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Rice (Oryza sativa L.) is the staple food for more than 50% world population and nitrogen (N) is one of the most yield-limiting nutrients for rice production worldwide. A greenhouse experiment was conducted to evaluate the efficiency of three N sources for lowland rice production. The N sources used were ammonium sulfate, common urea, and polymer-coated urea. There were three N rates, i.e. 100, 200, and 400 mg N kg−1 applied with three sources plus one control treatment (0 mg N kg−1). Growth, yield, and yield components were significantly increased either in a linear or quadratic fashion with the addition of N fertilizers in the range of 0-400 mg kg−1 soil. Maximum grain yield was obtained with the addition of ammonium sulfate at 100, 200, and 400 mg kg−1 of soil. Common urea and polymer-coated urea were more or less similar in grain production at 100 and 200 mg N kg−1. However, at 400 mg N kg−1 treatments, polymer-coated urea produced the lowest grain yield. Most of the growth and yield components were positively related to grain yield, except spikelet sterility which was negatively related to grain yield. Nitrogen use efficiency decreased with increasing N rate in all the three N sources. Maximum N use efficiency was obtained with the addition of ammonium sulfate at lower as well as at higher N rates compared with other two N sources. [ABSTRACT FROM AUTHOR]

The use of cultivar with nutrient-use efficiency is an important strategy in the management of plant nutritional status, particularly potassium (K), because its high demand and the progressive impoverishment caused by the use of inadequate amounts cause frequent deficiency symptoms observed in soybean [Glycine max(L.) Merrill] crops. This study was conducted in greenhouse conditions in a completely randomized design with four replicates in an Typic Quartzipsamment soil aimed to assess the effect of applying two rates of K (50 and 200 mg kg−1) on growth, shoot dry weight yield (SDWY) and seed yield (SY), nutritional status, yield components, and efficiency of K use in eleven cultivars of different characteristics and growth habits. The SDWY, SY, number of seeds per pod, number of pods, and estimated 100-seed weight showed significant interaction between cultivar and the K rates, with greater values at the rate 200 mg K kg−1. Similarly, the concentration of nitrogen (N), phosphorus (P), K, calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) in leaves and grains varied according to the K rates and in the cultivar. The most K-use efficient cultivars were BMX Magna RR, BRS 232, BRS 284, BRS 294RR, NA 5909RR, and Vmax RR, whereas FTS Campo Mourão RR was inefficient. Regarding response to fertilization, the cultivars Vmax RR, BMX Magna RR, NA 5909RR, BRS 284, and BRS 294RR were found to be efficient and responsive, whereas the cultivar FTS Campo Mourão RR, BRS 232, BMX Potência RR, BRS 295RR, TMG 1066RR, and TMG 1067RR are inefficient and responsive to K application in the soil. [ABSTRACT FROM AUTHOR]

Lowland rice significantly contributes to world as well as Brazilian rice production and information on genotypes potassium-use efficiency is limited. A greenhouse experiment was conducted with the objective to evaluate lowland rice genotypes for potassium (K)–use efficiency. Ten genotypes were evaluated at 0 mg K kg−1(low) and 200 mg K kg−1(high) of soil. Grain yield and shoot dry weight were significantly affected by K as well as genotype treatments. Genotypes CNAi 8860, CNAi 8859, BRS Fronteira, and BRS Alvorada were the best in relation to K-use efficiency because they produced best grain yield at low as well as at higher K levels. Shoot dry weight, number of panicles per pot, and 1000-grain weight had highly significant (P < 0.01) association with grain yield. Spikelet sterility, however, had significant negative association with grain yield. These plant parameters were mainly influenced by genotypes, indicating importance of selecting appropriate genetic material for improving grain yield. Soil K depletion was significant at harvest, suggesting large amount of K uptake by lowland rice genotypes. [ABSTRACT FROM PUBLISHER]

