Nitrogen studies in Lolium perenne grown for seed I. Level of application

In field trials in 1971–73, perennial ryegrass cv. S23 and S24 were given up to 200 kg ha^?1 nitrogen (N) and dry weight, seed yields and seed yield components measured. Optimum levels of applied N ranged from 80 kg ha^?1, where livestock had grazed the crop in the establishment year or where residual N levels were about 70 kg ha^?1, to 120 kg ha^?1 where residual N was low. Application of more than 120 kg ha^?1 did not increase yields further because of increased lodging and increased production of vegetative tillers. Seed set was 37–55% in S24 and 25–29% in S23 and was decreased by lodging.     

Nitrogen utilization efficiency of safflower hybrids and open-pollinated varieties under Mediterranean conditions

The identification of the factors determining nutrient utilization of safflower (Carthamus tinctorius L.) is useful for the successful introduction of the crop to the cropping system of a region. A field study was conducted to compare and analyze the relative importance of the various component traits causing variation in nitrogen utilization efficiency (NUE) of safflower under Mediterranean conditions. Ten genotypes, four hybrids and six open-pollinated varieties, were grown for two growing seasons without irrigation, on a silty clay (Typic Xerorthent) soil. Seed yield varied greatly among genotypes and ranged from 923 to 3391 kg ha⁻¹. Hybrids showed a mean seed yield superiority of 12.5% against varieties. Seed yield was the most important component of seed N yield and its contribution to the total variation in seed N yield among genotypes was at least 53%. NUE for biomass production during the seed-filling period was lower compared to that during the vegetative period. Genotypes differed in NUE for seed production (NUE_s) and the differences followed those of nitrogen harvest index (NHI). The contribution of NHI to the total variation in NUE_s among genotypes was much greater compared to that of yield per unit seed nitrogen and accounted for more than 79%. NUE_s is positively correlated with seed yield, suggesting that high yield was probably associated with more efficient exploitation of nitrogen. NUE_s is negatively correlated with (leaf + stem) N concentration at maturity, meaning that low straw N concentration may be indication of higher NUE_s. Results indicated that selection for NUE in safflower should be based on multiple criteria rather than just one criterion and also should be accompanied by evaluation for seed yield to ensure an improvement in both traits.     

The response of a perennial ryegrass (Lolium perenne L.) seed crop to nitrogen fertilizer application in the absence of moisture stress

Responses of perennial ryegrass (Lolium perenne L.) to nitrogen (N) fertilizer application rates and timings vary widely, because water is often limiting. Yield response to N fertilizer application during autumn, late‐winter and spring, and the associated efficiency of use of these inputs, was assessed under conditions of non‐limiting soil moisture during two, one‐year lysimeter studies in Canterbury, New Zealand. There were significant (P < 0·05) increases in seed and herbage yields with increasing N fertilizer application. Seed yields differed with year; greatest yields were 300 g m^?2 in 1996 and 450 g m^?2 in 1997. Seed head numbers (r²=0·77), seeds head^?1 (r²=0·92) and herbage yield (r²=0·92) were the major determinants of seed yield in both years. Irrigation required to maintain the soil between 70% and 90% of field capacity was directly related (r²=0·94 and 0·99 in 1996 and 1997 respectively) to increases in herbage yield. Seed yield, seed quality (thousand seed weight and percentage of seed > 1·85 mg), efficiency of water use, efficiency of N fertilizer use and apparent N fertilizer recovery were greatest when N fertilizer was applied at a rate of 50 kg N ha^?1, 50 or 100 kg N ha^?1 and 150 kg N ha^?1 in autumn, late‐winter and spring respectively; further increases in spring N fertilizer stimulated vegetative growth, but not seed yield. As a management strategy, applying N fertilizer to match the N requirements of the crop during the reproductive stage of growth will result in high yields of high quality seed while minimizing environmental impact.     

