Humic acid and Fulvic acid effects on yield and yield components of rice (cv. Tarom) in different planting date and transplant treatments by amounts of phosphorus compounds

The use of fertilizers that consider increasing yield while preserving production resources and increasing the productivity of production inputs is necessary and inevitable. One of the most important issues affecting environmental health and food production sustainability is the use of organic fertilizers instead of chemical fertilizers. This experiment was carried out in the form of split split plots in a randomized complete block design with three replications in Sari, Iran, region in the in the two years(2017 and 2018). Experimental factors include the combination of humic acid and fulovic acid with equal proportions as the main factor in four levels of zero (control), 3, 6 and 9 g/l, the combination of phosphoric acid solution and mono ammonium phosphate as a secondary factor in four levels (Control), 5, 10 and 15 g/l and planting date as a sub-factor in three levels were 25 April, 4 and 14 May. The results showed that the combination of humic acid and fulovic acid increased grain yield per plant, feeding seedlings with different amounts of phosphorus compounds increased the grain yield. The highest grain yield was obtained from the consumption of 3 g/l humic acid and folic acid, which showed an increase of 28.09% compared to the control. The highest grain yield was obtained by treatment of 5 g/l of seedling feed with different amounts of phosphorus compounds, which indicated a 28.98% increase in grain yield. The highest grain yield was obtained by treatment of 5 g/l of seedling feed with different amounts of phosphorus compounds, which indicated a 28.98% increase in grain yield. Grain yield  in sowing date of 4 and 14 May was better than 25 April. Grain yield had positive significant correlation with all off measured traits at %1 level. Based on the results, the use of humic acid and folvic acid along with feeding the seedlings with different amounts of phosphorus compounds in different planting dates improved grain yield. The suitable sowing date could be more effective by making better use of environmental factors and improving vegetative properties and allocating more photosynthetic material to the seed.