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1.
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.  相似文献   

2.
A better understanding of the impact of fertilizer nitrogen (N) on biomass and N accumulation, and their partitioning into different plant components is needed to optimize crop yield and quality. A field experiment with spring wheat (Triticum aestivum), hulless (Avena nuda), and hulled (Avena sativa) oats was conducted for 3 years in Ottawa, ON, Canada, to determine the crop responses to N addition (0, 75, and 150 kg N ha–1). Biomass, N, and phosphorus (P) accumulation and partitioning into different plant components were examined during the growth season. Lodging score was determined for all crops when it occurred and again at harvest. During the growth season, both hulless and hulled oats and the wheat cultivar showed almost similar patterns of N and P accumulation with maximum contents at late grain filling or at harvest. Plant N concentration was up to 60 g kg–1 during the seedling stage, decreased gradually with advancing growth stages, and was lowest at harvest. Nitrogen treatments significantly increased plant N and P contents. At heading stage, N treatments enhanced dry matter (24%–45%), N (35%–135%), and P (27%–45%) contents in plant components (i.e., culm, leaf, and head), but also enhanced crop lodging, especially in oats. Both hulled and hulless oats had higher total plant N (5%–35%), N : P ratio, and dry‐matter content in leaf (6%–43%) and head (0%–129%) along with higher P (up to 27%) in culm than the wheat cultivar. The wheat cultivar accumulated greater dry matter and higher N content in kernels than both hulled and hulless oats at harvest. Both hulled and hulless oat cultivars exhibited similar lodging susceptibility to N addition (75 or 150 kg N ha–1), produced lower dry weight and lower kernel N, and hence lower grain yield than the wheat cultivar. The larger vegetative dry‐matter accumulation at heading coupled with higher P content in culms under high‐N‐supply conditions may be related to severe lodging in oat cultivars.  相似文献   

3.
The differential response of two contrasting cassava cultivars to different rates of soil‐applied nitrogen (N) on the number of tuberous roots, harvest index, yield, nitrogen uptake, and fertilizer‐nitrogen‐use efficiency was studied over a period of 2 years on a typic Plinthustults in Kerala state in Southern India. The experiment was laid out in a split‐plot design with two popular cultivars of cassava, namely Sree Vijaya (6 months) and M‐4 (10 months) in the main plots, and eight urea‐N rates (0, 12.5, 25, 50, 75, 100, 150, and 200 kg ha–1) in subplots. Half of the N was applied at the time of planting and the other half 60 d later. The study revealed significant differences between the two cultivars regarding their response to fertilizer‐N application. The tuberous‐root yield of the short‐duration cultivar Sree Vijaya increased significantly up to 100 kg N ha–1 whereas the yield of the long‐duration cultivar M‐4 increased significantly only up to 50 kg N ha–1 rate. Also the N‐use‐efficiency parameters (i.e., agronomic, recovery, and physiological efficiencies) were higher in Sree Vijaya than in M‐4 but declined at N rates beyond 100 kg ha–1. The more efficient N use in the short‐duration cultivar was associated with a higher N uptake and a more efficient internal use.  相似文献   

4.
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.  相似文献   

5.
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.  相似文献   

6.
Accumulation of dry matter and plant nutrients by perennial grass over the growing season is dependent upon harvest interval and availability of water and applied nutrients. Mathematical models are frequently incorporated in the analysis, design, and operation of systems for land application of reclaimed water (municipal or agricultural). The objective of the present work was to measure response of warm‐season Coastal bermudagrass [Cynodon dactylon (L.)] to irrigation with reclaimed municipal wastewater and to evaluate parameters for a simplified model. Grass was harvested at intervals of 2, 4, and 6 wk. Measurements included yields (dry matter and digestible organic matter) and plant nutrient uptake (N, P, and K). The probability model described time trends rather well. The linear model parameter A showed linear dependence on harvest interval At over the range studied, in agreement with results from the literature. Maximum values for a harvest interval of 6 wk were 16.5 Mg ha‐1 (dry matter), 8.0 Mg ha‐1 (digestible organic matter), 350 kg N ha‐1,57 kg P ha‐1, and 272 kg K ha‐1.  相似文献   

