Anotace:
The aim of this work was to identify and quantify the relationships between dry matter content and key energy nutrients (water-soluble carbohydrates and starch) in silage maize hybrids (Zea mays L.) during vegetation development in the foothills of Slovakia. This work summarises the results of 9 experiments carried out at three locations (2016 to 2021: 140 different hybrids; 1,320 measured samples). Dry matter content was determined by a combination of gravimetric determination and measurement of water content in dried samples using the NIRS method (prediction model R2 0.987). We also determined the content of water soluble carbohydrates (prediction model R2 0.994) and starch (prediction model R2 0.978) in dry matter using the NIRS method. Using 3rd and 4th degree polynomial models, we evaluated the contents of these nutrients at a dry matter content level of 300 g.kg-1, which we can consider as a basic starting point for reaching maize silage maturity. Across individual years, and across groups of hybrids grouped according to silage maturity determined by dry matter content, water soluble sugar content reached 140 g.kg-1 of dry matter and starch content reached 280 g.kg-1 of dry matter at a dry matter content of 300 g.kg-1. We found the lowest variation coefficient (7.53%) when evaluating the relationship between dry matter and the sum of water-soluble carbohydrates together with starch. We suggest using this parameter as a second criterion for determining silage maturity, and also for classifying hybrids in silage maturity groups with rounding to a ten-day period.