The effect of planting patterns and irrigation intervals on quantitative and qualitative yield of forage maize under drip irrigation system in Pishva-Varamin

According to the country's position in terms of water resources, implementation of newest plant pattern methods and application of advanced irrigation systems can be help to reduce existing threats. The aim of this study was to reduce irrigation water and to keep the highest crop yield.

For this purpose, the evaluation of the irrigation interval and planting pattern on the yield of forage maize (cultivar ZP434), an on-farm experiment was conducted in ChaltaZian, Pishva, as split-plot based on Randomized CompleteBlock Ddesign with three replications at 2017. This experiment in which main plots were irrigation intervals and sub-plots were planting patterns. Sub-plots size were 9 × 8 m. Irrigation treatments were carried out at three levels of 4, 6 and 8day intervals (I1, I2, and I3, respectively) with the same time and amount of water in each irrigation interval by drip irrigation. Treatments of planting pattern were also arranged in three levels of one row with spacing of 70 cm, two rows with spacing of 70 cm and two rows with spacing of 140 cm (P1, P2 and P3, respectively). P1 and P2 are the traditional planting patterns in Iran, and the P3 was considered as the newest arrangement of corn cultivation. In this experiment, a set of quantitive traits (stem diameter, plant height, number of grain per spike, spike weight, the ratio of spike weight to biological weight, the percentage dry material, fresh yield per hectar and dry yield per hectare), Qualitative traits (crude protein, percentage of neutral detergent fiber, percentage of acid detergent fiber, ash, crude fat, percentage of Non-fiber Carbohydrates) and the traits related to economic profit and water use efficiency were studied.

results showed that irrigation treatments had significant effect on stem diameter, plant height, the ration of ear weight to total weight, the percentage of dry matter and forage yield at 0.05 of probability and dry matter yield (ha-1) at 0.01 of probability. Also, the effect of planting pattern was significant on plant height (at 0.05 of probability) and stem diameter, number of seeds per ear, ear weight, the ration of ear weight to plant weight, yield (ha-1) and dry yield (ha-1) (at 0.01 of probability). Also, the results of quality analyze showed that irrigation treatments and plant pattern had significant effect on crude protein and crude fat at 0.05 (crude protein on irrigation treatments and crude protein and crude fat on plant pattern treatments) and at 0.01 (the irrigation treatments on crude fat). The interaction effect was significant on water use efficiency, gross profit and net profit. The result of water use efficiency showed that in all irrigation treatments, P3 was the best treatment. I2 was the best irrigation treatment for the net profit, and by checking the results of slicing the interaction on I2 irrigation treatment we found, they had no-significant effect between plant pattern treatments.

The current study, indicated that irrigation with 6 days interval against 4 days interval can produce the same crop yield using lower water in irrigation. Also, planting pattern of two rows with 140 cm space used lower water compared with one row with spacing of 70 cm, and two rows with spacing of 70 cm. Totally, results indicated the new planting pattern of P3 and irrigation interval of I2 used 3200 m3.ha-1 and the highest crop yield compared with two other planting patterns in I3 that used 5900 m3.ha-1 water. Using the new planting pattern irrigation water reduced and crop yield and the economic efficenciy were at the highest level. The quality of sillage also had not changed significantly.