Rice is a staple food for about 50 percent of the world’s population. Potassium (K) is absorbed in large amounts by rice plants and adequate amounts of this element are fundamental to improve productivity and maintain sustainability of the cropping systems. A greenhouse experiment was conducted to determine the adequate rate of K for lowland rice grown on a Brazilian Inceptisol. The K rates used were 0, 50, 100, 200, 400, and 600 mg K kg−1soil. Most of the growth, yield, and yield components were significantly and quadratically increased with increasing K levels. Based on a quadratic equation, maximum grain yield was obtained with the addition of 371 mg K kg−1soil. Maximum plant height and shoot dry weight were obtained at 414 and 398 mg K kg−1soil, respectively. Root growth (maximum length and dry weight) was also significantly increased in a quadratic fashion with the increasing K rate in the growth medium. Maximum root length was achieved at 58 mg K kg−1whereas maximum root dry weight was obtained with the addition of 394 mg K kg−1soil. Plant height, shoot dry weight, 1000-grain weight, root length, and root dry weight were significantly associated with grain yield. Hence, manipulation of these growth and yield components with the addition of K fertilizer can improve yield of lowland rice in varzea soils of central part of Brazil. Potassium uptake increased significantly in a quadratic fashion with increasing K rate. However, K-use efficiency (mg grain per mg K applied) decreased significantly with increasing K rate in a quadratic fashion. Maximum grain yield was obtained with 117 mg kg−1Mehlich 1–extractable K, base saturation of 53 percent, Mg saturation of 9 percent, K saturation of 2 percent, and Ca/Mg ratio of 4. [ABSTRACT FROM AUTHOR]

Lowland rice is an important crop for humans, and information on potassium (K)–use efficiency for this crop is limited. A greenhouse experiment was conducted to evaluate agronomic characteristics of 12 lowland rice genotypes for K utilization. The K levels used were 0 mg kg−1(low, natural level of soil) and 300 mg kg−1(high). Plant height, straw yield, grain yield, panicle number, grain harvest index, 1000-grain weight, and spikelet sterility were significantly affected by K and genotypes treatments. The K × genotype interactions were significant for most of these growth, yield, and yield components, indicating that genotypes responded differently under two K rates. Furthermore, selection is possible for low as well as high K rates for lowland rice genotypes. Contribution of growth and yield components and agronomic efficiency in improving grain yield was in the order of agronomic efficiency > grain harvest index > 1000-grain weight > panicle number > shoot dry weight. There was significant decrease in soil K at harvest at low as well as at high K levels, indicating greater K requirements for lowland rice genotypes. Further, rice genotypes were significantly different in uptake and utilization of P, K, Al, and H+Al, as indicated by soil analysis at harvest. [ABSTRACT FROM PUBLISHER]

The magnesium (Mg) use efficiency in the selection of common bean (Phaseolus vulgarisL.) varieties may contribute to increased nutritional status and grain yield. Therefore, the present study aimed to assess common bean varieties following the application of Mg regarding productivity (yield), soil fertility, physiological components, and nutritional status. The experiment was conducted in a completely randomized design in a 5 × 2 factorial scheme with three replicates. Five common bean varieties [BRS Estilo, IPR Tangará, IPR Campos Gerais (CG), IAPAR 81, and BRS Ametista] supplemented with two Mg concentrations [low (0 mg kg−1) and high (100 mg kg−1)] using magnesium chloride (MgCl2) as a source in an Ustoxix Quatzipsamment were assessed. The yield of shoot dry weight (SDW) and grains varied significantly between varieties and Mg rates. The high Mg concentration has negatively affected the yield of SDW and grains of variety IPR Tangará, and the opposite was observed for the other varieties. The physiological components associated with photosynthesis are directly related to the yield of SDW and grains. The concentrations of phosphorus (P), calcium (Ca), sulfur (S), and boron (B) in leaves and of S, B, iron (Fe), and manganese (Mn) in grains differed among the varieties and interactions of rates and varieties for B, indicating the presence of genetic factors in nutrient uptake. [ABSTRACT FROM PUBLISHER]

Rice is a staple food for more than 50 percent world’s population. It is mainly grown under two ecosystems, known as upland and lowland. Soils on which these two types of rice are grown are mostly deficient in phosphorus (P). Two field experiments were conducted (one with upland rice and another with lowland rice) with the objective to determine responses of upland and lowland rice to two sources of P fertilizers. The P sources were mono-ammonium phosphate and polymer coated mono-ammonium phosphate. The P rates used in the two experiments were 25, 50, 100, and 200 kg P2O5 ha−1plus one control treatment. Plant height and grain yield of upland rice significantly increased with the addition of P fertilization. Similarly, plant height, straw yield, grain yield, panicle density, 1000-grain weight, P concentration, and uptake of lowland rice were significantly increased with the application of P fertilization. The response of these plant parameters to P fertilization was quadratic in nature. Rate of P for maximum growth, yield, and yield components varied for both upland and lowland rice. Maximum grain yield of upland rice was obtained with the addition of 108 kg phosphorus pentoxide (P2O5) ha−1by mono-ammonium phosphate and 105 kg P2O5 ha−1by polymer-coated mono-ammonium phosphate. Similarly, maximum grain yield of lowland rice was obtained with the addition of 143 kg P2O5by mono-ammonium phosphate and 151 kg P2O5by polymer-coated mono-ammonium phosphate. There were no significant differences between both the P sources for the growth, yield, and yield components of upland and lowland rice. Phosphorus-use efficiency defined in several ways decreased with increasing P rate in lowland rice. [ABSTRACT FROM AUTHOR]

