Ispitivanje je izvršeno na Oglednom polju Instituta za kukuruz u Zemun Polju, na zemljištu tipa černozem. Naš doprinos ovoj problematici je pokušaj da se ustanovi kakav uticaj ispoljavaju gnojiva, gustina i meteorološki uvjeti godine na formiranje zaperaka. Istovremeno ustanovili smo i uticaj navedenih faktora kao i vremena zakidanja zaperaka na prinos kukuruza. Gnjojenje ogleda izvršeno je kompleksnim (4:11:9) i dušičnim (KAN) gnojivom (N-25%). Ispitivane su sljedeće varijante gnojiva: (G-1) kontrola negnojeno
(G-2) 240 kg/ha N - 90, P₂O₅ - 80, K₂O - 70 kg/ha
(G-3) 360 kg/ha N - 135, P₂O₅ - 120, K₂O - 105 ka/ha
(G-4) 240 kg/ha (isto kao G-2) + 20 t stajnjaka/ha
Ispitivane gustine sklopa bile su sljedeće:
(G-1) 30.486 biljaka/ha - 80x82+2 biljke/kućici
(G-2) 35.210 biljaka/ha - 80x71+2 biljke/kućici
(G-3) 40.322 biljaka/ha - 80x62+2 biljke/kućici
(G-4) 50.000 biljaka/ha - 80x50+2 biljke/kućici
Zakidanje zaperaka izvršeno je u sljedećim fazama rasta i razvića biljke kukuruza:
(V-1) u fazi 6 - 7 listova
(V-2) u fazi 9 - 11 listova
(V-3) u fazi metličenja
(V-4) kontrola (zaperci nisu zakinuti)
Na osnovu naših ispitivanja mogu se izvesti sljedeći zaključci: Na veći ili manji procenat pojavljivanja zaperaka utjecale su meteorološke prilike godine. U odnosu na negnojenu varijantu, mineralno a još više mineralno stajsko gnojivo utjecale su na pojavu većeg postotka zaperaka. Postotak zaperaka smanjivao se s povećanjem gustine sklopa. Vrijeme zakidanja zaperaka utjecalo je na prinos u signifikantno opravdani razlikama u godini koja je u drugoj polovini vegetacije kukuruza imala veliki nedostatak padalina (1967). U trogodišnjem prosjeku prinos je veći za 5,51% ako su zaperci uklonjeni u fazi biljaka 6-7 listova prema prinosu biljaka gdje zapetci nisu uklonjeni. I kod intenzivne pojave zapetaka uklanjanje istih u kasnijim fazama rasta i razvitka biljaka nema opravdanja pošto ne utječe na prinos. Na bogatom černozemu negnojene varijante, prinos je gotovo isti ako su zaperci-uklonjeni sa varijantom gnojenja neuklonjenih zaperaka. U većim gustinama sklopa gde je manji postotak zaperaka iste nije potrebno uklanjati pošto ne utječu na smanjenje prinosa.The investigations were conducted on the Experimental Field of the Maize Research Institute Zemun Polje on a chernozem type of soil. As a contribution to this problematics we made an attempt to establish the effect of fertilizers, plant population and current meteorological conditions on tillering. We have also investigated the effects of the quoted factors, as well as the time of removing tillers, on maize yield. In these trials complex (4:11:9) and nitrogen (KAN) fertilizers (N-25%) were applied. The following fertilizer variants were investigated:
(DJ-1) control nonfertilized
(DJ-2) 240 kg/ha N - 90, P₂O₅ - 80, K₂O - 70 kg/ha
(DJ-3) 360 kg/ha N - 135, P₂O₅ - 120, K₂O - 105 kg/ha
(DJ-4) 240 kg/ha (the same as DJ-2) + 20t manure/ha
The investigated plant populations were the following:
(G-1) 30,486 plants/ha - 80x82+2 plants/hill
(G-2) 35,210 plants/ha - 80x71+2 plants/hill
(G-3) 40,322 plants/ha - 80x62+2 plants/hill
(G-4) 50,000 plants/ha - 80x50+2 plants/hill
The removing of tillers was carried out during the following stages of development of the maize plant:
(V-1) during the 6-7 leaf stage
(V-2) during the 9-11 leaf stage
(V-3) during taseling
(V-4) control (tillers were not removed)
Based on our investigations, the following conclusions can be drawn: 1. A higher or lower percentage of tillering was affected by current meteoroogical conditions. 2. In comparison to the nonfertilized variant, mineral fertilizers, but even more so mineral fertilizers + stable manure caused a higher parcentage of tillering. 3. The percentage of tillering incressed with increased with increasing plant population. 4. The time of removing tillers affected yields significantly in the year (1967) in which there had a shortage in rainfall during the second half of the maize vegetation period. 5. A three-year average showed that yields were higher by 5,56% provided the tillers were removed during the 6-7 leaf stage, as compared to yields of plants in which tillers were not removed. 6. The removing of tillers in the later stages of development to the plants, was found not to be justified as it had no effect on yields. 7. As for the monfertilized variant on the rich chernozem type of soil, the zield was almost the same as when the tillers were removed in the variant of fertilizing unremoved tillers. 8. At higher plant populations where the percentage of tillens is low, it is not necessary to remove tillers as these do not cause a decrease in yield
