Document Type : Research Paper
Authors
1 Crop and Horticultural Science Research Department, Ilam Agricultural and Natural Resources Research and Education Center, AREEO, Ilam, Iran.
2 Crop and Horticultural Science Research Department, Ilam Agricultural and Natural Resources Research and Education Center, AREEO, Ilam, Iran
Abstract
Objective: This research was carried out with the aim of investigating the effect of different nitrogen sources on the yield and morphophysiological traits of four lentil cultivars under rainfed conditions.
Method: The field experiment was carried out during the 2020–2021 cropping season at the Chardavol Agricultural Research Station, Ilam, Iran. A factorial experiment was arranged in a randomized complete block design (RCBD) with three replications. The first factor consisted of four autumn-sown lentil cultivars: Kimia, Gachsaran, Bilesavar, and a local mass landrace. The second factor included five nitrogen treatments: (1) control (no nitrogen), (2) inoculation with Azospirillum, (3) inoculation with Azotobacter, (4) combined inoculation with both bacteria, and (5) application of chemical nitrogen fertilizer. Measured physiological traits included total chlorophyll content, relative water content (RWC), and root growth. Agronomic traits consisted of plant height, number of branches per plant, number of pods and seeds per plant, grain yield, biomass, harvest index (HI), and seed protein content. Standard protocols were used for measurements, and data were analyzed using ANOVA; treatment means were compared using the Duncan test at 5% significance level.
Results: The results showed that the highest chlorophyll a and b, relative leaf water content, root growth, plant height, branching, number of pods per plant and number of grain, grain yield, biomass, harvest index and percentage of seed protein were observed in the chemical nitrogen fertilizer treatment and in the Kimia cultivar; however, in many of these traits, inoculation with Azospirillium bacteria had very close or equal results to chemical fertilizer. On the other hand, inoculation of the Kimia cultivar with Azospirillium in traits such as root structure, vegetative growth, and physiological capacity and yield components did not differ significantly from the chemical fertilizer treatment.
Conclusions: The results of this study showed that among the cultivars, Kimia cultivar and among the nitrogen sources, nitrogen fertilizer improved morphological traits. This, along with increasing the relative leaf water content and photosynthetic pigment concentration, ultimately led to an improvement in grain protein percentage, biological yield, grain yield, and harvest index. It is noteworthy that although nitrogen fertilizer was more effective in increasing morphological and functional traits than other sources, plant growth-promoting bacteria, especially Azospirillium, also played a prominent role, so that in many traits they were able to show a performance close to nitrogen fertilizer. These findings indicate the high capacity of growth-promoting bacteria as effective supplements or sustainable alternatives to nitrogen fertilizers, which can maintain or improve plant yield while reducing the use of chemical fertilizers.
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