Genetic analysis of seed‐related traits in smooth bromegrass (Bromus inermis) under well‐watered and water‐stressed conditions

In forage grasses, knowledge about the genetic basis of seed production and its association with related traits under water stress is very limited. Half‐sib families derived from the polycross of twenty five smooth bromegrass genotypes were evaluated in the field in well‐watered and water‐stressed environments during 2012 and 2013. Results showed that drought stress had a negative effect on seed yield and reduced phenotypic variation for seed yield and agro‐morphological traits. High genotypic variation was observed among families for seed yield and its components. Narrow‐sense heritabilities (h²) ranged from 0·22 (flag leaf weight) to 0·81 (days to anthesis). These moderate‐to‐high heritability estimates for seed yield and its components indicate that phenotypic selection can be successful to achieve genetic progress for these traits. Seed yield had a positive correlation with 1000‐seed weight, number of ears per plant, number of seeds per panicle, seed weight per panicle and panicle length.     

Nitrogen fertilization effects on lesquerella production

Progress has been made towards the commercialization of Lesquerella fendleri (Gray) Wats. as a fall-planted oilseed crop for the southwestern United States. Research to develop suitable cultural practices for commercial production of lesquerella has been underway since the late 1980s; however, information is limited on the plant’s nitrogen (N) requirement. Field experiments were conducted during two growing seasons to determine the optimum amount and timing of N applications for lesquerella production. Yield results indicate that lesquerella grown on desert soils is strongly influenced by N fertilization. Nitrogen rates as high as 180 kg N ha⁻¹ increased seed yield. Seed oil content decreased as the N rate was increased. The increase in seed yield at the higher N rates generally offsets the decrease in oil content, but oil yields appeared to be near maximum at 180 kg N ha⁻¹. Split-applications of N in the Spring increased seed and oil yields in one of two seasons. Nitrogen had no influence on 1000-seed weight or lesquerolic acid content of the oil. No Spring leaf blade total N level was identified as being related to maximum seed yield. A suggested N management program for lesquerella production is to apply a small portion of N at planting time and the major portion of N in several applications during the period from onset of bloom through full bloom (February–April).     

Effect of seed piece removal on yield and agronomic characteristics of Russet Burbank potatoes

There is inadequate information available to ascertain the length of time seed pieces contribute to the yield and agronomic characteristics of potatoes (Solanum tuberosum L.) under field conditions. Previous studies have not accounted for root system disturbance during seed piece removal. In 1994, 1995, and 1997 a field study was conducted using Russet Burbank to determine whether seed piece removal at each of three growth stages affects yield and agronomic characteristics. A trowel was used to tunnel into the side of potato hills to remove seed pieces by hand either at emergence, at 20- cm plant height, or at first bloom. Control plots consisted of plants with root systems disturbed on the same date as seed removal (disturbed control) or not treated (non-disturbed control). Seed pieces were analyzed for solids, sucrose, and reducing sugars before planting and after removal at each growth stage in 1997. Removing seed pieces or disturbing roots at all growth stages significantly decreased total and U.S. No. 1 yields compared with non- disturbed control. Total yield from plots disturbed at emergence was 37.8 Mg ha^-1 compared to 22.1 Mg ha^-1 when the seed pieces were removed. Disturbing seed pieces at emergence resulted in U.S. No. 1 yield of 21.2 Mg ha^-1 compared with 10.6 Mg ha^-1 when seed pieces were removed at the same growth stage. For U.S. No. 1 yield, a difference between removing the seed pieces and disturbing the root systems was still evident at the 20-cm plant height growth stage (15.4 Mg ha^-1 vs 20.3 Mg ha^-1, respectively). Disturbing plants at emergence or at 20-cm plant height growth stage reduced the number of tubers per plant to 8.8 for both treatments compared to 9.7 for the non-disturbed control. Removing seed pieces at these same growth stages further reduced tubers per plant to 6.9 and 7.6, respectively. Vines of plants with seed pieces removed at emergence were shorter and remained green later into the season compared with disturbed and non-disturbed control treatments. Percent solids in seed pieces decreased from 20.68 at planting to 5.03 at first bloom. Seed piece percent sucrose remained constant from planting through the 20-cm plant height growth stage and then fell to nearly zero at first bloom. Reducing sugar in the seed pieces atplanting and emergence was 0.67%, rose to 1.08% at the 20-cm plant height growth stage, and then decreased to 0.89% at first bloom.     

