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The introductory chapter explains how mushrooms develop. The complex fungal life cycle involves the germination of spores, the expansion of feeding colonies, and mating processes that can involve tens of thousands of sexes in a single mushroom species. The study of these mechanisms began with the Florentine genius, Anton Micheli in the eighteenth century, and, later, engaged fascinating personalities including children's author Beatrix Potter, Worthington Smith (who got most of his facts spectacularly wrong), and Elsie Wakefield (who got her facts right). The modern study of mushroom development is a challenge for the field of molecular genetics and computer simulations have provided useful insights. Recent changes in seasonal patterns of mushroom fruiting may relate to global climate change.

Photosynthesis involves biological energy transduction, the transformation of light energy into chemical energy, and photosensory pigments, which play an important role in the process. Phytochrome, a photosensory pigment, regulates plant growth and development. This chapter explores research works on light-induced seed germination and the role of phytochrome to regulate plant growth and development, including seed germination. Pioneering work by Hendricks and colleagues looked at photo-reversible phytochrome responses. The use of herbicides to control weeds and the adverse affects of weeds on the environment and public health are discussed. With the persistent use of herbicides, over time weeds have developed resistance, a resurgence, and eventual replacement. The evolution of herbicide-resistant weeds and the harmful effects of herbicides lead to the development of an integrated weed-management program. Plowing presents a simple and effective method of weed control. The emergence of nighttime plowing to control weeds and its limitations are also presented.

Plant diversity within the Serengeti ecosystem is often overlooked. A logical focus is on broad factors such as climate, topographic heterogeneity and fire frequency. Subsequently, the issue of compositional stability through time and space and what factors may influence the turnover of species through time. The chapter concludes by comparing plant diversity in the savanna/grassland habitats of Serengeti to other, similar grassland and savanna systems around the world.

This chapter initially discusses Maimonides' argument that palm trees grow in a permanent state of exception, and stand for all other trees and plants, as they are excluded from the sphere of the living. They occupy the “zone of indistinction between nature and right,” between legal limits and unlimited violence. For Maimonides, the palm is a deficient tree, barely reminiscent of the miracle of Creation, the memory of which is preserved in the generative power of vegetation. The sphere regulating vegetative functions was set into motion by God; the germination of seeds is a reminder of the act of Creation. The Maimonidean plant may not live as animals do, but each time it returns to the earth as a seed, it renews and reaffirms the Creator's will. Despite being a proponent of allegorical sense, the plant itself is meaningless. Whereas germination is a symbol reaffirming the continuity of Creation, the death of plants are downright insignificant.

For the transformation of a seed to a seedling complex physical and biochemical changes occur within a seed before germination can proceed. Germination is controlled by diverse seed dormancy mechanisms in plant species that delays germination until the conditions are most favourable for seed germination and seedling establishment (Thompson 1970). Baskin and Baskin (1998) identified four benefits for the evolution of seed dormancy in plants: (i) persistence in risky environments as seed banks, (ii) decreased intraspecific competition, (iii) improved chances of seedling establishment and (iv) increased fitness (seed production) of the individual and the species as a whole. They showed that seed dormancy may be caused by any one of physiological, morphological, physical, chemical and mechanical constraints or by a combination of more than one of these factors. For instance, seeds may possess an embryo with a physiological inhibiting mechanism, immature embryo, impermeable seed coat or may contain chemical inhibitors and hard woody fruit walls. In all of these cases seed dormancy is eventually broken by one or more of the following treatments: after ripening, heat treatment, cold temperature stratification, prolonged exposure to high temperatures, exposure to light, softening of seed coat by microbes or physical scarification, leaching of inhibiting chemicals, ageing of seeds and other subtle changes in the habitat. In temperate North America with snow cover during winter months the seeds of a large majority of sand dune species—Cakile edentula, Ammophila breviligulata, Calamovilfa longifolia, Iva imbricata, Croton punctatus, Uniola paniculata—and others require cold stratification at <4°C for 4–6 weeks to break their dormancy requirements. Seeds of some species such as A. breviligulata and U. paniculata that require cold stratification at the northern end of their range lose this requirement in the south (Seneca 1972). At southern locations exposure to high temperatures may be required to fulfil the dormancy requirements. Winter annuals, Vulpia ciliata, Cerastium atrovirens, Mibora minima and Saxifraga tridactylites, that grow and mature their seeds in early summer on sand dunes at Aberffraw, North Wales, require exposure to high soil temperatures to overcome a state of dormancy in a certain proportion of seeds at the time of dispersal (Carey and Watkinson 1993; Pemadasa and Lovell 1975).

This chapter first considers the influence of the understory filter on dispersal, germination, and survival of tree seeds and seedlings individually. It then explains the effects of the understory filter on tree seedling community attributes such as tree seedling distribution, species composition, and diversity; the influence of the understory filter on seedling growth; and the role of the understory in determining the size structure of tree seedling communities. The filtering activity of the understory is complex not only because of its activity at multiple life stages of a tree, but also because the understory itself is a complex and changing mosaic of understory plants. The chapter concludes by discussing the spatial and temporal distribution of understory plants and how the mosaic nature of the understory affects the complexity of the understory filter.

This chapter examines the scientific experimentations aimed at identifying the germination stimulants and compounds present in certain plant forms. It surveys the effects of the different methods, namely wood charring and the bioassay-driven fractionation process, that led to the observation that germination-affecting chemicals may be water soluble, thermostable, and active in low concentrations.

