Effects of Crop Residue and Nitrogen Rates on Yield and Yield Components of Two Dryland Wheat (Triticum aestivum L.) Cultivars

Abstract

In most southern parts of Iran, wheat (Triticum aestivum L.) residues have been traditionally burned or removed; that is often criticized for soil organic and nutrient losses, reducing soil microbial activity and increasing CO₂ emission. A 2-years (2005?2007) field study was carried out at the College of Agriculture, Shiraz University, Shiraz, Iran, to evaluate the influence of crop residues management and nitrogen (N) rates on dryland wheat. The experiment was conducted as strip split plot with four replications. Horizontal plots were three crop residues rates (0, 500 and 1000 kg ha-¹), vertical plots consisted of two dryland current wheat cultivars (CVs) (Azar 2 and Nicknejad), and sub-plots were three N rates (0, 35, and 70 kg N ha-¹). Increasing crop residue rates increased soil organic carbon. Number of spike per plant, grains per spike, grains per plant and 1000-grain weight of both CVs significantly increased with increased N and residue rates in both years. The lowest grain yield was obtained from 1000 kg ha-¹ residue incorporation without N application showing the soil N imbalance. The optimum crop growth and the highest grain yield was achieved from the highest crop residues and N rates, indicating that the most reliable system for dryland wheat production in the region is complete residues incorporation into the soil following disking, seeding with chisel seeder and application of 70 kg N ha-¹.     

Nitrogen and Potassium Fertility Impacts on Aggregate Sheath Spot Disease and Yields of Rice

Abstract

Aggregate sheath spot (AgSS), a disease caused by Rhizoctonia oryzae-sativae, is one of the major rice (Oryza sativa L.) diseases in California. A three year study was initiated in 1998 to evaluate the effect of nitrogen (N) and potassium (K) fertility on the severity of AgSS. A field with a history of AgSS was divided in two: in one the straw was incorporated and in the other the straw was removed. Rice was fertilized annually with five rates of N ranging from 0 to 200 kg ha-¹ (main plot) and six rates of K ranging from 0 to 125 kg ha-¹ (sub-plot). Soil K levels in both fields declined over time and by the third year, soil K was below the critical level of 60 μg K g-¹ soil in both fields. There was a grain yield response to K fertilizer in all 3 years in the field where straw was removed and in the third year when straw was incorporated. Where there was a significant response to K fertilization, yields increased by 560 kg ha-¹. In all fields and years there was a significant yield response to N fertilizer. AgSS severity decreased with increasing N and K fertilizer rates and leaf N and K concentrations at panicle initiation. Furthermore, the leaf N concentration required for maximum rice yields was lower than the leaf N concentration which resulted in the lowest severity of AgSS .     

Soybean inoculation: Dose, N fertilizer supplementation and rhizobia persistence in soil

The effect of rate of application of Sinorhizobium (Ensifer) fredii SMH12 or Bradyrhizobium japonicum USDA110 inoculants on grain yields of soybean [Glycine max (L.) Merrill] cv. Osumi was studied in a field experiment laid out in Southern Spain. All inoculant doses tested (10⁴, 10⁵, 10⁶ and 10⁷ rhizobia/seed) produced higher seed yields than those obtained in un-inoculated plots. Increments in nodule dry weight, seed yield and seed N content were observed when the number of rhizobia applied to seed increased from 10⁴ up to 10⁷. The addition of N fertilizer to inoculated soybean plants (50 kg N/ha applied at R1 or R4 stage) did not increase seed yields in comparison with treatments that were only inoculated. Survival of strains SMH12 and USDA110 was monitorized for three years in two different soils of Southern Spain after soybean inoculation. Rhizobia survival was varied dependent on the soil and the rhizobia strain used.     

