THE EFFECTS OF VARIETIES, PHOSPHORUS AND STAGE OF GROWTH AT APPLICATION ON THE TOLERANCE OF COWPEA (Viqna unquiculata (L.) Walp.) TO NORFLURAZON
THE EFFECTS OF VARIETIES, PHOSPHORUS AND STAGE OF GROWTH AT APPLICATION ON THE TOLERANCE OF COWPEA (Viqna unquiculata (L.) Walp.) TO NORFLURAZON
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Date
1984-06
Authors
ABDULKAREEM, ZAKARIYYA ADAMU
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Abstract
Two greenhouse experiments and nine field trials were
conducted on the Institute for Agricultural Research Farm,
Samaru, between 1981 and 1982, to evaluate the effects of
varieties, levels of phosphorus and stages of crop growth at
the time of herbicide application on the tolerance of cowpea
to norflurazon.
The varietal response trials were conducted both in the
greenhouse and in the field using four cowpea varieties
namely Ife Brown, IAR/ACC.335, IAR/ACC.341 and IAR/ACC.355.
The other two sets of trials were only conducted in the field
using Cv Ife Brown. Phosphorus levels evaluated were 0, 40
and 80 kg P2 O5/ha while the stages of growth of crop at the
time of application were pre-emergence, at emergence, three
weeks after emergence and six weeks after emergence, Norflu
razon was applied pre-emergence at the rates of 0, 0.2, 0.4
and 0.8 kg a.i./ha in the varietal and phosphorus trials.
Rates of 0, 0.4, 0.8 and 1.2 kg a.i./ha were used in the
growth stage trial.
Norflurazon at the rates of 0.4 kg a.i./ha and above in
both the greenhouse and field trials resulted in cowpea leaf
chlorosis irrespective of crop variety, phosphorus level or
stage of crop growth of crop at the time of application.
Reduction in leaf and root dry matter production was observed
although the toxicity of the herbicide was more severe in
the greenhouse.
The cowpea varieties used responded differentially to
the herbicide treatments as reflected especially in leaf dry
weight in the greenhouse and shoot dry matter production in
the field, with varieties ACC.355 and Ife Brown exhibiting
more tolerance in the greenhouse and field respectively.
However, in most cases the interactions between the herbicide
rates and cowpea varieties were not significant,, Norflurazon
was more toxic at 0.8 kg a.i./ha than the lower rates.
Increasing the level of applied phosphorus from 40 to 80
kg P2O5/ha did not result in added advantage on cowpea grain
yields. Phosphorus application slightly obviated norflurazon
toxicity on cowpea, especially at the rate of 0.8 kg a.i./ha.
Norflurazon applied at emergence appeared to be more
toxic to cowpea than when applied at any other stage of growth
although the effect was non-significant. However, the crop
tolerated up to 0.4 kg a.i./ha of the herbicide irrespective
of stage of growth
Description
A thesis submitted to the Postgraduate School
Ahmadu Bello University
in partial fulfilment of the requirements for
the Degree of Master of Science in Agronomy
DEPARTMENT OF AGRONOMY
FACULTY OF AGRICULTURE
AHMADU BELLO UNIVERSITY
ZARIA, NIGERIA.
JUNE, 1984
Keywords
VARIETIES,, PHOSPHORUS,, APPLICATION,, TOLERANCE,, (Viqna unquiculata,, NORFLURAZON