Dry bean (Phaseolus vulgarisL.) is an important food legume for the South American population. In South America it is eaten every day by all sections of the population along with rice. The average yield of this legume is low in South America and use of inadequate rates of fertilizers, including potassium (K), is one of the main factors. A greenhouse experiment was conducted to evaluate thirty dry bean genotypes for K-use efficiency. The K rates used were 0 mg kg−1(low) and 200 mg kg−1(high). Soil used in the experiment was an Oxisol. There was a significant response of potassium level and genotypes for most of the growth, yield, and yield components. In addition, K × genotype interactions were also significant for most of the traits evaluated. The K × genotype significant interaction indicates different responses of dry bean genotypes to change in K levels. Based on grain yield efficiency index, genotypes were classified as efficient, moderately efficient, and inefficient in K-use efficiency. Grain yield showed a significant positive association with straw yield, number of pods per plant, number of grain per pod, root length, and grain harvest index. Overall, maximum grain yield was obtained with Mehlich 1–extractable 76 mg K kg−1soil and K saturation of 3.2 percent. [ABSTRACT FROM AUTHOR]

Dry bean is an important legume for human consumption worldwide. Low soil fertility, including zinc (Zn) deficiency, is one of the main factors limiting yield of this legume in South America, including Brazil. The objective of this study was to evaluate 30 dry bean genotypes for zinc (Zn)–use efficiency. The Zn rates used were 0 mg Zn kg−1(low) and 20 mg Zn kg−1(high) of soil. Grain yield, straw yield, number of pods, hundred-seed weight, number of seeds per pod, maximum root length, and rood dry weight were significantly affected by Zn and genotype treatments. The Zn × genotype interactions were also significant for growth, yield, and yield components, indicating that some genotypes were highly responsive to the Zn application while others were not. Based on seed yield efficiency index (SYEI), genotypes were classified as efficient, moderately efficient, and inefficient in Zn-use efficiency. Most efficient genotypes were CNFP 10104, BRS Agreste, BRS 7762 Supreme, CNFC 10429, BRS Estilo, CNFC 10467, BRS Esplendor, and BRS Pitamaba. The most inefficient genotype was BRS Executive. Remaining genotypes were moderately efficient in Zn-use efficiency. [ABSTRACT FROM AUTHOR]

