چكيده لاتين :
Introduction
Salinity is one of the most important and adverse environmental constraint restricting growth and development of plant particularly in arid and semiarid regions. One approach to improve the salt stress problem is the use of plant growth promoting rhizobacteria (PGPR) and Mycorrhiza. The PGPR are a group of rhizosphere colonizing bacteria that produces substances to increase the growth of plants, synthesize different phytohormones, including auxins, cytokinins, and gibberellins, synthesize enzymes that can modulate plant growth and development. Arbuscular mycorrhizal fungi (AMF) symbiosis is considered a valuable component in most agricultural systems due to their role in plant nutrition and soil health. Soil microorganisms such as Arbuscular mycorrhizal fungi represents a key link between plants and soil mineral nutrients. Thus, they are collecting growing interest as natural fertilizers. Iron is the third most limiting nutrient for plant growth and metabolism. It is well known that iron is important component of many vital enzymes, and also participates in the synthesis of chlorophyll, indole-3-acetic acid (IAA), electron transport, chlorophyll biosynthesis and photosynthesis, and a structural stabilizer for proteins, membrane and DNA-binding proteins. The problem of soil salinization is a scourge for agricultural productivity worldwide. Iron deficiency also is a common nutritional disorder in many crop plants, resulting in poor yields and reduced nutritional quality. Since, application of bio fertilizers and iron is one of the most important strategies for alleviation of salinity stress effects. Therefore, the aim of this study was to evaluate the effects of bio fertilizers and iron on yield, chlorophyll content and some components of grain filling period of barley (Hordeum vulgare L.) under salinity stress.
Materials and Methods
A factorial experiment was conducted based on randomized complete block design with three replications at research greenhouse of faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili during 2016. Factors experiment were included bio-fertilizers in four levels (non-application of biofertilizer, application of Azospirilium, mycorrhiza (Glomus Intraradices), both application of mycorrhiza and Azospirilium), foliar application with nano iron oxide at four levels (0, 0.3, 0.6 and 0.9 g l-1), soil salinity in four levels (0, 50, 25 and 75 mM NaCl). A two part linear model was used to quantifying the grain filling parameters. In this study, total chlorophyll, chlorophyll a, b, carotenoid, grain filling components, yield and yield components of barley were investigated. Grain dry weight and number were used to calculate the average grain weight for each sample. Total duration of grain filling was determined for each treatment combination by fitting a bilinear model:
Effective grain filling duration (EGFD) was calculated from the below equation: EGFD = the highest grain weight (g)/ratio of grain filling (g day-1).
Results and Discussion
Means comparison showed that the highest yield (2.46 g per plant), grain filling rate (0.00279 g day 1), effective grain filling period and grain filling period (39.96 and 26.53 days respectively), chlorophyll a (87.1 mg g 1 FW), chlorophyll b (0.68 mg g 1 FW), total chlorophyll (2.55 mg g 1 FW) and carotenoid (0.6 mg g 1 FW) were obtained at treatment of application Azospirilium, mycorrhiza, 0.9 g l-1 of nano iron oxide under no saline condition. While the lowest amount of traits was obtained in no application of bio fertilizer and nano Fe oxide under on saline condition. Grain yield was decreased in 25, 50 and 75 mM levels by 5.23, 21.93 and 26.14%, respectively. While, application of biofertilizers and nano Fe oxide compensated 11.79%, 12.64% and 15.45% respectively from yield reduction in compared to control.
Conclusions
It seems that, both application of biofertilizers and nano Fe oxide can be suggested as stabilizers stress in barley under soil salinity conditions. So, salinity of 25, 50 and 75 mM NaCl decreased 5.23, 21.93 and 26.14%, respectively from grain yield and application of biofertilizers and nano Fe oxide compensated 11.79%, 12.64% and 15.45% respectively from yield reduction in compared to control.
