Vegetable Production and Practices

Gregory E Welbaum

• Publisher: CAB International
• Year: 2015
• ISBN:
  9781789244908
• Topic: Biological Sciences
• Subtopic: Horticulture
• Index: Biological Sciences

This comprehensive new textbook takes a scientific approach to explaining the principles of modern conventional and sustainable commercial vegetable production. The book describes the basic botany of vegetables, environmental requirements for successful growth and development, mineral nutrition, field establishment, harvesting methods and post-harvest handling practices. Professor Gregory E. Welbaum is a former commercial vegetable grower whose family farm has been involved in crop production for several generations. He has taught both classroom and online vegetable crop classes at Virginia Tech for over two decades. Vegetable Production and Practices has been specifically designed to accompany courses in vegetable crop production, so is ideally suited to inspire students in crop and horticultural sciences, as well as provide a useful reference for experienced practitioners.

1 Vegetable History, Nomenclature, and Classification

Introduction

All societies and ethnic groups eat vegetables because they are essential for maintaining human health. In simple terms, modern vegetable science deals with growing herbaceous plants for human consumption to meet basic nutritional needs. As the world’s population grows, the demand for vegetables will continue to grow as well. Vegetable science, sometimes called olericulture, is one of the most dynamic and important fields of the agricultural sciences. The importance of vegetables has never been greater.

What is a Vegetable?

Most definitions of a vegetable are not botanically based. Vegetable definitions are rather arbitrary by nature and commonly based on usage rather than plant morphology. For example, one widely used definition of a vegetable is: a herbaceous plant or portion of a plant that is eaten whole or in part, raw or cooked, generally with an entree or in a salad but not as a dessert. Of course there are exceptions to this definition. Rhubarb, watermelon and cantaloupes are all considered vegetables but commonly used as desserts. Mushrooms are fungi and not plants but are generally considered to be vegetables, and their production is described in a later chapter.

Since “vegetable” is not a botanical term, some vegetables botanically speaking are also fruits. In a botanical sense, a fruit describes a ripened ovary containing seeds together with adjacent parts that are eaten at maturity. For example, tomato, pepper, bean and cantaloupe botanically speaking meet the definition of fruit, but because of the way they are traditionally used and produced they are considered to be vegetables. Therefore, since there are essentially two classification systems, some commodities may be classified as a vegetable based on their usage while at the same time they are botanically fruits.

Vegetables are a horticultural food crop. Other horticultural food crops include small fruits and tree fruits, which are usually grown as perennials. Vegetable crops may be either annuals or perennials. From a production standpoint, a vegetable crop may be defined as a high-value crop that is intensively managed and requires special care after harvest. Agriculturalists often segregate agronomic or “field” crops into a separate category as crops that are extensively grown and less intensively managed in comparison to vegetable and the other horticultural crops. Wheat, cotton, soybean, sugarcane and rice are all examples of agronomic crops. Many agronomic crops are grains that are planted and destructively mechanically harvested at full physiological maturity at the end of their life cycles. In contrast, many vegetable crops are harvested in an immature state, while still fragile, so great care must be taken to preserve their quality from the field to the consumer.

There are some exceptions to these general production definitions. Some agronomic crops such as tobacco are intensively managed and are valuable in a monetary sense but are considered agronomic for historical reasons. Irish potato is considered to be a vegetable by some but an agronomic crop to others depending on the region, type and scale of production. Corn and soybeans can be either agronomic or vegetable crops depending on the cultivars grown, their stage of maturity at harvest and their end use. While these definitions are not perfect, they do have value in allowing us to group different crops and types of production to understand better the more unique aspects of vegetable production, management and handling compared to other crops. So in summary, “vegetable” is a term based on the usage of herbaceous plants or portions of plants that are eaten whole or in part, raw or cooked, generally with an entree or in a salad but not as a dessert, that are intensively managed and may require special care after harvest to maintain quality.

