Mother stalk culture does not improve plant survival or yield of spring and summer-forced asparagus in South Carolina

Short productive lifespan is a major problem with asparagus (Asparagus offi cinalis L.), whether harvested in the spring or forced in late summer in co astal South Carolina. A modification of the Taiwanese system of mother stal k (MS) culture might enhance asparagus longevity and yield, The objective o f this research was to determine if modified MS culture improved plant surv ival and yields in spring or summer-forced harvests compared with conventio nal spring clear-cut (CC) harvesting or with nonconventional summer-forced CC harvesting,'Jersey Giant' asparagus was harvested for 3 years (1994-96) using the following harvest systems: 1)spring CC (normal emergence in Febru ary in this location); 2) spring MS followed by summer MS (mow fern down on 1 Aug. and establish new mothers); 3) spring MS only; 4) summer CC only (m ow fern on 1 Aug. and harvest); and 5) summer MS only. All systems were har vested for approximate to 7 weeks. All MS plots produced 40 mother stalks p er 12-m row length each year before harvesting began. All mother stalks wer e trellised and tied to prevent lodging. Three-year total yields (kg . ha(- 1)) and stand reduction(%) for nonharvested controls, spring CC harvesting, spring MS culture, spring MS combined with summer MS, summer CC, and summe r MS were: 0 and 54%, 1621 and 96%, 779 and 99%, 1949 and 86%, 4001 and 58% , 3945 and 58%, respectively. All spring harvesting systems failed because by midsummer, aged fern, harvest pressures, and, apparently, higher rates o f crown respiration reduced crown carbohydrate reserves. Yearly repetition of these stresses ultimately killed the spring-harvested plants. The MS cul ture did not ameliorate stand loss by significantly increasing carbohydrate reserves. Yields of summer-forced asparagus were consistently acceptable b ecause aged ferns were removed at about the time they apparently became ine fficient photosynthetically. After termination of the summer harvest season and with recovery in the following spring, ample carbohydrates were produc ed well before summer forcing began again in August the following year. The refore, plant longevity was better sustained by summer forcing than by trad itional spring harvesting.