Chlorophyll Meter Readings, Leaf Area Index, and Their Stability as Assessments of Yield and Quality in Sugar Beet Cultivars Grown in Two Contrasting Environments

• Published in: Crop science 2014-01, Vol.54 (1), p.265-273
• Main Authors: Tsialtas, J. T., Baxevanos, D., Maslaris, N.
• Format: Article
• Language: English
• Subjects: Chlorophyll; Cultivars; Environmental conditions; Genotype & phenotype; Genotypes; Growing season; Irrigation; Leaves; Seasons; Sugar; Sugar industry; Temperature
• ISSN: 0011-183X; 1435-0653
• DOI: 10.2135/cropsci2013.03.0186

ABSTRACT Across 2 yr and two locations in central Greece, 12 sugar beet (Beta vulgaris L.) cultivars were tested for yield (fresh root weight [FRW], sugar yield [SY], and white sugar yield [WSY]), sucrose content (SC) (% in fresh root weight), and their stability. Cultivar differences in photosynthetic machinery were nondestructively assessed by leaf chlorophyll (soil plant analysis development [SPAD] readings) and leaf area index (LAI) measurements on four occasions during the growing season, within the first week of June, July, August, and September 2004 and 2005. Values over the four measurements conducted during the growing season of the physiological parameters (SPAD value over the four measurements conducted during the growing season [SPADM] and LAI value over the four measurements conducted during the growing season [LAIM]) and measurements of SPAD in June (SPAD1) and LAI in July (LAI2) showed broad‐sense heritability similar or even higher than those of yields. Both SPAD1 and LAI2 correlated positively with SPADM and LAIM, respectively, indicating that a single measurement, at a certain time point, might assess cultivar performance over the growing season. Three cultivars (Corsica, Palma, and Creta) performed best among the 12 genotypes, combining the highest WSY and stability as a genotype and genotype × environment biplot analysis depicted. Despite the fact that no relationship between SPAD and yields (FRW, SY, and WSY) or SC was found, cultivars instable in SPAD, as assessed by the Shukla stability variance (σ2i) (σ2i of SPAD1 and σ2i of SPADM), were shown to be the high yielding ones. On the contrary, cultivars with high and stable LAIs (LAI2 and LAIM) had the highest and more stable yields. Under the Mediterranean conditions of this work, where sugar beets suffer successive defoliations and regrowths, cultivars to yield better are those that sustain high LAI canopies with adapting “greenness” to the prevailing environmental conditions.