Effect of irrigation hult and humic acid foliar application on agronomic, qualitative and physiological characteristics in red bean cultivar D81083

Introduction Rapid population growth in developing countries have resulted to adverse effect such as food shortages and malnutrition. Lack of protein in the diet is accounted for the largest portion. Pulses with high amounts of protein are the second largest source of food after cereals. Among pulses, beans as a supplier of plant proteins in many countries, particularly developing countries has high consumption. Area under cultivation of bean is 240000 hectares with an average yield of 1500 kg per hectare in Iran. In arid and semi-arid area due to excessive exploitation of water resources, the water shortage is constantly evolving and according to the climatic conditions that are considered hot and dry, and sensitivity of bean to drought further research in this field is clear. Humic acid is extracted from different sources, such as humus and, soil and using chelating essential elements improve and increase fertility and productivity of soil, especially in conditions of stress. As we mentioned before, purpose of this study was evaluating effect of water stress and use of humic acid on agronomic, physiological and quality traits. Materials & Methods This experiment was performed at agricultural Research Station in Arak, Iran in 2014. The experiment was performed in split plot arangment based on randomized complete block design with three replications. The main factor was irrigation hold at 3 levels: complete irrigation (control), irrigation hold at flowering stage and irrigation hold at pod stage and sub factor was humic acid foliar application in three levels of non humic acid application (control), 1.5 and 3 liters per hectare humic acid 12% at pre flower satage and pod stges applications. In this study the red bean seed was from D81083 cultivar. In this study, biological yield, grain yield, number of seeds per pod, number of pods per plant, harvest index, seed weight, chlorophyll a, b and a+b content, RWC, iron, zinc and protein contents in grains and also, leaf electrolyte electrical conductivity were measured. Analysis of data was done with SAS software and comparisons of means were performed with Duncans multiple range test at 0.05 statistically significant level. Results & Discussion Mean comparison of irrigation treatment indicated that the highest seed yield was in complete irrigation and hold irrigation at pod stage and lowest rate was for hold irrigation at flowering stage. In this experiment, use of humic acid in normal conditions and in conditions of hold irrigation at flowering and pod stage could be increase the yield. The highest harvest index was in complete irrigation and hold irrigation at pod stage. The results showed that the highest 100 seed weight was from control and hold irrigation at pod stage treatment and the least weight was from hold irrigation at flowering stage which shows the sensitive stage for bean is cut-irrigation at flowering stage and maybe the need for water is low in pod stage. Among yield components, seeds per pod had significant correlation with yield. The highest number of pods per plant during irrigation hold was at flowering stage and control treatment and irrigation hold at pod stage had the lowest rate of pods per plant. Most of seed protein obtained from hold irrigation at flowering stage and the lowest amount of it was in hold irrigation at pod stage. The effect of hold irrigation and the effect of humic acid opplication was as well as the interaction bouth. There were significant differences on levels of iron and zinc in seeds. The highest amount of chlorophyll a, b and a+b were in hold irrigation at flowering stage. The effect of 3.5 liter per hectare foliar application of humic acid could be increase total chlorophyll. Hold Irrigation treatment also had a significant effect on the leaf relative water content in pod stage. Conclusion The results showed that the irrigation hold had significant effect on all studied traits. Generally, the highest and lowest yield was related to complete irrigation treatment but in some cases the hold irrigation at flowering stage was the same result. The effect of hold irrigation at pod stage was the same as complete irrigation treatment which this point can be used in saving water. Also, Spraying with different amounts of humic acid showed that the humic acid improved the agronomic characteristics and quality of the beans in range of 1.5 litter per ha. Therefore, Using of humic acid may improve agronomic, qualitative and physiological characteristics of red bean.