Effect of mepiquat chloride and nitrogen levels on yield,growth characteristics,and elemental composition of cotton

A 3-year study was conducted to determine the effects of mepiquat chloride and N levels on yield and quality of cotton (Gossypium hirsutum L.). Mepiquat chloride (MC) treatments did not significantlyaffect yields; however, cotton lint yields (1980) were 688, 949, 1,011, and 1,045 kg/ha for N rates of 0, 45, 90, and 135 kg/ha, respectively. Nitrogen by MC interactions on yield were not significant for any of the 3 years. MC treatments reduced plant height for all N levels. Plant height averages over all N levels were reduced 15–33% by the addition of MC. The MC treatments significantly increased the percent of Ca and Mg in the cotton leaves on a dry-weight basis. Nitrogen concentrations of the leaves were not affected by MC treatments. Leaf N levels were not significantly affected by N fertilization in 1979, but leaf N levels in 1980 were significantly increased at the 90 kg N/ha rate when compared with the check treatment.     

Effects of Irrigation and Nitrogen on the Performance of Aerobic Rice in Northern China

Aerobic rice is a new production system in which specially-developed varieties are grown under non-flooded, non-puddled, and non-saturated soil conditions. In 2003-2004, irrigation x Nitrogen experiments were carried out near Beijing using variety HD297. Water treatments included four irrigation levels, and Nitrogen treatments included different fertilizer N application rates and different numbers of N splits. The highest yields were 4460 kg/ha with 688 mm of total (rain plus irrigation) water input in 2003 and 6 026 kg/ha with 705 mm of water input in 2004. Because of the quite even distribution of rainfall in both years, the four irrigation treatments did not result in large differences of soil water conditions. There were few significant effects of irrigation on biomass accumulation, but yield increased with the total amount of water applied. High yields coincided with high harvest index and high percentages of grain filling. The application of fertilizer N either reduced biomass and yield or kept it at the same level as 0 N and consistently reduced the percentage grain filling and 1 000-grain weight. With the highest water application, five splits of N gave higher yield than three splits, whereas three splits gave higher yield than five splits with lower water applications.     

The effect of stem and cob borers on maize subjected to different nitrogen treatments

The influence of four nitrogen levels (0, 60, 90 and 120 kg N/ha) on growth of maize and development of lepidopterous pests was investigatdd in a field trial. Nitrogen had a positive effect on both plant growth variables (plant height, stem diameter and yield), and development and survival ofSesamia calamistis andEldana saccharina, and thereby increased the incidence of dead hearts and stem tunneling. However, the percent yield loss due to artificial infestation decreased with increasing N application rate from 20% to 11% in the in the 0kg/ha and 120kg/ha treatment, respectively. Using a multiple regression analysis, plant height, plant diameter and stem tunneling were found to be the most important variables explaining the variability in maize yield.     

Effects of delayed soil and foliar N fertilization on yield and N2 fixation of soybean

Summary Field experiments were conducted to determine the effects of the amount, time and method of fertilizer N application on the efficiency of N uptake, N₂ fixatio and yield of soybean. Soil and foliar fertilizer N, applied during the pod-filling stage were absorbed by plants with equal and high efficiency, compared to an appreciably lower utilization efficiency for N applied before seedling emergence. These results reveal that the soybean roots were active in N uptake during these late stages of growth. Nitrogen fertilization during pod-filling resulted in significant yield increases over the control treatment which received an early application of 20 Kg N/ha. Seed yield increases were, however, more pronounced than total dry matter yield, and virtually all of the late-applied N was translocated into the pods. Nitrogen fixation in soybean was not influenced by the application of 40 kg N/ha to plants as soil or foliar N during the pod-filling stage. However, 80 kg N/ha supplied during pod-filling as 40 kg soil plus 40 kg foliar N/ha significantly reduced the amount of N₂ fixed. The results obtained in these studies suggest that inadequate N supply during pod-filling limited soybean yields, and that by the judicious application of fertilizer N during the late stages of growth, it was possible to enhance soybean yields without necessarily inhibiting N₂ fixation.     

