Plant Nutrient Dynamics in Stressful Environments

The papers included in this special issue cover a broad range of aspects ranging from genetics and breeding to crop production in the field. Climate change, intensified agriculture, modifications of land use, or pollution are often accompanied by larger fluctuations including extreme events. The growing world’s population and nutrient deficiencies in agricultural products for human or animal nutrition, or pollutants in harvested products in some regions (quality of yield), are important points to be integrated in a comprehensive analysis aimed at supporting agriculture on the way into a challenging future. It is therefore necessary to develop suitable models to identify potentials and risks. Instabilities (e.g., caused by climatic factors or pests) should be detected as early as possible to initiate corrections in the nutrient supply or in other growth conditions. Sensitive detection systems for nutrient disorders in the field can facilitate this task, and are therefore, highly desirabl

More shade, better coffee

Research suggests that growing coffee in tandem with trees improves the quality of coffee. Worldwide, coffee producers are suffering from low prices, with overproduction partly to blame. Countries such as Kenya and Brazil produce coffee in the full sun, a practice which produces higher yields, but poorer quality beans. One answer, according to researcher Ciro Righi, of the University of Sao Paulo in Brazil, is to use agroforestry systems to grow coffee. Trees create a favourable climate for coffee growth and production. Shade coffee, grown under trees, results in better quality coffee that can be sold at a higher price, he says. Righi made the claim at a recent seminar on coffee and rubber agroforestry systems, held at the Nairobi headquarters of the World Agroforestry Centre (ICRAF). He cited research in his native Brazil which shows that shade reduces temperature variations and keeps coffee plants and upper soil layers from overheating, making them less vulnerable during the dry season. The cover provided by plant canopy reduces water loss through evapotranspiration. Fodder legume trees trimmed several times a year can improve coffee plant nutrition by fixing nitrogen and recycling nutrients. The Brazilian studies show that rubber production in agroforestry systems is 50% higher than in single crop farms. The shade provided by trees also increases the formation of fruit buds on the coffee plants. Farmers benefit twice over they get better quality coffee and can sell products from the trees to earn extra income. In Brazil, rubber and coffee have proved to be a winning combination. But experts caution that care should be taken to avoid trees which do not lose leaves, as coffee still needs some sunlight. ICRAF s Dr Chin Ong says that in East Africa, Melia volkensi is the best tree species to use with coffee, since it has the same qualities as rubber.Research suggests that growing coffee in tandem with trees improves the quality of coffee. Worldwide, coffee producers are suffering from low prices, with overproduction partly to blame. Countries such as Kenya and Brazil produce coffee in the full sun,