The Evolution of Vegetable Production

Over the years, world vegetable production has increased. For example, there was over a four-fold increase in world vegetable production from 1970 until 2009 (FAO, 2011). The long-term increase has largely been the result of a series of technological advances. The first were labor-saving technologies such as the moldboard plow, and power equipment such as trucks, tractors and harvesting equipment. Subsurface drainage systems were developed to improve productivity of chronically waterlogged soils. During the first half of the 20th century, low-cost commercial fertilizers were mass-produced, leading to dramatic improvements in fertility management and productivity. In the 1930s, new plant-breeding techniques led to development of more productive cultivars. One of the major genetic advancements during this period was the development of F-1 hybrid cultivars, which increased the productivity of some vegetables by 30% or more. Many view the period after World War II as the chemical era of agriculture as many synthetic pesticides, e.g. fungicides, insecticides and herbicides, became readily available. Chemicals were intended to more easily control crop pests to enable a large-scale, single-crop production system called monoculture where only a single crop is grown in a field and all other vegetation is excluded. The monoculture system and the related technologies like chemical pest control and concentrated synthetic-fertilizer usage were designed in part to reduce the amount of labor needed in agriculture so that one person could effectively manage more crop-production acreage and increase productivity.

During the 1970s and 1980s, concerns about human health issues led to interest in and the development of more sustainable and low-input approaches to vegetable production. Also in the past 50 years, conservation tillage practices have been developed to reduce soil erosion, decreasing the number of passes made over a field to decrease soil compaction. Plastic mulches were developed to modify soil temperatures, control weeds, reduce leaching and use less water to produce vegetables. Trickle-irrigation systems were developed to precisely apply water and nutrients to vegetable crops throughout the season. Raised-bed production systems improved drainage, encouraged better root development and reduced disease. During this same time frame, computer technology also impacted both production and management issues, increasing production efficiency.

Despite these advances, there seems to be declining interest in vegetable science as a discipline in the academic circles of many developed countries. Government sponsorship of research on applied aspects of vegetable science in many developed countries has declined in recent years as funding has been diverted to more basic research in plant science. There is a perception that research on vegetable-crop production is no longer a high priority in countries with developed agriculture industries because most of the production-related questions have already been answered or are being addressed by the private sector. Some believe that production has become “cookbook”, so advanced training is no longer necessary.

Most agriculturalists would agree that research has played an important role in advancing vegetable science to its current state. Innovative new research will be necessary in the future to meet the needs of a growing global population for safe, nutritious and sustainably produced vegetables. The need for primary information about vegetable production for the developing world remains great. Both now and in the future, research and education programs will be needed to address food safety and security issues.

In many developed countries, only a very small percentage of people are involved in food production. This has led to misconceptions and uncertainty about where vegetables come from, the effect production has on the environment, and whether or not vegetables are safe to eat. Consumers need to be educated about their food supply to intelligently discuss timely topics such as the risks and benefits of transgenic crops. Accurate scientific information needs to be readily available about this and other key issues. Vegetable science is truly fundamental to our very existence because it is a discipline that deals with the basic needs of the human race rather than its wants.

The following is a partial list of challenges that face commercial vegetable growers in many areas of the world; novel research approaches will be required to solve them. Understanding and controlling the causes of biological contamination on vegetable crops is a major challenge. Developing highly productive and efficient sustainable vegetable production systems is another. Improving the quality and nutritional value of commercial vegetables is an ongoing challenge. There is an opportunity to fully utilize the Global Positioning System (GPS) and its related technologies to improve vegetable-production efficiency. Decreasing the environmental footprint caused by intensive commercial vegetable production while using less water and energy will only increase in importance in the future.

In developed countries of the Americas and Europe, the commercial vegetable industry is dominated by large corporations with multiple production areas that can continuously produce a wide range of crops to supply supermarket chains throughout the year (Cook, 2001). Grocery chains prefer dealing with single suppliers for convenience, economies of size and uniformity of product. Vegetable industries in North America and Europe have evolved so that vegetables are grown in regions best suited for a particular crop for shipment, often to distant markets in population centers. The shift from local production to optimum production away from population centers has been occurring for decades (Cook, 2001). In the USA, Canada and some European countries, studies show that the average vegetable purchased in a supermarket traveled over 2,400 km (1,500) miles from the field before it was sold (Carlsson-Kanyama, 1997; Pirog and Benjamin, 2003). Shipping vegetables from distant markets is very energy intensive and the current realities of energy costs bring into the question the sustainability of growing vegetable...