Influence of Potassium Rates and Sources on Seed Cotton Yield and Yield Components of Some Elite Cotton Cultivars

Abstract

A field experiment was conducted at Central Cotton Research Institute, Multan, Pakistan on Miani soil series, silt loam soil (Calcaric, Cambisols and fine silty, mixed Hyperthermic Fluventic Haplocambids) to assess the response of four cotton (Gossypium hirsutum L.) cultivars to potassium (K) fertilization. The treatments consisted of four cotton cultivars (CIM-448, CIM-1100, NIAB-Karishma, S-12), four potassium rates (0, 62.5, 125, 250 kg K ha^?1), and two sources of potassium fertilizer [muriate of potash (KCl) and sulphate of potash (K₂SO₄)]. The cotton cultivars differed significantly in response to various potassium fertilizer levels and its sources with respect to seed cotton yield and its components. The highest yield was obtained with the application of 250-kg K ha^?1, however, it was economical to add 125 kg K ha^?1. Seed cotton yield of cv. CIM-448 was considerably greater than that of the other cultivars in K-unfertilized treatments, which was related to cultivar differences in K uptake efficiency in utilizing native potassium nutrient. Potassium added as muriate of potash caused a significant depression in seed cotton yield than that of sulphate of potash. The increase in yield seemed to have resulted largely from the higher K concentration of leaf tissues at bloom stage and available soil-K because of potassium application. A significant relationship between the yield and number of bolls per plant (r = 0.92**) and boll weight (r = 0.85**) indicated that these two growth attributes were responsible for enhancing the quantum of final harvest of seed cotton.     

Distribution profiles of dry matter and total nitrogen in leaves and stems of oriental field‐grown tobacco plants at different nitrogen levels

Oriental tobacco plants (Nicotiana tabacum L. cv Myrodata Agrinion) were grown without nitrogen (N) fertilization (N₀) and with added ammonium nitrate at a rate of 50 kg‐ha^‐1 (N₁) and 100 kg‐ha^‐1 (N₂). Non‐uniform patterns for leaf FW and DW changes per node showed a decreasing trend from lower to upper nodes during the vegetative stage. From approaching flowering to fruit set, these patterns became more uniform. Plants which were fertilized with N had increased leaf FW and DW accumulation levels and non‐uniform distribution patterns, primarily during the reproductive stage, and leaves of the lower nodes were found in the older plants. By contrast, the median values of leaf FW for the unfertilized plants were reduced during the reproductive period. The DW/FW×100 ratio values revealed a stable relationship between leaf FW and DW from the vegetative to the reproductive stage, while modified patterns of DW/FW×100 appeared later in the plant cycle. Nitrogen fertilization resulted in an early appearance of modified patterns of DW/FW×100 in the plant life cycle and higher accumulation of dry matter per unit leaf area. Patterns of total leaf N concentration showed an increasing trend from the lower to the upper nodes for all plant ages and treatments. Total N concentration values varied from 1.6%, 1.9%, and 1.8% on a dry matter basis, for the lower node up to 5.5%, 6.3%, and 6.1% for the upper node in young tobacco plants in the N _o , N₁, and N ₂ treatments, respectively. After fruit set, a more uniform distribution of total leaf N was observed among the leaves in all treatments. Concentration values for total leaf N in older plants varied from 1.9%, 2.1%, and 2.2% for the lower node up to 3.4%, 3.3% and 3.2% for the upper node in the N ₀ , N₁, and N₂ treatments, respectively. These results suggest a progressive decrease with plant age for total leaf N concentration in the plant as a whole. The increased N fertilizer level affected the total N level in young plants but not in the older ones. Inflorescence and fruit set periods are critical for plant N balance except for the plants which received the increased N fertilization. The determined total stem N concentration was less than that for the leaves. This change in the stem, similar to leaves, showed an increasing trend from the basal to the upper part and a decreasing trend from the vegetative to the reproductive stage. The total stem N level declined from 1.0–1.2%, 1.6–1.7%, and 2.2–2.9% on a dry matter basis to 0.5–0.6%, 1.0–1.2%, and 1.2–1.6% for the basal, middle, and upper part of the stem, respectively.     

