Small Fruit Crop Responses to Leaf Intercellular CO2, Primary Macronutrient Limitation and Crop Rotation

Many environmental abiotic stress factors and farming practices can contribute to influence plant physiological development and crop productivity. Environmental variations in CO₂, water, radiation, and nutrients are among the most significant abiotic stress factors to influence crop performance. Farming practices such as nutrient supply and crop rotation are especially important to ensure healthy crop production. This paper is focused on understanding small fruit crop physiological responses to primary macronutrient limitation under different crop rotation conditions through summarizing the results of two separate field studies conducted in Nova Scotia, Canada. The field studies have investigated the physiological development of strawberry (Fragaria × ananassa Duch.) crops under reduced primary macronutrient supplies in different types of crop rotation regimes. It is concluded that strawberry plants treated with 25%-reduced K–N inputs could promote strawberry K/N assimilation to render the plants healthier with significantly higher leaf intercellular CO₂ concentrations, plant photosynthesis, carboxylation, and water use efficiency. These physiological advantages could lead to advance berry formation and produce significantly higher marketable yields (P < 0.05). Higher leaf intercellular CO₂ concentrations inhibited leaf/ fruit NO₃ ⁻ ion retention, but this inhibition did not occur in retention of leaf/fruit K⁺ ions and total dissolved solids. Also, 50%-reduced macronutrient P inputs could result in a suitable nursery plant P/N retention ratio (0.14–0.17) for optimum nursery formation in wheat–ryegrass–ryegrass–strawberry (WRRS) and corn–ryegrass–ryegrass–strawberry (CRRS) rotation systems. High P inputs could hurt the strawberry nursery crops by prohibition of plant P/N uptake. Overall, maximum NPK deficiency (control plots) could cause plant stress, and unlimited macronutrient supplies could constrain more fruit formation and nutritional attributes than reduced NPK inputs. Limited primary macronutrient supplies would be a profitable strategy to enhance plant macronutrient assimilation and physiological development while reducing uses of nonrenewable fertilizers and environmental risk to promote sustainable, low-input small fruit crop production.