7.
Many of the poorly drained clayey soils of the Mississippi River delta region in Arkansas are used for soft red winter wheat (Triticum aestivum L.) production. Oftentimes, excessive rainfall occurs between the last N application and physiological maturity, resulting in soil conditions conducive to denitrification. Studies were conducted in 1989 and 1990 to evaluate late N applications on five wheat cultivars on a Sharkey silty clay (very fine, montmorillonitic, nonacid, thermic, Vertic Haplaquepts) at Keiser, AR. A linear‐move irrigation system was used to maintain excessive soil moisture conditions throughout the spring growing season to best insure denitrification conditions. After the recommended spring N was applied, N as urea was applied at rates of 0, 34, and 68 kg ha‐1 at growth stage (GS) 9 in 1989 and GS 10 in 1990. Ammonium nitrate was also evaluated at the 34 kg N ha‐1 rate. Grain yield, yield components, whole‐plant N concentration, grain N content, and whole‐plant N uptake were evaluated. Grain yield increased each year with late N applications. The optimum N rate was 34 kg ha‐1 with no difference between the N sources, urea and ammonium nitrate. The yield component accounting for this grain yield increase were kernels per spike in 1989 and kernel weight and kernels per spike in 1990. Whole plant N concentration increased each year and grain N content increased in 1990 with the late N application. The N sources affected N nutrition similarly.  相似文献   

8.
Legumes grown for grain may or may not contribute net N benefits to soil and succeeding crops. An experiment was conducted to assess N2 fixation attributes of six mungbean cultivars and two groundnut cultivars (Tainan 9 and Non-nod), which determine their residual benefit to the subsequent maize. Nodule number and dry weight of mungbeans peaked early (at 45 days) and declined thereafter strongly. In groundnut nodulation peaked later and declined only by 50% towards the final harvest. The N2-fixing groundnut produced higher total dry matter yield than mungbeans; however, mungbeans produced higher seed yields. Dry matter harvest index and nitrogen harvest index (NHI) were higher in mungbeans (average 0.44 and 0.69) than groundnut (0.23 and 0.47, respectively, in Tainan 9). The percentage of nitrogen derived from air (%Ndfa, 15N isotope dilution) ranged from 54% to 62% in mungbeans, similar to that of groundnut (64%). However, Tainan 9 fixed more N2 (82 kg N ha–1) than mungbeans (35–50 kg N ha–1) and resulted in a positive soil net N balance (+22 kg N ha–1) while negative values were found for Non-nod groundnut and mungbeans (–3 to –12 kg N ha–1). Maize grown after groundnut Tainan 9 had the highest total dry weight and total N uptake. This was equivalent to maize grown in fallow plots, which received 60–90 kg N ha–1, while the respective benefits after mungbeans were 30–60 kg N ha–1. Maize yield was directly related to the amount of residue N returned. Thus, the combination of high N yield, residue quality, %Ndfa and low NHI proved most beneficial to soil fertility and the succeeding crop.  相似文献   

9.
Abstract

Field experiments were conducted for periods of 14 or 15 years at four sites on Thin Black Chernozemic soils in south‐central Alberta to determine the effect of source and time of N application on dry matter yield (DMY), protein yield (PY), protein concentration, N use efficiency and recovery of N applied to bromegrass (Bromus inermis Leyss.) grown for hay. Two sources of N (urea and ammonium nitrate ‐ A.N.) were applied at four times (early fall, late fall, early spring and late spring) at a rate of 112 kg N ha‐1. Urea was generally less effective in increasing DMY, PY, protein concentration, N use efficiency and % N recovery than A.N. The average, DMY, PY, protein concentration, N use efficiency and % N recovery with A.N. were 4.38 t ha‐1, 445 kg ha‐1, 104 g kg‐1, 21.2 kg DM kg‐1 N ha‐1 and 40.2%, respectively. In the same order, the values with urea were 3.90 t ha‐1, 376 kg ha‐1, 99 g kg‐1, 16.9 kg DM kg‐1 N ha‐1 and 30.2%, respectively. The DMY was greatest with early spring application for A.N., while the protein concentration, PY and % N recovery were greatest with the late fall application for both urea and A.N. The increase in DMY or recovery of applied N with urea as a percentage of the increase with A.N., was greatest with application in late spring and least with application in early fall. In conclusion, urea was less effective than A.N. as a forage fertilizer and early spring application was most effective for increasing DMY.  相似文献   