Zinc Fertilization Impact on Irrigated Cotton Grown in an Aridisol: Growth,Productivity, Fiber Quality,and Oil Quality

Zinc (Zn) deficiency is widespread in calcareous soils. Therefore, we conducted a 2-year field experiment to investigate the impact of graded Zn levels on growth, yield, and fiber and oil quality of cotton (Gossypium hirsutum L., cv. CIM-473) grown in a calcareous Aridisol having 0.54 mg diethylenetriaminepentaacetic acid (DTPA)-extractable Zn kg^?1 soil. Zinc use increased boll bearing, boll weight, seed index, and seed cotton yield (P ≤ 0.05). Maximum yield increase was 15%, with 7.5 kg Zn ha^?1; however, greater Zn levels depressed yield. Leaf chlorophyll, membrane permeability, seed protein, and oil content and quality improved (P ≤ 0.05), and fiber quality remained unaffected with Zn use. Critical Zn concentration in cotton leaves was 36 mg kg^?1. Positive relationships of leaf Zn concentration were observed with boll weight, protein content, total unsaturated fatty acids, and fiber characteristics. Thus, Zn fertilization of low-Zn Aridisols is suggested for improving cotton productivity and seed quality.     

Vegetative and reproductive dry weight inhibition in nitrogen‐ and phosphorus‐deficient Pima cotton 1

Whether the extent of dry weight inhibition by nitrogen (N) or phosphorus (P) deficiencies on different plant parts is the same and whether imposing moderate N and P deficiencies selectively suppress undesirable vegetative growth has not been studied in Pima cotton (Gossypium barbadense L.). The purpose of this study was to determine the extent to which dry matter accumulation in leaves, stems, and reproductive structures is inhibited by N and P deficiencies in Pima cotton. The study was conducted in 1991 and 1992 in a Uvalde silty clay loam soil (fine‐silty, mixed, hyperthermic Aridic Calciustolls). The treatments included applied rates of 0, 67, 135, 202, and 269 kg N ha^‐1 in a factorial combination with 0, 15, 29, and 44 kg P ha^‐1. Nitrogen deficiency (0 kg N ha^‐1) significantly (P≤0.05) reduced leaf (LDW) and stem (SDW) dry weights in both years and reproductive dry weight (RDW) in 1992. Nitrogen deficiency suppressed dry weight accumulation in leaves to a greater extent than in stems. Relative to 269 kg N ha^‐1, the 0 kg N ha^‐1 treatment resulted in a maximum LDW reduction of 62% at 144 DAP (days after planting) in 1991 and 36% at 121 DAP in 1992, compared with a corresponding SDW reduction of only 39% in 1991 and 25% in 1992. Dry weight accumulation in reproductive parts was the least affected by N deficiency. The decline in LDW associated with senescence and defoliation began earlier in treatments that received 0 or 67 kg N ha^‐1 than treatments that received ≥135 kg N ha^‐1. Phosphorus affected LDW and SDW in 1991, but its differential effect on LDW, SDW, and RDW was much smaller than that of N. Imposing a moderate level of N deficiency, not P deficiency, may be an effective Pima cotton management strategy to selectively suppress undesirable vegetative growth and enhance maturity.     

NITROGEN RATES AND ITS TIME OF APPLICATION INFLUENCE DRY MATTER PARTITIONING AND GRAIN YIELD IN MAIZE PLANTED AT LOW AND HIGH DENSITIES

Best nitrogen (N) management practices are most important for increasing maize (Zea mays L.) productivity and profitability in Northwest Pakistan. Field experiments were performed at the New Developmental Research Farm of NWFP Agricultural University, Peshawar during summer 2002 and 2003. Factorial experimental treatments were two plant densities (D₁ = 60,000 and D₂ = 100,000 plants ha^?1) and three N rates (N₁ = 60, N₂ = 120 and N₃ = 180 kg N ha^?1) as main plots, and six split N applications in different proportions at different growth stages of maize (cv. ‘Azam’) in two equal, three equal, three unequal, four equal, five equal and five unequal splits at sowing and with first, second, third, and fourth irrigation at two week intervals as subplots. Application of the higher N rate (180 kg ha^?1) with 4 to 5 splits significantly increased leaf, stem, ear, and total plant dry weight at silking and physiological maturity as well as grain yield plant^?1 at both low and high plant densities. Variation in dry matter partitioning and grain yield in maize due to fluctuation in the rainfall data of the two years suggests zonal specific effective N management practices for sustainable maize production in different agro-ecological zones of Northwest Pakistan.     

