Effect of environmental conditions and cultural practices on yields and quality of onion

Abstract

Cultural practices need to be adapted for the biological characteristics of onion and environmental conditions of a region by creating optimum conditions for growth and development throughout the entire biological cycle and not just during a particular cultural practice cycle. This is all the more important because environmental conditions in field production cannot be changed and the yield and quality of onion bulbs depend on total production during a period of two or three years (from seed to seed). All favorable and unfavorable conditions throughout the biological cycle impact on the yields and quality of commercial onion bulb. Onion is a vegetable with a root that does not go deep into the soil, so ideally the nutrients should be in a readily available form in the root zone (0-25 cm depth). Regardless of the cultivar, it is very important to provide enough nutrients, most importantly nitrogen, in the first half of the growing season so as to enable the development of a larger leaf mass. A study of ours with over 30 different cultivars carried out in 1975-1983 has shown that the losses are much smaller when commercial bulbs are stored at 2°C than 18°C and that the differences are smaller in cultivars that do not store well. It has also been determined (Lazić, B. et al., 1983) that the coefficient of correlation between dry matter, sugar, and sucrose contents and losses during storage is very-low (0.39, 0.18, and 0.39), which shows that these are not the most important factors in the storage process. It needs to be noted that cultivars with good storage ability did not differ in their storage quality and duration (IX-III) when produced under different environmental conditions (although the sites Novi Sad and Sremska Mitrovica are relatively close) (Lazić, B. et al., 1981). All the results presented (from the effects of sowing date, cultivar, and place and time of production to bulb maturity) indicate the importance of not only the correct choice of cultivar but also of high-quality production throughout the entire two- or three-year biological cycle of onion growing.

Biološke specifičnosti pre svega dužina dana, uslovljavaju izbor sorte, vremena i načina proizvodnje. Sorta samo pri odgovarajućoj dužini dana, temperaturi i optimalnom odnosu crvenih i infracrvenih zraka obrazuje lukovicu. Masa lukovice i vreme zrenja uslovljeni su vremenom setve, kvalitetom sadnog materijala, đubrenjem i momentom ubiranja. Od dužine perioda mirovanja, što je sortna specifičnost zavisi mogućnost čuvanja. Rane i slatke sorte (sadržaj suve materije manji od 12%) imaju kratak period mirovanja za razliku od ljutih sorti (sadržaj suve materije veći od 12%), ali to zavisi od zrelosti i zdravstvenog stanja lukovice, načina manipulacije, u vreme i posle berbe i od uslova čuvanja. Za prinos i kvalitet konzumne lukovice neophodna je kvalitetna proizvodnja u čitavom (dvo ili trogodišnjem) biološkom ciklusu proizvodnje crnog luka.