Herbage Yield, Morphological Development and Nutritive Value of Lucerne During Growth Season in Central Slovenia: Analysis of Time Patterns

Abstract

IZVLEČEKČas košnje je zelo pomemben dejavnik količine in kakovosti pridelka krme enovrstnih koševin. Zato smo želeli analizirati časovne poteke pridelka zelinja, morfološkega razvoja in parametrov kakovosti lucerne med rastno sezono ter jih povezati s časom košnje. Poljski poskus v split-plot zasnovi z dvema blokoma smo izvedli v Ljubljani leta 2016. Glavne parcele so predstavljale 4 rastne cikluse (C1-C4), podparcele pa 9 tedenskih terminov za merjenje pridelka in vzorčenje zelinja. Rast lucerne je bila v prvi polovici rastne sezone boljša kot v drugi. Pridelek zelinja je v zadnjih dveh ciklusih hitro dosegel maksimum in se nato zmanjševal. Statistična analiza je pokazala, da so linearni regresijski modeli primerni za opisovanje časovnih potekov naslednjih spremenljivk: morfološkega razvoja (PRF), surovih beljakovin (SB), vlaken, netopnih v nevtralnem detergentu (NDV) in neto energije za laktacijo (NEL). Morfološki razvoj lucerne je bil hitrejši poleti kot pomladi ali jeseni, vendar je po tej lastnosti med ciklusi izrazito odstopal samo prvi. Kakovost lucerne je bila predvsem zaradi počasnejšega razvoja v celoti najboljša v C1, kar se je bolj odrazilo pri NDV in NEL kot pri SB. C1 je bil po kakovosti lucerne enakovreden samo C4 na začetku rasti. Upoštevajoč pridelek in vsebnost NEL je bila optimalna starost lucerne ob košnji od 28 do 35 dni spomladi in poleti ter od 35 do 42 dni jeseni.Ključne besede: lucerna; pridelek; morfološki razvoj; hranilna vrednost; časovni potek ABSTRACT HERBAGE YIELD, MORPHOLOGICAL DEVELOPMENT AND NUTRITIVE VALUE OF LUCERNE DURING GROWTH SEASON IN CENTRAL SLOVENIA: ANALYSIS OF TIME PATTERNSCutting time is a pivotal factor affecting herbage yield and nutritive value of forage crop monocultures. Therefore, our objectives in this lucerne study were to analyse temporal patterns of herbage yield, morphological development and quality parameters over growth season, and to relate these patterns to the time of cutting. A field experiment in split-plot design with two block replications was conducted in Ljubljana in 2016. Four growth cycles (C1-C4) were assigned to the main plots, and nine weekly intervals at which herbage yield was measured and herbage samples taken were assigned to the sub-plots. Dry-matter herbage yield accumulated faster during the first half of the season than during the second one. It peaked early in each of the last two growth cycles and after that started to decrease. Statistical analysis showed that linear regression models are acceptable to describe time patterns of morphological development stages (MSW) and contents of crude protein (CP), neutral detergent fibre (NDF) and net energy for lactation (NEL). MSW increased faster during the summer than during the spring or autumn, but only C1 was distinct in this pattern. Lucerne forage quality was generally the highest in C1 mainly due to slower morphological development. This high quality reflected more in NDF and NEL than in CP. In respect of the quality, only C4 at the beginning of the growth was equivalent to C1. Cons...