Adriana G. Kantolic

Crop Development: Genetic Control, Environmental Modulation and Relevance for Genetic Improvement of Crop Yield

Publisher Summary This chapter discusses the particularities of development of wheat and soybean to highlight the importance of identifying the genetic and environmental controls of the phenological pattern. This knowledge is a prerequisite to understand, predict, and manipulate the association between crop cycles, the resources, and the environmental constraints to favor the coincidence of the critical period with the most favorable conditions. Although the cycle to match crops and environmental factors has been determined in most production systems, further improvement is feasible by manipulation of critical periods. The critical period may occur before (e.g., in wheat) or after (e.g., in soybean) flowering, but it is clear that in both species, in spite of their large morphological and physiological differences, the growth during this period defines crop yield in most environments. Improving the knowledge of genetic and environmental drivers of the expression of the genes that control flowering time should improve the precision in positioning the critical period, when the highest level of resources is expected and stresses are less likely.

Beneficial effects of solar UV‐B radiation on soybean yield mediated by reduced insect herbivory under field conditions

Ultraviolet-B radiation (UV-B: 280-315 nm) has damaging effects on cellular components and macromolecules. In plants, natural levels of UV-B can reduce leaf area expansion and growth, which can lead to reduced productivity and yield. UV-B can also have important effects on herbivorous insects. Owing to the successful implementation of the Montreal Protocol, current models predict that clear-sky levels of UV-B radiation will decline during this century in response to ozone recovery. However, because of climate change and changes in land use practices, future trends in UV doses are difficult to predict. In the experiments reported here, we used an exclusion approach to study the effects of solar UV-B radiation on soybean crops, which are extensively grown in many areas of the world that may be affected by future variations in UV-B radiation. In a first experiment, performed under normal management practices (which included chemical pest control), we found that natural levels of UV-B radiation reduced soybean yield. In a second experiment, where no pesticides were applied, we found that solar UV-B significantly reduced insect herbivory and, surprisingly, caused a concomitant increase in crop yield. Our data support the idea that UV-B effects on agroecosystems are the result of complex interactions involving multiple trophic levels. A better understanding of the mechanisms that mediate the anti-herbivore effect of UV-B radiation may be used to design crop varieties with improved adaptation to the cropping systems that are likely to prevail in the coming decades in response to agricultural intensification.

Genetic and environmental effects on crop development determining adaptation and yield

Abstract The understanding of crop phenology is critical for both improvement of yield potential and adaptation to stress. Matching ‘critical’ phases (when the most important yield components are determined) and best environmental conditions is crucial to maximize yield. The processes regulating crop development are complex and are strongly influenced by genetic and environmental factors. In this chapter, we describe the main developmental stages, delimiting major phenological phases of wheat and soybean, and the relationships between crop phenology, adaptation and yield determination. Analysis of environmental control of development is restricted to the main drivers: temperature, including temperature per se and vernalization (for wheat), and photoperiod. The effects of major genes are outlined: Vrn, Ppd and Eps in wheat and Dt (growth habit) and genes of the series E and J in soybean. Finally, we integrate the environmental and genetic effects on phenology into the determination of crop adaptation and yield potential.

Soybean fruit development and set at the node level under combined photoperiod and radiation conditions

Highlight Long days during post-flowering postpone elongation and active growth of dominant pods within a node, which extends flowering and allows pod set at usually dominated positions.