EFFECT OF TIME AND METHODS

OF WEED REMOVAL ON YIELD

AND QUALITY OF COWPEA

PRODUCTION

KARITA N JONATHAN

REG NO. A22/1736/2010BSc. AGRIC.:CROP PROTECTION OPTION

SUPERVISOR: PROF. E.S. ARIGA

Introduction Cowpea (Vigna unguiculata) is an important

major food legume crop consumed by millions

of tropical and sub-tropical inhabitants of

developing countries.

Some varieties are short and

bushy, prostrate, or tall and vine-like

It has a multiple contributions not only to

household food security (due to high protein

content) but also as a cash crop (for grain and

fodder) and nitrogen fixation (Tarawali et

al.,2000)

Weed interference can cause up to 96% yield

loss on this crop (Amador Ramirez et al,.2001)

Problem Statement

Weed competition is most critical during the first 20-40 days of cowpea growth yet most farmers do not control weeds during this period.

Poor yield obtained by cowpea farmers in tropics are often due to late or inadequate weeding and knowledge of critical periods of high weed competition to water, nutrients, light and space

Market demand for cowpea as a vegetable and source of protein from seed is currently higher than supply.

Justification

Knowing the effects of method and time of

weed removal in cowpea production will

enable farmers to control weeds before critical

period, increase yield and improve quality.

Understanding the market demand and supply and

the income farmers will gain from cowpea, will

enable most farmers in the tropical regions

contribute significantly in reducing poverty and

food insecurity.

ObjectivesBroad objective:

To contribute towards reducing weed effect on both yield and

quality of Cowpea

Specific objectives

(i)To determine the influence of the time of weed removal on

total weed population per species

(ii) To establish the effects of various methods of weed

removal on the amount of yield obtained

Hypotheses:

(i) Weed removal has no effect on the yield of cowpea

(ii)Weeds pose no competition on growth and yield in cowpea

production

Materials and MethodsExperimental site:

• The experiment was carried out at Field station farm, department of plant science and crop protection, Upper Kabete campus.

Altitude of 1940m, latitude of 1⁰5´S and longitude of 36⁰44’E.

• It receives a bimodal rainfall averaging 1000 mm p.a,12-23⁰C temperature range

Land preparation and planting:

The land was ploughed and harrowed by hand. Cowpea (var. Kunde-1) seeds were planted at a spacing of 15x30cm after DAP was applied /hole at the rate of 200kg/ha

Continue… The design was randomized complete block

design arranged in split plot with hand picking

and hoeing as main plots and the sub-plots

included weedy, weed free and farmer’s

practice (2 weeding at 30th and 60th DAP)

which were replicated thrice.

Hand picking was done by uprooting technique

while Hoeing was done by a jembe while

weedy treatment is left un-interfered

throughout the growth season of the crop

Continue... Both hand picking and hoeing was carried

out after weed count has been done to

determine weed regeneration potential by

species at various weeding periods of 2, 4, 6

and 8 WAP

Data Analysis:

The data collected was entered in excel

and Analysis of variance(ANOVA) using

GenStat discovery program

RESULTS

Fig. 1: Effects of method weed

control practice on total yieldCONTROL

METHOD

WEED

CONTROL

PRACTICE

MEAN YIELD

(SEED)/PLOT (g)

YIELD LOSS

ASSOCIATED

WITH

WEEDS(%)

Weed free 190.3 79.6

HAND-PULLING Weedy 38.8

Farmer’s practice 152.2

Weed free 173.7 86.2

HOEING Weedy 23.9

Farmer’s practice 193.4

LSD (P<0.05) 33.39

CV (%) 5.2

Weed species Treatments means/m²

Hand

pulling –

weed free

Hand pulling -

2weedings

Hand

pulling -

weedy

Hoeing

weedy

Hoeing -2

weeding

Hoeing weed

free

Average

Datura spp 2.3 8.8 11.4 4.8 9.0 15.2 8.6

Mex spp 0.1 0.7 6.4 9.7 15.3 4.7 6.3

Galliansoga spp 4.83 4.83 10.42 7.67 4.17 2.3 5.71

Xanthium spp 0.667 0.167 0.833 0.167 0.00 0.00 0.36

Nicandra spp 1.00 0.50 1.67 1.17 0.75 0.58 0.94

Digitaria spp 2.67 6.17 2.33 2.17 2.08 4.0 3.24

Fig.2: Effects of methods of weed removal on mean No. of some weeds per

species.

Fig.3 :Effects of time of weed removal and method of weed removal on

total no. of weeds

0

50

100

150

200

250

2 4 6 8

TO

TA

L N

O O

F W

EE

DS

/M²

WEEKS AFTER PLANTING

H.pulling weedy free

H.pulling twice

H.pulling weedy

Hoeing twice

Hoeing weedy

Hoeing weedy free

Discussion

Weed free practices are not significantly

different because weeds are continuously

removed hence minimal weed interference

to the crop

In Hand pulling-farmer’s practice, there is

lower mean yield compared to hoeing

farmer’s practice because some weeds

particularly perennial weeds (Xanthium

pungens) were not effectively removed as the

stumps regenerate immediately.