The effect of supplemental irrigation, time and methods of Fe fertilizer application on qualitative and quantitative traits of chickpea (Cicer arietinum L.)

Introduction Chickpea (Cicer arietinum L.) is one of the most important grain legumes in the south Asia and WANA (West Asia North Africa). In Iran, chickpea is the most important pulse crop of rain-fed systems, traditionally grown in rotation with wheat and barley. The annual cultivation and production of chickpea in Iran is about 0.5 million hectares and 270 thousand tons, respectively. High protein content in chickpea seed (about 20-30%) makes it a good food source for developing countries and low-income people. Among the micro-nutrients, iron (Fe) is used more for plants. Fe deficiency has adverse effects on plant morphology and physiology. Earlier studies have shown that Fe deficiency reduced seed yield in chickpea, soybeans, rapeseed and wheat. In a study, application of iron fertilizer increased the branching and yield components of chickpea. In another study, application of iron fertilizer increased the branching and yield components of chickpea. A study showed that Fe deficiency reduced the water use efficiency of chickpea. In another study, iron sulfate foliar application improved the symptoms of Fe deficiency and increased the yield in low-yielding cultivars, but did not have much effect on high yielding cultivars. Foliar application of iron sulfate also increased the seed iron content. The objective of this research was to study the effects of Fe fertilizer on quantitative and qualitative characteristics of chickpea. Comparison of time and methods of Fe fertilization in chickpea was another aim of this study.   Materials & Methods This research was carried out at the Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran, in 2011. The experiment was conducted as split plot based on randomized complete block design with three replications. Dryland conditions and supplementary irrigation were considered as the main factors as well as the time and methods of application of Fe fertilizer as the sub factors. Fe fertilizer treatments included as follow: without application of Fe fertilizer (Fe1), soil application of Fe fertilizer during planting (Fe2), Fe spraying at branching stage (Fe3), Fe spraying during flowering (Fe4) Fe spraying during pod filling (Fe5), Fe soil application+Fe spraying at branching stage (Fe6), Fe soil application+Fe spraying during flowering (Fe7), Fe soil application+Fe spraying during pod filling (Fe8). For irrigation treatment, two supplemental irrigations were performed at flowering and podding stages of chickpea. For rainfed conditions, these irrigations were prevented. To soil application, Fe-EDDHA (OMEX Company, Germany) as much as 10 Kg ha-1 was used. For leaf spraying, a solution of iron sulfate (Cavin Company, Iran) was used as much as 1 lit ha-1. The planting date was March 15, 2011. The density was 50 plants per square meter. Each plot consisted of six rows, five meters long, 25 cm distance between two rows.   Results & Discussion The results showed that the supplementary irrigation had significant effects on biological yield, grain yield, harvest index, straw yield, the number of pods per plant, 100 seed weight and seed protein content. For these traits, the supplementary irrigation treatment was superior to rainfed conditions. However, supplementary irrigation did not have significant effects on the number of seeds per pod, grain iron content and grain fiber content. The effect of Fe fertilizer on biological yield, grain yield, harvest index, the number of seeds per pod, grain iron content and grain protein content were significant. Straw yield, the number of pods per plant, 100 seed weight and grain fiber content were not influenced by time and methods of Fe fertilizer. The highest grain yield (1614 Kg ha-1), biological yield (3683 Kg ha-1), the number of seeds per pod (1.45 seeds) and seed protein content (27.72%) were obtained in Fe7 treatment. Fe8 treatment had the highest seed iron content.   Conclusion The supplemental irrigation improved seed yield and its components. Also, supplementary irrigation increased the seed iron content, but reduced the seed protein content. The time and methods of application of Fe fertilizer increased the quantitative and qualitative grain yield. Therefore, it seems that in order to increase the quantitative and qualitative grain yield of chickpea, the supplementary irrigation with application of Fe fertilizer (as soil and foliar application) can be recommended.