10.
Hybrid rice (Oryza sativa L.) cultivars play an important role in rice production due to its high yield potential. Optimum nitrogen (N) rate is necessary to achieve the maximum yield of hybrid. The main objective of this study was to reveal the responses of yield and yield component of hybrid rice ‘Eryou 107’ to different N rates in Nanjing and Taoyuan, a special eco-site. Leaf area index (LAI), dry matter accumulation was also compared. Rice yield showed a quadratic response to N rates at both sites with maximum yields approximately 10 t ha?1 at the 195 kg ha?1 N rate in Nanjing and maximum yield above 18 t ha?1 at the 375 kg ha?1 N rate in Taoyuan. Panicle per m2 was positively linear related to N rate at both sites in both years, while spikelets per panicle showed a quadratic relation. Larger sink size was the primary contributor to higher yields in Taoyuan compared with Nanjing, and panicle per m2 was the main cause. With the increasing N rate, LAI increased linearly and the dry matter accumulation first increased than declined at both sites. Greater effects of N rates on yield and yield components, LAI, and biomass was observed in Taoyuan than Nanjing. Higher LAI, biomass, and larger sink size resulted in the higher yields and more N rate for maximum yields in Taoyuan, compared with Nanjing.  相似文献   

11.
Information on the combined use of organic and inorganic fertilizers on wheat (Triticum aestivum L.) productivity is lacking under moisture stress conditions of Northwest Pakistan. The present experiment was designed to ascertain the combined effect of organic and inorganic fertilizer management on rainfed wheat. Four levels of farm yard manure, FYM, (0, 10, 20, and 30 Mg FYM ha?1) and nitrogen (0, 30, 60, 90, and 120 kg N ha?1) were used. The experiment was conducted at the Agriculture Research Farm of NWFP Agricultural University Peshawar, Pakistan during crop season of 2003–04. The experiment was laid out in randomized complete block design with four replications. Plant height, productive tillers m?2, grains spike?1, grain yield, straw yield, and harvest index were significantly higher in plots which received 30 Mg FYM ha?1. In the case of nitrogen (N) no distinctive differences between the effect of 90 and 120 kg ha?1 was observed for most of the parameters. Nitrogen application at 90 kg ha?1 had significantly higher; plant height, grains spike?1, grain yield, straw yield, and harvest index as compared with the lower levels, i.e., 0, 30, and 60 kg N ha?1 but were at par with 120 N kg ha?1. Significantly higher numbers of productive tillers m?2, grains spike?1, grain yield, straw yield and harvest index were recorded with application of 30 Mg FYM ha?1 + 90 kg N ha?1. The present study suggested that application of 30 Mg FYM ha?1 + 90 kg N ha?1 are promising levels for higher production of wheat under moisture stress conditions. Further research work is needed to ascertain the effect of N above 90 kg ha?1 under different moisture regimes.  相似文献   

