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The Role of Potassium Fertilization in Rice Production PDF Print E-mail

Rice is a major cereal produced worldwide. It is an important staple crop in Asian countries, as an important energy source for human diets. Besides the main benefits of potassium (K) fertilizer management in plant growth and yield, K nutrition also helps to improve plant overall health by reducing the severity of nutritional and pests and diseases.

     Rice (Oryza sativa L.) production plays a main role in world food security. It is the second most produced crop in the world, feeding about 30% of the total population. Most of the production area is concentrated in Asian countries. In this crop, K is absorbed in large quantities during rapid crop growth and plays an important role in plant water balance. Rice production has increased over the past decades thru improved cultivars with higher yield potential which have higher nutrition requirements, which results in depletion of natural soil K pools. Additionally, poor crop management practices exacerbate the need for proper K fertilizer management to improve or maintain rice yields.  Moreover, K fertilization helps to ameliorate the effects of nutritional disorders, such as rice bronzing, which is a common issue in lowland rice production. Also, it helps to increase plant resistance to certain pest and diseases, like stem borers, which severely decrease rice yields when not controlled properly. K deficiency usually appears between the beginning of internode elongation and seed heading. Developing symptoms include stunted plants with thin stems and a dark green color, necrotic spots at leaf tips progressing to the leaf base, including drying of leaf edges, sterile flowers, and root damage.
    Available research shows the importance of the right application rate of fertilizer in rice production. A study to determine the effects of K rates on the incidence of stem borers (Lepidoptera) and rice yield was conducted by Sarwar (2012). The study consisted of the following K rates: 40, 50, and 60 kg/ha of K2O equivalent, using SOP as the K source. Results showed significant reductions on the incidence of stem borers with the highest reduction in dead hearts and white heads occurring when applying 60 kg/ha of K (Table 1). Similarly, rice yields increased as K rates increased with the highest yield observed when 50 and 60 kg/ha of K were applied, averaging 2302 g/3m2 (Figure 1), while the non-treated control showed the lowest yield with about 25% reduction in final rice grain weight.

Table 1. Effects of K rates on the infestation incidence of stem borers (Lepidoptera) in rice production (from Sarwar, 2012).

K rates (kg/ha)

Stem borer infestation (%)

Dead hearts

White heads

0

4.3 az

7.1 a

40

3.0 b

5.3 b

50

2.6 bc

3.5 c

600

2.4 c

3.3 c

P value (P ≤ 0.05)

 

 

*Significant at P≤0.05 levelz. Values followed by the same letter do not differ at the 0.05 level.

 

Effects of K application rates on rice final weight (from Sarwar, 2012).
Figure 1. Effects of K application rates on rice final weight (from Sarwar, 2012).

    Rice bronzing is a common nutritional disorder related to iron toxicity, which is a common problem in lowland (flooded) rice. For instance, Sub-Saharan Africa lowland rice production accounts for more than 50% of the total production. Rice over these areas is produced in low fertility soils with high iron (Fe) content in non-soluble form, but under flooded conditions, it turns to soluble, increasing Fe uptake to the plant, where it accumulates in the shoots causing bronze spots starting from leaf tips and moving downwards to leaf base.
    Other research showed that K fertilizer helped reducing severity of rice bronzing as K tissue levels increased together with plant biomass (Lia et al., 2001; Yamauchi, 1989). Additionally Yamauchi (1989) reported that the application of SOP reduced rice bronzing, while chloride-containing compounds increased the severity of rice bronzing.
    Additionally, leaf tissue concentrations below 1.4% of K at mid-tillering and 1% during panicle initiation and flag leaf appearance are considered critical thresholds for K deficiencies. Fertilizer management helps to improve plant growth but also allows increasing fertilizer use efficiency, which would lead to higher yields translated to higher economic returns for growers. Furthermore, K fertilizer management, especially with SOP, is key to improve rice plant growth and yield. Soil analysis before planting will help determine K application needs during the season.


Full articles:

Li, H., Yang, X., and Luo, A. (2001). Ameliorating effect of potassium on iron toxicity in hybrid rice. Journal of Plant Nutrition, 24(12), 1849-1860.

Yamauchi, M. (1989). Rice bronzing in Nigeria caused by nutrient imbalances and its control by potassium sulfate application. Plant and Soil, 117(2), 275-286.

Sarwar, M. (2012). Effects of potassium fertilization on population build-up of rice stem borers (lepidopteron pests) and rice (Oryza sativa L.) yield. Journal of Cereals and Oilseeds, 3(1), 6-9.

 
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