Differences in Growth and Potassium-Use Efficiency of Two Cotton Genotypes

To study the differences in growth and potassium (K)–use efficiency of two different K-use-efficiency cotton genotypes, a pot experiment was conducted in 2007. Experimental materials include two cotton genotypes (HG103 and LG122) and two K application levels (0 and 0.23 g kg^–1 soil). The initial dates of various growth stages, plant heights, numbers of leaves, squares, and bolls, and the amount of litter during the whole growing season were recorded. The distribution and accumulation of dry matter and K content in various organs were measured to compare the differences in K-use efficiency. Significant differences (P < 0.05) between the two genotypes and K levels were found in initial bolling time. At the reproductive growth stage, the plant heights and leaf number of HG103 were less than those of LG122. Greater numbers of squares and bolls were recorded from HG103 than LG122 with K application. Significant differences (P < 0.05) existed in dry matter and K contents in each organ in the two genotypes and K-application levels. The seed cotton yields of HG103 were 3.24 times larger than those of LG122 with K application and 1.77 times larger than those of LG122 with the marginal K treatments. Reproductive-to-vegetative ratios (RVR) and harvest indices (HI) of LG122 were less than those of HG103 whether K was applied or not. The ratios of K in reproductive organs to vegetative organs for LG122 were 0.47 and 0.51 with K application and the marginal treatments, respectively, and for HG103 were 0.66 and 0.75 respectively. The K accumulations in root, stem, and litter of LG122 were more than those of HG103, whereas those in leaves and bolls were less than those of HG103. These results indicated that HG103 transferred more photosynthesis products and K to cotton reproductive organs than LG122.     

Critical nitrogen content and nitrogen nutrition index for sweetpotato crop

Abstract

Sweetpotato is an important tuber crop for the food security in Island countries of the South Pacific. The allometric relationship between tissue nitrogen (N) concentration and aerial dry matter is unknown. We determined critical N (N_c) content from vegetative stage to harvesting, and estimated the range of variation in N nutrition index (NNI) from two field experiments with varied rates of N (0, 25, 60, 125 and 180?kg N ha^?1 in 2015 and 0, 50, 125, 175 and 250?kg N ha^?1 in 2017). A unified critical N curve (N_c = 3.338?W^?0.307) where W?=?aerial dry matter with W?≥?1.38 t ha^?1, was constructed based on the N concentration in the aerial dry matter. The calculated NNI ranged from 0.69 to 1.23 in 2015 and 0.54 to 1.17 in 2017. The preliminary N_c dilution curve and NNI determined could potentially be used as a parameter for N management.     

Dry Matter,Nitrogen, Phosphorous,and Potassium Partitioning,Accumulation, and Use Efficiency in Transgenic Cotton-Based Cropping Systems

