Abiotic and Biotic Stress Limitations to Crop Productivity

Environmental factors including water stress, nutrient deficiency, high or low temperatures, chemical (Al-toxicity, salinity) and physical soil constraints (e.g., compaction), and biotic factors reduce crop yield. Deficit of water and nitrogen, and soil constraints have a larger impact on canopy size and duration, hence growth reductions are closely linked with reduced intercepted radiation; radiation use efficiency is generally less responsive to stress. Extreme temperatures at critical stages usually reduce harvest index and yield. Other stresses can be neutral, positive, or negative for the harvest index; this depends on the nature, timing, intensity, and duration of stress and its relative impact on total and harvestable biomass. Biotic agents such as pests, diseases, and weeds can reduce crop yield substantially, hence the importance of appropriate crop protection practices.