There is a demand for higher productivity to sustain an ever-increasing global population. The current annual rate of increased production for major crops is insufficient to meet the future projected food demands. In addition, climate change followed by environmental uncertainty makes the attainable/achievable yield increasingly variable. Furthermore, due to inefficient use of resources, the harvested yield lags behind the attainable yield. Thus, the current hottest challenge is to bridge a considerable yield gap.
Among several factors contributing to the yield gap, the inability of individual plants to sufficiently capture inputs is a radical source. The weakness of low ‘plant yield efficiency’ is directly related to the optimal plant density; since water is the most crucial input, the phenomenon is more pronounced in rainfed crops. There is a general consensus that under stressful conditions (i.e. drought) optimal resource use is accomplished only at low plant densities. On the other hand, due to the inability of individual plants to respond to additional inputs, modern varieties may reach the attainable yield of favorable environments at high plant densities. As conditions of growing seasons are difficult to predict during the planting period, the established plant density may deviate from the one suitable for the season, and farmers may sustain a yield penalty. The maize collapse events of 2012 in Iowa and 2018 in Germany are a clear indication that crop adaptation to spacing is necessary, so as to avoid crop failure in dry seasons without compromising the attainable grain yield during favorable seasons. Consequent benefits of crop adaptation to spacing, via improved plant yield efficiency, would be the mitigation of the acquired plant-to-plant variability in order to optimize further the resource use, as well as better compensation in both the common situation of missing plants and when multigenotypic varieties are preferred as a means to counteract unpredictable acute stresses (in both cases individual plants would be able to utilize the input share of missing neighbors). Adaptation to crop spacing would also expand the optimal planting date; adoption of the low-input cropping where it is necessary would prevent soil degradation and protect natural resources and environment.
Looking forward, new complementary approaches are needed as a prerequisite to improve plant resource use efficiency as a means of crop adaptation to spacing, aiming at the same time to improve crop productivity in a more environmentally friendly way. For example, individual plants capable of utilizing inputs may take advantage of increased atmospheric carbon dioxide as a means to stimulate plant growth and seed yield contributing to advanced soil carbon sequestration. The above are some of the key topics that merit investigation to promote stability via plasticity and flexibility to the environmental diversity, enhancing food productivity.
Articles allowing to enhance mechanistic understanding of the following sub-themes are welcome to the collection (descriptive studies will not be taken under consideration):
• Major crop plants response to plant population across environment and justifications.
• Plant physiological response to plant population and/or planting density.
• Variation in genotypes within a crop in response to plant population and selection towards plants that adjust for environment (plasticity).
• How soil water and soil biological and physicochemical properties might relate to plant response to planting density.
• Planting population relation to other yield components.
• Environmental indicators for planting density/plant population by crop.
• Molecular and genomics that relate to plant response to plant population from fields like breeding, agronomy, physiology, soil science, molecular and genomic approaches.
There is a demand for higher productivity to sustain an ever-increasing global population. The current annual rate of increased production for major crops is insufficient to meet the future projected food demands. In addition, climate change followed by environmental uncertainty makes the attainable/achievable yield increasingly variable. Furthermore, due to inefficient use of resources, the harvested yield lags behind the attainable yield. Thus, the current hottest challenge is to bridge a considerable yield gap.
Among several factors contributing to the yield gap, the inability of individual plants to sufficiently capture inputs is a radical source. The weakness of low ‘plant yield efficiency’ is directly related to the optimal plant density; since water is the most crucial input, the phenomenon is more pronounced in rainfed crops. There is a general consensus that under stressful conditions (i.e. drought) optimal resource use is accomplished only at low plant densities. On the other hand, due to the inability of individual plants to respond to additional inputs, modern varieties may reach the attainable yield of favorable environments at high plant densities. As conditions of growing seasons are difficult to predict during the planting period, the established plant density may deviate from the one suitable for the season, and farmers may sustain a yield penalty. The maize collapse events of 2012 in Iowa and 2018 in Germany are a clear indication that crop adaptation to spacing is necessary, so as to avoid crop failure in dry seasons without compromising the attainable grain yield during favorable seasons. Consequent benefits of crop adaptation to spacing, via improved plant yield efficiency, would be the mitigation of the acquired plant-to-plant variability in order to optimize further the resource use, as well as better compensation in both the common situation of missing plants and when multigenotypic varieties are preferred as a means to counteract unpredictable acute stresses (in both cases individual plants would be able to utilize the input share of missing neighbors). Adaptation to crop spacing would also expand the optimal planting date; adoption of the low-input cropping where it is necessary would prevent soil degradation and protect natural resources and environment.
Looking forward, new complementary approaches are needed as a prerequisite to improve plant resource use efficiency as a means of crop adaptation to spacing, aiming at the same time to improve crop productivity in a more environmentally friendly way. For example, individual plants capable of utilizing inputs may take advantage of increased atmospheric carbon dioxide as a means to stimulate plant growth and seed yield contributing to advanced soil carbon sequestration. The above are some of the key topics that merit investigation to promote stability via plasticity and flexibility to the environmental diversity, enhancing food productivity.
Articles allowing to enhance mechanistic understanding of the following sub-themes are welcome to the collection (descriptive studies will not be taken under consideration):
• Major crop plants response to plant population across environment and justifications.
• Plant physiological response to plant population and/or planting density.
• Variation in genotypes within a crop in response to plant population and selection towards plants that adjust for environment (plasticity).
• How soil water and soil biological and physicochemical properties might relate to plant response to planting density.
• Planting population relation to other yield components.
• Environmental indicators for planting density/plant population by crop.
• Molecular and genomics that relate to plant response to plant population from fields like breeding, agronomy, physiology, soil science, molecular and genomic approaches.