DIVERSITY OF PHYSIOLOGICAL TRAITS IN JERUSALEM ARTICHOKE GENOTYPES UNDER NON-STRESS AND DROUGHT STRESS

Physiological traits such as SPAD Chlorophyll Meter Reading (SCMR), specific leaf area (SLA) and harvest index (HI) play an important role in crop yield. The objectives of this work were to study the effect of drought stress on HI, SCMR and SLA and explore genetic variability for these physiological traits in Jerusalem artichoke (JA) (Helianthus tuberosus L.). Field experiments were conducted in the dry period of 2010/11 and 2011/12 in the Northeast of Thailand using a strip plot design with four replications. A horizontal factor was three different water regimes (W1: 100% Crop water requirement (ETcrop), W2: 75% ETcrop and W3: 45% ETcrop) and a vertical factor was 40 JA genotypes. Measurements on HI, relative water content (RWC), SLA and SCMR were conducted at 40, 60 and 70 days after transplantation. Drought stress significantly reduced RWC and SLA but significantly increased SCMR. High variations in SCMR (32-59) and SLA (78-213 cm(2) g(-1)) were found among genotypes. The correlations between HI and SCMR (r = 0.56 to 0.78, p <= 0.01) were positive and significant, whereas the respective ones between HI and SLA (r = -0.60 to -0.76, p <= 0.01) were negative and significant as those between SCMR and SLA (r = -0.73 to -0.90, p <= 0.01). These findings suggested that SCMR was linked with SLA and HI in JA. SCMR could be used as a physiological trait for indirect selection for HI and productivity under various water regimes in JA.