P.S. Bindraban

Physiology and modelling of traits in crop plants: implications for genetic improvement

Abstract Crop growth models have excellent potential for evaluating genetic improvement, for analyzing past genetic improvement from experimental data, and for proposing plant ideotypes for target environments. Crop models used for these plant breeding applications should be sufficiently mechanistic that processes can be investigated in a manner familiar to crop physiologists and plant breeders. In addition, the crop models must consider a sufficient number of cultivar-specific traits descriptive of life cycle phases, vegetative traits, and reproductive growth attributes. In this paper, we discuss how crop models consider genetic variability within a species (cultivar variation), how varietal characteristics can be determined from variety trial or other data, how crop models can be used to evaluate past genetic improvement, and how crop models can be used to hypothesize ideotypes for specific environments. We conclude that crop growth models can partially reproduce genotype by environment interactions when considered across broad ranges of weather and sites, and that crop models can be used to help plant breeders target cultivar improvement for specific environments. However, more physiological insight into primary processes such as source–sink relationships and morphological development will be needed for enhanced application of the models in breeding programmes.

A review of the use of engineered nanomaterials to suppress plant disease and enhance crop yield

Nanotechnology has the potential to play a critical role in global food production, food security, and food safety. The applications of nanotechnology in agriculture include fertilizers to increase plant growth and yield, pesticides for pest and disease management, and sensors for monitoring soil quality and plant health. Over the past decade, a number of patents and products incorporating nanomaterials into agricultural practices (e.g., nanopesticides, nanofertilizers, and nanosensors) have been developed. The collective goal of all of these approaches is to enhance the efficiency and sustainability of agricultural practices by requiring less input and generating less waste than conventional products and approaches. This review evaluates the current literature on the use of nanoscale nutrients (metals, metal oxides, carbon) to suppress crop disease and subsequently enhance growth and yield. Notably, this enhanced yield may not only be directly linked to the reduced presence of pathogenic organisms, but also to the potential nutritional value of the nanoparticles themselves, especially for the essential micronutrients necessary for host defense. We also posit that these positive effects are likely a result of the greater availability of the nutrients in the “nano” form. Last, we offer comments on the current regulatory perspective for such applications.

Revisiting fertilisers and fertilisation strategies for improved nutrient uptake by plants

Meeting human needs within the ecological limits of our planet calls for continuous reflection on, and redesigning of, agricultural technologies and practices. Such technologies include fertilisers, the discovery and use of which have been one of the key factors for increasing crop yield, agricultural productivity and food security. Fertiliser use comes, however, at an environmental cost, and fertilisers have also not been a very economically effective production factor to lift many poor farmers out of poverty, especially in African countries where application on poor soils of unbalanced compositions of nutrients in fertilisers has shown limited impact on yield increase. Agronomic practices to apply existing mineral fertilisers, primarily containing N, P and K, at the right time, the right place, in the right amount, and of the right composition can improve the use efficiency of fertilisers. However, the overall progress to reduce the negative side effects is inadequate for the desired transformation toward sustainable agriculture in poor countries. Globally, there have been no fundamental reflections about the role and functioning of mineral fertilisers over the past 5 decades or more, and compared to other sectors, dismal investments have been made in mineral fertiliser research and development (R&D). In this paper, we reflect on current fertilisers and propose a more deliberate adoption of knowledge of plant physiological processes—including the diversity of mineral nutrient uptake mechanisms, their translocation and metabolism—as an entry point in identifying the physicochemical “packaging” of nutrients, their composition, amount and timing of application to meet plant physiological needs for improved instantaneous uptake. In addition to delivery through the root, we suggest that efforts be redoubled with several other uptake avenues, which as of now are at best haphazard, for the delivery of nutrients to the plant, including above ground parts and seed coating. Furthermore, ecological processes, including nutrient-specific interactions in plant and soil, plant-microorganism symbiosis, and nanotechnology, have to be exploited to enhance nutrient uptake. It is hoped that concerted R&D efforts will be pursued to achieve these strategies.

