international fertilizer correspondent
No 6
international fertilizer correspondent No 6 |
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LATEST RESEARCH FINDINGS
- on impact of K on pests and diseasesby J. Williams and S.G. Smith (2001), Better Crops Vol. 85, No.1, pp. 7-9.
Severity of AGSS, i.e. aggregate sheath spot (Rhizoctonia oryzae) and stem rot disease (Sclerotium oryzae) decreased with increasing leaf K percent at panicle initiation. The combination of high N and low K was particularly important in enhancing stem rot disease. K had a significant role in both plant nutrition and the course of disease. However, as the authors stress, it is important to recognize that the role of K fertilization is primarily plant nutrition. Potassium is a fertilizer and not a fungicide.
A group of Brazilian scientists found from field and pot experiments that the use of potash suppressed the incidence of leaf blight (Cercospora kikuchii), stem cancer (Diaporthe phaseolum) in soybean, and Phomopsis in soybean seeds. More recent findings are published by Mascarenhas, H.A.A, Ito, M.F., Tanaka, R.T., Ambrosano, G.M.B., Muraoka, T. and Q.A.C. Camargo: Influencia da calagem e adubacao potassica no cancro da haste da soja. Summa Phytopathologica 24, pp. 156-160, 1998.
by Oosthuyse, S.A., Subhadrabandhu, S. and Pichakum., A. (2000) in Proceed. 6th Intern. Symp. on Mango, Pattaya City, Thailand, 6-9 April 1999, Vol. 2, Acta Horticulturae, No. 509, pp. 719-723.
Mono potassium phosphate, MKP sprays, alone or in mixture with fungicides, is effective in retarding the development of powdery mildew on mango inflorescence, and can be used to reduce the cost of powdery mildew control in mango (CABI Accession No. 20001007153).
by Tamim, M., Goldschmidt, E.E., Goren, R. and Shachnai, A. (2000), Alon-Hanotea 54: 4, 152-157.
Superficial rind pitting SRP causes serious damage to fruits and losses to growers. Fruits with SRP had lower rind K contents than healthy fruits. Spraying with 9% ‘Bonus’ 13-2-44 increased leaf K concentration and reduced the incidence of SRP significantly. It is hypothesized that K deficiency leads to malfunction of biomembranes, causing water loss followed by cell collapse and local necrosis SRP (CABI Accession No. 20000311086).
LATEST RESEARCH FINDINGS
- on impact of K on stressby Lingle, S.E., Wiedenfeld, R.P. and Irvine, J.E. (2000): J. Plant Nutrition 23: 4, 469-486.
Salinity of irrigation water reduces yield and juice quality in sugar cane, but cultivars vary in the degree of reduction. Genotypes which accumulate more potassium may be more resistant to salinity than genotypes that accumulate less. However, the testing of two varieties which differ in the degree of K accumulation showed that both varieties respon-ded similarly to increased salinity in terms of yield and quality components although the juice of the two varieties showed differences in their concentration of minerals. Increased salinity reduced stalk height and total soluble solids and sucrose in juice. An increase in K accumulation did not appear to increase salt tolerance (CABI Accession No. 20000707437).
by Al Karaki, G.N. (2000), J. Plant Nutrition 23: 3, 369-379.
At low K rates, salinity decreased shoot and root dry weight and leaf area. Addition of K ameliorated the effects of NaCl and improved the growth parameters. Salinity reduced net K uptake and, to a lesser extent, K translocation from the roots to the shoot. The inhibitory effect of salinity on K translocation was greater at low K supply. Addition of K decreased Na uptake. The results indicate that K supply contributes to salt tolerance of tomato (CABI Accession No. 20000310230).
by Coker, D.L., Oosterhuis, D.M., Dugger, P., and Richter, D. (2000), 2000 Proceed. Beltwide cotton conference, San Antonio, USA, 4-8 January 2000: Vol. 1, pp. 634-636.
