Optimum Timing of Potassium Nitrate Spray Applications to `French' Prune Trees

Abstract

<jats:p>During the fruit growing season, April through August 1990, 1991, and 1992, four sprays of 20-22 liters/tree of KNO<jats:sub>3</jats:sub> were applied to `French' prune trees (<jats:italic>Prunus domestica</jats:italic> L. syn. `Petite d'Agen). Spray applications of KNO<jats:sub>3</jats:sub> were compared to single annual soil applications of KCl (1.4-2.3 kg/tree) and sprays of urea + KNO<jats:sub>3</jats:sub> with respect to leaf K and N, fruit size, drying ratio, and dry yield. Potassium nitrate sprays were as effective, or better, than soil-applied K in maintaining adequate levels of leaf K throughout the season. Treatment effects were not carried over into the next year. Lowest leaf K was found in trees where no K had been applied. Those values were below the adequate level of 1.3% K and the untreated group developed K deficiency symptoms. Consistent effects on leaf K were not obtained when urea was applied and no negative effect on leaf K was demonstrated. Equivalent dry yields per tree were obtained by foliar and soil K applications. There was no best time for KNO<jats:sub>3</jats:sub> sprays. Yield per tree was not enhanced when foliar K-N sprays were applied to trees that had levels of 1.3% K or more as of 15 Apr. 1992. Trees that were below optimum K in April tended toward improved dry yields after four K-N sprays. Trees that had no applied K were lowest yielding. Drying ratios and fruit size (number of fruit per kilogram) were not different among K treatments. Dry yields per tree were increased without a decrease in fruit size or an increase in drying ratio with either soil or foliar K application. These results suggest that foliar KNO<jats:sub>3</jats:sub> sprays applied four times throughout the growing season can be used to correct incipient K deficiency in `French' prune and to obtain dry yields equivalent to those obtained with soil applications of KCl.</jats:p>

Effects of Foliar Potassium Fertilization on Fruit Growth Rate, Potassium Accumulation, Yield, and Quality of ‘Kousui’ Japanese Pear

“…Spraying with KNO 3 was previously reported to increase fruit size in 'Patharnakh' japanese pear (Gill et al, 2012), and the increase was greatest at a dose of 1.5% KNO 3 . A study of plum trees [Prunus salicina (Southwick et al, 1996)] revealed that there was a correlation among the dry weight, size of fruit, Total sugar = fructose D sorbitol D glucose D sucrose; sweetness value = fructose · 1.75 D glucose · 0.70 D sorbitol · 0.40 D sucrose · 1.00. Vertical bars indicate SE; 1 mgÁg L1 = 1000 ppm.…”

Effect of Soil Potassium Fertilization and Foliar Spray of Different Potassium Sources on Growth, Yield and Fruit Quality of William Banana Plants. تأثير التسميد الارضى والورقي بمصادر مختلفة من البوتاسيوم على النمو والمحصول وصفات ثمار الموز الوليامز

“…In addition, it controls many enzyme activities in plants by modulating the rate of photosynthesis and increasing the rate of translocation from leaves through the phloem to storage tissue, which leads to improve yield and fruit quality (Saykhul et al, 2013). Furthermore, Southwick et al (1996) reported that the uptake of potassium absorption from the foliar spray might be more predictable and efficient than uptake from the soil, where soil-cation interactions may delay the process.…”

Labeling an Egg Parasitoid, Anagrus epos (Hymenoptera: Mymaridae), with Rubidium within an Overwintering Refuge

“…A 5,000-ppm solution of Rb was applied twice to prune foliage on each spraying date. Based on experience with foliar potassium treatments, 2 sprays of 5,000 ppm should result in greater uptake than a single 10,000-ppm spray (Southwick et al 1995). The solution was applied using a large (>350 L) herbicide sprayer with dual spray guns fitted with fine-spray nozzles.…”