Crop and Weed Growth in a Sequence of Spring Barley and Winter Wheat Crops Established Together from a Spring Sowing (Relay Cropping)

A relay cropping system of cereals, whereby winter wheat (Triticum aestivum L.) was undersown in two‐row spring barley (Hordeum distichum L.), was established in a field trial in central Sweden in 1999 and continued until 2000. The purpose of the study was to examine crop and weed responses to different plant densities of the undersown winter crop. Winter wheat was sown at four seed rates (187, 94, 47 and 0 kg ha^?1) immediately after the sowing of barley. Barley was harvested in the first autumn after sowing and winter wheat in the second autumn. The grain yield of barley was not affected by the seed rate of wheat, and averaged 4580 kg ha^?1. Winter wheat did not vernalize during the first growing season but remained at the vegetative stage. The grain yield of wheat was 1990 kg ha^?1 for the lowest and 5610 kg ha^?1 for the highest seed rate of wheat. Whilst the undersowing process itself stimulated weed emergence in this experiment, increasing the undersowing seed rate reduced the population of perennial weeds by 40–70 %. In the second growing season, the total biomass of weeds was 66 % higher at the highest seed rate compared with the lowest seed rate.     

Management of Italian and Perennial Ryegrasses for Seed and Forage Production in Crop Rotations

Italian ryegrass (Lolium multiflorum Lam.) and perennial ryegrass (L. perenne L.) can be grown for seed and forage in cold winter regions provided the stand persists well over winter. Seed yield and plant characteristics during primary growth, and forage yield during regrowth, were determined for two Italian and one perennial ryegrass cultivars in Atlantic Canada. Establishment methods and dates included sowing ryegrass in cultivated soil alone or with barley in mid‐May and, after harvesting the barley crop, by sowing ryegrass following conventional or reduced cultivation and by no‐till drilling into barley stubble in mid‐August and early September. Despite some winterkill, particularly in Italian ryegrass, seed and forage yields were adequate in post‐establishment growing seasons. Seed yield for Italian ryegrass was greatest (1270 kg ha^?1) when it was sown into cultivated soil in mid‐August and least (890 kg ha^?1) when sown alone in May. Italian ryegrass yielded 15–17 % more seed when plots were established in mid‐August rather than in mid‐May or early September. Italian ryegrass cv. Lemtal had a greater density of fertile tillers (1030 m^?2) in the sward than cv. Ajax (860 m^?2) and its tiller density was greater when seeded into cultivated soil in September than in mid‐August. There were fewer spikelets per seed head for sowing Italian ryegrass with barley in May than for the other methods of establishment. Forage yield in regrowth was greater for Italian ryegrass cv. Ajax (2770 kg ha^?1) than for cv. Lemtal (2480 kg ha^?1). Seed yield of perennial ryegrass was greater when seeded in mid‐May than in mid‐August or early September. The seed yield of perennial ryegrass was greater when it was sown with barley in May and harvested for grain, than when it was sown alone or with barley harvested at late milk stage. The establishment methods for mid‐August and early September sowing had little effect on seed yield. However, the no‐till and reduced tillage methods resulted in a greater tiller density than sowing into the cultivated seedbed. Fertile tillers tended to be denser under reduced cultivation for sowing in August. Forage yield of perennial ryegrass regrowth was not influenced by the sowing method and timing. In conclusion, Italian and perennial ryegrasses produce adequate seed and forage regrowth under different establishment methods and timing. However, the poor persistence of Italian ryegrass may limit commercial production after the establishment year in Atlantic Canada.     