Effect of Plant Growth Regulators on Agronomic Characteristics,Lint Quality,Pests, and Predators in Cotton

Field experiments were conducted with some commercial plant growth regulators (PGRs) to determine their effects on agronomic characteristics, pest densities, and predators when administered as a foliar spay on cotton at Adnan Menderes University Agricultural Research Center located in Aydin, Turkey, during the 2006 and 2007 cotton-growing seasons. The three commercial PGRs, Pix, Tonic, and Turbo pamuk, were sprayed at recommended doses and application time during the study. Application of PGRs significantly positively affected the yield, plant height, average number of open bolls, and predators, and significantly decreased the population densities of some economically important cotton pests. However, lint quality, ginning turnout, and average of seed cotton weight were not affected by the treatments. More yield was obtained in Pix- and Turbo pamuk-treated plots. The lowest densities of Bemisia tabaci, Frankliniella spp., and leaves infested with Liriomyza trifolii were recorded in Pix-treated plots. Although Turbo pamuk and Tonic numerically lowered the pest population densities compared to the control, the changes were not significant and these PGRs were not as effective as Pix. Furthermore, Empoasca spp. was not affected by the treatments. Populations of predators were not affected by the PGRs in Aranea orders, but were affected in Heteroptera, Neuroptera, Coleoptera, and Thysanoptera. Pix proved more suitable than others to producing resistance against pests and increasing the yields. PGRs neither enhanced any insect attack nor reduced predators in the study. Therefore, PGRs may be considered a component of Integrated Pest Management to provide higher yields in cotton.     

Nitrate reductase activity,biomass, yield,and quality in cotton in response to nitrogen fertilization

In the production of cotton (Gossypium hirsutum L.), nitrogen fertilization is one of the most costly crop practices, but important to reach high yields. However, high nitrogen (N) content in plants does not always translate into a high fibre production. One way of assessing the efficiency of the N fertilizer is through the enzymatic activity of the nitrate reductase (NR). This is a key enzyme in N assimilation, whose activity is regulated by a number of endogenous and exogenous factors that determine yield. The aim of this study was to assess the effect of N fertilization on yield, fibre quality, biomass, and NR enzymatic activity in vivo in the cotton variety Fiber Max 989. The evaluated application rates were 0, 50, 100, and 150 kg/ha of N, using urea as a source (46% N) in a randomizedblock design with three replicates. At harvest, the maximum yield of seed cotton and the greatest accumulation of total foliar biomass through time was reached after applying 150 kg N/ha. The different N-application rates did not affect the components of cotton-fibre quality. The activity of endogenous NR was greater on plants where 150 kg N/ha were applied. The highest cotton yield and N contents were obtained on these plants. Therefore, the NR activity in vivo could be used as a bioindicator of the N nutritional level in cotton.     

Bahiagrass,Corn, Cotton Rotations,and Pesticides for Managing Nematodes,Diseases, and Insects on Peanut

Florunner peanut was grown after 1 and 2 years of Tifton 9 bahiagrass, corn, cotton, and continuous peanut as whole-plots. Pesticide treatments aldicarb (3.4 kg a.i./ha), flutolanil (1.7 kg a.i./ha), aldicarb + flutolanil, and untreated (control) were sub-plots. Numbers of Meloidogyne arenaria second-stage juveniles in the soil and root-gall indices of peanut at harvest were consistently lower in plots treated with aldicarb and aldicarb + flutolanil than in flutolanil-treated and untreated plots. Percentages of peanut leaflets damaged by thrips and leafhoppers were consistently greater in flutolaniltreated and untreated plots than in plots treated with aldicarb or aldicarb + flutolanil but not affected by cropping sequences. Incidence of southern stem rot was moderate to high for all chemical treatments except those that included flutolanil. Stem rot loci were low in peanut following 2 years of bahiagrass, intermediate following 2 years of corn or cotton, and highest in continuous peanut. Rhizoctonia limb rot was more severe in the peanut monoculture than in peanut following 2 years of bahiagrass, corn, or cotton. Flutolanil alone or combined with aldicarb suppressed limb rot compared with aldicarb-treated and untreated plots. Peanut pod yields were 4,186 kg/ha from aldicarb + flutolanil-treated plots, 3,627 kg/ha from aldicarb-treated plots, 3,426 kg/ha from flutolanil-treated plots, and 3,056 kg/ha from untreated plots. Yields of peanut following 2 years of bahiagrass, corn, and cotton were 29% to 33% higher than yield of monocultured peanut.     