Characterizing leaf gas exchange responses of cotton to full and limited irrigation conditions

Plant responses to water deficit need to be monitored for producing a profitable crop as water deficit is a major constraint on crop yield. The objective of this study was to evaluate physiological responses of cotton (Gossypium hirsutum) to various environmental conditions under limited water availability using commercially available varieties grown in South Texas. Soil moisture and variables of leaf gas exchange were measured to monitor water deficit for various varieties under different irrigation treatments. Lint yield and growth variables were also measured and correlations among growth parameters of interest were investigated. Significant differences were found in soil moisture, leaf net assimilation (A_n), stomatal conductance (g), transpiration rate (T_r), and instantaneous water use efficiency (WUE_i) among irrigation treatments in 2006 while no significant differences were found in these parameters in 2007. Some leaf gas exchange parameters, e.g., T_r, and leaf temperature (T_L) have strong correlations with A_n and g. A_n and WUE were increased by 30–35% and 30–40%, respectively, at 600 μmol (CO₂) m⁻² s⁻¹ in comparison with 400 μmol (CO₂) m⁻² s⁻¹. Lint yield was strongly correlated with g, T_r, WUE, and soil moisture at 60 cm depth. Relative A_n, T_r, and T_L started to decrease from FTSW 0.3 at 60 cm and FTSW 0.2 at 40 cm. The results demonstrate that plant water status under limited irrigation management can be qualitatively monitored using the measures of soil moisture as well as leaf gas exchange, which in turn can be useful for describing yield reduction due to water deficit. We found that using normalized A_n, T_r, and T_L is feasible to quantify plant water deficit.     

Influence of Crop Nutrition on Grain Yield, Seed Quality and Water Productivity under Two Rice Cultivation Systems

The system of rice intensification (SRI) is reported to have advantages like lower seed requirement,less pest attack,shorter crop duration,higher water use efficiency and the ability to withstand higher degree of moisture stress than traditional method of rice cultivation.With this background,SRI was compared with traditional transplanting technique at Indian Agricultural Research Institute,New Delhi,India during two wet seasons (2009-2011).In the experiment laid out in a factorial randomized block design,two methods of rice cultivation [conventional transplanting (CT) and SRI] and two rice varieties (Pusa Basmati 1 and Pusa 44) were used under seven crop nutrition treatments,viz.T 1,120 kg/hm2 N,26.2 kg/hm2 P and 33 kg/hm2 K;T 2,20 t/hm2 farmyard manure (FYM);T 3,10 t/hm2 FYM+ 60 kg/hm2 N;T 4,5 t/hm2 FYM+ 90 kg/hm2 N;T 5,5 t/hm2 FYM+ 60 kg/hm2 N+ 1.5 kg/hm2 blue green algae (BGA);T 6,5 t/hm2 FYM+ 60 kg/hm2 N+ 1.0 t/hm2 Azolla,and T 7,N 0 P 0 K 0 (control,no NPK application) to study the effect on seed quality,yield and water use.In SRI,soil was kept at saturated moisture condition throughout vegetative phase and thin layer of water (2-3 cm) was maintained during the reproductive phase of rice,however,in CT,standing water was maintained in crop growing season.Results revealed that CT and SRI gave statistically at par grain yield but straw yield was significantly higher in CT as compared to SRI.Seed quality was superior in SRI as compared to CT.Integrated nutrient management (INM) resulted in higher plant height with longer leaves than chemical fertilizer alone in both the rice varieties.Grain yield attributes such as number of effective tillers per hill,panicle length and panicle weight of rice in both the varieties were significantly higher in INM as compared to chemical fertilizer alone.Grain yields of both the varieties were the highest in INM followed by the recommended doses of chemical fertilizer.The grain yield and its attributes of Pusa 44 were significantly higher than those of Pusa Basmati 1.The seed quality parameters like germination rate and vigor index as well as N uptake and soil organic carbon content were higher in INM than those in chemical fertilizer alone.CT rice used higher amount of water than SRI,with water saving of 37.6% to 34.5% in SRI.Significantly higher water productivity was recorded in SRI as compared to CT rice.     

Effects of Water-Saving Irrigation and Nitrogen Fertilization on Yield and Yield Components of Rice (Oryza sativa L.)

