AN EASY AND FAST METHOD TO ESTIMATE CYNARA CARDUNCULUS SEED YIELD BASED ON HEAD WEIGHT AND NUMBER

摘要

This paper aims (a) to derive empirical relationships to predict cynara seed yield per head and per unitarea, avoiding laborious extraction of seeds from its complex inflorescence structure; (b) to determine the headweightdistribution per unit area; and (c) to estimate the range of Cynara cardunculus seed yield. We analyzed 16field experiments, varying in crop age and environmental conditions in Greece. Seed yield per head (SYhead) can beaccurately predicted as a linear function of dry head weight (Hw): SYhead = 0.429 · Hw – 2.9 (r2=0.96; n=617). Basedon this relationship, we developed a simple two-parameter equation to predict seed yield per unit area (SY): SY = HN ·(0.429 · μ – 2.9), where HN is the total number of heads per unit area and μ is the mean head weight (g head-1),respectively. The models were tested against current and published data (n=180 for head-level; n=35 for unit arealevelmodel), and proved to be valid under diverse environmental and management conditions. Attainable cynara seedyields ranged from 190 to 480 g m~(-2) y~(-1), on dry soils and on aquic soils (shallow ground-water level). This variationin seed yield was sufficiently explained by the analyses of head-weight distribution per unit area and variability ofseed/head weight ratio at head level. This work provides basal information of crop reproductive effort and reveals thegreat potential of cynara as a biomass and oil crop for bioenergy production.