Effects of level,time, and splitting of urea on the yield of irrigated direct seeded rice

Summary To determine effects of level and time of application of urea on grain yields, components of grain yield, and nitrogen use efficiency by irrigated direct seeded rice (Oryza sativa L. var. IR 298-12-1-1-1), three field experiments were conducted at the Gezira Agricultural Research Station during the period 1976–78. The treatments included the factorial combination of three levels of nitrogen as urea (0,75 and 150 kg N/ha) two or three splits, and three times of topdressing of urea (early season application, 10 days after rice emergence, DRE; maximum tillering stage, 40 DRE; and panicle initiation stage, 75 DRE).Without application of nitrogen, grain yields averaged 1.5 t/ha. The yields averaged for rate and time of split significantly increased with increase in nitrogen applied to 3.9 and 5.0 t/ha, but nitrogen use efficiency (kg rice/kg N) decreased from 31 to 23 with the application of 75 and 150 kg N/ha respectively.As compared to other treatments of time of urea application, topdressing of urea at maximum tillering and panicle initiation stages significantly improved nitrogen use efficiency by promoting production of more panicles per unit land area, and increasing grain weight. Three splits were no better than the two splits given at maximum tillering and panicle initiation stages.     

Response of irrigated wheat to residual and fertilizer nitrogen

Summary A cotton and a wheat experiment were conducted in sequence to evaluate the effect of residual and fertilizer N on wheat with a water table fluctuating between 65 and 125 cm. Cotton treatments, replicated four times, consisted of 3 irrigation treatments as main plots and 6 N levels as subplots (0, 25, 50, 75, 100, 125 kg N/ha). After cotton the plots were planted to wheat and each subplot was divided into two equal sub-subplots. One received N at a rate similar to that previously applied to cotton and the other sub-subplot was left without N application for evaluating the residual effect. Determination of N forms in the soil before wheat indicated that NO₃-N content of the top 25 cm increased from 4.4 to 16.3 ppm as N applied to cotton increased from 0 to 125 kg/ha. On the other hand, mineralizable-N was greater in the control than in the fertilized treatments, suggesting a priming effect on the mineralization of soil N. The residual effect on wheat was related to mineralizable-N rather than to NO₃-N as grain yield was higher for the control than for the residual fertilizer N treatments. The yield was also higher for the more frequent than for the less frequent irrigation treatments, which may be attributed to increase in mineralization with soil water content. Wheat response to N application was significant. But high N levels accompanied by frequent irrigation enhanced lodging with subsequent reduction in yield. Measuring N uptake by grain and straw indicated 37% recovery of fertilizer N. It was concluded that under the prevailing conditions of high water table wheat response was largely dependent on the applied fertilizer due to insignificant residual N availability.     

Analysis of Growth and Productivity of Green Chickpea Using Nitrogen and Phosphorus Fertilization

Chickpea contains high levels of protein, vitamins and minerals. Acceptable chickpea yield is the result of meeting nitrogen and phosphorus requirements. The effect of appropriately meeting such requirements reflects on growth and can easily be evaluated using growth analysis. This research determined: (a) The effect of nitrogen and phosphorus fertilization on phenology, net assimilation rate, number of green leaves, leaf area, leaf area index and leaf area duration; (b) Green chickpea yield and number of pods due to fertilization; and (c) The combination of nitrogen and phosphorus fertilization that yields the most net revenue. Nitrogen and phosphorus fertilization was evaluated; each at the doses of 0, 75 and 150 kg ha^–1 (N0, N75, N150; P0, P75 and P150, respectively). The combination of the levels of both nutrients generated nine combinations of treatments which were distributed in the field in a randomized complete block design in an arrangement of divided plots with four repetitions. Timing of phenological phases were similar among treatments. Nitrogen and phosphorus fertilization increased number of leaves, leaf area index, and leaf area duration that translated into increased green chickpea yield (GCY). Combinations N150-P75 and N150-P150 produced the highest GCY. The highest net revenue and revenue per peso invested was obtained with N150-P75.     