Phosphorus (P) deficiency is one of the most yield-limiting factors in lowland rice production on Brazilian Inceptisol. The objective of this study was to evaluate eight P sources for lowland rice production. The P sources were simple superphosphate (SSP), polymer-coated simple superphosphate (PSSP), ammoniated simple superphosphate (ASSP), polymer-coated ammoniated simple superphosphate (PASSP), triple superphosphate (TSP), polymer-coated triple superphosphate (PTSP), monoammonium phosphate (MAP), and polymer-coated monoammonium phosphate (PMAP). These P sources were applied in four rates (i.e., 50, 100 200, and 400 mg P kg−1) + one control treatment (0 mg P kg−1). Plant height, straw yield, grain yield, panicle number, and root dry weight were significantly increased in a quadratic fashion with increasing P levels from 0 to 400 mg kg−1of all the P sources evaluated. However, overall maximum root length and P-use efficiency were significantly less at greater P levels. Based on regression equation, maximum plant height was obtained with 262 mg P kg, maximum straw yield was obtained with 263 mg P kg−1, maximum grain yield was obtained with 273 mg P kg−1, and maximum panicle density was obtained with 273 mg P kg−1. Plant growth and yield components had significant positive association with grain yield, except maximum root length. Based on grain yield and average P rate of maximum grain yield, which is 273 mg kg−1, P sources were classified for P-use efficiency in the order of PSSP = TSP > PTSP > PASSP > SSP > MAP > ASSP. Soil chemical properties [pH; P; potassium (K); calcium (Ca); magnesium (Mg); hydrogen (H) + aluminum (Al); cation exchange capacity (CEC); base saturation; Ca, Mg, and K saturation; acidity saturation; Ca/Mg, Ca/K, and Mg/K ratios] changed significantly with the addition of different P treatments. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is one of the most yield-limiting nutrients for upland rice production in Brazilian Oxisol soils. A field experiment was conducted for two consecutive years at the National Rice and Bean Research Centers Experimental Station Capivara with the objective to evaluate 10 promising genotypes of upland rice for N-use efficiency. The N rates used were 0 kg ha−1(low) and 100 kg ha−1(high). Plant height, shoot dry weight, grain yield, panicle number, and 1000-grain weight were significantly influenced by N and genotype treatments. Nitrogen × genotype interactions were not significant for most of the growth, yield, and yield components, indicating that differences among genotypes were consistent across N rates. Based on grain yield efficiency index (GYEI), genotypes were classified as N efficient or inefficient. Among 10 genotypes, four genotypes were efficient and six were moderately efficient in N use in the first year. In the second year, three genotypes were efficient and seven were moderately efficient in N use. Genotype BRA 052015 was classified as efficient in N use in both the years. Grain harvest index and GYEI had significant linear relationships with grain yield. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativaL.) is a staple food for more than 50% of the world’s population, and phosphorus (P) is one of the most yield-limiting nutrients for rice production in tropical acidic soils worldwide. A greenhouse experiment was conducted to evaluate efficiency of six P sources for upland rice production. The P sources used were simple superphosphate (SSP), polymer-coated SSP (PSSP), triple superphosphate (TSP), polymer-coated TSP (PTSP), monoammonium phosphate (MAP), and polymer-coated MAP (PMAP). There were four P rates [50, 100 200, and 400 mg phosphorus (P) kg−1] applied with four sources plus one control treatment [0 mg phosphorus (P) kg−1]. Plant height, straw yield, grain yield, panicle density, root dry weight, maximum root length, and 1000-grain weight were significantly increased with increasing P rates in the range of 0 to 400 mg P kg−1. However, P-use efficiency (mg grain produced per mg P applied) was decreased with increasing P rate. Based on regression equation, overall maximum plant height was obtained with the application of 235 mg P kg−1, maximum straw yield with the application of 265 mg P kg−1, and maximum grain yield at 227 mg P kg−1. Based on maximum grain yield, the P source were classified as PMAP > SSP = MAP > PSSP > TSP > PTSP in the upland rice production efficiency. Overall, maximum panicle density was obtained with the addition of 231 mg P kg−1and maximum 1000-weight was obtained with the addition of 226 mg P kg−1. Similarly, overall root dry weight and maximum root length were achieved with the application of 261 and 298 mg P kg−1of soil. Most of the growth and yield components had a significant positive association with grain yield. Optimum soil acidity indices such as pH; exchangeable calcium (Ca), magnesium (Mg), and potassium (K); Ca, Mg, and K saturation; base saturation; and acidity saturation were established for maximum upland rice grain yield. [ABSTRACT FROM PUBLISHER]

Rice is a main food crop for about half of the world's population, and phosphorus (P) is the main limiting nutrient in rice production in tropical lowlands. A greenhouse experiment was conducted to evaluate P requirements of lowland rice grown on a lowland soil (Inceptisol). Dry matter, grain yield, and yield-attributing characteristics were significantly (P< 0.01) influenced by P fertilization. Based on quadratic response, maximum shoot dry weight and grain yield were obtained with the application of 190 mg P kg−1of soil. Maximum panicle, tiller number, and plant height were obtained with the application of 177 192, and 175 mg P kg−1of soil, respectively. Mehlich 1–extractable P for maximum grain yield was 15.6 mg kg−1of soil. Variability in grain yield with plant growth and yield parameters was in the order of tiller > shoot dry weight > panicle number > spikelet sterility > plant height > grain harvest index > panicle length > weight of 1000 grains. Phosphorus uptake in shoot and concentration and uptake in grain significantly (P< 0.01) increased grain yield. However, variability in grain yield was greater with concentration and uptake of P in the grain. Similarly, P harvest index was also significantly associated with grain yield. Agronomic P-use efficiency, apparent P-recovery efficiency, and P-utilization efficiency decreased quadratically with increasing P rates, whereas physiological P-use efficiency increased quadratically and agrophysiological P-use efficiency decreased linearly with increasing P rates. Agrophysiological and utilization P-use efficiencies had significant positive correlation with grain yield. [ABSTRACT FROM AUTHOR]