A better understanding of the fate of nutrients in transgenic cotton (Gossypium hirsutum L.) fields will improve nutrient efficiencies, will optimize crop growth and development, and may help to enhance soil quality. A study was made to evaluate and quantify the effect of cropping system [sole cotton and groundnut (Arachis hypogaea) intercropping with transgenic cotton] and nitrogen (N) management [control (0N), 100% recommended dose of nitrogen (RDN) through urea, substitution of 25% RDN through farmyard manure (FYM), and substitution of 50% RDN through FYM] on dry matter (DM) and nutrient partitioning and accumulation by transgenic cotton and groundnut at New Delhi during 2006–2007. Soil and plant samples were collected and analyzed at 60, 90, and 120 days after sowing and at harvest. Results revealed that intercropping of groundnut with cotton did not significantly affect DM and nutrient partitioning in cotton, but residual soil fertility in terms of potassium permanganate (KMnO₄) N showed an improvement in contrast to Olsen's P and ammonium acetate (NH₄OAc)–exchangeable K over sole cotton. At harvest, of total DM assimilated, leaves constituted 10–20%, stem 50%, and reproductive parts of cotton accounted for the rest. For each kilogram of seed cotton produced, the crop assimilated 61 g of N, of which 23 g was partitioned to harvested seed cotton. Substitution of 25% RDN through FYM, being on par with 100% RDN through urea, recorded greater DM, nutrient uptake in different parts of cotton, agronomic N-use efficiency (9.5 kg seed cotton kg N^?1), and apparent N recovery (83.3%) over 50% RDN substitution through FYM and control. The control, being on par with 50% RDN substitution through FYM, recorded significantly greater DM and nutrient uptake by intercropped groundnut over other treatments. Apparent N and potassium (K) balance at the end of study was negative in all treatments; however, the actual change in KMnO₄ N was positive in all the treatments except control. Our study suggests that intercropping of groundnut with transgenic cotton and substitution of 25% dose of N through FYM is sustainable in tropical countries.     

杂交棉与常规棉干物质积累和氮磷钾吸收分配及产量比较

利用田间试验,研究了杂交棉豫杂35和常规棉中棉41在施N 225、P2O 5 90、K2O 135 kg/hm2条件下的干物质积累和氮磷钾吸收分配及产量形成特点。结果表明,杂交棉和常规棉的干物质及氮磷钾的阶段积累量变化趋势基本相同;而杂交棉的干物质和氮磷钾在各时期的积累量和日积累强度均明显高于常规棉。随着生长发育进程杂交棉后期干物质和氮磷钾的阶段积累比例比常规棉的高,表明杂交棉在后期有较强的生长和积累的优势。所以,加强杂交棉的后期管理能更好的发挥其增产潜力。杂交棉和常规棉的干物质和氮磷钾在各器官的分配,均表现随生长发育转向生殖器官的比例不断提高,但杂交棉略高于常规棉。在本试验条件下,杂交棉皮棉产量1778.23 kg/hm2,一生吸收 N、P2O5、K2O总量分别为 242.92、82.12、247.76 kg/hm2,N∶P2O5∶K2O=1∶0.34∶1.02;常规棉皮棉产量1377.21 kg/hm2,一生吸收 N、P2O5、K2O总量分别为195.42、65.64、194.09 kg/hm2,N∶P2O5∶K2O=1∶0.34∶0.99。     

Dry matter production,nutrient uptake,and growth of cotton as affected by potassium fertilization

Insufficient potassium (K) nutrition produces detrimental effects on cotton (Gossypium hirsutum L.) lint yield and fiber quality. To further understand the deleterious effects caused by K deficiency, a 2‐yr (1991 and 1992) field study was conducted to determine how dry matter partitioning and nutrient concentrations of various plant tissues for the cotton genotypes, ‘DES 119’ and ‘MD 51 ne’, were altered by varying the application rate of fertilizer K and nitrogen (N). All plots received a preplant application of 112 kg N ha^‐1, and half of the plots were later sidedressed with an additional 38 kg N ha^‐1. Within each N treatment, half the plots received 112 kg K ha^‐1, preplant incorporated, with the remaining plots not receiving any fertilizer K. Dry matter harvests were taken three times in 1991 and two times in 1992. At cutout (slowing of vegetative growth and flowering), plants that received K fertilization had a 14% more leaf area index (LAI), a 3% increase in the number of main stem nodes, and a 2% increase in plant height. However, those plants had a 12% lower specific leaf weight (SLW) than plants receiving no K fertilization. By the end of season, the of K fertilization had resulted in more stem (21%), bur (13%), seed (19%), and lint weight (20%), but harvest index was not affected. Varying the level of N fertilization did not affect any of these dry matter parameters at any harvest. In general, the larger plants produced under K fertilization had reduced concentrations of N, phosphorus (P), magnesium (Mg), and sodium (Na) in the various plant parts. While N uptake efficiency was not affected by K fertility, plants that received K fertilization had increased efficiency of fertilizer N use and of N utilization within the plant. The smaller LAI of the K deficient plants probably reduced the photosynthetic capacity per plant. A reduced assimilation capacity could explain the inefficiency of N use, lint yield reductions, and poorer fiber quality often associated with K deficiencies.     

