Response on yield and nutritive value of two commercial maize hybrids as a consequence of a water irrigation reduction

The present study investigated in a practical farm condition the response of two commercial maize hybrids (maturity class FAO rating 700) grown for silage production on chemical composition and digestibility of whole maize plant as consequence of a severe water irrigation reduction. Based on different irrigation applications, water restricted (WR) and fully irrigated (FI) plots received 50 and 200 mm of irrigation water, respectively. A split-plot factorial arrangement in a randomised complete block design with two main plots (WR and FI) and two sub-plots (hybrid A and B) with 12 replications/ treatment was performed. Studied parameters were dry matter (DM) yield, harvest index (HI), chemical composition, rumen in situ DM and neutral detergent fibre disappearance (DMD and NDFD, respectively), indigestible NDF (iNDF), 7h in vitro starch degradability (7hIVSD) and net energy (NE) for lactation content. Total DM and grain yields, HI and chemical composition differed (P<0.05) between FI and WR crops and only slight differences were recorded between hybrids. When compared to FI plants, WR had lower starch and higher fibre contents (P<0.05). Higher DMD (59.2 vs 56.4% DM) and NDFD (61.0 vs 58.4% NDFOM) were measured for FI with respect to WR crops, whereas iNDF was about 36% higher (P<0.05) in WR than FI. Lastly, WR plants had a lower NE content than FI plants (P<0.05). Our research showed that a drastic reduction in water irrigation negatively affected whole plant yield, chemical composition and nutrient availability of forage maize.