Evaluation of NemX,a New Cultivar of Cotton with High Resistance to Meloidogyne incognita

The level of resistance to root-knot nematode, Meloidogyne incognita, in NemX, a new cultivar of the Acala-type upland cotton, was evaluated in relation to four resistant breeding lines (N6072, N8577, N901, and N903) and four susceptible cultivars (Maxxa, SJ2, Royale, and Prema). In growth pouch tests, an average of only 4 nematode egg masses was produced on roots of NemX or the resistant lines, compared to a significantly higher average of 21 on the susceptible cultivars. In pot tests, the nematode reproduction factor (RF = Pf/Pi) in NemX and the resistant lines averaged 0.7, compared to a significantly higher average of 10 on the susceptible cultivars. Root galling in NemX or other resistant cotton averaged 15%, compared to 74% on the susceptible cultivars, in either pot or field tests. In plots with low levels of nematode infestation (Pi ≤ 150 second-stage juveniles [J2]/500 g soil), lint yield of NemX averaged 1,370 kg/ha and was less than the yield of susceptible Maxxa (1,450 k g /h a ). However, in plots with medium or high levels of nematode infestation (Pi = 151-300 or >300 J2/500 g soil, respectively), yields of NemX decreased only slightly and averaged 1,300 or 1,050 kg/ha, respectively, whereas yields of Maxxa were severely reduced to 590 or 503 kg/ha, respectively. Fusarium wih symptoms were observed on both NemX and Maxxa, and percent occurrence increased with increasing preplant nematode density. In plots with the highest nematode densities, 22% of NemX and 65% of Maxxa plants were wilted. NemX was highly effective against five M. incognita isolates and moderately effective against a sixth isolate that had been exposed to resistant cotton over several seasons. These results showed that NemX is as resistant to M. incognita as the four breeding lines, and much more resistant than the tested susceptible cultivars of cotton.     

Comparative effect of potassium chloride and potassium sulfate on the yield and protein content of wheat in three different rotations

Comparative effects of potassium chloride and potassium sulfate at various levels of potassium on the performance of ARZ variety of wheat were studied at Agriculture Research Station Dera Ismail Khan, N.W.F.P., Pakistan. The experiment was laid out in three different rotationsviz, rice-wheat, maize-wheat and fallow-wheat. Potassic fertilizers were applied at the rate of 0, 37, 74, 111 and 148 kg k/ha alongwith the basal dose of 135 kgN plus 44 kg P/ha. Wheat yield data showed that the application of 37 kg K/ha of potassium chloride was found better in case of rice-wheat and fallow-wheat rotation and 37 kg K/ha of potassium sulfate for maize-wheat rotation. On the average of the three rotations, potassium sulfate at the rate of 74 kg K/ha (90 kg K₂O/ha) was found better and economical. Both the sources were almost equally effective but potassium sulfate out-yielded potassium chloride. Protein content of grains was significantly increased due to K application irrespective of the source and potassium sulfate was found with significantly higher protein content than potassium chloride.     

Effect of nitrogen application on flowering and yield of eggplant (Solanum melongena L.)

Effect of nitrogen application on number of flowers per plant, number of different types of flowers per plant, length of style, number of fruits per plant and fruit yield/ha of eggplant was investigated under controlled greenhouse conditions. Nitrogen was supplied at 50, 75, 100, 125, 150, 175 and 200 kg N/ha with one control (no nitrogen) treatment. Nitrogen supplied at 200 kg N/ha gave best results and significantly produced the highest number of flowers per plant, fruits per plant and yield (32.24 ton/ha) over control plants. Nitrogen failed to influence style length and type of flowers i.e. long, medium, pseudo-short and short styled flowers. Nitrogen application at 150 and 175 kg N/ha showed comparable results with nitrogen applied at 200 kg N/ha.     