Boron Requirement of Irrigated Cotton in a Typic Haplocambid for Optimum Productivity and Seed Composition

Boron (B) deficiency hampers cotton (Gossypium hirsutum L.) growth and productivity globally, especially in calcareous soils. The crop is known as a heavy feeder of B; however, its reported plant analysis diagnostic norms for B-deficiency diagnosis vary drastically. In a 2-year field experiment on a B-deficient [hydrochloric acid (HCl)–extractable 0.47 mg B kg^?1], calcareous, Typic Haplocambid, we studied the impact of soil-applied B on cotton (cv. CIM-473) growth, productivity, plant tissue B concentration, and seed oil composition. Boron was applied at 0.0, 1.0, 1.5, 2.0, 2.5, and 3.0 kg B ha^?1, as borax (Na₂B₄O₇·10H₂O), in a randomized complete block design with four replications, along with recommended rates of nitrogen (N), phosphorus (P), potassium (K), and zinc (Zn). Boron use improved crop growth, decreased fruit shedding, and increased boll weight, leading to seed cotton yield increases up to 14.7% (P < 0.05). Improved B nutrition of plants also enhanced seed oil content (P < 0.05) and increased seed protein content (P < 0.05). Fiber quality was not affected. Fertilizer B use was highly cost-effective, with a value–cost ratio of 12.3:1 at 1 kg B ha^?1. Fertilizer B requirement for near-maximum (95% of maximum) seed cotton yield was 1.1 kg B ha^?1 and HCl-extractable soil B requirement for was 0.52 kg ha^?1. Leaf tissue B requirement varied with leaf age as well as with plant age. In 30-day plants (i.e., at squaring), B-deficiency diagnosis critical level was 45.0 mg kg^?1 in recently matured leaves and 38.0 mg kg^?1 in youngest open leaves; at 60 days old (i.e., at flowering), critical concentration was 55.0 mg kg^?1 in mature leaves and 43.0 mg kg^?1 in youngest leaves. With advancement in plant age critical B concentration decreased in both leaf tissues; that is, in 90-day-old plants (i.e., at boll formation) it was 43.0 mg kg^?1 in mature leaves and 35.0 mg kg^?1 in the youngest leaves. As critical concentration range was narrower in youngest leaves (i.e., 35–43 mg kg^?1) compared with mature leaves (i.e., 43–55 mg kg^?1), B concentration in youngest leaves is considered a better indicator for deficiency diagnosis.     

Effects of long-term mineral fertilization on microbial biomass,microbial activity,and the presence of <Emphasis Type="Italic">r</Emphasis>- and <Emphasis Type="Italic">K</Emphasis>-strategists in soil

Long-term effects of mineral fertilization on microbial biomass C (MBC), basal respiration (R _B), substrate-induced respiration (R _S), β-glucosidase activity, and the r–K-growth strategy of soil microflora were investigated using a field trial on grassland established in 1969. The experimental plots were fertilized at three rates of mineral N (0, 80, and 160 kg ha⁻¹ year⁻¹) with 32 kg P ha⁻¹ year⁻¹ and 100 kg K ha⁻¹ year⁻¹. No fertilizer was applied on the control plots (C). The application of a mineral fertilizer led to lower values of the MBC and R _B, probably as a result of fast mineralization of available substrate after an input of the mineral fertilizer. The application of mineral N decreased the content of C extracted by 0.5 M K₂SO₄ (C _ex). A positive correlation was found between pH and the proportion of active microflora (R _S/MBC). The specific growth rate (μ) of soil heterotrophs was higher in the fertilized than in unfertilized soils, suggesting the stimulation of r-strategists, probably as the result of the presence of available P and rhizodepositions. The cessation of fertilization with 320 kg N ha⁻¹ year⁻¹ (NF) in 1989 also stimulated r-strategists compared to C soil, probably as the result of the higher content of available P in the NF soil than in the C soil.     

