Effect of sowing date on yield and quality of high moisture ear and grain production for maize

High moisture ear and grain production of maize (Zea mays L.) has advantages in comparison with dry grain production because longer maturity hybrids might be grown and there are no grain drying costs. A two year study was carried out at the Faculty of Agriculture experimental field Maksimir to evaluate the effect of delayed sowing dates on yield and quality of high moisture ear and grain production when compared to optimum sowing date. Maize hybrids belonging to the maturity groups FAO 200 (PR39K38) and 300 (PR38PO5) were sown at optimum (early May) and two delayed sowing dates (middle May and early June) and grown under intensive cropping system. When compared to optimum sowing date, grain and ear yield significantly decreased with delayed sowing dates despite the fact that grown hybrids reached physiological maturity before the first autumn frosts. These yield reductions at delayed sowing dates were mainly associated with fewer grains per ear, and partly due to lighter 1000-grain weights. Both hybrids resulted in similar ear yield; however, a longer maturity hybrid (PR38PO5) had larger grain yields than a shorter-maturity hybrid (PR39K38) because the latter had significantly smaller shelling index (82,1%) than the former one (87,0%). Sowing date and growing conditions showed no significant effect on grain protein and oil contents. Hybrids also had similar grain protein content, whereas PR38PO5 had absolutely small, but significantly higher grain oil content than PR39K38. Thus, delayed sowing of the maize hybrids of FAO 200 - 300 maturity groups might occur into early June with no effect on grain quality, but with significant yield losses when compared to optimum sowing date.