Fortification of micronutrients for efficient agronomic production: a review

Micronutrients are essential mineral elements required for both plant and human development. However, micronutrients are often lacking in soils, crop, and food. Micronutrients are therefore used as fertilizer to increase crop productivity, especially when the application of conventional NPK fertilizers is not efficient. Here, we review the application of micronutrients in crop production. Reports show that micronutrients enhance crop nutritional quality, crop yield, biomass production, and resiliency to drought, pest, and diseases. These positive effects range from 10 to 70xa0%, dependent on the micronutrient, and occur with or without NPK fertilization. We discuss the uptake by plants of micronutrients as nanosize particulate materials, relative to conventional uptake of ionic nutrients. We also show that packaging of micronutrients as nanoparticles could have more profound effects on crop responses and fertilizer use efficiency, compared to conventional salts or bulk oxides.

Quantifying N response and N use efficiency in Rice-Wheat (RW) cropping systems under different water management

About 0·10 of the food supply in China is produced in rice-wheat (RW) cropping systems. In recent decades, nitrogen (N) input associated with intensification has increased much more rapidly than N use in these systems. The resulting nitrogen surplus increases the risk of environmental pollution as well as production costs. Limited information on N dynamics in RW systems in relation to water management hampers development of management practices leading to more efficient use of nitrogen and water. The present work studied the effects of N and water management on yields of rice and wheat, and nitrogen use efficiencies (NUEs) in RW systems. A RW field experiment with nitrogen rates from 0 to 300 kg N/ha with continuously flooded and intermittently irrigated rice crops was carried out at the Jiangpu experimental station of Nanjing Agricultural University of China from 2002 to 2004 to identify improved nitrogen management practices in terms of land productivity and NUE. Nitrogen uptake by rice and wheat increased with increasing N rates, while agronomic NUE (kg grain/kg N applied) declined at rates exceeding 150 kg N/ha. The highest combined grain yields of rice and wheat were obtained at 150 and 300 kg N/ha per season in rice and wheat, respectively. Carry-over of residual N from rice to the subsequent wheat crop was limited, consistent with low soil nitrate after rice harvest. Total soil N hardly changed during the experiment, while soil nitrate was much lower after wheat than after rice harvest. Water management did not affect yield and N uptake by rice, but apparent N recovery was higher under intermittent irrigation (II). In one season, II management in rice resulted in higher yield and N uptake in the subsequent wheat season. Uptake of indigenous soil N was much higher in rice than in wheat, while in rice it was much higher than values reported in the literature, which may have consequences for nitrogen fertilizer recommendations based on indigenous N supply.

Transforming Inundated Rice Cultivation

Almost 90% of global rice is produced under inundated conditions, i.e. in fields with a standing water layer of 5 to 15 cm during the major part of the growing season. Recently, inundated rice cultivation has come under pressure due to declining availability of water and labour, increasing demand for rice and other food items, increasing claims on limited land resources, and increasing concern for environmental pollution. These changes in ecological, social and economic conditions call for a transformation in rice cultivation to comply with current and future developments. This paper focuses on management practices at the field scale affecting water productivity and other system characteristics and illustrates the consequences of some of these practices at the farm level based on case studies, while the promise of reduced water input in rice cultivation for options of regional allocation of water is demonstrated for a basin that supplies the metropolitan region of Jakarta. The paper discusses future options and opportunities for transforming inundated rice cultivation to comply with changing conditions.

Nanofertilizers: New Products for the Industry?

Mineral fertilizers are key to food production, despite plant low nutrient uptake efficiencies and high losses. However, nanotechnology can both enhance crop productivity and reduce nutrient losses. This has raised interest in nanoscale and nanoenabled bulk fertilizers, hence the concept of nanofertilizers. Nevertheless, large-scale industrial production of nanofertilizers is yet to be realized. Here, we highlight the science-based evidence and outstanding concerns for motivating fertilizer industry production of nanofertilizers, including the notion of toxicity associated with nanoscale materials; scant nanofertilizer research with key crop nutrients; inadequacy of soil- or field-based studies with nanofertilizers; type of nanomaterials to produce as fertilizers; how to efficiently and effectively apply nanofertilizers at the field scale; and the economics of nanofertilizers. It is anticipated that the development and validation of nanofertilizers that are nondisruptive to existing bulk fertilizer production systems will motivate the industrys involvement in nanofertilizers.