Sesame response to nitrogen management under contrasting water availabilities

Sesame is mainly cultivated under traditional, low-input agro-systems. Recent breeding developments promoted the modernization and mechanization of sesame cultivation. However, only a few articles have been published concerning fertilization requirements for both modern and traditional agro-systems. In field trials at two locations,we determined the response of irrigated sesame to nitrogen(N). Three promising sesame lines were tested combining two irrigation levels with four N levels. At a high ...     

Kenaf seed storage duration on germination,emergence, and yield

Kenaf (Hibiscus cannabinus L.) is a potential alternative crop being developed for fiber production. Because planting area varies dramatically from year to year, seed supplies may greatly exceed use so that the excess seed must be stored for one to several years. The objectives of this study were to determine the effect of seed storage duration at 10 °C on germination, vigor, emergence, and yield. Replicated trials were established at Starkville, MS in 1999 and 2000 to evaluate field emergence and biomass yield of kenaf seed from five ‘Everglades 41’ (‘E41’) harvest year seed lots stored at 10 °C in ambient relative humidity for up to 4 years. Germination of these same seed lots under standard (20–30 °C) and cool (20 °C) temperatures, and seed vigor was evaluated over time. Field emergence was the same for the different seed storage durations up to 4 years, but was directly affected by drought conditions for each planted year. Biomass yields ranged from 12.39 to 14.57 Mg ha⁻¹ in 1999 and 16.82 to 18.47 Mg ha⁻¹ in 2000, but were not different between storage durations. Seed germination remained greater than 80% regardless of storage duration. Electrolyte leakage, based on conductivity, was 38–50% less with freshly harvested seed than seed stored for 4 years at 10 °C. However, neither the conductivity nor accelerated aging test were reliable predictors of field emergence. Kenaf seed stored up to 4 years at 10 °C retained germination rates acceptable for commercial use. Neither field emergence nor biomass yield was affected by seed storage duration.     

Deficit irrigations during soybean reproductive stages and CROPGRO-soybean simulations under semi-arid climatic conditions

This study was carried out to determine the effect of water stress on five different generative stages of soybeans and to evaluate the CROPGRO-soybean model under semi-arid climatic conditions. The study was conducted at the Faculty of Agricultural Engineering, Harran University research field in 2003 and 2004 growing seasons. Plants received full irrigation during vegetative stages, after which it was cut off at different reproductive stages (treatments): R_1-2, beginning of flowering and full bloom; R₃, beginning of pod; R₄, full pod; R₅, beginning of seed; and R₆, full seed. The control treatment was full irrigation throughout. Observed yields ranged from 1955 (R₆) to 3684 kg ha⁻¹ (control) in 2003, and from 1867 (R₆) to 3952 kg ha⁻¹ (control) in 2004, respectively. Generally, in both of the years any water stress imposed on soybeans in three different generative stages (R₃, R₅, and R₆) resulted in substantial yield reduction compared with full irrigation; yield reduction was greatest at the R₆ stage. Biomass and 1000 seed weight also showed significant difference. Overall, CROPGRO-soybean simulated parameters from all treatments were higher compared with observed ones. Although simulated yield results were close to measured ones, they could not track observed yield patterns. Generally, the CROPGRO-soybean simulation model failed to satisfactorily mimic observed soybean yield, biomass, and 1000 seed weight and therefore it is suggested not to be used for similar scenarios and climatic conditions.     

