Irrigation effects on asparagus yield and spear quality vary with cultivar and season in Michigan
Field experiments were conducted to evaluate the impacts of irrigation on yield and quality of green asparagus on sandy soils in Michigan, USA. Our primary objectives were to evaluate the effects of 1) irrigation during the fern growth period (June-August) on yield the following season (Experiment 1), and 2) overhead irrigation during the harvest period (May-June) on soil and air temperatures, spear quality and yield (Experiment 2). Experiment 1 was initiated from crowns in 2010 to evaluate the long-term impacts of irrigation system (none, overhead or subs-surface drip) on yields of two cultivars (Guelph Millennium [GM] and Jersey Supreme [JS]). Irrigation was applied during the fern growth period (July and August) in 2011-2016 whenever soil volumetric water content fell below 50% of available water. Experiment 2 was conducted during the 2014-2017 harvest seasons to evaluate the short-term impact of irrigation (overhead vs none) on air and soil temperatures, spear quality and yield. Irrigation during the fern growth period resulted in increases in 5-year cumulative yields of approximately 9% for GM, with the largest annual yield benefits (>20%) occurring following hot, dry conditions in 2011. In contrast, irrigation during fern growth provided no cumulative yield benefits for JS. Irrigation during the harvest provided few benefits during the 2014, 2015 or 2017 seasons, when conditions were relatively cool and wet. However, under hot-dry conditions in 2016, harvest-season irrigation reduced air and soil temperatures, increased the yield of JS, and improved tip quality of both varieties. In particular, the number of spears with open tips was reduced by approximately 50% following two out of four irrigation events in 2016. Our results suggest that overhead irrigation systems reduce the risks associated with drought and heat stress, and are a worthwhile investment for production of GM on sandy soils in Michigan.
Brainard, D.C., Byl, B., Hayden, Z., Noyes, D.C., Werling, B. and Bakker, J. (2018). Irrigation effects on asparagus yield and spear quality vary with cultivar and season in Michigan. Acta Hortic. 1223, 101-116
irrigation, cultivars, Michigan, spear quality, temperature response