Effect of applied nitrogen on leaf production interval, extension rate and leaf longevity of Northern Gamba and guinea grasses

Abstract

Effect of four levels of N-application on field swards of Northern gamba (Andropogon gayanus) and Guinea grasses (Panicum maximum c.v S112) were studied during 20 and 30-weeks period in 1985 and 1986 respectively. Northern gamba grass was compared with Guinea grass c.v S112 during the two periods, July – November, 1985 and April to October, 1986. The application of N-fertilizer significantly (P<0.05) increased the rate of production of leaf premordia and the extension rate but retarded leaf longetivity in the two species. During the 1985 study period, Northern gamba grass on the average, took 12 days to produce one leaf without N-application and 8.7day where 450 KgNha^-1 was applied, and in 1986, it took 12.6 days without days without N-application and 9.9 days were 450KgN/ha^-1 was applied. Guinea grass took 10.0 days and 7.8 days in 1985 and 1986 to produce a leaf on the average, with 450Kg/N/ha^-1 compared with 12.7 and 9.4 days for 1985 and 1986 respectively with no N. The study on leaf extension rate was undertaken for 1986 only because that was the longest growing season that had 30 weeks in this study. Species differences in terms of N-application on leaf extension rate was significant (P<0.05). The average effect of N application for Northern gamba grass (2.48 cm/day) was significantly higher than 1.79 cm/day obtained from Guinea grass where 450KgNha^-1 was applied. The effect of N application on leaf longevity for the two study periods, 1985, (20 weeks) and 1986 (30 weeks) was not significant (P<0.05). The increased leaf production interval and leaf extension rate followed closely, the high rates of N-application. The implications of these findings are discussed.

Keywords: nitrogen fertilizer, leaf production, leaf extension rate and leaf longevity of two grass species

Global Journal of Pure and Applied Sciences Vol. 12(1) 2006: 45-49