Study of Irrigation Halt and Humic Acid on Seed Yield, Its Components and Correlation between Traits of Red Bean

BACKGROUND: Humic acid is a natural polymeric composition which is produced as a result of decaying organic matters in soil, peat and lignin to increase crop product. OBJECTIVES: Assessment the effect of different irrigation regime and humic acid on red bean production and correlation coefficient between measured traits. METHODS: Current research was done via split plots experiment based on completely randomized blocks design with three replications. Main factor consisted irrigation halt at three levels (I1: Complete irrigation or control, I2: halt irrigation at flowering stage, I3: halt irrigation at pod stage) and humic acid foliar application dosages at three levels (H1: Control, H2: using 1.5 L.ha-1, H3: 3 L.ha-1 humic acid) belonged to subplots. RESULT: The effect of irrigation halt and humic acid on biological yield, seed yield, harvest index, number of pods per plant and seeds per pod and 100 seed weight were significant. Mean comparison result of interactions effect of treatments revealed the highest seed yield (3758.4 kg.ha-1) was in complete irrigation with 3 L.ha-1 humic acid consumption and the lowest one (2170.1 kg.ha-1) belonged to irrigation halt at flowering stage. So, this reduction in the irrigation at flowering stage was about 6% by consumption of 3 L.ha-1, and was improved to 38%. CONCLUSION: flowering stage is the most critical stage of growth of red beans in response to irrigation regimes and foliar application of humic acid could be used as a new method to decrease damage caused by halt irrigation, so halt irrigation in pod stage with use 3 L.ha-1 humic acid is recommended to achieve maximum yield.