Abstract

The effects of nitrogen (N) application (32, 72 and 112 kg N ha-¹ in 2000, and 32, 92 and 152 kg N ha-¹ in 2001) and water-saving irrigation and their interaction on grain yield and yield components of the rice cultivar Champa-Kamphiroozi, which is a local cultivar in a semi-arid area in the south of Islamic Republic (I.R.) of Iran, were investigated. The plants were cultivated under sprinkler irrigation (1.0 ET_p and 1.5 ET_p), intermittent flooding (1-day and 2-day intervals) and continuous flooding (control). The experiments were conducted on a clay loam-clay soil under a semi-arid environment using four replications in a split plot design with irrigation method as main plots and N levels as subplots. The results indicated that intermittent flooding irrigation at 2-day intervals was as effective as continuous flooding for grain yield, showing high water-use efficiency (WUE). The soil moisture tension in the root zone before each irrigation under this condition was –300 to –400 cm. Sprinkler irrigation and intermittent flooding increased WUE by 20 to 60%, compared with continuous flooding, and the increase in N application rate to 112-152 kg ha-¹ increased grain yield under any irrigation condition. Under sprinkler irrigation, grain yield was low and percentage of unfilled grain was high, although WUE was high. However, by adopting sprinkler irrigation, the amount of nitrogen fertilizer application necessary for cultivation was reduced. Furthermore, when nitrogen application must be limited due to groundwater pollution, the amount of nitrogen fertilizer necessary for cultivation can be reduced.     

Phosphorus Balance and Soil Phosphorus Status in Paddy Rice Fields with Various Fertilizer Practices

Abstract

Excess phosphorus (P) has accumulated in Japanese paddy soils, due to fertilizer P inputs over crop requirement for several decades, and improvement of the excess of P is necessary in view of environmental conservation. This study aimed to evaluate the input/output balance of P related to soil P status in paddy rice systems, and to obtain a practical indication. Irrigated rice (Oryza sative L.) was cultivated on a gley soil from 1997 to 2006. Six field plots fertilized with commercial fertilizer, animal waste composts, green manure and none were included. Phosphorus input varied among plots from 0 to 73 kg ha-¹ yr-¹. Rice P uptake was approximately 20 kg ha-¹, indicating no response to the P input. This was attributed to a large amount of plant-available Bray- and Truog-P in our soils. In our fields, paddy rice could be cultivated with no P-containing fertilizer or amendment. As a result, increase in the P input led to an increase in partial P balance (PPB). Cumulative increase in PPB resulted in the increase in soil total P, whereas cumulative decrease of PPB tended to decrease it. Excess accumulation of the soil P results in a loss of P into the environment. We concluded that P fertilization should be restricted to 20 kg ha-¹ yr-¹ (corresponding to 46 kg ha-¹ yr-¹ as P₂O₅), based on evenly balanced P input with the rice P uptake. It is also important to include all of the P-containing fertilizers and amendments when determining the amount of application.     

Ingestive behaviour of beef cattle offered different forms of lucerne (Medicago sativa L.)†

A change-over design was used to establish the ingestive behaviour of twelve adult Angus cows (Bos taurus), live weight (LW) of 475 ± 18 kg, while grazing luceme (Medicago sativa L.) (T₁), eating from a swath of freshly cut lucerne (T₂), or eating wilted lucerne from a swath (T₃). In the first experiment, the herbage dry matter (DM) allowance was 4-7 kg h^?1 and in T₁ the available herbage DM mass (>5 cm) was 2892 kg ha^?1. Herbage DM intake was 2.5, 1.6 and 2.0 kg h^?1 (0.53,0.35 and 0.41 kg (100 kg LW)^?1h^?1) for T₁, T₂ and T₃, respectively. Cattle grazed at 29 bites min^?1 and ate the swathed lucerne at 6 bites min^?1. Herbage DM intake per bite was 1-2, 4-9 and 6-7 (2-5,104 and 14-4 mg(kg LW)^?1)for T₁, T₂ and T₃, respectively. The DM content of the luceme was 227, 263 and 309 g kg^?1 for the same sequence. In a second experiment with luceme of available herbage DM mass of 5321 kg ha^?1 and an allowance of 7- 3 kg h^?1 cows grazed lucerne at 2-9 kg h^?1, ate freshly cut material at 21 kg h^?1 and wilted herbage at 25 kg h^?1 (0.61, 0.45 and 0.52 kg (100 kg LW)^?1h^?1), respectively. Leaf accounted for 80%, 68% and 54% of intake for T₁, T₂ and T₃, respectively. Swathing lucerne reduced the diet selectivity by forcing cattle to take large bites that required many jaw movements to form a bolus that could be swallowed. It appeared that the mechanics of bolus formation determined ingestive behaviour of cattle eating swathed herbage.     

