Crescimento e produção de milho associados com o intervalo hídrico ótimo

Abstract

The least limiting water range (LLWR) has been widely used as an agronomic indicator of soil physical quality, however only a few studies have linked the LLWR to the plants growth and yield. The scarce results are insufficient to confirm or rebut the efficiency of LLWR, but indicate a discrepancy between LLWR and crop yields. The purpose of this study was to analyze the correlation of LLWR with variables of growth and grain yield of corn (Zea mays L.) in eight crops (four each in the growing seasons of 2010/11 and 2011/12) on a Hapludox, under different compaction levels. Treatments consisted of no-tillage, with chiseling and additional compaction. The plant height (PH), leaf area index (LAI), effective root depth (Ze), grain yield, and 1000-grain weight of the eight corn cultivars were determined. The LLWR was determined for six combinations of penetration resistance and matric potential used at the lower limit: (2:-0.8), (3:-0.8), (4:-0.8), (2:-1.5), (3:-1.5), and (4:-1.5), expressed in MPa. The LLWR was weakly associated with PH, LAI and Ze. The correlation coefficients varied between -0.20 and 0.36, and most correlations were not significant. In addition, the best linear function explained only 17% of the PH variation due to the LLWR variation. There was no correlation between LLWR and corn yield. These results indicate that although LLWR is sensitive to soil compaction, it is not robust enough as agronomic indicator to orient the compaction management of crops destined mainly for grain production.