Forage soybean production for seed in mediterranean environments

Despite several experiments on row spacings and seeding rates of grain soybeans, limited information is available on the most suitable row spacing and seeding rate for tall and robust forage type soybeans grown for seed. The objectives of this study were to investigate seed yield, oil and protein content, and several morphological traits as affected by row spacing (20, 40, 60 and 80 cm) and seeding rate (330,000, 660,000, 990,000 and 1,320,000 seeds ha⁻¹) in tall and robust forage type soybeans in three irrigated Mediterranean environments in Turkey in a randomized split plot design with three replications in 2004 and 2005. Row spacings had no significant effect on plant height but tall and profusely branched plants developed in wide row spacing and light seeding conditions. Seed yield responded positively and linearly to row spacing up to 60 cm and then decreased slightly in all locations. Seed yield was the highest at 990,000 seeds ha⁻¹ seeding rate in all three locations (3072.5 kg ha⁻¹ in Bursa LSD = 214.7 kg ha⁻¹, 3295.1 kg ha⁻¹ in Mustafakemalpasa LSD = 298.6 kg ha⁻¹ and 3311.3 kg ha⁻¹ in Samsun LSD = 321.1 kg ha⁻¹). Averaged across years, locations, row spacings, and seeding rates the mean seed yield was an impressive 3013.4 kg ha⁻¹ compare with 3500.0 kg ha⁻¹ average seed yield of grain types. Crude protein and oil content of forage type soybean were not significantly affected by row spacings and seeding rates. It was concluded that forage type soybeans can be grown for multiple purposes at the 990,000 seeds ha⁻¹ seeding rate and 60 cm row spacings in Mediterranean environments.     

A process model for explaining genotypic and environmental variation in growth and yield of rice based on measured plant N accumulation

The objective of this study was to develop a mechanistic model for simulating the genotypic and environmental variation in rice growth and yield based on measured plant N accumulation. The model calibrations and evaluations were conducted for rice growth and yield data obtained from a cross-locational experiment on 9 genotypes at 7 climatically different locations in Asia. The rough dry grain yield measured in the experiment ranged from 71 to 1044 g m⁻² over the genotypes and locations. An entire process model was developed by integrating sub-models for simulating the processes of leaf area index development, partitioning of nitrogen within plant organs, vegetative biomass growth, spikelet number determination, and yield. The entire process model considered down-regulation of photosynthesis caused by limited capacity for end-product utilization in growing sink organs by representing canopy photosynthetic rate as a function of sugar content per unit leaf nitrogen content. The model well explained the observed genotypic and environmental variation in the dynamics of above-ground biomass growth (for validation dataset, R² = 95), leaf area index development (R² = 0.82) and leaf N content (R² = 0.85), and spikelet number per unit area (R² = 0.67) and rough grain yield (R² = 0.66), simultaneously. The model calibrations for each sub-model and the entire process model against observed data identified 10 genotype-specific model parameters as important traits for determining genotypic differences in the growth attributes. Out of the 10 parameters, 5 were related to the processes of phenological development and spikelet sterility, considered to be major determinants of genotypic adaptability to climate. The other 5 parameters of stomatal conductance, radiation extinction coefficient, nitrogen use efficiency in spikelet differentiation, critical leaf N causing senescence, and potential single grain mass had significant influence on the yield potential of genotypes under given climate conditions.     

Yield components,dry matter,LAI and LAD of soybeans in Northeast China

Pod and seed number are the most important yield components of soybean [Glycine max (L.) Merr.]. Leaf area index (LAI), leaf area duration (LAD) and dry matter accumulation during the reproductive period strongly influence yield components. Our objectives were: to investigate if differences in yield components exist among genotypes differing in both yield and maturity; and to examine the dynamics of dry matter accumulation, LAI, and LAD during the reproductive period for the high-yielding genotypes. Sixteen soybean genotypes within three maturity groups were grown in Hailun, China in a randomized complete block design with three replications, across 2 years. Maturity groups were selected to differ by approximately 7 days in mean days to R₇ (5% of pods are mature pod color). Dry matter accumulation, LAI, and LAD were measured at R₂, R₄, R₅, and R₆ stages, respectively in each year. Yield, yield components and harvest index were determined at maturity. Late maturity genotypes had higher yield than early ones. Majority of the seed yield and components were positioned in the middle and upper part of the plant. Both pod number and seed number were higher in high-yield genotypes in each group. Seed number per pod contributed to increased yield in the high rainfall year but was not related to the variation in yield of the genotypes evaluated. Significant variations were found for LAI, LAD and dry matter within each maturity group. Higher accumulation of dry matter, higher LAI and LAD during reproductive stages were found to be closely related to high-yield genotypes in each group. No relationship was found between harvest index (HI) and seed yield.     

