02992naa a2200229 a 450000100080000000500110000800800410001910000230006024501350008326000090021830000150022752022870024265000160252965000140254565000160255965300190257565300230259465300200261770000190263770000190265677300870267515402632019-11-13       1991    bl uuuu     u00u1 u    #d1 aCHRISTENSEN, L. P.  aPotassium fertilization of Thompson Seedless grapevines using two fertilizer sources under drip irrigation.h[electronic resource]  c1991  ap. 227-232  aDrip irrigation is suitable lor injection 01 soluble lertilizer due to ease in unilormity 01 application and efficiency 01placement. A potassium (K) lertilization trial was initiated in 1984 to determine the inlluence 01rate, frequency 01 application, and K source on correcting K deliciency in a drip irrigated vineyard. Own-rooted Thompson Seedless vines on a K delicient sandy loam soil were used lor study. The eight treatments compared two rates (0.1 and 0.2 kg K/vine) 01two K sources (K2S04 and KCI) under two application methods--single treatment (1X) and weekly partitioned treatment (8X) over 8 weeks. Single treatment (1X) 01 higher rates 01 K2SO. at DA and 0.8 kg K/vine as well as O lertilizer were also compared. Vine response as measured by bloom petiole K levels was most immediate with the 1X applications but by veraison in the year 01 treatment the partitioned 8X applications resulted in higher petiole K. Thereafter, in 1985 and 1986, application method (1X VS. 8X) did not show differences in inlluencing petiole K. Fertilizer rate treatments increased petiole K and reduced visual K deliciency symptoms linearly. Ali lertilizer treatments showed response in petiole K increase and visual symptom reduction Ior two seasons, 1984 and 1985. However, by 1986 only the 1X treatments continued to show higher petiole K than O lertilizer. Petiole CI was increased with CI as a K source but without apparent CI toxicity problems. No other differences due to K source (SO. vs. CI) were shown except lor higher petiole K lrom SO. in one year of measurement, 1985. Soil samples taken in December 011984 at incremental distances from the emitter showed greatest concentration of K directly below the emitter for the low 1X and ali 8X treatments. Highest 1X treatment rates increased K levels at the 0.5 m distance and depth. The study demonstrates the feasibility 01 K lertilizer application to vineyard under drip irrigation as 1X or partitioned treatment at varying rates 01K2S04 and KCI. Higher rates 01K2S04 at DA kg K and above can provide correction beyor.d t'J.'O years in the sei! type studied hera, Hates of I&ltCI abcve 0.2 kg K/v'ine VoJeie not used in the study to avoid possible CI toxicity problems. KEY WORDS: potassium, irrigation, drip, Thompson Seedless  aIrrigação  aPotássio  aViticultura  aFertilização  aNutrição mineral  aUva sem semente1 aPEACOCK, W. L.1 aBIANCHI, M. L.  tAmerican Journal of Enology and Viticulture, Davisgv. 42, n. 3, p. 227-232, 1991.