Nitrogen and genotype effects on assimilate partitioning and resistance to Striga in maize
type: CreativeWork
description: The parasitic angiosperm Striga (Striga hermonthica Del. Benth) infects tropical cereals causing heavy losses. Investigations were undertaken in western Kenya in 1989 and 1990 to determine if the occurrence of Striga in maize (Zea mays L.) could be mediated by amount, source and timing of N availability; and if the efficacy of N is contingent upon its regulation of assimilate partitioning. An additional objective was to determine how level is influenced by genotype. One experiment evaluated N rates of 0, 30, 60 and 90 kg ha$\sp{-1}$ supplied as either urea, $\rm Ca(NO\sb3)\sb2.$ $\rm NH\sb4NO\sb3,$ $\rm (NH\sb4)\sb2SO\sb4,$ or $\rm (NH\sb4)SO\sb4$ plus the nitrification inhibitor dicyandiamide (DCD), while a second experiment evaluated similar N rates applied at 14, 21, 28 and 35 days after planting. Regarding genotypes, one experiment evaluated the maize cultivars KCB, H632, H512 and H622, while another examined 16 diverse genotypes. Although Striga infection generally decreased with increasing N availability, the impact was partially dependent on the severity of infestation. All N rates decreased infection in 1990, while only 90 kg N reduced infection in 1989. Under high parasite intensities in 1989, only urea reduced Striga (26%), while in 1990, infection was significantly reduced (30%) by all sources of N. In both years, N applied at 28 DAP resulted in the least infection. Although assimilate partitioning during vegetative growth was unresponsive to N treatments, N availability during reproductive growth altered partitioning in favor of the ear over vegetation. This alteration resulted in increases in grain yield (64%) and harvest index (27%), and a decrease in the concentration of total non-structural carbohydrate (TNC) (16%). An up to 3-fold range was observed among maize genotypes in their resistance to Striga. In general, Striga infestation decreased with shorter maturities such that the earliest genotypes to mature, were also the most resistant. This resist…
abstract: The parasitic angiosperm Striga (Striga hermonthica Del. Benth) infects tropical cereals causing heavy losses. Investigations were undertaken in western Kenya in 1989 and 1990 to determine if the occurrence of Striga in maize (Zea mays L.) could be mediated by amount, source and timing of N availability; and if the efficacy of N is contingent upon its regulation of assimilate partitioning. An additional objective was to determine how level is influenced by genotype. One experiment evaluated N rates of 0, 30, 60 and 90 kg ha$\sp{-1}$ supplied as either urea, $\rm Ca(NO\sb3)\sb2.$ $\rm NH\sb4NO\sb3,$ $\rm (NH\sb4)\sb2SO\sb4,$ or $\rm (NH\sb4)SO\sb4$ plus the nitrification inhibitor dicyandiamide (DCD), while a second experiment evaluated similar N rates applied at 14, 21, 28 and 35 days after planting. Regarding genotypes, one experiment evaluated the maize cultivars KCB, H632, H512 and H622, while another examined 16 diverse genotypes. Although Striga infection generally decreased with increasing N availability, the impact was partially dependent on the severity of infestation. All N rates decreased infection in 1990, while only 90 kg N reduced infection in 1989. Under high parasite intensities in 1989, only urea reduced Striga (26%), while in 1990, infection was significantly reduced (30%) by all sources of N. In both years, N applied at 28 DAP resulted in the least infection. Although assimilate partitioning during vegetative growth was unresponsive to N treatments, N availability during reproductive growth altered partitioning in favor of the ear over vegetation. This alteration resulted in increases in grain yield (64%) and harvest index (27%), and a decrease in the concentration of total non-structural carbohydrate (TNC) (16%). An up to 3-fold range was observed among maize genotypes in their resistance to Striga. In general, Striga infestation decreased with shorter maturities such that the earliest genotypes to mature, were also the most resistant. This resist…
author: Mumera, Louis Musundi
language: eng
keywords: Agriculture, Agronomy, Biology, Plant Physiology
date published: 2011-05-07T14:13:44Z
date modified: 2026-07-22T22:25:21Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/23426