Seed Weight of Nodulating and Non-nodulating Soybeans at Different Nitrogen Levels and Years

Abstract

Seed weight (weight per seed) is an important trait in soybean [Glycine max (L) Merr.] that affects its production, processing, marketing and consumer preferences. To determine the effects of nitrogen fertilizers and climatic conditions on seed weight, a five-year field experiment was conducted by growing four nodulating cultivars and 13 non-nodulating lines at 4 levels of nitrogen fertilizer (0, 2, 10 and 20 g m^–2). The variation in seed weight due to the difference in the fertilizer level and climatic condition of the year was greater in non-nodulating lines than in nodulating cultivars. This resulted in a lower heritability estimate in non-nodulating lines (0.49) than in the nodulating cultivars (0.85). Nitrogen fertilizer increased the seed weights of non-nodulating lines but did not affect the seed weights of the nodulating cultivars. The high response of the non-nodulating lines to nitrogen fertilizer may be attributed to their strong dependence on fertilizer and soil nitrogen due to their lack of ability to fix nitrogen in symbiosis. The small seeds produced during the years with low temperatures and early onset of frost may have been caused by the slow seed growth rate and short seed filling duration.     

The effects of nitrogen and iron fertilization on growth,yield and fertilizer use efficiency of soybean in a Mediterranean-type soil

Poor seed yield of soybean in Mediterranean-type environments may result from insufficient iron (Fe) uptake and poor biological nitrogen (N) fixation due to high bicarbonate and pH in soils. This study was conducted to evaluate the effects of N and Fe fertilization on growth and yield of double cropped soybean (cv. SA 88, MG III) in a Mediterranean-type environment in Turkey during 2003 and 2004. The soil of the experimental plots was a Vertisol with 176 g CaCO₃ kg⁻¹ and pH 7.7 and 17 g organic matter kg⁻¹ soil. Soybean seeds were inoculated prior to planting with commercial peat inoculants. N fertilizer rates were 0, 40, 80, and 120 kg N ha⁻¹ of which half was applied before planting and the other half at full blooming stage (R2). Fe fertilizer rates were 0, 200 and 400 g Fe EDTA (5.5% Fe and 2% EDTA) ha⁻¹. It was sprayed as two equal portions at two trifoliate (V2) and at five trifoliate stages (V5). Plants were sampled at flower initiation (R1), at full pod (R4) and at full seed (R6) stages. Application of starter N increased biomass and leaf area index at R1 stage whereas Fe fertilization did not affect early growth parameters. N application continued to have a positive effect on growth parameters at later stages and on seed yield. Fe fertilization increased growth parameters at R4 and R6 stages, and final seed yield in both years. This study demonstrated an interactive effect of N and Fe fertilization on growth and yield of soybean in the soil having high bicarbonate and pH. There was a positive interaction between N and Fe at the N rates up to 80 kg N ha⁻¹. However, further increase in N rate produced a negative interaction. Fertilization of soybean with 80 kg N ha⁻¹ and 400 g Fe ha⁻¹ resulted in the highest seed yield in both years. We concluded that application of starter and top dressed N in combination with two split FeEDTA fertilization can be beneficial to improve early growth and final yield of inoculated soybean in Mediterranean-type soils.     