Yield formation of five crop species under water shortage and differential potassium supply

A long‐term field experiment on a Haplic Phaeozem, established 1949 with four levels of potassium (K) supply (5, 69, 133, and 261 kg K ha^?1), was analyzed for the interaction between K supply and yield loss of five crop species by water shortage. The crop species were cultivated simultaneously side‐by‐side in the following rotation: potato (Solanum tuberosum L.), silage maize (Zea mays L.), spring wheat (Triticum aestivum L.), beet (Beta vulgaris L.), and spring barley (Hordeum vulgare L.). The treatment with 133 kg K ha^?1 supply had a nearly balanced K budget. In the treatments with lower supply, the soil delivered K from its mineral constituents. On the low‐K plots (especially on those with only 5 kg K ha^?1), crops suffered yield depressions of nearly all main harvest products (cereal grains, potato tubers, beet storage roots, silage maize) and by‐products (straw, beet leaves) by up to 40.7% of dry matter. Only wheat grains were an exception. Potassium concentrations in the harvested plant parts decreased nearly in parallel to the reduction of their dry matter yields, with the exception of cereal grains, which kept stable concentrations even in the treatment with only 5 kg K ha^?1. A comparison of four year‐pairs with differing levels of precipitation in yield‐relevant periods showed an average water shortage‐induced depression of dry matter yields by 19.7% in the main harvest products. The severity of this yield depression was not mitigated by elevated K supply, with the exception of beet leaves, where the dry matter production was stabilized by high K supply. In this crop, the reduction of storage‐root yield was associated with a decrease in harvest index and was therefore obviously caused by an inhibition of assimilate translocation from the leaves into these organs, in contrast to cereals, where water shortage primarily affected dry matter production in vegetative organs. It is concluded that the physiological causes of yield reduction by drought stress and the possibility of its amelioration by K supply differ between plant species and organs.     

Field evaluation of N2 fixation and N partitioning in climbing bean (Phaseolus vulgaris L.) using 15N

Summary The common bean (Phaseolus vulgaris L.) is generally regarded as a poor N₂ fixer. This study assessed the sources of N (fertilizer, soil, and fixed N), N partitioning and mobilization, and soil N balance under field conditions in an indeterminate-type climbing bean (P. vulgaris L. cv. Cipro) at the vegetative, early pod-filling, and physiological maturity stages, using the A-value approach. This involved the application of 10 and 100 kg N ha^-1 of ¹⁵N-labelled ammonium sulphate to the climbing bean and a reference crop, maize (Zea mays L.). At the late pod-filling stage (75 days after planting) the climbing bean had accumulated 119 kg N ha^-1, 84% being derived from fixation, 16% from soil, and only 0.2% from the ¹⁵N fertilizer. N₂ fixation was generally high at all stages of plant growth, but the maximum fixation (74% of the total N₂ fixed) occurred during the interval between early (55 days after planting) and late podfilling. The N₂ fixed between 55 and 75 days after planting bas a major source (88%) of the N demand of the developing pod, and only about 11% was contributed from the soil. There was essentially no mobilization of N from the shoots or roots for pod development. The cultivation of common bean cultivars that maintain a high N₂-fixing capacity especially during pod filling, satisfying almost all the N needs of the developing pod and thus requiring little or no mobilization of N from the shoots for pod development, may lead to a net positive soil N balance.     

Response of Cotton and Wheat Cultivars to Soil-applied Boron in a Boron-deficient,Noncalcareous Typic Ustochrept