Nutrient Uptake by ‘Alamo’ Switchgrass Used as an Energy Crop

Field studies were conducted in 2000 and 2001 to examine yields and nutrient removal by Alamo switchgrass (Panicum virgatum L.) grown at eight locations within five states in the upper southeastern USA. Plots, which had been established for >5 years as part of a larger study, were cut either once (late fall) or twice (midsummer and late fall). Plots cut once received 50 kg N per hectare per year, while twice-cut plots received 100 kg N per hectare per year. Nutrient concentrations of and nutrient removal by harvested biomass were determined. Partitioning of nutrients into leaf and stem fractions was determined at the time of the midsummer harvest in 2000. Biomass production during 2000 and 2001 averaged 15.9 Mg/ha per year across all sites and was as high as 21.7 Mg/ha per year at one site. Two cuttings plus the additional 50 kg N per hectare did not generally increase seasonal yields; and, in one quite productive location, that management caused a yield reduction. Nitrogen removal with two cuts was much higher than with a single cut due largely to the higher N content in the midsummer harvest. Over the 2 years, twice as much N was removed with the two annual cuts as with one cut. Nitrogen removal exceeded the amounts of N applied in both managements, suggesting N was being supplied via mineralization or other processes. Phosphorus removal also increased significantly with the two-cut management. Seasonal K and Ca removals were more similar between the two managements. Nitrogen and P concentrations generally declined basipetally in tillers, with older leaves and internodes having lower concentrations of both nutrients. Potassium was more uniformly distributed than N throughout the tiller components (leaf and stem). Calcium was higher in older leaf blades. Levels of soil P, K, and Ca at most locations appeared not to be limiting biomass production and were adequate for long-term productivity.     

Mepiquat chloride seed treatment and germination temperature effects on cotton growth,nutrient partitioning,and water use efficiency

Cotton seed (Gossypium hirsutum L. cv. “Stoneville 825”), treated with 0, 0.2, 1.0, and 2.0 g active ingredient (a.i.) mepiquat chloride (MC) kg^?1, was evaluated for the effect of MC on early plant growth. Emergence rate and total emergence of MC-treated seed and control were similar regardless of germination temperature. However, the number of leaves and squares and the dry weight of leaves, stems, and roots for hydroponically grown cotton plants were significantly lower at lower germination temperatures (15°C for 3 day/30°C for 1 day and 15°C for 4 days) than at higher germination temperatures (30°C for 4 days and 30°C for 3 days/15°C for 1 day). All MC treatments significantly decreased the number of nodes, leaves, and squares, as well as dry weight of leaves, stems, and roots, as compared to control plants at 28 days after emergence. MC seed treatments also significantly reduced plant height and total leaf area compared to controls. Water-use efficiency (WUE) was significantly lower for the 1.0 g a.i. MC treatment than for control plants. In general, the highest rate of MC seed treatment resulted in greater concentrations of calcium, phosphorus, and nitrogen in plant leaves and stems and also in greater concentrations of magnesium, phosphorus, and nitrogen in roots than in controls.     

Mepiquat chloride seed treatment and germination temperature effects on cotton growth, nutrient partitioning, and water use efficiency

Cotton seed (Gossypium hirsutum L. cv. Stoneville 825), treated with 0, 0.2, 1.0, and 2.0 g active ingredient (a.i.) mepiquat chloride (MC) kg^–1, was evaluated for the effect of MC on early plant growth. Emergence rate and total emergence of MC-treated seed and control were similar regardless of germination temperature. However, the number of leaves and squares and the dry weight of leaves, stems, and roots for hydroponically grown cotton plants were significantly lower at lower germination temperatures (15°C for 3 day/30°C for 1 day and 15°C for 4 days) than at higher germination temperatures (30°C for 4 days and 30°C for 3 days/15°C for 1 day). All MC treatments significantly decreased the number of nodes, leaves, and squares, as well as dry weight of leaves, stems, and roots, as compared to control plants at 28 days after emergence. MC seed treatments also significantly reduced plant height and total leaf area compared to controls. Water-use efficiency (WUE) was significantly lower for the 1.0 g a.i. MC treatment than for control plants. In general, the highest rate of MC seed treatment resulted in greater concentrations of calcium, phosphorus, and nitrogen in plant leaves and stems and also in greater concentrations of magnesium, phosphorus, and nitrogen in roots than in controls.     

Impact of cotton planting date and nitrogen fertilization on Bemisia argentifolii populations

The silverleaf whitefly (Bemisia argentifolii Bellows and Perring) is a widely distributed pest of cotton (Gossypium hirsutum L.) and the population levels may be affected by rates of nitrogen fertilization and planting date. Field experiments were conducted to investigate the impact of cotton planting date and nitrogen fertilization on silverleaf whitefly population dynamics. Cotton was planted on 26 April and 8 June, for the early and late plantings, respectively. Nitrogen treatments consisted of soil applications of 0, 112, 168 and 224 kg of nitrogen per hectare. The population levels of adult whiteflies were much higher on early-planted cotton than on late planting. Also, increased numbers of adult whiteflies on both early and late plantings occurred with increasing amounts of applied nitrogen.Applied nitrogen increased seed cotton yields of early plantings but had no effect on the yields of late plantings.     

