چكيده لاتين :
Introduction
Wheat, being a major source of human food, occupies a significant portion of cultivated area of globe mostly located in altitude from a few meters to more than 3,000 m above sea level. High temperature resulting from delay in planting date is one major environmental factor limiting growth and productivity of wheat. Plants need phosphorus in relatively large quantities, and its role cannot be played by any other elements. Phosphate bio-fertilizers bacteria such as Bacillus and Pseudomonas increased soil soluble phosphorus by secreting organic acids and phosphatase enzyme. In most of the Iranian soils pH is high and they are also calcareous. In this type of soils, solvability of micronutrients is less and it decreases absorption of micronutrients by plant, finally requirement of plants increases to this elements. This experiment was conducted to study the effects of planting date, Bio-fertilizer containing phosphate solubilizing bacteria and elements foliar application of zinc and boron on physiological and agronomic traits of bread wheat (Aflakcultivar).
Materials and Methods
To study the effects of planting date, bio-fertilizer containing phosphate solubilizing bacteria and elements foliar application of zinc and boron on physiological and agronomic traits of bread wheat (Aflakcultivar), an experiment was conducted at split factorial design based on randomized complete blocks with 16 treatments and three replications in Ramhormoz city in farming Year 2015-16. The experimental factors were included planting date in two levels (21 November and 5 January) as the main factor and use of bio-fertilizer in two levels of seed non-inoculated and seed inoculation with phosphate solubilizing bacteriaand elements foliar application of zinc and boron in four levels by water (control), zinc (3 L ha-1), boron (3 L ha-1) and zinc (3 L ha-1) + boron (3 L ha-1) to form of factorial as sub factor. Solutions for foliar application were prepared by using Zinc- chelate (7.5%) and Boron (5%). In this experiment, traits measured were involved leaf chlorophyll index (SPAD), leaf proline content, cell membrane stability index, maximum quantum efficiency of PSII (Fv/Fm), grain yield, biological yield and harvest index. To determine leaf chlorophyll index (SPAD), digital chlorophyll meter (SPAD-502) was used. To determine leaf proline content Bates et al., (1973) method was used. To determine cell membrane stability index (CMSI) Luttset al., (1996) method was used and according to equation 1. The Fv/Fm was measured with a portable Photosynthetic Efficiency Analyser PEA (Walz, Germany) and according to equation 2.
1: CMSI=(1-(EC1/ EC2))×100
2: Fv/Fm= (Fm-F0)/Fm
Where in this equation EC1 is primary electrical conductivity, EC2 is secondary electrical conductivity, Fm is the maximum fluorescence, F0 is the minimum fluorescence, and Fv is the variable fluorescence (Fm-F0). Grain yield was estimated after physiological maturity and through total spikes harvested from the level of 1 m-2 per plot and after removing 0.5 m from the beginning and end respective planting rows. To measure the biological yield at maturity, after removing 0.5 m from the beginning and end respective planting rows from the level of 1 m-2 per plot all the plants were harvested and weighted for each plot separately. Harvest index was determined by the equation grain yield/biological yield × 100. Analysis of variance was performed by using general linear model (GLM) procedure of statistical analysis system (SAS version: 9.1). Traits means were compared by LSD test at 5% probability level.
Results and Discussion
The results showed that with delay in planting due to terminal heat stress all traits such as leaf chlorophyll index (SPAD), cell membrane stability index, Fv/Fm, grain yield, biological yield and harvest index except leaf proline content decreased significantly. Seed inoculation with bio-fertilizer containing phosphate solubilizing bacteria improved significantly all physiological and agronimic traits of bread wheat (Aflakcultivar) except harvest index in both the optimum planting dates and delayed. Between the different levels elements foliar application of zinc and boron, combined application of zinc+boron was more effective on physiological and agronomic traits of bread wheat (Aflakcultivar), and could reduce the harmful effects caused by the delay in planting. The interaction of seed inoculation with bio-fertilizer containing phosphate solubilizing bacteria and elements foliar application of zinc and boron except harvest index improved significantly harmful effects caused by the delay in planting on traits leaf chlorophyll index (SPAD), leaf proline content, cell membrane stability index, Fv/Fm, grain yield and biological yield to values 3.37%, 12.29%, 6.48%, 3.02%, 17.25% and 24.04%, respectively. Between interaction of bio-fertilizer containing phosphate solubilizing bacteria and elements foliar application of zinc and boron, the use of zinc nutrient than application of combining it with boron was more effective in reducing the harmful effects resulting from delay in planting.
Conclusions
In general it can be concluded that the optimum planting date (21 November), seed inoculation with bio-fertilizer containing phosphate solubilizing bacteria and elements foliar application of zinc and boron especially zinc, is three strategies appropriate management to improve physiological and agronomic traits of bread wheat (Aflakcultivar)in the Ramhormoz city.