Field experiments were conducted to study the response of cotton genotypes (G. arboreum Bt cv. RCH 650 BGII; non-Bt cv. F 2228; G. herbaceum cv. FDK 124) and wheat and triticale genotypes (T. aestivum cv. PBW 622; T. durum cv. PDW 314; triticale cv. TL 2908) to direct and residual B application (0, 0.5, 1.0, and 2.0 kg B ha^?1 as borax) using a Typic Ustrochrept, neutral, noncalcareous, loamy sand and B-deficient soil. A significant response of 218 and 231 kg ha^?1 in seed cotton yield was recorded with an application of 1.0 kg B ha^?1 to cotton and 2.0 kg B ha^?1 to wheat. A significant response of 152 kg ha^?1 grain yield of wheat was observed with the application of 0.5 kg B ha^?1 to wheat, while no residual effect of B was observed when B was applied to cotton. On the basis of agronomic and B uptake efficiency, genotypes of cotton (RCH 650 BG II > FDK 124 > F 2228) and wheat (PDW 314> TL 2908> PBW 621) responded differentially to B application, thus indicating that yield of Bt cotton and durum wheat will be reduced more than the other cultivars under B deficiency.     

Effect of nitrogen rates applying controlled-release and conventional urea blend in maize

Abstract

Blending polymer-sulfur coated urea (PSCU) and conventional urea (U) for maize (Zea mays L.) fertilization can supply nitrogen (N) during the crop cycle with a single application. Proper placement of PSCU?+?U (0.15?m below and 0.1?m to the side of seed row) in band application at sowing is necessary to reduce salt stress that can decrease dry weight (DU) and N uptake (NU) of maize plant compromising maize yield. It is not clear the proper N rate in the proper placement for band application of PSCU?+?U at maize sowing to avoid salt stress. In the current literature, reduction of N rates are being recommended using PSCU?+?U without consider the probably salt stress provided by high rates of PSCU?+?U. DW and NU in maize plant as well as soil pH and electrical conductivity (EC) were evaluated in a greenhouse pot trial. N treatments were equivalent to 0, 90, 180, 360 and 540?kg N ha^?1 applied incorporated in band in two contrasting soils (Rhodic Eutrustox and Typic Haplustox) using 70%PSCU + 30%U. At V10 (vegetative leaf stage 10), DW and NU of maize aerial part had quadratic behavior in response to increase N rates in the Typic Haplustox soil. In the Rhodic Eutrustox was not observed known behavior for DW and NU in response to increase N rates. Soil pH and EC was higher in the fertilizer row than sowing row. A N rate above of 180?kg N ha^?1 using 70%PSCU + 30%U incorporated in bands can reduce DW and NU in early maize plant growth associated with salt concentration of N fertilizer in a Typic Haplustox soil, which could compromise maize yield.     

Bio‐inoculant improves nitrogen‐use efficiency and cotton yield in saline soils

Improved nutrient‐use efficiency is important to sustain agricultural production. The goal of our study was to investigate the effects of Azovit® (Azotobacter chroococcum) inoculation of seed with N fertilization on crop yield, nutrient uptake, and N‐use efficiency (NUE) of irrigated cotton (Gossypium hirsutum L. cv. C‐6524) in secondary saline soil under continental climatic conditions of Uzbekistan. A randomized complete block design in a 4 × 2 split‐plot experiment was established in the fall of 2013. The main plot was N fertilization (0, 140, 210, and 280 kg ha^?1) and the subplot was Azovit inoculation. Azovit inoculation consistently increased the seed and lint yields of cotton by 25 and 27.9%, respectively, at 210 kg N ha^?1 compared to the respective control. Azovit with 210 kg N ha^?1 significantly increased the cotton harvest index by 21%, when compared to the control. Likewise, nutrient uptake and NUE of cotton were higher when N (210 kg ha^?1) was applied with Azovit, as compared to other treatment combinations. An extrapolation of the relationship of relative yield vs. N fertilization showed that Azovit at 210 kg N ha^?1 was sufficient to obtain near‐maximum cotton production (90%) with highest NUE, as compared to the respective control. The results suggest that Azovit with 210 kg N ha^?1 produces cotton yield higher and/or comparable with the currently used rates of 280 kg N ha^?1 or higher, suggesting savings of 70 kg N ha^?1 for cotton production in saline soils under continental climatic conditions.     

