WHITE ASPARAGUS PRODUCTION WITH OPAQUE PLASTIC ROW COVERS

Abstract

Black and white plastic row covers were established over field-grown `Jersey Giant' asparagus on 10 Mar 89. Season soil temps in uncovered, white, and black plastic treatments were 17.4, 15.9, and 16.8°C, respectively. Night air temp under plastics was about 1.4°C higher than no plastic. Day temps under black plastic were typically >10° higher than no cover. Temps under white plastic were intermediate. Spears were cut for 7 weeks beginning on 27 March. Black plastic improved early yield only at the third cutting week. There was no consistent plastic cover effect on spear diameter. Marketable and total yield were improved with the use of plastics. Spear number/ha was not affected. Spear weight (after trimming to 15 cm length) was greater when grown under plastic, whereas spear length was reduced. There were no differences between treatments in spear fiber, but spears grown under plastic covers had higher soluble solids and nitrates, and lower ascorbate, protein and phenolic levels than did uncovered spears. Very little chlorophyll and carotenoids were produced in the absence of light, but there was a color intensity difference between spears grown under the two different plastics.