控释尿素减施对双季稻田氮素渗漏淋失的影响

大量施用氮肥引起的土壤氮素淋失是稻田氮素损失的一个重要途径.为探究自然降雨过程中典型双季稻田氮渗漏淋失特点,采用田间渗漏池法,通过大田小区试验,研究控释尿素减施对稻田土壤60 cm深处渗漏水中氮淋失和水稻产量的影响.结果表明: 施肥初期出现氮渗漏淋失峰值,这是防控的关键时期;双季稻生长季控释尿素减氮20%(0.8CRU)和减氮30%(0.7CRU)处理全氮淋失量分别为42.3和37.7 kg·hm^-2,均显著低于常规尿素(CU)处理(53.9 kg·hm^-2),且0.7CRU处理显著低于等氮量控释尿素(1.0CRU)处理(51.3 kg·hm^-2);各施氮处理全氮渗漏淋失率为11.9%～13.5%,处理间差异不显著.0.8CRU和0.7CRU处理较CU处理明显提高了水稻产量和氮肥吸收利用率,显著增加了氮收获指数.总之,控释尿素减氮 20%～30%能保证水稻产量和防控稻田氮渗漏淋失.     

Effect of irrigation frequency and nitrogen on groundnut yield and nutrient uptake

Summary Field experiments were conducted during 1979 and 1980 summer seasons on sandy loam soils of low moisture retentive capacity to study the effect of high frequency irrigation at different levels of N on groundnut yield and nutrient uptake (NPK). Four irrigation frequencies (irrigation at 2, 4, 6 and 8 cm cumulative can evaporation, corresponding to irrigation once in 3, 5, 7 and 10 days respectively) and four levels of nitrogen (0, 20, 40 and 60 kg N/ha) were tested in a factorial randomized block design with three replications. Pod yield of groundnut was maximum (3,293 kg/ha) when irrigations were scheduled at 4 cm cumulative can evaporation (once in 5 days). Addition of N did not increase the pod yield. N and P uptake by the crop was maximum (180 kg N and 18 kg P/ha) with high frequency irrigation of scheduling irrigation at 4 cm cumulative can evaporation. Highest uptake of N (183 kg/ha) and P (19 kg/ha) was with a combination of 20 kg N/ha and high frequency irrigation (4 cm CCE). K uptake was low with low irrigation frequency, while it was highest (67 kg K/ha) at 20 kg N/ha.     

Effect of crop residue management on the yields of different crops and on soil properties

The effects of chopped (6–9 cm) and unchopped (long) crop residues of wheat (Triticum aestivum L.) and rice (Oryza sativa L.) in corn (Zea mays L.)— wheat and rice-wheat rotations on grain yield and soil properties were investigated in 27 field experiments during 9 years. Experiments on chopped wheat residue involved the treatments of two main plots with residue incorporation at 0 and 4 t/ha before sowing of corn and wheat and having subplots with 0, 40, 80 and 120 kg N/ha. The results obtained for 4 years showed that the incorporation of wheat residue not only improved the soil physicochemical properties but also increased the grain and stover yields of corn significantly. The yield obtained with 80 kg N in conjunction with 4 t/ha chopped wheat residue was identical to that with 120 kg N/ha alone. But the wheat yield was depressed significantly upon the incorporation of wheat residue before the sowing of wheat in all the years of investigation.The experiments on the management of unchopped wheat residue in corn-wheat rotation and of unchopped wheat (6 t/ha) and rice (12 t/ha) residues in rice-wheat rotation, involved three main treatments: physical removal, in-situ incorporation and in-situ burning of residues. Main treatments were tested at 60, 120 and 180 kg N/ha level over 5 years. Irrespective of N application, the residue management treatments had non-significant effects on the succeeding crop yield in all the years. Burning of residue improved the yield by about 0·2 t/ha, whereas residue incorporation did not affect the yield either of corn or rice. On the other hand, the wheat yield was depressed by 0·1–0·2 t/ha in both the rotations.The effect of applied N irrespective of residue management was significant in some years up to the level of 120 kg and in others, 180 kg N/ha.