Intercropping of orchardgrass and alfalfa improves soil fertility,forage yield,feeding values and land use efficiency while limiting ruminal greenhouse gas emissions

Intercropping has been a globally accepted practice for forage production, however, consideration of multiple performance criteria for intercropping including forage production, feed use efficiency and ruminal greenhouse gas emissions needs to be further investigated. A two-year field study was conducted to evaluate forage dry matter (DM) yield, nutritive value, feeding values and land-use efficiency as well as ruminal carbon dioxide (CO₂) and methane (CH₄) emissions of intercropped orchardgrass (Dactylis glomerata) and alfalfa (Medicago sativa) sown in five intercropping ratios (100:0, 75:25, 50:50, 25:75, and 0:100, based on seed weight) and three nitrogen (N) fertilizer levels (0, 50, and 100 kg ha⁻¹). Increasing alfalfa proportion and N fertilizer level increased soil nutrients and the two-year total DM yield. Intercropping increased both land and nitrogen use efficiency (NUE) compared with monocultures. Greater NUE was obtained when N fertilizer was applied at 50 kg ha⁻¹, compared with 100 kg ha⁻¹. Increasing the proportion of alfalfa in intercrops increased the crude protein yield and rumen undegraded protein yield. Harvested forage intercrops were incubated with ruminal fluid for 48 h. Degraded DM yield, CO₂ and CH₄ emissions increased with increasing alfalfa proportion in intercrops. Overall, the 75:25 of orchardgrass-alfalfa intercrops was recommended as the best compromise between high forage productivity, superior feed use efficiency and low ruminal greenhouse gas emissions through complementary effects. The results indicate that the appropriate N fertilization level would be 50 kg ha⁻¹ for acquiring higher nitrogen use efficiency and forage productivity.     

The implications of controlling grazed sward height for the operation and productivity of upland sheep systems in the UK. 3. The effect of choice of genotype, level of nitrogen fertilizer and lamb:ewe ratio

Grazed sward surface height was controlled within the range 3·25–4·75 cm during spring and summer in two experiments. In Experiment 1, the effects of stocking two breeds of ewe of similar size but different potential levels of reproductive performance [Brecknock Cheviot (C) and Beulah Speckled Face (B)] at different annual stocking rates of twelve (SR₁₂) and twenty (SR₂₀) per hectare, rates of nitrogen fertilizer of 100 (N₁₀₀) and 200 (N₂₀₀) kg N ha^?1 annum^?1 and different lamb:ewe ratios (C_1·2, B_1·2 and B_1·5) were measured in four treatments (SR₂₀N₂₀₀C_1·2; SR₂₀N₂₀₀B_1·2; SR₂₀N₂₀₀B_1·5; SR₁₂N₁₀₀C_1·2) replicated three times. In each of three years animal performance and yield of silage from areas of pasture surplus to grazing requirements were measured. In Experiment 2, breed B was compared with the Welsh Mule (W) breed, a larger with a higher potential reproductive performance, at two stocking rates, two rates of nitrogen fertilizer and two lamb:ewe ratios set on the basis of results from Experiment 1 (SR₁₈N₂₀₀B_1·5; SR₁₂N₁₀₀B_1·5; SR₁₈N₂₀₀W_1·5; SR₁₈N₂₀₀W_1·7). The treatments were replicated three times. The same terminal sire (Suffolk) was used in both experiments. A primary aim of the experiments was to test the validity of the experimental procedures used for comparing breeds of sheep where nutrition is provided predominately from grazed pastures. In Experiment 1, there was no difference between breeds C and B in the live weights of individual lambs at weaning at the same SR (20), N rate (200) and lamb:ewe ratio (1·2). Breeds C and B produced similar total yields of lamb (633 kg lamb ha^?1± 10·5) and silage (193 kg DM ewe^?1± 37·7), but breed B had a higher level of potential reproductive performance (1·59 vs. 1·37 lambs ewe^?1: P < 0·001). The treatments SR₂₀N₂₀₀B_1·5 and SR₁₂N₁₀₀C_1·2 produced, respectively, greater and lesser yields of lamb (725 vs. 384 kg lamb ha^?1, P < 0·001) and lesser and greater yields of silage (123 vs. 327 kg DM ewe^?1, P < 0·001). In Experiment 2, the live weight of lambs at weaning from breed W were heavier than from breed B (29·1 vs. 26·2 kg lamb^?1, P < 0·01) but there was no significant difference in total yield of lamb weaned between breeds W and B at the same SR (18), N rate (200) and lamb:ewe ratio (1·5) (747 kg lamb ha^?1± 19·2), or in the yield of silage (66 kg DM ewe^?1± 16·4), but breed W had a higher potential reproductive performance (1·85 vs. 1·58 lambs ewe^?1, P < 0·05). The treatments SR₁₈N₂₀₀W_1·7 and SR₁₂N₁₀₀B_1·5 produced, respectively, greater and lesser yields of lamb (840 vs. 473 kg lamb ha^?1, P < 0·001) and similar and greater yields of silage (60 vs. 141 kg DM ewe^?1, P < 0·05). The experimental approach adopted and the management protocols used provided a basis for ranking the performance of the breeds of ewes examined at appropriate levels of annual stocking rate, N-fertilizer input and lamb:ewe ratio.     

