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

Abstract

Namjenska proizvodnja kukuruza (Zea mays L.) za vlažno zrno i klip ima prednosti u usporedbi s proizvodnjom suhog zrna, budući da se mogu uzgajati hibridi dulje vegetacije i zato što nema troškova sušenja. Dvogodišnji pokusi provedeni na pokušalištu Maksimir Agronomskog fakulteta u Zagrebu imali su za cilj istražiti utjecaj naknadnih rokova sjetve na prinos i kvalitetu vlažnog zrna i klipa kukuruza u usporedbi s onim iz optimalnog roka sjetve. Hibridi kukuruza vegetacijskih skupina FAO 200 (PR39K38) i 300 (PR38P05) sijani su unutar optimalnog i dva naknadna roka sjetve i uzgajani u uvjetima intenzivne agrotehnike. Prvi naknadni rok sjetve bio je sredinom svibnja, a drugi početkom lipnja. Prinos zrna i klipa značajno je opao u naknadnim rokovima u usporedbi s optimalnim rokom sjetve, unatoč činjenici da su istraživani hibridi dostigli stadij fiziološke zrelosti prije prvih jesenskih mrazeva. Pad prinosa u naknadnim rokovima sjetve prvenstveno je rezultat manjeg broja zrna na klipu, a dijelom i smanjene mase 1 000 zrna. Oba hibrida ostvarila su sličan prinos klipa, ali je hibrid dulje vegetacije (PR38P05) imao značajno veće prinose zrna od hibrida kraće vegetacije (PR39K38,) jer je potonji hibrid imao značajno manji indeks krunjenja (82,1 %) od prvoga (87,0 %). Rok sjetve i vegetacijska sezona nisu utjecali na sadržaj proteina i masti u zrnu. Hibridi se također nisu razlikovali po sadržaju proteina, dok je PR38P05 imao apsolutno mali, ali značajno veći sadržaj masti u zrnu od PR39K38. Za proizvodnju vlažnog zrna i klipa u naknadnimm rokovima sjetve do prve dekade lipnja mogu se uspješno uzgajati hibridi grupa FAO 200 i 300 uz zadržavanje kvalitete, ali niže prinose, u usporedbi s onim iz optimalnog roka sjetve.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 (PR38P05) 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 (PR38P05) 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 PR38P05 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