Study of agronomic traits and their relationship in promising lentil lines under rain-fed conditions

Lentil is grown for its biological nitrogen fixation ability and high proteins as well as human and animal nutrition capacity. Terminal drought, lack of suitable varieties and quality seeds have challenged the efforts of breeders to increase its productivity. Assessment of genetic diversity for desired traits in germplasm collections plays a critical role in formulating crop enhancement strategies. The aim of this study was to investigate the agronomic, phenological and morphological traits of advanced lentil lines received from the International Center for Agricultural Research in the Dry Areas (ICARDA) and to identify the relationships between important and effective traits using different statistical methods.

This experiment was conducted on 15 promising lentil lines received from ICARDA along with two check cultivars (Gachsaran and Sepehr) in a randomized complete block design with three replicates under rain-fed conditions at Sarab-Changai Research Station, Lorestan Agricultural and Natural Resources Research and Education Centre, Khorramabad during 2019-2020 cropping year. Sowing was done by hand at four row plots, 4 m length, and 0.25 m row spacing as 200 seeds per square meter density. Fertilization with chemical fertilizers was performed based on soil test. The weeds control was manually performed twice. The total rainfall received was 542 millimeters in the cropping year. Different traits were measured according to standard guidelines for lentil during each stage.

According to the results, the “number of two-seeded pods per plant” followed by number of empty pods per plant, number of one-seeded pods per plant, seed yield per plant, weight of pods per plant and number of fertile pods per plant had the highest coefficient of variation (78.78%) and phenological traits had the least variability. The results of analysis of variance showed a significant genetic diversity between the studied genotypes in terms of most traits. The mean of seed yield per plant was 2.66 g plant-1. Genotypes 6, 14 and 17 (Sepehr) by 6.02, 5.06 and 4.15 g plant-1, respectively had the highest amount. The correlation between grain yield per plant and most of the traits, especially yield components, was positive and significant. The genotypes were classified in three clusters. According to cluster analysis using Ward method, the genotypes of third cluster had high yield and yield components in compare with other clusters. Based on the SIIG index, the genotypes 6, 11, 14 and 17 with the highest SIIG values (0.727, 0.584, 0.569 and 0.537, respectively) were known as the best genotypes. On the other hand, genotypes 15, 2, 9, 10 and 5 with the least amount of SIIG value (0.185, 0.284, 0.323, 0.324, 0.357 and 0.362 respectively) were known as the weakest genotypes under rain-fed conditions. The highest direct positive effect on “seed yield per plant” belonged to the “number of fertile pods per plant” and therefore this trait can be applied as selection criteria. Fifteen agronomic traits have been classified into five groups which expressed 90.82% diversity of the total variation according to the factor analysis.

In this study, the studied genotypes were significantly different for most of the studied traits. Genotypes 6, 14 and 17 (Sepehr) were known as the best genotypes based on the results of various statistical methods including mean comparisons, cluster analysis and SIIG index. Therefore, they have the potential to be used in the future breeding and subsequent agronomic research programs. The number of fertile pods per plant had the most direct positive effect on seed yield. Therefore, it can be considered as a criterion for selecting superior genotypes.