Effects of partial rootzone drying on yield,yield components,and irrigation water use efficiency of canola (<Emphasis Type="Italic">Brassica</Emphasis>?<Emphasis Type="Italic">napus</Emphasis> L.)

Effect of PRD (partial rootzone drying) on yield and yield components of canola (Brassica napus L.) was investigated in greenhouse conditions. The treatments were: T₁, full watering of both sides of roots; T₂, alternate irrigation on both sides; T₃, half of irrigation water in T₁ was given to one side; T₄, same as T₃ but without plate; T₅, same as T₂ but without plate. In T₁, T₂, and T₃ treatments, the boxes were evenly separated into two compartments with thin plates. The results showed that grain yield of T₁ to T₅ treatments was 18.11, 16.38, 12.44, 9.29, and 8.66 g plant⁻¹. T₂ treatment increased plant height by 46.9% and 1000-seed weight by 17.8%, but reduced lateral branches by 16.7% and number of pods by 24%, over T₁ treatment. T₂ treatment was the most efficient (irrigation water use efficiency = 0.679 kg m⁻³) and treatment T₅ was the least efficient (0.359 kg m⁻³). The difference between irrigation water use efficiency (IWUE) of T₂ and T₅, and T₃ and T₄ treatments, was significant (p < 0.05). Therefore, halving the amount of applied irrigation water and applying this water alternatively on both sides of the root zone will produce the highest IWUE. This study showed that PRD irrigation management has high influence on rooting system of canola. This phenomenon could affect nutrients uptake and consequently all aspects of plant growth and development.     

Critical water content and water stress coefficient of soybean (Glycine max [L.] Merr.) under deficit irrigation

The objective of this research was to investigate the critical water content (θ _c) and water stress coefficient (K _s) of soybean plant under deficit irrigation. This research was conducted in a plastic house at the University of Lampung, Sumatra in Indonesia from June to September 2000. The water deficit levels were 0–20%, 20–40%, 40–60%, 60–80%, and 80–100% of available water (AW) deficit, arranged in Randomized Completely Block (RCB) design with four replications. The results showed that the soybean plant started to experience stress from week IV within 40–60% of AW deficit. The fraction of total available water (TAW) that the crop can extract from the root zone without suffering water stress (p) was 0.5 and θ_c was 0.305 m³ m⁻³. The values of K _s at p=0.5 were 0.78, 0.86, 0.78, and 0.71 from week IV to week VII, respectively. The optimum yield of soybean plant with the highest yield efficiency was reached at 40–60% of AW deficit with an average K _s value of 0.78; this level of deficit irrigation could conserve about 10% of the irrigation. The optimum yield of soybean plant was 7.9 g/pot and crop water requirement was 372 mm.     

