Wang et al. investigated the role of light quality, specifically, low red to far-red ratios , on photo protection during cold stress in tomato. They showed that L-R/FR activated two pathways associated with cyclic electron flow : the PGR5/PGRL1A- and NDH dependent complexes, respectively. These CEF complexes help to reduce cold-induced photo damage of the photosynthetic machinery by accelerating the thermal dissipation of excess energy, enhancing ROS scavenging, and reducing the hyper reduction of the electron transport chain. This work therefore provides a better understanding of the mechanistic relationship between varying light quality and low temperature in plant photosynthetic performance in temperate climates when seasonal variation induces these conditions. Spring frosts cause important economic losses in many fruit-producing areas of the world, and there is interest in identifying feasible approaches to mitigate these risks. Ethylene controls fruit ripening in climacteric species but it also plays an important role in plant stress responses . Published literature on the use of ethylene or ethylene-based compounds for protecting temperate fruit orchards against frost damage was reviewed . Experimental evidence of ethylene modulation of bud dormancy and blooming were presented and discussed. It was suggested that ethylene-delayed bloom and the associated frost protection may result from either the slowing down of floral bud responsiveness to seasonal temperature changes, an antagonistic interaction with other hormones such as abscisic acid or gibberellins, plant sensing of exogenous ethylene as a stress signal leading to longer dormancy, or ethylene-enhanced ROS accumulation resulting in extended bus dormancy.
Because chilling stress in plants often leads to ROS accumulation, the questions arises whether improving the antioxidant capacity of tissues by the exogenous application of antioxidant treatments may help improve tolerance to cold as well as to other types of abiotic stress. To this purpose, Tang et al. treated low bush blueberry seedlings with hydrogen sulfide,vertical farming racks and found that treated plantlets performed better under low temperatures than the untreated controls, as shown by the alleviation of membrane peroxidation, the reduction of chlorophyll and carotenoid degradation, and the lessening of photo system I and II photo inhibition. Conversely, the application of hypotaurine, a H2S scavenger, aggravated the oxidative symptoms under cold stress. Brassinolide is an important plant stress hormone shown to promote plant resistance to low-temperature environments. Zhang et al. investigated the effects of exogenous BR on the photosynthetic characteristics, leaf anatomical structure, and chloroplast ultra structure of two species of tung tree seedlings under different temperature conditions. The results suggested that long-term low temperatures significantly reduced the photosynthetic efficiency of tung tree seedlings, affecting the formation of the internal structure of plant leaves and destroying the integrity and function of the chloroplast. To prevent this, external application of BR to tung tree seedlings could enhance the photosynthetic potential of tung trees by maintaining the stability of the leaf structure and morphology and alleviating the damage caused by cold injury. In summary, the papers in this collection illustrated the breadth of research aimed at understanding chilling responses in horticultural crops, but more importantly provided new insights that will further our future basic and applied research in this area.
Agriculture has been an important engine of economic development, and the mainspring of economic progress in agriculture has been productivity improvements driven by technological change that is fueled by re search and development . Since World War II, agricultural productivity has more than doubled in the United States, as in many other countries. California agriculture today produces more than twice the output of 1950, using roughly the same total input — although with less labor and land, and more capital and purchased inputs. These gains can be attributed to new biological, mechanical and chemical technologies, including improved genetic material, machines, fertilizers and pesticides, and knowledge. The current wave of technological progress continues this pattern, while emphasizing information technologies and biotechnology — in particular genetically modified crops. For many, GM crops represent the hope for a future with less hunger and malnutrition, and for a more sustainable agriculture with more varied, cheaper and safer food. For others they are cause for serious concern about the environment and food safety. Regardless of how we may feel about it, the juggernaut of technological change continues and the biotechnology revolution is well under way in the United States and other countries. The challenge for public policy is to determine what regulations should be applied to govern the development and use of these technologies, and what other types of intervention may be necessary, such as public investments in research to correct for private-sector under investment. In the case of horticulture — the cultivation of fruits and vegetables, tree fruits and nuts, turf grass, flowers and ornamental crops — these is sues are sharply drawn because the private sector has not found it profitable to develop or commercialize many GM crops in the current political, legal and market environment.
