Evaluation of physiological growth indices and radiation use efficiency in different peanut genotypes in Guilan province

Rainfed planting of peanuts in Guilan province has a history of more than 120 years. The use of late cultivar NC2 in most of the peanut fields in this region during the last 45 years has provided the basis for the spread of diseases and severe functional fluctuations in the production of this plant. The light soil texture in the fields of this plant also increases the yield fluctuations of this cultivar in the low rainy years by reducing the available moisture for peanut plants. As a result, the introduction of new cultivars adapted to the climatic conditions of the region, which have good pod yield in rainfed conditions, is one of the most important necessity for Guilan province. Therefore, the present study was designed and conducted to investigate and compare physiological indices and radiation use efficiency in 14 new peanut genotypes and compare them with NC2 cultivar.

This study was conducted as a randomized complete block design with three replications in two years 2016 and 2017 in Astaneh Ashrafiyeh city. 14 peanut genotypes along with NC2 cultivar, which is the dominant cultivar in the region, formed experimental blocks. All genotypes were planted flat and in rainfed conditions. Heat unit throughout the growth period, crop growth rate, pod growth rate, partitioning coefficient, radiation use efficiency, pod yield, grain yield, biological yield and harvest index were studied in all genotypes and NC2 cultivar and were compared with this cultivar.

The results of this study indicated that the highest heat units from planting to harvesting maturity were observed in NC2 cultivar and ICGV02317 and ICGV92222 genotypes, respectively, while ICGV00350 and ICGV87846 genotypes had the lowest heat units during the growing season. The highest values of crop growth rate, pod growth rate, radiation use efficiency, pod yield and grain yield were obtained from NC2 cultivar and ICGV00420, ICGV99019 and ICGV92116 genotypes.

According to the results, in rainfed conditions, 3 genotypes ICGV00420, ICGV99019 and ICGV92116 reached the harvesting maturity stage faster than NC2 cultivar with a lower heat unit in this area while in many of the measured traits were similar to the mentioned cultivar. The results also indicated that the mentioned genotypes can be considered as an alternative to planting NC2 cultivar in the region's farms according to the calculated physiological indices and radiation use efficiency because these genotypes had suitable radiation use efficiency, pod and grain yield under rainfed cultivation conditions.