Gas Exchange Analysis for Estimating Net CO2 Fixation Capacity of Mangrove (Rhizophora stylosa) Forest in the Mouth of River Fukido,Ishigaki Island,Japan

Abstract

Mangrove trees have been considered to possess a higher carbon fixation capacity than terrestrial trees although a reliable method to estimate their CO₂ fixation capacity has not been established. In this study, net CO₂ fixation in above-ground of Rhizophora stylosa was estimated as the difference between photosynthetic absorption and respiratory emission of CO₂. In order to estimate these parameters, photosynthetic rates of single-leaves in response to light and temperature and the respiratory rates of leaves and branches in response to temperature were measured. Furthermore, we established a model of diurnal change in temperature. Monthly averages of the diurnal temperature change were used for correcting the CO₂ absorption and emission. The effect of temperature modification on the estimation of net CO₂ fixation was examined, and the net CO₂ fixation capacity estimated with and without temperature modification was compared. Biomass accumulation estimated without temperature modification (i.e. corrected only for the light intensity) was 6.1 tons ha-¹ yr-¹, while that estimated with temperature modification (i.e. corrected for both light intensity and temperature) was 13.0 tons ha-¹ yr-¹. A doubling of the estimated values of net CO₂ fixation as observed in this study was caused by the decrease in respiratory CO₂ emission by half, which results from temperature modification. These findings suggest that temperature modification in gas exchange analysis could improve the accuracy of estimation of the net CO₂ fixation capacity.     

磷硒配施对郑麦9023硒吸收及土壤硒形态转化的影响

为给通过合理施用磷肥来提高冬小麦籽粒硒含量提供参考依据,以冬小麦品种郑麦9023为供试材料进行盆栽试验,设置3个磷水平(0、80、160mg·kg~(-1),分别表示为P_0、P_(80)和P_(160))和2个硒水平(0和1mg·kg~(-1),分别表示为Se_0和Se_1),共6个处理。结果表明,在Se_0水平下,籽粒产量随着施磷量的增加而逐渐提高,而在Se_1水平下,籽粒产量随着施磷量的增加呈先增加后降低的趋势,在P_(80)处理下籽粒产量最高。在Se_1水平下,施磷显著增加了小麦各器官以及整株硒累积量,但是施磷降低了硒从颖壳向籽粒中的迁移系数,显著降低了各器官的硒含量。施硒可提高土壤各形态硒的含量,提高水溶态和可交换态硒的比例。在Se_0水平下施磷可以提高土壤水溶态硒、可交换态硒、铁锰氧化物结合态硒所占总硒的比例;而在Se_1水平下,施磷增加了土壤水溶态硒、有机物硫化物结合态硒、残渣态硒的含量及比例,但是降低了可交换态硒、铁锰氧化物结合态硒的含量及比例。因此,适宜的磷硒配施可通过影响土壤中各种形态硒的转化过程,促进土壤硒向水溶态硒的转化,提高土壤硒的有效性,进而促进郑麦9023对土壤硒的吸收累积,达到增产的效果。     

Crop establishment methods: foliar and basal nourishment of rice (<Emphasis Type="Italic">Oryza sativa</Emphasis>) cultivation affecting growth parameters,water saving,productivity and soil physical properties

