Effects of climate change on crops and weeds: scope for developing cultivars better adapted to both abiotic stress and an ability to suppress weeds

Authors: KORRES, NICHOLAS - University Of Arkansas; NORSWORTHY, JASON - University Of Arkansas; TEHRANCHIAN, PARSA - University Of Arkansas; GITSOPOULOS, THOMAS - Agricultural Research Institute Demeter; LOKA, DIMITRA - University Of Arkansas; OOSTERHUIS, DERRICK - University Of Arkansas; Gealy, David; MOSS, STEPHEN - Rothamsted Research; MILLER, RYAN - University Of Arkansas; PALHANO, MATHEUS - University Of Arkansas

Submitted to: Agronomy for Sustainable Development
Publication Type: Review Article
Publication Acceptance Date: 1/4/2016
Publication Date: 2/18/2016
Citation: Korres, N., Norsworthy, J.K., Tehranchian, P., Gitsopoulos, T.C., Loka, D.A., Oosterhuis, D.M., Gealy, D.R., Moss, S.R., Miller, R.M., Palhano, M. 2016. Effects of climate change on crops and weeds: scope for developing cultivars better adapted to both abiotic stress and an ability to suppress weeds . Agronomy for Sustainable Development. 2016. 36:12.

Interpretive Summary: The ongoing changes to our climate, which we anticipated may persist for decades or centuries, may lead to complex challenges for the broad range of agricultural production systems and practices used throughout the world to feed and clothe its inhabitants. This review provides insights into some of the likely new scenarios and challenges that such climate shifts may pose for crop productivity, new ways that weeds may interact with or stress these crops, and possible approaches to alieve or minimize such problems. Carbon dioxide (CO2) is a basic and essential compound required for photosynthesis, a process that is responsible for the growth and survival of all plants (crops and weeds) on earth. Thus, the changing climatic components that are most likely to affect the performance of crops and weeds, and their interactions, are increased CO2 levels and the accompanying increases in temperature and extended periods of drought. To better understand this reasoning, it is important to understand that all crop and weed plants have one of two basic, but distinctly different, photosynthetic systems used by all plants. The most prevalent one is called, the C-3 photosynthetic pathway, which is used by crop plants such as wheat, oats, soybean, and rice, and weed plants such as red rice, red stem, coffeebean, velvetleaf, foxtails, and wild oats. The second and less prevalent one is called the C-4 photosynthetic pathway, which is used by crop plants such as corn and grain sorghum, and weed plants such as barnyardgrass, nutsedge, and pigweed. Most C-4 plants can naturally tolerate high temperatures or desert-like environments, and can efficiently absorb CO2 from air even when temperatures are very high and CO2 concentrations are relatively low due to their specialized biochemical and cellular makeup. Most C-3 plants grow better under non-stressed and cooler conditions, but are limited in their ability to absorb CO2 and grow at “lower” concentrations of CO2 (such as those historically present in the environment during the last century), especially at high temperatures. Because C-3 plants have been biologically limited by the relatively “lower” levels of CO2 of the past, it is likely that increasing CO2 levels in the atmosphere will generally benefit this group of plants more than C-4 plants. In contrast, increased temperatures, particularly at night, are more likely to favor crops and weeds with the C-4 pathway because of their naturally greater tolerance to higher temperatures compared with C-3 plants. Increased droughts are likely to reduce the growth, photosynthetic efficiency, and yield of all crops. As with crops, we would expect that increased CO2 will particularly benefit C-3 weed plants, potentially improving their growth, vigor, and seed production, all of which are likely to make these weeds more difficult to manage. Weeds of the future may interact with crops in complex ways. In a scenario in which there are widespread water or plant nutrient shortages, weeds that best exhibit a combination of stress tolerance, competitive ability, and other specialized competitive and survival traits are most likely to gain an advantage. These plants may replace or displace the weed plants that were previously the most troublesome and costly in various crops and regions because the conditions most suitable to support aggressive populations of weed plants may shift into new and different geographic areas as worldwide temperatures increase over time. Thus, with the future uncertainties of a changing climate, growth of both crops and weeds are likely to be affected, sometimes benefiting the crop, and sometimes the weeds. Identifying or developing crop varieties with particular ‘anti-weed’ and ‘stress-tolerance’ traits may help farmers adapt their crop production approaches to better co-exist with climate changes and also to improve the tole

Technical Abstract: The challenges of climate change on agricultural production are multifaceted. The parameters most likely to affect the performance of crops and weeds are increased CO2 levels, increases in temperature, and extended periods of drought. It is likely that increased CO2 concentration will benefit crops with a C-3 photosynthetic pathway, whereas increased temperatures, particularly night temperatures, will favor crops with the C-4 pathway. Drought will negatively affect the dry weight accumulation, photosynthetic efficiency, and final yield of all crops. As with crops, increased CO2 will affect positively weeds with a C-3 photosynthetic pathway and potentially enhance dry weight and reproductive capacity. The habitable zone of many weed species will change with increases in temperature. Under water or nutrient shortage scenarios, an r-strategist weed that exhibits a combination of stress tolerance-competitive ability and ruderal characteristics will most probably prevail. Climate change is likely to affect growth of both crops and weeds, sometimes benefiting the crop, and sometimes the weeds. Choice of cultivar could be a dual purpose, easily manipulative adaptation method against both climate changes and weed suppression. An understanding of the changes in the complex interactions between crops and weeds, as a consequence of climate change, will be critical to making informed predictions of the likely impact on crop production.