Generally, grape vines produce extraneous shoots (“suckers”) on the plant in addition to those growing beyond the few desired on the cordon wanted for proper vine growth. Generally, again, suckers are less fertile than the primary shoots, they crowd the canopy of the vine, and their growth utilizes resources required for proper growth of the primary shoots. Further, the chaotic growth makes it difficult to manage the harvest. A crowded canopy (as will be discussed subsequently) is not a healthy one for grape growth. As shown in Figures 12.1 and 12.2 and noted earlier, buds (the small part of the vine that lies between the vine’s stem and the leaf stem or petiole) can start alongside the beginning of leaves at the base of the apical meristem. The buds swell and eventually produce shoots. As the shoot grows the flowers appear on a stem from the node, from where leaves have also sprung. That is, grape nodes hold buds that grow into leaves and inflorescences or “clusters of flowers” (i.e., the reproductive portion of a plant) arranged on a smaller stem growing from the node. It is not yet clear, despite recognizing the flow of nutrients and auxins as well as changes in proteins, how, after vernalization (i.e., the ability to flower so that fruit can be set—but only after exposure cold), the plant decides which, leaf or stem bearing flowers, should sprout from the node. The fundamentals of the coming forth of the buds are often outlined as a three-step process. First there is the formation of uncommitted primordia (primordia refer to tissues in their earliest recognizable stages of development) called “anlagen” (from German, in English, “assets” or “facilities”) at the apices of lateral buds. Second, differentiation of anlagen to form inflorescence primordia or tendril primordia occurs. Finally, flowers form from the inflorescence primordia when activated by phytohormones, nutrients, and growth regulators and when the external conditions of light and temperature are correct.

Application of limestone to a soil changes the (a) soil physical properties by encouraging granulation and improving tilth; (b) soil chemical properties by decreasing soil acidity, increasing availability of a number of essential plant nutrients, and decreasing levels of aluminum, iron, and manganese that potentially may be toxic; and (c) soil biological properties by improving conditions for micriobial organic matter decomposition with release of nitrogen, phosphorus, and sulfur for plant use, and by stimulating root development. Granulation Encouraged. Applying lime to soils improves soil physical conditions by encouraging granulation and crumb formation and aggregation. Tilth Improved. Tilth is the ability to work or cultivate a soil. By improving physical conditions with more granulation and crumb formation, soil tilth is improved. Lowering H+ Concentration (Acidity). When lime is applied to a soil, acidity is reduced and pH is raised. This is especially important in the humid regions where rainfall and other factors constantly make a soil more acid (explained in Chapter 9). Plant Nutrient Availability Increased. Liming a soil will increase availability of plant nutrients by (a) increasing Ca and Mg in the soil from added liming material; (b) adjusting soil to a higher pH so that N, P, K, S, and Mo are solubilized; and (c) reducing solubility of potentially toxic levels of Fe, Al, or Mn. Lowering of Potentially Toxic Levels of Al, Fe, and Mn. At very low soil pH, Al, Fe, and Mn are soluble and may be present in a high enough concentration to be toxic to plant growth. When lime is applied, the pH increases and these three elements become less soluble and less available for plants. Microbial Decomposition Enhanced. Soils that are limed provide conditions for active microbial decomposition of organic materials in soils, resulting in mineralization and release of N, P, and S in forms that plants can use. Liming also increases the amount of humus formed, thereby improving water infiltration and water-holding capacity. Furthermore, liming soils stimulates other types of biological transformations, such as nitrification, N-fixation, and S-oxidation, that improve plant growth. Deep Rooting Stimulated.

Humans cultivate more than 200 species of plants, but this chapter reviews responses of 5 important cereal crops to drought. These crops are maize (Zea mays L.), rice (Oryza sativa L.), wheat (Triticum aestivum and Triticum turgidum L. var. durum), sorghum (Sorghum bicolor [L.] Moench), and pearl millet (Pennisetum glaucum [L.] R. Br), which provide the majority of food in the world. In general, farmers cultivate millet in the most drought-prone environments and sorghum where a short growing season is the greatest constraint to production. Some sorghum cultivars set grain in as short as 50–60 days (Roncoli et al., 2001). Rice is grown under a wide range of environments, from tropical to temperate zones, from deep water-flooded zones to nonflooded uplands. Rice productivity is limited mostly by water (IRRI, 2002). Drought limits, to a varying extent, the productivity of all of these crops. Although water is likely the most important manageable limit to food production worldwide, we should recognize that water management cannot be isolated from nutrient, crop, and pest management. Life on earth depends on green plants, which capture solar energy and store chemical energy by the process of photosynthesis. Although plants use a small amount of water in the reactions of photosynthesis and retain small amounts of water in plant tissues, as much as 99% of the water that plants take up is lost through transpiration (i.e., gaseous water transport through the stomata of leaves). Stomata, which are small pores on leaf surfaces, must open to allow carbon dioxide to enter leaf tissues for photosynthesis and plant growth, but open stomata also allow water to escape. In addition to transpiration, there are several other avenues of water loss from a crop system. Water may exit the crop system by evaporation from the soil, transpiration of weeds, deep drainage beyond the root zone, lateral flow beneath the soil surface, or runoff. We can sum the daily additions and losses of water to form a water balance equation: . . . S = G + P + I − E − T − Tw − D − L − R [2.1] . . .