A 3-year field experiment was carried out with tillage crop establishment (TCE) and rice nourishment in north-western India to evaluate the effect of five crop establishment methods and seven fertility treatments on crop production, water productivity, profitability, and soil physical quality. Maximum panicle length (30.9 cm) was noted with F₃ treatment and minimum (22.7 cm) with F₀ treatment. Zinc application methods and timing had significantly effect on paddy yield. Maximum yield (5.22 t ha^?1) was achieved in treatment F₃ and minimum yield (2.65 t ha^?1) was noted in F₀ treatment. Results also revealed that root dry weight, root volume, and root length were recorded with higher values in F₃ treatment and minimum in F₀ treatment. TCE methods were recorded with higher values in raised beds system than T₅ at all growth stages. Treatments T₁ and T₂ reduced the mean maximum soil temperature at transplanting zone depth by 3.6 and 2.7 °C compared to the T₃. Paddy yield in T₃ was always significantly less than in T₅. On average, treatment T₄ recorded about 13 % lower water use and 3.7 % higher water productivity compared to T₅. Treatment T₅ had higher bulk density. The cumulative infiltration for 498 min was about 2 times in treatment T₁, 5 times in T₃ and more than 8 times in T₄ of the values in T₅. Mean weight diameter of aggregates was higher in T₄ followed by the T₁ and lowest in T₅. The study reveals that TCE methods T₁ and T₄ with F₃ nourishment could be more viable options for rice crop in order to save input costs and enhance profitability.     

Impact of organic manure and chemical fertilizers on artemisinin content and yield in Artemisia annua L

Artemisinin isolated from the aerial parts of Artemisia annua L. is a promising and potent antimalarial drug. It posses remarkable activity against both chloroquinine resistant as well as chloroquinine sensitive strains of Plasmodium falciparum. It is also useful in the treatment of cerebral malaria. The relatively low content of artemisinin in A. annua and unavailability of cost effective and viable synthetic protocol however, are major obstacles to the commercial production of the drug. The enhanced production of artemisinin is hence, highly desirable, which can be achieved by adequate and judicious supply of plant nutrients. The present experiment was therefore, designed to study the effect of organic manure (15 tonnes ha⁻¹) and chemical fertilizers (N₄₀₊₄₀, P₄₀, K₄₀, S₁₅₊₁₅ kg ha⁻¹; nitrogen, phosphorus, potassium and sulphur) on the accumulation of artemisinin and biomass in various plant parts through the developmental stages of A. annua L. Artemisinin yield (kg ha⁻¹) was also determined through the developmental stages of A. annua L. Artemisinin content and artemisinin yield of dried leaves were increased significantly at pre-flowering stage in the plants treated with NPKS (27.3% and 53.6%) and NPK (18.2% and 33.5%), respectively, when compared with control. Maximum dry yield of leaf ranging from 2596 to 3141 kg ha⁻¹ was observed at pre-flowering stage with various treatments.     

Grain Nitrogen Concentration in Wheat Grown under Intensive Organic Manure Application on Andosols in Central Japan

Abstract

Grain nitrogen concentration (N%) is a major determinant of grain quality in winter wheat. The objective of this study was to compare the responses of wheat grain N% to organic manure with those to inorganic fertilizer in long-term experiments. We analyzed the grain N accumulation using soft wheat (Kinunonami) and hard wheat (Yumeshihou) cultivars grown with a high rate of organic manure application (OM; 80 t ha-¹ yr-¹ for >10 years and 30 t ha-¹ yr-¹ during the three years of the present study) and with standard (SF; 204–252 kg N ha-¹ yr-¹) or low (LF; 102–126 kg N ha-¹ yr-¹) rates of inorganic fertilizer for three years in Japan. The results agreed with previous research on the underlying mechanisms for grain N% under conventional fertilizer management: both sink and source regulation affected N accumulation in grains, and the accumulation of N in grains and of dry matter in grains are independent. Grain N% was significantly higher in the OM treatment than in the SF and LF treatments as a result of lower dry matter accumulation in the grains. High straw N% led to higher N accumulation in grains in the OM treatment during the late grain-filling period in Yumeshihou. Our results suggest that too much organic manure was applied, i.e., more than was required to optimize grain N%, when manure application was designed to produce a grain yield equivalent to that in conventional fertilizer management. We discuss ways to stabilize grain N% under intensive organic manure application.     