12.
Wheat cultivars (‘AC Barrie’, ‘Brook Field’, ‘Hoffman’, and ‘Norwell’) with different protein concentrations were compared under four nitrogen (N) levels (0, 50, 100 and 150 kg ha?1) in an environment-controlled greenhouse, and the same experiment with an additional N level (200 kg N ha?1) was repeated in the field in 2007. In the greenhouse experiment, application of 100 kg N ha?1 resulted in significantly greater grain yield due mainly to higher number of grains per spike and heavier mean grain weight; in the field study, the 150 kg N ha?1 treatment produced the greatest yield (P<0.01) primarily due to more number of grains per spike. Crude grain protein percentage was increased significantly with each increment of N up to the highest level; however, protein yield (kg ha?1) increased significantly with fertilizer up to 150 kg N ha?1. Leaf chlorophyll contents were increased linearly with increment of N levels up to 150 kg ha?1 both in the greenhouse and field trials while leaf area indices continued to increase up to the highest application rate (200 kg N ha?1). Canopy reflectance, expressed as normalized difference vegetation index (NDVI), attained maximum value with 150 kg N ha?1 in the field experiment. Among the varieties tested, “Hoffman” out-yielded other three varieties due to heavier grain weight. Although highest grain and/or plant crude protein content were recorded in ‘AC Barrie’, it was the variety ‘Hoffman’ that produced the highest total protein (kg ha?1) with largest NDVI and leaf area index (LAI) values.  相似文献   

13.
Nitrogen (N) fertilizer is generally the most costly input for winter wheat (Triticum aestivum L.) production. Therefore, it was important to maximize fertilizer use efficiency and minimize N losses to the environment. One of the mechanisms responsible for decreased N use efficiency (NUE) was plant N loss. The objectives of this experiment were to determine fertilizer N recovery in winter wheat when produced for forage and grain, and to quantify potential plant N losses from flowering to maturity in winter wheat. Two long‐term (>25 years) winter wheat (Triticum aestivum L.) N rate fertility experiments (Experiment 222 and Experiment 502) were selected to evaluate 15N fertilizer recovery. Percent 15N recovery was determined from all microplots in plant tissue at flowering, in the grain, and straw at harvest and in the soil. Fertilizer N(15NH4 15NO3) was applied atratesof 0, 45, 90, and 135kg N ha‐1 in Experiment 222, and 0, 22, 45, 67, 90, and 112 kg N ha‐1 in Experiment 502. The ratio ofNO3 ‐to NH4 + in wheat forage at flowering was positively correlated with estimated plant N loss. Estimated plant N loss (total N uptake in wheat at flowering minus N uptake in the grain and straw at maturity) ranged from a net gain of 12 kg N ha‐1 to a loss of 42 kg N ha‐1, and losses increased with increasing N applied.  相似文献   

14.
Abstract

Accurate estimates of cotton (Gossypium hirsutum) dry matter accumulation and nitrogen content are important for both production and environmental reasons. One of the important factors in estimate accuracy is sample size. The objective of this investigation was to determine the cotton sample size necessary for acceptable estimates of cotton dry matter, lint yield, and shoot N per 100 kg of lint ratio (NLR) values. Three cotton cultivars (DeltaPine 90, DeltaPine 5415, and Stoneville 474) were planted on 13 May 1997 in an Eunola loamy sand (fine‐loamy, siliceous, thermic Aquic Hapludult) in 9.3‐m2 subplots of a split‐split plot design. Split plots were four sampling dates. Split‐split plots were four sampling techniques [a) four randomly selected plants (4RP), b) 0.3 meter of row (0.3‐m), c) one meter of row (1‐m), and d) two meters of row (2‐m)]. Each entire subplot was harvested on each sampling date after sampling by the four techniques. Shoot dry matter for the whole plot was 7.2 Mg ha‐1, and lint yield was 1.46 Mg ha‐1. Cotton shoot dry matter and NLRs were significantly overestimated by both the 4RP and 0.3‐m techniques, but not by the 1‐ and 2‐m techniques. The NLRs of cultivar subplots varied with cultivar from 9.1 to 11.4. The earliest maturing cultivar, DeltaPine 90, had the lowest NLR and the latest maturing cultivar, Stoneville 474, had the highest NLR. Accurate estimates of cotton dry matter accumulation and N content will likely require 1‐m samples, and 2‐m samples should further improve precision. The NLRs were similar to data (NLR <15) that suggest 1.6 Mg ha‐1 (3‐bale/acre) cotton lint yields can be achieved with less than 250 kg ha‐1 of shoot‐accumulated N.  相似文献   

