K-use Efficiency Research Articles

POTASSIUM-USE EFFICIENCY IN COMMON BEAN GENOTYPES

Potassium (K) is one of the most important nutrients limiting yield of common bean in South America. Use of K-efficient crop genotypes along with K fertilizer may be a viable strategy to improve yield and reduce cost of production. A greenhouse experiment was conducted to evaluate K-use efficiency of 10 promising genotypes of common bean (Phaseolus vulgaris L.). The genotypes were grown on an Oxisol at 0 mg K kg−1 (low K) and 200 mg K kg−1 (high K) of soil. Shoot dry weight, grain yield, number of pods, number of grains, 100-grain weight, grain harvest index, and K harvest index were significantly (P < 0.01) affected by level of K as well as genotype, except for the number of pods by genotype. Significant genotypic differences in K-use efficiency were found. On the basis of K-use efficiency (mg grain weight/mg K accumulated in shoot and grain), genotypes were classified as efficient and responsive (ER), efficient and nonresponsive (ENR), nonefficient and responsive (NER), and non-efficient and non-responsive (NENR). Only genotype Diamante Negro was only classified as ER, and genotypes Carioca, Pérola, Rosinha G-2, and Xamego were classified as ENR. Genotypes LM93300166 and LM93300176 were in the group NER, and in the NENR group were genotypes Iraí, Jalo Precoce, and Novo Jalo. From a practical point of view, genotypes which produce high grain yield at a low level of K and respond well to added K are the most desirable because they are able to express their high yield potential in a wide range of K availability.

Effect of potassium application in rice (Oryza sativahwheat (Triticum aestivum) cropping system

Nine fertilizer treatments comprising levels, time of application and one control were evaluated on cultivators fields of western Uttar Pradesh to study the effect of potassium application in rice (Oryza sativa L.)-wheat [Triticum aestivum (L.) emend. Fiori, Paol.] cropping system. The highest values of yield attributes, yield, and N and K uptake were recorded at K,, irrespective of the time of K application in both the crops. Simultaneous application of nitrogen and potassium proved superior to lone application of nitrogen. The maximum K-use efficiency and benefit : The absolute cost ratio were obtained with .K,N, control treatment showd the lowest values of yield attributes, yield and N and K uptake in both the crops. The depletion of exchangeable K was more in K control (53-97 kg Klha) and low in the treatment receiving K (18-47 kg ma).

Differential responses to K deficiency among soybean cultivars

The seed yield per unit of potassium applied differed for five soybean cultivars which were grown to maturity under different K regimes in a glasshouse. Whereas Dodds was the most responsive cultivar to moderate increases in K supply, the cultivar Bragg was the most efficient in its ability to produce seed with low levels of available K; Lee and Forest were the least efficient cultivars while Bossier and Dodds were of intermediate efficiency. The basis for the efficiency of cv. Bragg was that the growth of its tops, as indicated by mature stem weights and its roots, were less affected by reduced K supply than those of other cultivars. This enabled it to produce more pods under K-deficient regimes, resulting in a greater seed yield per plant. The percentage reduction in oil/protein ratios in the seed of the five cultivars under moderate K deficiency correlated closely with reductions in seed yield. However, changes in this ratio were poorly related to the K percentages in the seed. All cultivars experienced an impairment of plant senescence under K deficiency as evidenced by a reduction in leaf abcission and a delay in pod maturity. The existence of genetic diversity in K-use efficiency means that breeding programmes could utilize K-efficient germplasm in developing new cultivars for soils not naturally high in potassium.

Contribution of rice straw to potassium supply in rice-fallow-rice cropping pattern

A field experiment was conducted through 2001-2004 at the Bangladesh Rice Research Institute (BRRI), Gazipur Farm with a view to determining the contribution of rice straw to K supply and K-use efficiency for the next crop in Rice-Fallow-Rice cropping pattern. Two levels of chemical potassium-0 (K0) and 66 kg K/ha (K66) from muriate of potash (MoP)- were tested with or without straw incorporation. Results showed that the use of K either from inorganic fertilizer or from rice straw increased the plant height, panicles/m2, grain and straw yields of rice in both Boro and T. Aman seasons. However, the effect of K was more distinct in Boro season. On an average, 1.33 t/ha yield benefit of Boro rice was obtained with rice straw incorporation in K0 plot. Application of K significantly increased the total K and P uptake of rice crops. Agronomic efficiency, partial factor productivity and physiological efficiency of K decreased with the increasing K level regardless of K sources in Boro season. Potassium replenishment through chemical fertilizer was not sufficient to balance K. However, incorporation of rice straw showed a positive K balance. Positive perceptible changes in soil characteristics and soil nutrient status (N, P and K) were observed due to K fertilization either from inorganic (MoP) or from organic sources. Key Words: Contribution of rice straw application; K-supply; rice-fallow-rice cropping pattern. DOI: 10.3329/bjar.v34i4.5839Bangladesh J. Agril. Res. 34(4) : 633-643, December 2009