Temperature,radiation, and duration dependence of high soybean yields: Measurement and simulation

Information about the relative contribution of various environmental and developmental factors to soybean production can help focus objectives for programs of crop improvement. The growth of high-yielding soybeans (Glycine max [L.] Merr.) was simulated in order to quantitatively analyze effects of temperature, radiation, and duration of crop growth on seed yield. Data from Saihoku Branch Station, Shinjo, Japan were used for comparison with the simulations. Field data were obtained from fields converted from paddy cultivation by installing drainage tile and from adjacent fields managed as conventional dryland cultivations. Soils on both field types were clayey humic andosols (Dystrandepts). In the model, mean air temperature controlled leaf appearance rate. Sunshine-hours were used as a measure of solar radiation. Observed dates of emergence and harvest maturity were used to estimate the duration of biomass accumulation. Observed values of apparent harvest index (0.576 g seed per g above-ground biomass) were used to calculate the seed yield from simulated biomasses. The model was based on the assumption that these crops did not experience water deficits or nutrient deficiences.Converted paddy fields produced unusually high seed yields (506–649 g/m²). Simulated yields corresponded with observed high yields for crops at Saihoku Station. Year-to-year variation in temperature, solar radiation and duration of crop growth accounted for a substantial portion of observed annual differences in yield. Year-to-year differences in duration of crop growth on the conventional fields especially influenced the simulated yields. Simulated changes in duration of crop growth on converted paddy fields changed yield at the rate of 5.3 g m⁻² day⁻¹.     

Seed growth of three perennial ryegrass cultivars sown on two dates and treated with trinexapac ethyl straw shortener

First‐year crops of diploid perennial ryegrass (cvs. Meridian, Bronsyn and Grasslands Impact) were sown on 1 April and 14 May 2008. Applications of trinexapac ethyl (TE) plant growth regulator at 0, 200 and 400 g a.i. ha^?1 were used to shorten stems to examine the impact of seed growth. Seed filling followed a consistent sigmoidal growth pattern with a lag phase of 127°C days, and linear duration of 390°C days. Time to 95% of final seed weight was 517°C days. Seed yield increases from TE were from higher numbers of first‐grade seeds m^?2, achieved by a higher rate of seed filling during the linear phase of 0·115 mg per °C day per spike. For all cultivars, the maximum stem dry weight occurred at 310–400°C days post‐anthesis, which suggest the stem was a strong sink. As seeds developed, their demand for assimilate increased and they drew more from the stem. At harvest, stem weights from TE treatments were 25% heavier than at anthesis, while untreated ‘Bronsyn’ and ‘Grasslands Impact’ stems were similar to those at anthesis. Thus, stems treated with TE contributed assimilates to increase seed yield but were still a net sink with assimilates in the stem at harvest. Trinexapac ethyl rate induced an inverse relationship between seed yield and stem height. This showed that competition for assimilate between stems and growing seeds limited the seed yield. Management or genetic factors that reduce stem height are likely to increase seed yields of perennial ryegrass.     

Influence of Seed Treatment with Uniconazole Powder on Soybean Growth,Photosynthesis, Dry Matter Accumulation after Flowering and Yield in Relay Strip Intercropping System

Abstract

The relay strip intercropping system of wheat-corn-soybean is widely used in southwest China. However, it is hard to produce soybean stably with this system, since the growth of soybean plants is slower under shading by corn at the seedling stage, and it is compensated by accelerated growth after the symbiotic stage. Soybean plants show excessive vegetative growth due to more rain during the flowering stage, which results in fallen petals, fallen pods and lower yield. This study investigated whether seed treatment with uniconazole powder (0, 2, 4 and 8 mg kg^–1 seed) suppresses excessive vegetative growth of soybean plants during the flowering stage and delays senescence of photosynthetically active leaves at the pod-setting stage. If such events are correlated with changes in photosynthesis, they may affect dry matter accumulation and seed yield in the relay stripping system. Uniconazole promoted biomass accumulation from 31 (R₃) to 61 (R₅) days after flowering (DAF) and seed yield. Seed treatment with uniconazole raised the net photosynthetic rate, stomatal conductance, transpiration rate, and total chlorophyll and chlorophyll a contents. In contrast, uniconazole reduced leaf area index (LAI) from 1 DAF (R₁) to 46 DAF (R₄) with the increase in uniconazole concentration, whereas, uniconazole significantly increased LAI at 61 DAF, and the greatest promotion occurred at 2 mg kg^–1 treatment. The study clearly showed that uniconazole effectively suppressed excessive vegetative growth of soybean during flowering stage, delayed senescence of photosynthetically active leaves at pod-setting stage and induced higher yield, which were related to the changes in photosynthetic rate, chlorophyll content, dry matter accumulation and LAI in the relay strip intercropping system.     