15.
Information on the effects of phosphorus (P) and sulfur (S) applications on crop response and soil-P status of two-row malt barley (Hordeum vulgare L.) under high-input conditions are limited in alkaline soils despite widespread fertilizer-P and -S use. A field study was conducted during the 2015 and 2016 growing seasons where the barley cultivars (ABI-Voyager and Moravian 69) were grown at five rates of P (0, 37, 73, 110, and 147?kg P ha?1) and three rates of S (0, 112, 224?kg S ha?1). ABI-Voyager had significantly greater biological yield (17,023?kg ha?1) and grain yield (7433?kg ha?1) but a lower (44%) harvest index (HI) than Moravian 69 (15,037?kg ha?1, 7168?kg ha?1 and 49%, respectively). Grain yield increased with rate of P-application until 37?kg P ha?1 where the maximum calculated yield was obtained at 98?kg P ha?1 by a quadratic model. Sulfur application had no significant effect on any of the measured crop or soil parameters. Olsen P increased linearly with greater fertilizer-P applications, indicating grain-P removal was not sufficient to reduce or retain STP concentrations at initial levels when P was applied. Crop-P uptake and soil-P response to fertilizer P applications are important, as remaining soil P is available for subsequent crop usage and may have potential negative environmental impacts. Thus, cultivar selection and appropriate fertilizer-P and S management will ensure optimal agronomic and economic returns while minimizing potentially negative environmental impacts for two-row malt barley produced in the western United States.  相似文献   

16.
Lack of environmentally safe handling of garbage is a growing problem in urban sub‐Saharan Africa (SSA). Composting the garbage for soil‐fertility management presents an opportunity for reducing the risks of environmental pollution. This study aimed at evaluating the agronomic effectiveness and nutrient‐utilization efficiency of urban market crop‐waste compost on a Eutric Ferralsol. The study was conducted in central Uganda with treatments including compost applied at 0, 5, and 10 t ha–1 (d.w. basis); inorganic N fertilizer at rates of 0, 40, and 80 kg ha–1 and inorganic P fertilizer at 0, 9, and 18 kg ha–1. Maize (Zea mays L.), variety Longe 4 was used as the test crop. The nutrient quality of the compost was medium with total N of 0.9% and total P of 0.45%. Compost significantly increased plant height, LAI, stover weight, and grain yield; however, there were no significant differences between the 5 and 10 t ha–1 rates. Nitrogen also had a significant effect on LAI and stover yield, though there was no significant difference between the 40 and 80 kg ha–1 rates. Likewise, P increased plant height with no significant difference between the 9 and 18 kg ha–1 rates. Mineral N at 40 kg ha–1 led to the highest increase in N uptake by plants (76%) above the control. Nitrogen‐ and P‐utilization efficiencies for the 5 t ha–1 compost rate were more than twice that of the 10 t ha–1 rate. The highest P‐utilization efficiency (69%) was obtained where 9 kg ha–1 P was applied with 40 kg ha–1 N, while the highest N‐utilization efficiency (48%) was obtained with the 5 t ha–1 compost applied together with N at 40 kg ha–1. From the above studies, it is clear that effectiveness of the 5 t ha–1 compost rate is the most promising.  相似文献   