The impact of water deficit on K deficiency and partitioning of K in cotton plants during peak boll development is not well understood. Field trials showed that stem and petiole K concentrations were significantly reduced from high to low soil K under well-watered, but not dryland, conditions. Foliar application of K consistently increased stem, petiole, and leaf K concentrations but only under low K conditions. Foliar application of K increased leaf K by a greater margin under dryland, low soil K compared to well-watered, low soil K conditions. Lint yield responded best to foliar K under low soil K and well-watered conditions. K deficiency in cotton appea-red to be exacerbated by water deficit, although water deficit did not reduce the efficacy of foliar-applied K (CABI Accession No. 20000711203).
LATEST RESEARCH FINDINGS
- on impact of K on qualityby Ni Wuzhong and R. Haerdter (2001), Pedosphere 11: 1, 77-82.
Field experiments with Chinese cabbage, autumn greens, winter greens, and summer greens (Brassica ssp.) revealed significant yield increases of marketable ware. In comparing the K form, use of SOP was in two out of three crop types superior to MOP. It could also be demonstrated that use of potash increased content of vitamin C and decreased nitrate content of the vegetables at the same time.
by Yuang-Ling, Wang-Shou Sheng, Wang-Zhi Hui, Huang-JianGuo, Yuan, L., Wang, Z.H. and Huang, J.G. (2000): Pedosphere 10: 1, 45-52.
Samples of made tea and soils from the tea area of Sichuan and Chongqing were collected and analysed. The soils are very acidic and poor in content of mineral nutrients. In made tea, contents of K and S varied considerably in contrast to N and P which showed only small variations in content although soil N and P varied substantially. High N concentration in made tea could result in the high free amino acids and low polyphenol contents of tea. Significant positive correlation was established between K and polyphenol in made tea. Teas with high ratio of polyphenol to free amino acids were usually good in taste and appearance (CABI Accession No. 20001911437).
by Milford, G.F.J., Armstrong, M.J., Jarvis, P.J., Houghton, B.J., Bellett-Travers, D.M., Jones, J. and Leigh, R.A. (2000): J. Agric. Science 135: 1, 1-10.
In a range of field trials on soils of different type and K index there were few yield responses even though the majority of trials were on soils of low K index and large quantities of fertilizers were applied. K offtake in the harvested beet increased asymptotically, not linearly, with yield and were much larger at a given yield on high K index soils than on low index soils. Beet K concentrations were not greatly affected by large application of fertilizer K but were strongly influenced by long-established differences in soil exchangeable K (K ex ) due to soil type, previous cropping or manuring history. The amount of K removed by a 60-70 t/ha crop of beet varied from 70 kg/ha K on low K index sandy loams to 120 kg/ha K on high K index clay soils. An analysis of individual fields showed that site and season variation in K content of beets was due to differences in K uptake driven by K ex and differential effects of N supply on K uptake and sugar yield. Total K content of the crop and K in beet, both increased linearly with crop N. Low yielding crops grown on soils in which N and K were freely available produced beet of poor K quality. However, the asymptotic relationship between beet K and yield implies that the processing quality of beet can be improved by increasing yield through better agronomy (CABI Accession No. 20000710595).
by Zhu, Y.G., Shaw, G., Nisbet, A.F. and Wilkins, B.T. (2000). Plant & Soil 220: 1/2, 27-34.
Short-term growth chamber experiments with wheat showed that low internal K concentration, i.e. K starvation, increased Cs influx rates by a factor of 10 compared to non-starved plants. Solution to plant tissue transfer factor values also increased by approximately an order of magnitude after K starvation treatment. The enhancement of Cs influx rates by K starvation could be offset by an increase in external K concentration. This shows that Cs influx into plant roots is subject to control by both internal and external K status. K starvation increases significantly the affinity of plant roots for Cs (CABI Accession No. 20001913154).
The CABI Accession number refers to the whole article available at biblioserv@cabi.org
