Evaluation of light use efficiency (LUE) in different cultivar of sugar beet.

To study the effect of genetical factors on radiation interception components, this experiments were carried out in Motahari Agricultural Research Station (Kamalabad, Karadj, Iran), Sugar Beet Seed Institute (SBSI) (35º59´ N. and 51º06´ E., alt. 1300 m.) during 2005-2007. Ten domestic and foreign sugar beet cultivars including Brigita, Palma, Shirin, Jolgah, Flores, Rasuol, 428, Gadook, DS 4027 and Zargan were studied in 2005, 2006 and 2007 in a Completely Randomized Block Design (CRBD) with three replications. In this study, root yield (RY) of diploid and triploid cultivars was not shown significant difference, but the foreign and normal cultivars RY significantly are higher than domestic and sugar cultivars by 15.6 and 10.5%, respectively. Cultivar effect on sugar content (SC) was significant (p0.01). Flores (16.33%) and 428 (14.41%) were the highest and lowest SC. Cultivar effect on sugar yield (SY) and white sugar yield (WSY) were significant (p0.01). Variation range of SY and WSY among of studied cultivars were 7.30 t/ha (11.65-18.87 t/ha) and 6.50 t/ha (8.90-15.34 t/ha), respectively. The SY and WSY in diploid cultivars (16.75 and 13.27 t/ha, respectively) are higher than triploids (15.15 and 11.61 t/ha, respectively), because of higher RY in triploid cultivars than diploids by 7.63% and not SC differences between ploidy. Foreign cultivars were higher RY and SC than domestic cultivars by 15.58% and 4.05%, respectively. Hence, SY and WSY of foreign cultivars (18.24 and 14.67 t/ha, respectively) were higher than domestic ones (15.23 and 11.78 t/ha, respectively). fi was not shown differences between studied cultivars. Foreign cultivars had better RUE than domestic ones (1.434 and 1.853 g.m-2.MJ-1, respectively). The main reason was higher RUE of foreign cultivars (1.536 g.m-2.MJ-1) in producing root system than domestic ones (1.098 g.m-2.MJ-1). In terms of RUE in producing shoot system, there was no significant difference between domestic cultivars (0.336 g.m-2.MJ-1) and foreign ones (0.317 g.m-2.MJ-1). According to the results it can be drived that considering the superiority of diploid cultivars comPARed to other ploidy levels, the breeding researches in moderate regions (like Karadj) should focus on breeding diploid cultivars. On the other hand, in these researches improving the main shortage of domestic cultivars i.e. low R/S ratio should be put in priority.