Effects of on- farm storage cover types and method of topping on sugar losses in sugar beet

Cover type of on–farm storages has an important role in reducing the freezing damage and respiration of beet roots in the pile. This experiment was conducted in 2006 in Karaj region in order to evaluate the effects of cover types of storage on the mass and sugar losses of both topped and untopped beets. The experimental design was a split plot factorial in RCBD with three replications. The main plots consisted of: a1- a layer of wheat straw with 10-15 cm depth, a2- a layer of sugar beet top with 10-15 cm depth, a3 - propylene cover with 0.55 mm diameter and a4- without cover as a check. The sub plots consisted of a combination of two storage durations: b1- 30 days and b2- 60 days with two types of beet topping: c1- topped and c2- untopped. The size of pile was 2 meters width, 1.5 meters height and 3 meters length in the N-S direction. Air temperature inside and outside the pile was recorded daily using a max- min thermometer. Weight and technical quality of beet samples were determined before and after storage. The results showed that mean air temperature under all covers were greater than uncovered treatments. Mass losses of sugar beet under covers were significantly less than those of uncovered treatment. Molassed sugar of beet under both straw and propylene covers were significantly less than other cover treatments. Mean sugar loss in the first 30 and 60 days were 489 and 279 g/t/d that may be related to greater respiration rate of sugar beet in 30- day storage. Sugar loss of untopped beet was 88 g/t/d less than that of topped beet. In conclusion, under conditions of this experiment, covering sugar beet with both propylene and straw covers under on-form storage had less molassed sugar and maybe considered as suitable pile covers. Sugar losses of untopped beets lacking any petiole were less than that of topped beets. Thus, untopped beets maybe recommended, for storing sugar beet in on-farm storage.