Response of growth and forage yield of pearl millet (Pennisetum galucum) to nitrogen fertilization rates and cutting height

Two field experiments were conducted in the experimental station farm, faculty of agriculture, Ain Shams University at Shalakan, Kalubia Governorate, during the two growing seasons, i.e. 2009 and 2010, to investigate the response of growth and forage yield production of pearl millet cv. Shandaweel 1 to nitrogen fertilization rates and cutting height above the soil surface. Four nitrogen rates as ammonium nitrate (33.5%N), 0, 30, 45, and 60kgN/fed, were arranged in the main plots and two levels of cutting heights (10 and 20cm above the soil surface) in the subplot with four replicates in split-plot design. In the second season, nitrogen application increased up to 75kgN/fed. The main results were as follows: Significant increases were appeared in plant height (cm), number of tillers/m2, number of leaves/m2, and leaf area index during the two growing seasons as nitrogen fertilization rates increased except at the third cut in the first season for plant height (cm) and number of tillers/m2, the first and second cuts of the first season for number of leaves/m2 and at the third cut during the first season of study for leaf area index, while leaf/stem ratio was not affected significantly during the two growing seasons. Green forage yield/fed was significantly increased as nitrogen application rates increased during the two growing seasons except at the third cut of the first season of study. Increasing nitrogen fertilization rates up to 75kgN/fed caused significant increases in dry forage yield during the three collected cuts in the second season of study and the second cut during the first season of study as well as in the combined results. Plant height (cm) was significantly affected as cutting height above the soil surface increased in the second cut (2009) and the first cut (2010) where plant height increased at 10cm as cutting height than at 20cm above the soil surface. Significant differences were appeared in number of tillers/m2 as cutting height varied from 10 to 20cm in the two studied seasons. The highest cut of number of tillers/m2 was scored at 20cm cutting height than those at 10cm in the second and third cuts during the two growing seasons. A number of leaves/m2 as well as leaf area index were influenced significantly as cutting height increased during the two growing seasons except in the second and third cuts during 2009 or the third cut during 2010 for number of leaves/m2 and in the second cut of the first season (2009) and the third cut during 2010 for leaf area index. Significant effects were noticed in leaf/stem ratio as cutting height differed in the second or third cut in 2009 and in the three collected cuts in combined analysis. Green forage yield, dry forage yield/feddan increase significantly as cutting height differed during the two growing seasons as well as the combined results except in the first cut during the first season of study for dry forage yield. Green forage yield as well as dry forage yield was significantly affected by the interaction between nitrogen fertilization rates and cutting height, where the highest yield was detected with adding 60–75kgN/fed and 20cm as cutting height (30.7ton/fed).