Nitrogen fertilization of promising cotton varieties in Ilocos Region [Philippines]
1998
Avila, E.M. | Aragon, M.L. (Cotton Research and Development Inst., Batac, Ilocos Norte (Philippines))
The study conducted at CRDI [Cotton Research and Development Inst.] Station in San Juan, Ilocos Sur [Philippines] to determine the yield performance of the three promising cotton varieties (McNair 220, D-113 N 96-16) against the commercial variety under different levels of nitrogen fertilizer and the relationship between seedcotton yield, nitrogen content of the leaves and level of nitrogen fertilizer. Seedcotton yield, earliness index and N content of the leaves of the three promising cotton varieties were comparable with the CRDI-1. In contrast, plant height at maturity, weight per boll and dry matter yield per plant varied significantly among the four cotton varieties. Results also showed that seedcotton yield and other agronomic components such as plant height at maturity, weight per boll, number of bolls per plant, earliness index, dry matter yield per plant, harvest index and N content of the leaves were significantly affected by increasing levels of N. The estimated response function to N application was described by the quadratic equation Y = 1.5619 + 0.0068 N - 0.000010 N square with a significant coefficient of determination (R square) of 0.82. The yield maximizing rate of N was 285 kg N/ha for a seedcotton yield of 2.40 tons/ha and the optimum level of N was calculated at 135 kg N/ha which was associated with a seedcotton yield of 2.16 tons/ha. The N content of the leaves varied significantly as affected by N fertilization. It fluctuated from 0.88 to 1.68 percent. Nitrogen content of 1.24 percent was satisfactory. However, the correlation analysis between levels of N and N content of the leaves was not significant
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