小麦玉米一体化群体配置对小麦冠层结构和产量影响

为探索冬小麦-夏玉米一体化种植中小麦的适宜群体配置模式,设置20 cm-20 cm（R₁）、12 cm-12 cm-12 cm-24 cm（R₂）及13 cm-20 cm（R₃）三种行距处理方式和120 kg·hm^-2（S₁）、157.5 kg·hm^-2（S₂）及195 kg·hm^-2（S₃）三种播量,研究了行距和播量对小麦冠层结构特征和光合特性及产量的影响。结果表明,不同处理对各指标的影响因小麦生育时期的变化而不同。在孕穗至开花期, R₁S₁处理的小麦叶片SPAD值、净光合速率（P_n）及气孔导度（G_s）高于其他处理,开花期后R₂S₂处理表现出明显的光合优势。其中,R₂S₂处理的小麦LAI、叶倾角（MTA）在开花期后高于其他处理,在花后10 d之后其SPAD、P_n值最高。在不同处理中,R₂S₂处理产量最高,这主要归因于其有较高的穗数和千粒重。因此,在本试验条件下小麦高产的最佳群体配置是行距12 cm-12 cm-12 cm-24 cm和播量157.5 kg·hm^-2。     

Utilizing rainfall and alternate wetting and drying irrigation for high water productivity in irrigated lowland paddy rice in southern Taiwan

Taiwan’s average annual rainfall is high compared to other countries around the world; however, it is considered a country with great demand for water resources. Rainfall along with alternate wetting and drying irrigation is proposed to minimize water demand and maximize water productivity for lowland paddy rice cultivation in southern Taiwan. A field experiment was conducted to determine the most suitable ponded water depth for enhancing water saving in paddy rice irrigation. Different ponded water depths treatments (T_2 cm, T_3 cm, T_4 cm and T_5 cm) were applied weekly from transplanting to early heading using a complete randomized block design with four replications. The highest rainwater productivity (2.07 kg/m³) was achieved in T_5 cm and the lowest in T_2 cm (1.62 kg/m³). The highest total water productivity, (0.75 kg/m³) and irrigation water productivity (1.40 kg/m³) was achieved in T_2 cm. The total amount of water saved in T_4 cm, T_3 cm and T_2 cm was 20, 40, and 60%, respectively. Weekly application of T_4 cm ponded water depth from transplanting to heading produced the lowest yield reduction (1.57%) and grain production loss (0.06 kg) having no significant impact on yield loss compared to T_5 cm. Thus, we assert that the weekly application of T_4 cm along with rainfall produced the best results for reducing lowland paddy rice irrigation water use and matching the required crop water.     

Plant and soil responses to nitrogen and phosphorus fertilization of bromegrass‐dominated haylands in Saskatchewan,Canada

Field experiments were conducted at three different sites in Saskatchewan, Canada (Colonsay, Vanscoy and Rosthern) over two years (2005 and 2006) to determine the effects of dribble‐banded and coulter‐injected liquid fertilizer applied in the spring of 2005 at 56, 112 and 224 kg N ha^?1 with and without P at 28 kg P₂O₅ ha^?1. The three sites were unfertilized, 7‐ to 8‐year old stands of mainly meadow bromegrass (Bromus riparius)‐dominated haylands. All fertilization treatments produced significantly (P ≤ 0·05) higher dry matter yield than the control in the year of application at the three Saskatchewan sites. There was no significant difference between the two application methods (surface dribble band vs. coulter injected) for any fertilizer treatments. The addition of 28 kg P₂O₅ ha^?1 P fertilizer along with the N fertilizer did not have a significant effect on yield in most cases. In the year of application, increasing N rates above 56 kg N ha^?1 did not significantly increase yield over the 56 kg N ha^?1 rate in most cases, but did increase N concentration, N uptake and protein concentration. A significant residual effect was found in the high N‐rate treatments in 2006, with significantly higher yield and N uptake. In 2005, the forage N and P uptake in the fertilized treatments were significantly higher than the control in all cases. The N uptake at the three Saskatchewan sites increased with increasing N rate up to the high rate of 224 kg N ha^?1, although the percent recovery of applied N decreased with increasing rate. The P fertilization with 28 kg P₂O₅ ha^?1 also increased P uptake. Overall, rates of fertilizer of approximately 56 kg N ha^?1 appear to be sufficient to produce nearly maximum forage yield and protein concentration of the grass in the year of application.