Composite micronutrient nanoparticles and salts decrease drought stress in soybean

Drought decreases crop productivity, with economic consequences for farmers. For soybean, drought particularly affects the reproductive phase. There is therefore a need for strategies that minimize drought effects, such as agronomic fortification with micronutrients. Here, we evaluated the mitigation of drought stress in soybean using composite formulations of three micronutrient nanoparticles, ZnO, B2O3, and CuO, and their salts: ZnSO4·7H2O, H3BO3, and CuSO4·5H2O, in a greenhouse. The micronutrients were soil or foliar applied 3xa0weeks after seed germination. Drought was imposed at 50% field moisture capacity. We measured parameters related to growth, yield, and nutrient uptake dynamics during 19xa0weeks. Results show that drought decreased soybean shoot growth by 27% and grain yield by 54%. Application of salt formulations to soil was more effective than foliar application, in mitigating drought stress. For foliar application, the effects of nanoparticles and salts were similar. On average, the formulations reduced drought effects by increasing shoot growth by 33% and grain yield by 36%. On average, the formulations increased shoot N by 28%, K by 19%, Zn by 1080%, B by 74%, and Cu by 954%. Likewise, the formulations, on average, increased grain N by 35%, K by 32%, Zn by 68%, B by 56%, and Cu by 13%. In contrast, drought did not alter shoot P, but the formulations, on average, reduced shoot P by 33%. Whereas micronutrient salts are known to reduce drought effects in plants, our findings demonstrate for the first time a novel use of micronutrient nanoparticles to boost crop performance and N and P uptake under drought stress.

European food and agricultural strategy for 21st century

Production ecological analyses reveal great differences in food production potential and food requirement between global regions, which implies the need for redistribution of food between surplus and deficit regions. The surplus production potential, current production and trade volumes of Europe along with the desires of its society for non-food functions from its land, favours a dual agricultural path for Europe. It can continue to guarantee its own food provision through a food-oriented path of intensive agriculture, while cherishing a socially-oriented pathway to meet non-food desires. Europe can assume an active role in world food security by using its surplus potential to supplement the deficit region Asia and by using its agricultural insight to facilitate processes towards sustainable agriculture in Latin America and to support overall agricultural development in Africa. The prospects for the coming decades for European agriculture are so favourable that there is little need to introduce agro-energy or heavy subsidy measures to stimulate or revitalise agricultural development within its territory.

Introduction: Water for Food and Ecosystems: How to Cut which Pie?

Two decades of awareness-raising and dialogues have clearly spelled out the water-related challenges the world is facing. Still, not enough concrete improvements have been realized on key issues, such as the coverage of potable water and sanitation services, and an adequate balance between water for food and ecosystems. Addressing these problems remains a continuous challenge that can only be confronted with an integrated approach, comprising knowledge generation, permanent communication between very different stakeholders, adequate capacity-building and continuous learning, and innovative technology development. With a view to the Fourth World Water Forum in Mexico, this contribution reviews such issues, drawing lessons from experience in a program on Water for Food and Ecosystems (funded by Netherlands Partners for Water initiative) and related on-going work in this area carried out by Wageningen University and Research Centre working closely with partner institutions inside and outside the Netherlands. The debate is structured around three key dimensions (i) balancing human and natural values of water, (ii) multiple stakeholder involvement, (iii) technological innovation. Visualized in the Triangle of Sustainability, the study recognizes the advances made in integrating political processes such as multi-stakeholder negotiation in water resource management as a way of achieving a better balance between the values of water, but warn against neglecting the potential for technical advances that can help increasing the size of the ‘cake’ as a whole.