Phyto-purification of livestock-derived organic waste by forage rice under subtropical climate

Soil and water pollution caused by organic waste is a concern for livestock-breeding areas. Nitrogen balance in a paddy-field water-purifying system in which cattle feces were applied was studied for 4 years to assess the suitability of the system for a subtropical area, Japan. Three successive harvestings using ratoon of forage rice following one rice transplanting were conducted with chemical fertilizer and high and low rates of cattle-feces application. Nitrogen load was 81.3–495.0 kg N ha^?1 year^?1, while nitrogen uptake was highly dependent on the yield of the first harvesting. Annual variation of forage rice yields was large, ranging from 15.5 to 26.8 Mg ha^?1 owing to fluctuation in the yield at second and later harvestings. On average, nitrogen was lost by leaching at a rate of 2.3–3.4 kg N ha^?1 year^?1. The nitrogen content in soil at a depth of 0–5 cm increased up to 12.2 kg N ha^?1 over the 4-year period compared with that before the field experiment. However, continuous application of cattle feces could slightly increase the nitrogen content in soil at a depth greater than 35 cm. Our results showed the ability of flooded forage rice to remove nitrogen at up to 320.1 kg ha^?1 year^?1 for a field to which cattle feces were applied. Further investigation is needed to produce a high and stable yield at second harvesting each year, to prevent the accumulation of soil nitrogen, and to assess gaseous nitrogen loss.     

An evaluation of the effect of exogenous glycinebetaine on the growth and yield of soybean: timing of application,watering regimes and cultivars

Various soybean cultivars were grown under different watering regimes in the field and greenhouse in south-eastern U.S.A. (1995 and 1996), and in the field in north-eastern Western Australia (1995). Aqueous glycinebetaine was applied at different growth stages onto their foliage with the objective of ameliorating effects of water stress on photosynthesis activity, nitrogen fixation, leaf growth, biomass accumulation and seed yield. There were cultivar differences in response to drought. Trends which suggest that exogenous glycinebetaine could improve photosynthesis activity, nitrogen fixation and leaf area development, were established. The observed seed yield increase of both well-watered and drought-stressed plants was associated with greater number of seeds following the application of 3 kg ha⁻¹ glycinebetaine. The results indicate that foliar-applied glycinebetaine possesses anti-transpirant properties and has the potential to improve drought tolerance and reduce the amount of water used for irrigation, without any significant decrease in economic yield. There is evidence that soybean could be classified as a low-accumulator of glycinebetaine.     

Effects of varying nitrogen doses on yield,yield components and artemisinin content of Artemisia annua L.

Artemisia annua L. is an aromatic-antibacterial herb that destroys malarial parasites, lowers fevers and checks bleeding, and of which the secondary compound of interest is artemisinin. The objective of the present study was to determine yield, yield components and artemisinin content of A. annua L. grown under four nitrogen applications (0, 40, 80 and 120 kg ha⁻¹) in the Çukurova region of Turkey in 2004 and 2005. Field trials were conducted at Çukurova University, Agricultural Faculty Field Crops Department. In the study, plant height, number of branches, fresh herbage yield, dry herbage yield, fresh leaf yield, dry leaf yield, essential oil content and artemisinin content (by high performance liquid chromatography, HPLC) were examined. By analysis of variance, nitrogen doses had no any statistical effect on the traits investigated except for artemisinin content. Artemisinin content of the dried leaves were significantly affected by nitrogen applications, which varied from 6.32 to 27.50 mg 100 g⁻¹. Contents were from 120 and 80 kg ha⁻¹ nitrogen for the years of 2004 and 2005, respectively.