K:Mg combination in Rubisco's activity, photosynthetic metabolism, antioxidant and relationships with coffee productivity

Abstract

Brazil is the world's largest producer and exporter of coffee and is also the second-largest consumer. Coffee is the second most consumed beverage worldwide after water, and its demand is on the rise in the market. However, to make it up, cultivation techniques are needed to overcome the adversities that affect the development of the plant, once coffee (Coffea arabica) has been affected by magnesium (Mg) deficiency. Mg is part of the chlorophyll molecule and has an important physiological role as an enzyme activator of rubisco. It is known as a forgotten element due to the scarcity of research concerning the nutritional and physiological part of Mg in plants. Besides, there are low amounts in the soil. Mg deficiency in coffee is possibly due to anthropogenic activities, such as the inadequate supply of potassium fertilizers, causing an antagonism of Mg absorption and resulting in lower productivity. Therefore, it is necessary to study K: Mg combinations as an alternative to promote better photosynthetic performance, the rubisco activity for better productivity, and beyond that, increase the nutritional value of the grain. The objective of this study is to evaluate the combination of Mg and K doses in a 6-year-old crop of Coffea arabica L. cv. Catuai Vermelho IAC 144, to study its photosynthetic and antioxidant metabolism, rubisco's activity, and the results in its productivity. In the end, propose recommendations on ways to apply Mg to avoid chlorosis and increase photosynthetic efficiency for greater productivity.