Soybean is an important crop for the Brazilian economy, and soil acidity is one of the main yield-limiting factors in Brazilian Oxisols. A field experiment was conducted during three consecutive years with the objective to determine soybean response to liming grown on Oxisols. Liming rates used were 0, 3, 6, 12, and 18 Mg ha−1. Liming significantly increased grain yield in a quadratic trend. Ninety percent maximum economic grain yield (2900 kg ha−1) was achieved with the application of about 6 Mg lime ha−1. Shoot dry weight, number of pods per plant, and 100-grain weight were also increased significantly in a quadratic fashion with increasing liming rate from 0 to 18 Mg ha−1. These growth and yield components had a significant positive association with grain yield. Maximum contribution in increasing grain yield was of number of pods per plant followed by grain harvest index and shoot dry weight. Uptake of nitrogen (N) was greatest and phosphorus (P) was least among macronutrients in soybean plant. Nutrient-use efficiency (kg grain per kg nutrient accumulation in grain) was maximum for magnesium (Mg) and lowest for N among macronutrients. Application of 3 Mg lime ha−1neutralized all aluminum ions in soil solution. Optimal acidity indices for 90% of maximum yield were pH 6.0, calcium (Ca) 1.6 cmolckg−1, Mg 0.9 cmolckg−1, base saturation 51%, cation exchange capacity (CEC) 4.8 cmolckg−1, Ca/Mg ratio 1.9, Ca / potassium (K) ratio 5.6, and Mg/K ratio 3.0. [ABSTRACT FROM AUTHOR]

Rice is staple food for more than 50% of the world's population. Nitrogen (N) is one of the most yield-limiting nutrients for lowland rice production around the world. Two field experiments were conducted at two locations for two consecutive years to evaluate N-use efficiency of 12 lowland rice genotypes. Growth, grain yield, and yield components were significantly influenced by N as well as genotype treatments. Location × year × genotype and location × year × N interactions were significant for most of the growth, yield, and yield components, indicating influence of these factors on yield and yield components. Overall, the most N-efficient genotypes measured in terms of grain yield were BRA 031032, BRA 031044, and BRA 02654 and the most inefficient genotypes were BRS Jaçana, BRS Fronteira, and BRA 02674. Genotypes had linear and quadratic responses to added N in the range of 0 to 200 kg ha−1. Nitrogen significantly influenced plant height, shoot dry weight, panicle number, and 1000-grain weights. Nitrogen-use efficiency (kg grain per kg N applied) varied from 33 to 49 kg grain per kg N applied, with an average value of 40 kg grain per kg N applied. The genotype BRA 031044 produced the greatest N-use efficiency, and the lowest N-use efficient genotype was BRS Fronteira. There was a significant linear association between N-use efficiency and grain yield. [ABSTRACT FROM AUTHOR]

Soil acidity is one of the major yield constraints to crop production in various parts of the world. Quantifying optimum soil acidity indices is an important strategy for achieving maximum economic crop yields on acid soils. Five field experiments were conducted for three consecutive years using dry bean as a test crop on an Oxisol. The lime rates used were 0, 12, and 24 Mg ha-1 for creating a wide range of soil acidity indices in a no-tillage cropping system. Grain yield of dry bean was significantly increased by improving soil pH, base saturation, calcium (Ca), magnesium (Mg), and potassium (K) saturation and reducing aluminum (Al) saturation. These soil acidity indices were higher in the 0- to 10-cm soil layer than the 10- to 20-cm soil layer for maximum grain yield. Across two soil depths, optimum values for maximum bean yield were pH 6.5, base saturation 67%, Ca saturation 48%, and Mg saturation 19%. Bean yield linearly increased with increasing K saturation in the range of 1.5 to 3% across two soil depths. There was a significant linear decrease in grain yield with increasing Al saturation in the range of 0 to 8% across two soil depths. Optimal values of soil indices for maximum bean yield can be used as a reference for liming and improving yield of bean crop on Oxisols in a no-tillage cropping system. Yield components, such as pod number, grain per pod, and 100-grain weight were significantly improved with liming, and bean yield was significantly associated with these yield components. [ABSTRACT FROM AUTHOR]