Science

Water for agricultural use accounts for a very high percentage of worldwide water consumption. In order to maximize productivity and profitability, while reducing the environmental impact of vegetable farming, growers must choose the correct irrigation system for their crop as well as determine the best methods for managing and scheduling irrigation. This chapter considers recent advances in irrigation techniques used in vegetable cultivation. It is divided into three main sections: irrigation systems, irrigation system performance, and irrigation scheduling. The author’s coverage of irrigation systems includes sprinkler irrigation, drip irrigation, surface flood/furrow irrigation, and subirrigation (including seepage irrigation, irrigation drain tiles, and subsurface drip irrigation). Irrigation system performance is then discussed in relation to efficiency, uniformity, and water-use efficiency. The section on irrigation scheduling includes irrigate anytime, “Feel and Appearance” irrigation, systematic irrigation, the crop water demand method, the soil water status method, and combined methods.

Root systems are responsible for the uptake of water and nutrients needed to support crop growth and development, ameliorate the effects of other stressors and increase vegetable production. Roots are crucial for maintaining plant water status and meeting shoot transpirational demands as the leaves assimilate carbon (C). This chapter focusses on the potential of root traits to support increases in yield, maximize the effective use of resources and provide abiotic stress tolerance in vegetable crops. The chapter discusses root traits and molecular indicators regarding water and nutrient uptake, root-microbe interactions, abiotic stress and technologies for crop improvement. Finally, the chapter looks ahead to future research trends in this area.

The major challenge faced by tomato production is the need to increase productivity by improving resistance and tolerance to crop stresses. Cultivar improvement depends on our ability to identify, study and leverage the genetic diversity present among tomato germplasm resources worldwide from which new resistance/tolerance traits can be selected and transferred via breeding and biotechnology. To achieve this, it is critical to combine the study of the genome, epigenome, transcriptome, proteome and metabolome. This chapter summarizes the current status and advances in our understanding of tomato stress responses. Furthermore, it discusses future trends in tomato stress biology and its potential implications for tomato improvement.

The operation of leaf stomata affects a plant’s photosynthesis, transpiration and respiration, and allows vegetable dry matter to be produced, which is required for production of the tomato fruit. The opening and closing of the stomata can be affected by various factors, and this in turn can have an effect on crop yield. After reviewing the role and functioning of the stomata, this chapter considers the main factors that affect stomata opening and closure, namely, soil water availability, light, CO2, relative air moisture, air temperature and wind. It then considers how these and other factors may interact, reviews the cultivational practices which can promote stomatal opening and briefly cover methods for determining the water status and transpiration rate of plants. The aim of the chapter is to provide novel insights into improving tomato yield by ensuring stomatal pores stay open for longer at appropriate times.

Many viruses transmitted by insects cause great damage to tomato crops in the field and in the greenhouse, seriously damaging tomato production in many regions of the globe. Management of insect transmitted tomato viruses is a race between the emergence of new viruses coupled with the proliferation of quickly adapting vectors and strategies that include physical and chemical protection from insects and development of virus-tolerant crops. The major insect-transmitted viruses infecting tomato are described in detail in this chapter, including viruses transmitted by aphids, thrips, whitefly and leafhoppers. The chapter explores the potential of technologies such as genetic engineering to combat insect-transmitted viruses and suggests future trends for research in this area.

Plant breeding is defined as identifying and selecting desirable traits in plants and combining these into one individual plant. Since 1900, Mendel’s laws of genetics provided the scientific basis for plant breeding. This chapter presents ‘conventional’ breeding technologies that have been applied in tomato breeding. The term ‘conventional’ breeding is defined as the integrated application of classic genetics principles and genomics through visual and/or molecular selection with non-GM (genetic modification) tools. In tomato breeding four conventional methods have played important roles, namely, true breeding, tomato hybrid breeding, introgression breeding and mutagenesis. In the genomics era, the ‘conventional’ tomato breeding cycle was and is being challenged by novel tools of plant breeding resulting from the availability of genomic tools and resources. At the end of the chapter, an outlook on biotechnology tools that are revolutionizing tomato breeding is provided.