Document Type : Research Paper
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Abstract
In this study, combined effects of nitrogen and phosphorus were investigated on the quantity and quality of sugar beet seed (variety 7233) under furrow and trickle irrigation. The experiment had split plot design in completely randomized blocks, adopting split factorial with three replications. The main plots were allocated to the two irrigation methods i.e. furrow and trickle (tape) irrigation systems, while the sub plots included 4 nitrogen levels (0, 60, 120, 180 kg/ha) and 3 phosphorus levels (0, 30, 60 kg/ha). The project was conducted at the Ekbatan station of the Agricultural Research Center of Hamedan in 2003- 04.The results of combined analysis showed that the effect of different treatments of N on the quantity of sugar beet seed yield was significant (α =%1).The effects of irrigation method, N, P, and their interactions were not significant on the percentage of the standard seeds. The interaction effect of irrigation method and N as well as the interaction effect of irrigation, P, and environment (year) on seed germination were significant. The results showed that increasing N application up to 88.5 kg/ha increased the amount of standard seed size, whereas higher amounts decreased the standard seed size. With increasing nitrogen fertilizer up to 120 kg, seed germination increased in trickle irrigation. The averages of yield under drip (tape) and furrow irrigation system were 2360 and 2210 kg/ha, respectively. But, with increasing phosphorus rate, changes in the germination percentage under both irrigation methods were not significant. The amount of water use efficiency increased with increase in nitrogen rate, and the difference between different treatments was significant (α =%1). Compared with furrow irrigation, tape irrigation reduced water consumption by about 50 percent. The amount of water use efficiency in trickle irrigation was 0.59 kg.m-3, more than twice the WUE in the furrows. Changing the irrigation method from furrow to trickle irrigation increased net income by about 18.6 million rails. The net value during 15 years was calculated at about 457.3 million Rials. Considering the internal rate of return (43.5%) and the benefit: cost ratio of 1.6, use of drip irrigation for production of sugar beet seed is economical.
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