What will happen in biotechnology applied to horticultural crops is up to the government, for a variety of economic reasons. Some of these aspects may be unique to GM horticultural crops but many are common to GM crops generally, and similar issues arise with some new non-GM technologies.Without government intervention, the rate of innovation will be too slow, reflecting both under investment in research and under adoption of some research results. Both problems are related to the nature of property rights for re search results. “Free-rider problems” occur when property rights are incomplete, and privateinves tors can capture only part of the re turns to their investments in certain types of research ; as a result, their incentives to invest are reduced. On the other hand, when the rights to research results are protected, such as by patents or trade secrets, the owner of a new variety can charge monopoly prices,maceta cuadrada 25 x 25 unduly limiting the use of that variety. Intellectual property rights are a double-edged sword: to the extent that they pro vide a greater incentive for investing in research they are also likely to result in lower adoption rates. Governments have addressed the incentive problems in agricultural research in several ways. Federal and state governments have funded agricultural research at public institutions such as the U.S. Department of Agriculture and state agricultural experiment stations associated with land-grant colleges. This approach allows an increase in total research with out the problems associated with monopoly pricing of inventions. How ever, even though the investment has paid handsome dividends, it is increasingly difficult to sustain the past levels of funding for public agricultural R&D, in the face of general budget problems and declining political sup port for public science funding, including agricultural science . Governments have also acted to strengthen IPRs applied to plants and animals as well as mechanical technologies; and changes in IPRs, especially in the 1980s, were crucial for the agricultural bio-technol ogy development that followed. Partly as a reflection of enhanced IPRs, in the United States, private-sector funding of agricultural research has been growing faster than public-sector funding and now exceeds it. The balance in agricultural R&D be tween the private and public sectors varies among types of research. For in stance, until recently the private sector emphasized agricultural R&D pertaining to mechanical and chemical technologies, especially pesticides, where IPRs are effective; and the government was more important in other areas such as improving crop varieties. Private involvement was dominant in crop variety research only in hybrid corn, where the returns were well protected by technical restrictions on copying or reusing saved seed, trade secrets and other legal rights. Changes in the institutional environment and the form of new IPRs, combined with new scientific possibilities associated with modern biotechnology, resulted in a shift in the private public balance in research to improve crop varieties.
As the balance shifts toward private re search, new attention must be paid to old questions about whether the private investment in crop research will be sufficient, whether the allocation of those resources will be optimal, whether the results will be adopted rap idly and widely, and what role the government should play.The development of new technologies through R&D is only one element of the picture. The technologies must also be approved for commercial application and economically attractive enough to be adopted by farmers. Biotech crops have been a commercial reality only for a few years but they have made very rapid inroads in some parts of the market. In particular, pest resistant and herbicide-tolerant corn, soybeans, canola and cotton were rap idly developed and adopted in the United States and to a lesser extent in other countries . To date, the successful GM crop varieties have emphasized “input traits,” related to reducing the use of chemical pesticides or making them more effective, rather than “output traits,” related to product quality. Why has there been rapid development and adoption of GM crop ping technologies for these crops and not other important crops, such as wheat and rice? The likely reasons re late to the nature of supply and demand for new technology, and the economics of adoption.The total benefits from farmers adopting any new cropping technology are approximately equal to the benefits per acre times the number of acres affected. With pest-resistant crop varieties, these benefits come primarily from reduced costs for applying chemical pesticides and increased yields, after an allowance for regulatory requirements for refugia to manage resistance. The distribution of these total benefits between farmers on the one hand, and the technology suppliers on the other, is determined by the size of the premium charged for the use of the new technology, but this premium also affects the incentives for farmers to adopt the technology. Economic studies suggest that farm ers and biotech companies have shared in the benefits of biotech crops and that the net benefits have been large. Gianessi et al. conducted 40 detailed U.S. case studies of biotech cultivars. They estimated that in 2001, eight biotech cultivars adopted by U.S. growers provided a net value of $1.5 billion to growers, reflecting increased crop values and cost savings. They further estimated that the 32 other case-study cultivars would have generated an additional $1 billion in benefits to growers if they had been adopted, bringing the total potential benefit in 2001 to $2.5 billion. Of this annual total, the lion’s share was for herbicide-tolerant crops , followed by insect-resistant crops . These estimates do not represent the total economic impact because the geographic analysis was limited in scope, and they do not include any benefits to the seed companies and biotech firms that produced the technology. Environmental concerns. Private benefits and costs from biotech crops accrue to growers and consumers of the products, along with seed companies and biotech firms. If the new technology involves environmental risks or replaces technology that involves environmental risks, there will be additional environmental costs and benefits to take into account as an element of national costs and benefits. For instance, pest-resistant crops can reduce the application of broad-spectrum chemical pesticides, which are hazardous to farm workers, compromise food safety and impose a burden on the environment. The economic studies to date have not assessed these environmental costs and benefits. However, Gianessi et al. estimated that adoption of the eight current cultivars allowed a redution in pesticide use of 46 million pounds in 2001, and the 32 potential cultivars could have allowed a further reduction of 117 million pounds. The relevant comparison then is between the environmental risks associated with these biotech crops and those associated with the annual burden on the environment of 163 million pounds of chemical pesticides that could be avoided by growing biotech crops instead – 66 million pounds in California alone, where 185.5 million pounds of pesticides were used in 1999 Market acceptance. On the demand side, farmers will adopt biotech varieties if the perceived net benefits to them are large enough, and this depends on the perceived market acceptance of GM crops. Concerns have been raised about the possibility that GM crops may be unsafe for consumers because of allergens or other, as yet unidentified risk factors, about risks to the environment and to the economy from uncontrolled genetic drift, and about the moral ethics of tampering with nature.