Potencial e lacunas de produtividade de milho em Santa Catarina

Abstract

Carrying out studies of yield potential (Yp), water-limited yield potential (Yw) and yield gaps (Yg) on a local scale allows us to understand the peculiarities and limitations of the interaction between genetics, management, and the environment. Likewise, it is possible to efficiently identify factors that are limiting yield and seek strategies to reduce yield gaps. The objectives of this study were: (i) to validate the Hybrid Maize model for Santa Catarina, Brazil; (ii) to estimate Yp, Yw, and Yg of corn for Santa Catarina; and (iii) to identify the biophysical and management factors that explain the Ygs in maize in Santa Catarina. To estimate Yp, Yw, and Yg, we used the method developed by the Global Yield Gap Atlas, in which there is a balance between the amount of data to be used and the representativeness of the study area. For the two potential estimates, we validated the Hybrid Maize model with data from experiments carried out under potential conditions, with the most used hybrids in each development cycle of maize producers in Santa Catarina. The model was efficient in simulating the growth (accumulation of dry matter), development (date of occurrence of the phenological stages), and yield of maize. The Yp and Yw determination rounds were carried out with the identified management representative of each region (seeding data, development cycle, seeding density). Management factors that are limiting farm productivity were identified through surveys conducted directly with maize producers (n=157). A comparison between high and low-yield farms (HP and LP) allowed identifying management practices that should receive investment to increase current yield and reach values close to 70% of Yw. The main results of the study for the determination of maize Yp in Santa Catarina (17.4 Mg ha-¹), Yw (14.9 Mg ha-¹), and attainable Yg (3.6 Mg ha-¹). In addition, it was identified that the main management practices that differ between AP and BP are: sowing date, plant population, the time between lime applications, phytosanitary management, and crop rotation. Likewise, if all crops reach 70% of Yw through improvements in management practices (10.4 Mg ha-¹), or an increase in maize production in Santa Catarina, in the current cultivation area, it would be 1. 2 million Mg year-¹. Reaching 75% of Yp (13 Mg ha-¹), Santa Catarina would increase its production by 2.1 million Mg year-¹. These yield increases would avoid the need to open new areas by 182 and 314 thousand ha, respectively.