ISHS Acta Horticulturae 670: I International Symposium on Root and Tuber Crops: Food Down Under
YIELD RESPONSE OF CALIFORNIA-GROWN RUSSET NORKOTAH POTATOES AND ITS LINE SELECTIONS TO NITROGEN FERTILIZATION |
| Authors: | M.R. Johnstone, R.E. Voss, H.A. Phillips |
| Keywords: | Total tuber yield, US No.1 yield, tuber number, plant vigor, N requirements, petiole nitrate concentration, Solanum tuberosum. |
| Abstract:
Within California and much of the U.S., Russet Norkotah (Norkotah) is widely grown for fresh-market due to its high consumer eye appeal and a large percentage of US No. 1’s. Norkotah was thought to have a higher nitrogen demand than other russet cultivars, although specific N requirements had not been determined for major California production areas. Therefore, to evaluate the response of California-grown Norkotah and selections TXNS 112, TXNS 223 and CORN 3 to N fertilization, four trials were conducted during 2000 and 2001. Sites were established in key production regions of the state. Regression modelling was used to evaluate N requirements for producing maximum yield. Generally, increasing N application resulted in greater vine vigor but did not delay maturity. As expected, Norkotah had lower plant vigor than its selections, even with high N applications. Increasing N concentration in the soil resulted in higher petiole nitrate concentration (PNC). There was considerable redistribution of petiole N to tubers during bulking, except under N-deficiency conditions. The sufficiency PNC range observed for Norkotah and its selections was between 15,000 to 17,000 mg•kg-1 NO3-N at tuber initiation. There was a strong correlation between total and US No.1 yield at the four sites (r = 0.99 to 0.65), the later accounting for the majority of increase in total yield. Quadratic modelling improved the r2 value and therefore was selected to describe the yield response of cultivars to N treatment. Based on predicted maximum total yield, TXNS 112 and CORN 3 (each 50 Mg•ha-1) out-performed Norkotah (43 Mg•ha-1) with a higher total yield potential under similar N applications (320 kg N•ha-1); TXNS 223 yielded modestly higher (47 Mg•ha-1) than Norkotah, but required an additional 20 kg N•ha-1 to achieve maximum predicted yield. Nitrogen use efficiency, a measure of tuber yield per N input, was highest for TXNS 112 and CORN 3; TXNS 223 and Norkotah both resulted in poorer N efficiency. Total tuber number also increased curvilinearly with higher N rates. With greater vine vigor and lower N requirements, TXNS selections may offer an appealing financial and environmental option to growers. | |
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