiza-٩ and Giza-١٦٨).

Nitrogen levels had significant effect on heading and plant height in the first season only and on flag leaf area in both seasons.

Absolute growth rate (AGR) was significantly affected by N levels at ٨٠ days from sowing.

Leaf area index (LAI) was significantly affected by N levels at ٨٠ and ١٠٠ days in the second season only.

Net assimilation rate (NAR) significantly increased with increasing N levels.

In general, all previous characters were increased with increasing N levels up to ١٢٥ kg N/fad.

Nitrogen use efficiency (NUE) significantly decreased with increasing N levels.

Seeding rates had significant effect on LAI at ٨٠ days in the first season and on AGR at ٨٠ in the first season as well as at ٨٠ and ١٠٠ days in both seasons, respectively.

The highest values for the previous traits were produced with seeding ٣٠٠ or ٤٠٠ grains/m٢ .

Seeding rates did not affect NAR.

Nitrogen use efficiency was not affected by seeding rates.

Plant height and heading significantly affected by cultivars.

AGR at ٨٠ days in the first season and at ١٠٠ days in both seasons significantly affected by cultivars.

LAI at ٦٠, ٨٠ and ١٠٠ days significantly affected by cultivars.

Cultivars significant affected NAR except at ١٠٠ days in the first season.

Cultivars did not affect NUE.

All interactions had a significant effect on growth characters in both seasons, except the effect of N levels × seeding rates on flag leaf area, LAI at ٦٠ days, plant height and number of tillers/ m٢ , N levels × cultivars on LAI at ٦٠ days, plant height and number of tillers/m٢ , seeding rates × cultivars on LAI at ١٠٠ days in both seasons, plant height and number of tillers/m٢ in the first season as well as LAI at ٨٠ days in the second one and N levels × seeding rates × cultivars on flag leaf area, plant height and number of tillers/m٢ in the first season.

The overall findings concluded that seeding Gemmiza-٩ or Giza-١٦٨ with ٣٠٠ or ٤٠٠ grains/m٢ and application of ١٢٥ kg N/fad., could be more beneficial in the study area.

Some interactions had significant effect on NAR.

Moreover, none of studied interactions significantly affected NUE.