Nitrogen and Potassium Fertilization Responses of Potato (Solanum tuberosum) cv. Spunta

A potato field experiment was conducted for 2 consecutive years to determine the effects of nitrogen (N) and potassium (K) fertilization rates on the yield and quality of potato cv. Spunta cultivated on soil low in N and K. A 3?×?4 complete factorial experiment was used with three rates of nitrogen (330, 495, and 660 kg N ha^–1) and four rates of potassium (112, 225, 450, and 675 kg K₂Ο ha^–1). An additional treatment without fertilization was used as the control. On soils low in N and K, potatoes showed low yield response to K fertilizer. The greatest tuber yields for both years were achieved at 495 kg N ha^–1 and 112 kg K₂O ha^–1 (29.81 t ha^–1) and 225 kg ha^–1 (27.13 t ha^–1), respectively. Differences in mean fresh weight due to treatment application were not significant. Application of 495 kg N ha^–1 significantly reduced harvest index (the ratio of tuber dry weight to the total dry weight at harvest) compared to 330 kg N ha^–1, but at 660 kg N ha^–1 harvest index achieved the greatest significant value. Potassium fertilization had no significant influence on harvest index. Nitrogen rates positively influenced the number of tubers. The addition of 450 kg K₂O ha^–1 significantly enhanced the number of tubers compared to the lower K rates, and the number was significantly decreased by the application of 675 kg K₂O ha^–1. Tuber dry-matter concentration was significantly promoted by N fertilization in both cultivation years, but it was negatively affected by K fertilization in the first year of cultivation. There was no change in tuber N with N application, but N application strongly increased nitrate (NO₃) concentration, which fluctuated between 360 and 1382 mg kg^–1 wet mass. Tuber NO₃ was negatively correlated with tuber yield, indicating that high levels of NO₃ in tubers can adversely affect yield. Tuber response to K fertilization was not in accordance with the rate of applied nutrient.     

Phosphorus–microbes interaction on growth,yield and phosphorus-use efficiency of irrigated cotton

The phosphorus-use efficiency of crops in high pH soil is low. A randomized complete block design in a 3 × 2 split-plot experiment was conducted on a high pH silt loam (Typic Ustochrepts) to evaluate whether P-solubilizing microbial (PSM) inocula were able to improve the P fertilization effects on irrigated cotton (Gossypium hirsutum L., cultivar CIM-482). Cotton was planted after seed treatment with PSM inoculation at 0, 22 and 44 kg P ha^?1. Results showed that soil microbial populations were significantly higher throughout the cotton-growing season in response to P fertilization and PSM inoculation. Both P fertilization and PSM inocula exerted a significant effect on cotton biomass and Puptake without an interaction. Economic analyses suggest that PSM inocula alone significantly increased P-use efficiency (8%), reduced cost and improved net income (by $36 ha^?1) of irrigated cotton production. Moreover, the relationship between relative yield and P fertilization with PSM inocula showed that 95% of the maximum yield of cotton was produced at 22 kg P ha^?1, whereas in the absence of PSM inocula, 95% relative yield was obtained at 36 kg P ha^?1, asaving of ～39% applied P with PSM inoculation.     

Potassium accumulation,partitioning, and remobilization in high-yield spring maize in Northeast China

Potassium (K) plays an important role in maize yield, but K accumulation characteristics in high yielding maize is still not well documented. A two-year field experiment was conducted to investigate the K accumulation characteristics of high yield (HY)（>15 t ha^?1）spring maize compared with medium yield (MY)（10–15 t ha^?1), and low yield (LY)（<10 t ha^?1). The maximum K accumulation stage in maize appeared between V6 and V12 stage (LY, MY, and HY was 125.46, 138.05, and 146.22?kg ha^?1, respectively). Most of the K (94.27–97.13%) was accumulated during vegetative stages. HY exhibited a significantly higher K accumulation than either MY or LY. For different organs, the K remobilization amount of leaf was the highest, and the remobilization amount of stalk was the lowest, the K remobilization amount of leaf and stalk showed as HY?<?MY?<?LY, same as the total K remobilization amount, but the K remobilization amount of sheath and husk plus cob showed the opposite order. These results indicated that sufficient nutrient supply for maize can not only accumulate more K but also delay leaf senescence and maintain high photosynthetic activity, resulting in reduced K remobilization from vegetative organs, and reduced K loss in whole plant.