Response of recycled hybrid maize (Zea mays L.) to different levels of nitrogen application

Date

4-2002

Degree

Bachelor of Science in Agriculture

Major Course

Major in Agronomy

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Joveno S. Lales

Abstract

Hybrid seed recycling is widely practiced in developing countries despite the consequent significant yield depression. High price of F1 hybrid seeds is the common reason for recycling though unreliable seed supply is at times a serious constraint. This study was conducted to determine the response of recycled hybrid seeds to different levels of nitrogen application with the hypothesis that yield reduction could be minimized through soil nitrogen manipulation. Four advanced generations (F1□F5) of the commercially grown modified single-cross hybrid C-818 were evaluated against the F1 hybrid generation and an open pollinated variety (USM our 5) at four levels of nitrogen (0, 60, 120 and 180 kg/ha). The field experiment was conducted using randomized complete block design in factorial arrangement with four replications.

Recycling, regarding of level of nitrogen application, resulted in significantly shorter F2 population with ears closer to the ground. thinner stalk, higher percentage of barren plants. lower ear fill, shorter and thinner ears, lower 1000-grain weight and lower grain yield. Regardless of filial generation, the level of nitrogen application significantly influenced the different agronomic Inns except ear diameter. Filial generation x nitrogen interaction significantly affected leaf area index (LAI) measured at mid-grain filling stage and grain yield. All filial generations responded positively to nitro, application at varying magnitudes with 120 kg N/ha apparently being the optimum. the F1 generation population showed higher LAI than the advanced generation population in each level of nitrogen application. Tendency to restore LAI was noted in each level of nitrogen application but was not sustained up to full restoration.

Variation in grain yield were linked to filial generation x nitrogen interaction. Similar to LAI, grain yield increased significantly in response to the different levels of nitrogen applied the F1 generation showed (as expected) the highest grain yield in each level of nitrogen applied. Yield depression of varying magnitude was noted in advanced generation in all levels of nitrogen application evaluated in the study. The highest level of response to nitrogen was noted in the first 60-kg increment of nitrogen. Response to the succeeding 60-kg N increments was small and varied among filial generations. The optimum level of nitrogen application appeared to be 120kg N/ha.

On the basis of grain yield, recycling C818 despite the attempt to mitigate yield depression through soil nitrogen manipulation was not a sound option. Savings on cost of seeds accruing from recycling was totally lost due to remarkable yield reduction. With assumed prices of F1 hybrid seeds and commercial seeds of P100 and P7 per kilogram, respectively, the minimum yield reduction that rendered as foregone income the monetary benefit accruing from using F2 seeds was 257 kg/ha.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2002 A42 S65

Document Type

Thesis

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