Growth Analysis of Spring Spinach under the Rowcover.

Abstract

Growth parameters of spinaches (Spinacia oleracea L.) grown inside and outside of spunbonded polypropylene rowcovers were calculated and compared each other to understand characteristics of plant growth under rowcovers made of poromeric materials. Plants were covered when two leaves unfolded in March. Solar radiation under the rowcover was about 85% of that outside the cover. The rowcover increased mean daily maximum air temperature and mean daily minimum soil temperature by 1.7°C and 0.6°C, respectively.The rowcover enhanced plant growth. Increase in dry matter production rate per unit of dry matter (RGR) under the rowcover brought the rapid growth of covered plants. Larger RGR under the rowcover was due to the increase in dry matter production rate per unit leaf area (NAR) at early growth stage and the increase in leaf area per unit dry matter (LAR) at subsequent stage. Leaf area per unit leaf dry matter (SLA) was affected by the rowcover more than ratio in dry matter of leaf and plant (LWR) . The primary factor of LAR under the rowcover was the increased SLA.