Relationships of Macronutrients and Non-Structural Carbohydrate Content in Clippings of Creeping Bentgrass Putting Greens in Japan

Creeping bentgrass (Agrostis stolonifera L.) is the predominant cool-season turfgrass of putting greens in Japan. Most areas of Japan are in the transition zone, and its hot and humid summer translates to many turf management challenges. Nonstructural carbohydrates are used by plants to sustain growth during periods of stress when photosynthesis is compromised and have been widely used as a physiological measure of stress tolerance. In our previous study, we demonstrated that the fructan concentration of leaf clippings can be used as an index for total nonstructural carbohydrates in creeping bentgrass. In this study, we examined the relationships between fructan concentration and macronutrient (N, P, or K) concentration in clippings from creeping bentgrass putting greens across >200 golf courses in Japan over an 8-yr period. The leaf fructan concentration tended to be high in December to February and low in August to September, before some increase in October. The leaf N concentration was less affected by season than fructan concentration, with a small increase seen from June to October and a small decrease in December. The leaf P concentration tended to be high in July and August and low in January and February. The leaf K concentration showed smaller seasonal change. The leaf N concentration was negatively correlated with fructan concentration in each month. The relationship between P and fructan concentration varied with season. The relationship between K and fructan was similar to that of P and fructan, but the correlation was much weaker.