17.
The yield of rice (Oryza sativa L.) has increased substantially with the development of new cultivars, but the role of potassium (K) requirement for the increase in grain yield and the genotypic advance is still unclear. In order to investigate this relationship a database of 1199 on‐farm measurements (harvest index 0.4) comprising > 400 modern rice cultivars was collected during 2005–2010 across major irrigated lowland rice–production regions of China. This was used to evaluate the relationships among K requirement, grain yield, and genetic improvement. Across all the sites and seasons, mean reciprocal internal efficiency of K (RIE‐K, kg K [t grain produced]–1) was 19.8 kg K (t grain)–1 and rice yield averaged 8.7 t ha–1. Considering four levels of grain yield (< 7.5, 7.5–9, 9–10.5, and > 10.5 t ha–1), the respective RIEs were 18.7, 19.4, 20.5, and 21.7 kg K (t grain)–1. The gradual increase in the RIE‐K with yield was attributed mainly to the increase in straw and grain K concentration and the decrease in the K harvest index. The RIE‐K values for ordinary inbred, ordinary hybrid, and “super rice” were 18.5, 20.1, and 19.9 kg K (t grain)–1, respectively. Examining the historical development of rice cultivars, the RIE‐K decreased from 40.9 (Nanjing1, early tall, inbred) in the 1950s to 19.8 (IR24, semi‐dwarf, ordinary inbred) in the 1970s, and then increased to 20.9 (Shanyou63, modern ordinary hybrid) in the 1980s and 20.6 kg K (t grain)–1 (II‐you084, “super” rice) in the 2000s. This variation in RIE‐K among grain‐yield levels and cultivars highlights the importance of information on rice K requirement in calculating K balance and optimal K‐fertilizer rate for rice production.  相似文献   

18.
Total dry matter (TDM) and nutrient accumulation, nutrient partitioning, and cumulative growing degree days at the time of maximum nutrient accumulation for two‐row spring barley (Hordeum vulgare L.) are not well quantified under high‐yielding irrigated conditions common in the semi‐arid western United States. Thus, five cultivars of barley were grown under irrigated conditions on a loam soil in the 2015 and 2016 growth seasons to determine these factors. Total nutrient accumulation was greatest at either the soft dough or maturity stage where specific nutrients were greater at one stage as compared to the other. Mean N accumulation was greatest at the soft dough stage (256 kg ha?1) where the regression model accounted for 80% of the variation in the data. Additionally, spike N increased from 91 to 105 kg ha?1 from soft dough to maturity. Specific nutrients (e.g., K) had significantly greater plant (i.e., culms plus leaves) accumulation between soft dough and maturity, 253 and 172 kg ha?1, respectively, where the spike at the same growth stages had an accumulation of 37 and 42 kg ha?1, respectively. In contrast, other nutrients (e.g., P) were remobilized to the spike as noted by the increase from 14 kg ha?1 at soft dough to 26 kg ha?1 at maturity. In addition to nutrient partitioning, linear regressions resulted in well‐correlated models between TDM and total nutrient accumulation (R2 = 0.35–0.88) for measured nutrients. Results from the current study provide critical data on nutrient accumulation as well as regression models for two‐row barley under high‐yielding conditions. This information can be used to improve harvest decisions as well as more accurately predict nutrient cycling in barley cropping systems.  相似文献   

19.
Abstract

Rice (Oryza sativa L.) research field plots are likely to have nearly complete weed control whereas normal farmer field‐grown rice often have considerably greater weed populations. Consequently, a disparity might exist between nitrogen (N) requirements for producing maximum yields, in weedy (such as in some farmer fields) versus weed‐free rice (such as field research plots). We conducted a 2‐year field study at Keiser, AR. Using paired plots, we compared weed control effects, at several preflood ? rates (0–112 kg ? ha‐1) on yield, yield components, harvest index and weed weights. Rice yield responses to preflood ? fertilization were similar with and without weed pressure. Consequently, ? fertilization recommendations based on research plots with little or no weed pressure are valid for research plots and grower fields with much greater levels of weed pressure.  相似文献   

20.
Soil hydric availability and nitrogen fertilization are important environmental factors that influence sugarcane production. In the present study, the physiological attributes SPAD index, maximum photochemical efficiency of photosystem II (Fv/Fm), leaf area index (LAI), chlorophyll and carotenoid content, and sugarcane productivity were assessed under different nitrogen doses (0, 50, 100, 150, and 200 kg N ha?1) applied in the form of urea via subsurface drip fertigation. The physiological attributes were determined 38, 121, 208, 291, and 381 days after the third harvest (DAH), and stalk and sugar productivity at 381 DAH. The 100 kg N ha?1 dose has produced better results for the sugarcane physiological attributes. Increasing doses of nitrogen applied via subsurface drip fertigation increased the productivity of stalks and sugar considerably.  相似文献   

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