effect of insecticidal control on the growth and yield characters of some varieties of Amarathus  in northern Nigeria

Description

ABSTRACT

Growth and yield of crops is the major concern of every farmer, but it is quit unfortunate that pest attack is one of the things that hinder good growth and yield. Generally, insecticides are used to control pest attack in our farmers. Lindane is listed among the Prior Informed Consent (PIC) insecticide, and agricultural uses of lindane have been banned in 52 countries due to its hazardous nature. However, lindane is still widely used in vegetable cultivation in Nigeria. The   effect of increasing rates of application of lindane (156.0, 244.0 and 312.0 g ha-1), unden (propoxur) (125.0, 187.5 and 250.0 g ha-1), dithane and karate (166.6, 209.8 and 333.3 g ha-1) on Amaranthus was studied to find out if it has any advantage that makes its use attractive to farmers despite its ban. Pesticide application had a higher effect on fungal population (50-70% reduction) than on bacterial population in the soil (23.0–38.4% reduction). Dithane suppressed bacteria most whereas karate suppressed fungal population most. Lower levels of chloride residues in tomato fruits corresponded to lower rates of lindane application. Lindane did not have any advantage over the other pesticides as it caused the least increase in yield. It is recommend that farmers are educated on the adverse effects of lindane use, and government enforces the restriction on lindane importation and use in agriculture.

 

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                           BACKGROUND OF THE STUDY

Amaranthus, collectively known as Amaranth is a cosmopolitan genus of herbs. Approximately, 60 species are recognized with inflorescence and foliage ranging from purple and red to gold (Grubben and Denton, 2004). Amaranth (Amaranthus spp.) is one of the important underutilized crop native to Central and South America. It is widely cultivated in various regions of the world as well as in Nigeria as food and leafy vegetable (Smitha, 2010). The crop belongs to the family Amaranthaceace and genus Amaranthus. There is no clear dividing line between a vegetable type and grain type (Olaniyi, 2007). The leaves of vegetable amaranth are nutritionally significant source of minerals included vitamin A, vitamin B₆, vitamin C and vitamin K (Grubben and Denton, 2004). Amaranth has a very high nutritional value, higher grain protein (13 – 19 %) and leaf protein (23 – 25 %) with high lysine and sulphur containing amino acids, which are limiting in other conventional crops (Joshi and Rana, 1995). Amaranth has been used for food by human in a number of ways. The grain is grind into flour for use in bread, noodles, pancake, cereals, granola, cookies and other flour based product (Putnam, 1990). Several studies have shown that, like Oats, amaranth is beneficial for people with hypertension and cardiovascular disease.

Regular consumption reduces blood pressure and cholesterol level which improved antioxidant stages and some more immune parameters (Olaniyi, 2007; Olaniyi et al., 2008; Kolawole and Sarah, 2009). It is also a potential source of forage (9.9 – 12.7 t ha^-1) dry matter as well as 74 – 148 t ha^-1 of silage (80 % moisture) (Putnam et al., 1989). Amaranthus cruentus L. is a tall annual herb topped with cluster of dark pink flower and can grow up to 2 m in height (Stallknecht and Schulz – scheaffer, 1993). It is one of the three amaranthus species cultivated as vegetable and grain source. The other two are Amaranthus caudatus L. and Amaranthus hypochondriacus L. (Olaniyi, 2007; Olaniyi et al., 2008). The growth of the vegetable crops is generally determined by so many climatic, agronomic and soil factors such as plant nutrient and proper spacing. Insect attack is known to have significant influence on vegetative growth of crops and subsequently increased yield.

Insecticides are used in controlling insect pests, diseases and weeds in agriculture. They are known to increase agricultural production tremendously as these chemicals act on pests that destroy agricultural produce. The behaviour of a pesticide in the environment depends on its stability, physico-chemical properties, the nature of the medium into which it is applied, the organisms present in the soil, and the prevailing climatic conditions (Graham-Bryce, 1981). It has been established that pesticides could become a nuisance if they are misused. Some of the negative effects of pesticide misuse include low crop yield, destruction of soil micro-fauna and flora, and undesirable residue accumulation in food crops (Edwards, 2016).

In advanced countries, strict pesticide regulation and enforcement mechanisms are put in place to ensure their safe use and proper handling. The control schemes further ensure that approval for the sale and use of pesticide is based on scientific data that support its effectiveness against target pests and that it is not unduly hazardous to human health and the environment. Pesticide use in most developing countries is, however, based solely on manufacturer’s recommendations. These recommendations, which include data on toxicological and environ-mental properties of the pesticides, though useful, may not be appropriate under local conditions since they were tested under different agro-climatic and socio-cultural conditions. With the intensification of agriculture and increasing usage of pesticides, the need to study the side effect of pesticides on various soil properties and on the host plant is very crucial.

A research was carried out and it was identified that lindane, unden, karate and dithane as the most used pesticides by vegetable growers. According to Brown (1978), lindane is used primarily as an insecticidal treatment for hardwood logs and lumber, seed grains and livestock. It is also used as an insecticide for several dozen fruits and vegetable crops and for personal hygiene as a scabicide (EPA, 2002). However, lindane is listed among the Prior Informed Consent (PIC) pesticides, and all agricultural uses of lindane have been banned in 52 countries due to its hazardous nature. Pharmaceutical uses of lindane have also been banned in some countries because it has been found to cause seizures and damage to the nervous system, and also to weaken the immune system (PANNA, 2017). Since lindane is used extensively for agricultural purposes, residues are often found in fruits, vegetables, milk and meat.

Despite the hazardous nature of lindane, farmers in Northern Nigeria continue to use the chemical as pesticide on their vegetable crops. This study focuses on the Growth and yield of Vegetable Amaranth (Amaranthus Cruentus L.) as Influenced insecticidal control.

1.2                                  PROBLEM STATEMENT

Amaranthus species is one of the plants often considered as the most important green leaf vegetable in Nigeria and other countries. Its production has been plagued with an array of factors including incidence of insect pest. Studies have shown that insecticide such as Lindane is listed among the Prior Informed Consent (PIC) insecticide, and agricultural uses of lindane have been banned in 52 countries due to its hazardous nature. This study was carried out to discuss the Growth and yield of Vegetable Amaranth (Amaranthus Cruentus L.) as Influenced insecticidal control.

1.3                                 PURPOSE OF THE STUDY

The objectives of this study were:

• To compare the effects of different rates of application of lindane and some other selected pesticides on vegetable yield and soil microbial activity, and
• To determine whether lindane has any advantage over the other pesticides that makes its use attractive, despite its ban in agriculture.

1.4                  LIMITATION AND SCOPE OF THE STUDY

There are different types of insecticides used by farmers in the northern Nigeria but in this work we only considering the use of lindane – type of insecticide. In this study, the effect of lindane on the growth and yield of vegetable Amaranth (Amaranthus Cruentus L.) as Influenced insecticidal control.

1.5                                                  RESEARCH QUESTIONS

1. How do insecticides affect Amaranthus yields?
2. How does insecticide affect plant growth?

• Do insecticides improve Amaranthus’ growth and yield?

1. What are the effects of insecticides?

1.6                            SIGNIFICANCE OF THE STUDY

This study will serve as a way of enlightening farmers mostly those in Northern part of Nigeria on the right insecticide to be used for their crops. It will be of optimum benefit to the producers of the insecticides – it will help them the study and amend their chemical composition of the insecticide.

It will help the government to decide the type of insecticide that should be allowed in the country.