|Abstract or Summary
- The effects of deficit irrigations and nitrogen rates on the yield and size distribution of 'Detroit Dark Red' table beets were investigated during 1985 and 1986. Beets were grown on a Chehalis silty clay loam (fine-silty, mixed , mesic Cumulic Ultic Haploxeroll) (7.5 cm of available water per 30 cm of soil depth) at a row spacing of 60 cm. Six irrigation treatments of 8, 18, 40, 60, 76, and 95 percent of evapotranspiration during 1985 and 6, 16, 41, 63, 86, and 95 percent during 1986 were imposed by a line source overhead sprinkler system. Nitrogen treatments of 125 and 250 Kg N/Ha were randomized over plots on either side of each sprinkler line. Water production functions developed for the root or total yield versus evapotranspiration or applied water (irrigation plus rainfall) conformed to a second degree polynomial equation. There was no statistical difference between the functions for the two nitrogen rates at the 5 percent level of significance. The 1986 root yield versus evapotranspiration and root yield versus water applied functions for the higher nitrogen level were Y = -65.154 + .557ET - 6.058*10⁻⁴ET² (R²= .74) and Y = 20.172 + .156WAT - 9.166*10 ⁻⁵ WAT² (R²= .83), respectively and did not reach maximums. Similar functions for the lower nitrogen level were Y = 17.76 + .212ET - 2.39*10⁻⁴ET² (R²= .81) and Y = 15.885 + .255WAT - 3.547*10⁻⁴WAT² (R²= .83), respectively. These did reach maximums of 63 and 62 MT/Ha at evapotranspiration and water applied levels of 460 and 360 mm, respectively. The 1985 root yield versus water applied for the two nitrogen levels were Y = 26.018 + .202WAT - 2.92 *10⁻⁴WAT² (R²= .83) for the higher nitrogen level and Y = 27.591 + .163WAT - 2.141*10 ⁻⁴WAT² (R²= .82) for the lower nitrogen level. Neither of these functions reached maximums in the range of applied water. Evapotranspiration data were not available for 1985. Roots were graded based on their diameter into five sizes. These from the smallest to the largest were: less than 25 mm, between 26 and 44, between 45 and 70, between 71 and 95, and larger than 96 mm. The yields of the two smallest grades did not change appreciably over the ET range. The yield of the third smallest conformed to the same type of function as did the root yield and reached its maximum at about the same ET as did the root yield. The yields of the two largest grades showed an increasing trend over the ET range. The percent dry matter in roots and leaves decreased over the ET range and reached a minimum at an ET level which was somewhat less than the ET level for maximum root yield and the middle size grade yield.