Nutrient Management Effects on Light Interception, Photosynthesis, Growth, Dry-matter Production and Yield of Indian Mustard (Brassica juncea)

A field experiment was conducted on sandy loam acidic soil to study the effect of nutrient managements on light interception, photosynthesis, growth, biomass production and yield of Indian mustard [Brassica juncea (L.) Czern & Coss.]. Plant height, number of branches per plant, number of siliqua per plant, number of seeds per siliquae, 1000‐seed weight, seed and oil yield of Indian mustard improved at 100 % recommended rates of NPK (N‐P‐K at 80‐17.2‐33.2 kg ha^?1) + 10 t ha^?1 farmyard manure (FYM) (T₃) compared with 100 % NPK rate (T₂). It was also at par with 100 % NPK + 10 kg ha^?1 borax + 20 kg ha^?1 ZnSO₄ (T₆) and 50 % NPK + 10 t ha^?1 FYM +10 kg ha^?1 borax + 20 kg ha^?1 ZnSO₄ (T₁₀). The rate of photosynthesis increased due to appropriate nutrient management treatments (T₃, T₆ or T₁₀) with concomitant increase in photosynthetically active radiation, internal CO₂ concentration and rate of transpiration and decrease in stomatal resistance. Consequent upon the higher rate of photosynthesis, dry‐matter accumulation increased. The crop receiving nutrient treatment T₃ or T₆ maintained higher light interception ratio (LIR), leaf area index (LAI), biomass production, crop growth rate (CGR) and net assimilation rate (NAR) that resulted in greater rate of photosynthesis, harvest index and seed yield. Similarly, T₁₀ was equally efficient in registering greater LIR, LAI, CGR, NAR and seed yield of mustard. The average seed yields were 1692, 1683 and 1668 kg ha^?1 in T₃, T₆ and T₁₀, respectively, and these three treatments were significantly superior to T₂ (1332 kg ha^?1), control (723 kg ha^?1) and other treatments. Significantly greater seed oil contents of 41.30, 40.60 and 41.07 % were recorded in T₃, T₆ and T₁₀, respectively. Thus, significant improvement due to appropriate combination of NPK, FYM, borax and ZnSO₄ was observed for uptake of nutrients.     

Effects of Nitrogen and Foliar Sulphur Interaction on Grain Yield and Yield Components in Barley

In this study, conducted from 1979 to 1986 in southern Spain, the objective was to analyze the effects of a possible interaction between soil-applied N and foliar S applied to barley (Hordeum vulgare L.) during tillering on grain yield and to identify the mechanism involved. From 1979 to 1982, we used rates of 20, 40, 60 and 80 kg a.i. N ha^?1, together with 12.5 or 25 kg foliar a.i. S ha^?1 during tillering. The results demonstrated that foliar S at both dosages acted as a partial (but not total) substitute for N, when the latter was applied at levels of 40 to 60 kg ha^?1. These effects of S did not appear to result only from a nutritive mechanism, but rather from a hormonal mechanism through the increase in ethylene biosynthesis. Therefore, during 1983 to 1986, we used 40, 60 and 80 kg a. i. N ha^?1, together with 12.5 a. i. S ha^?1 and 0.55 kg a.i. ethrel (2-chloroethyl-phosphonic acid) ha^?1. The results showed that the effects of S and ethrel on yield were practically the same. Assayed with 40 and 60 kg N ha^?1, S and ethrel acted as partial (but not total) substitutes for N, exceeding the yield of the control without S or ethrel, and equalling the yield obtained with 20 kg more of N ha^?1. The S or ethrel applied with 80 kg N ha^?1 presented an additive effect with the N. The increases in yield using S or ethrel were in all cases due to the increased final number of spikes m^?2, which was principally a consequence of the higher number of tillers formed but also a result of increased survival of tillers to form a viable spike. In addition, the positive effects of S on yield were greater the smaller the N dosage and the lower the annual yield. Finally, we present a possible mechanism of hormonal action, to explain how foliar S applied during tillering affects grain yield in barley.     

Wild Mustard (Sinapis arvensis L.) Competition with Three Winter Cereals as Affected by Nitrogen Supply

Two field experiments were carried out in northern Greece during the 1993–94 and 1994–95 growing seasons to investigate the effect of nitrogen (N) supply on interspecific competition between wild mustard (Sinapis arvensis L.) and wheat (Triticum aestivum L.), barley (Hordeum vulgare =distichum L.) and triticale (Triticosecale). The presence of 140 S. arvensis plants m⁻² until early March (averaged over N levels) did not have any adverse effect on the dry weight of all crops. However, its further presence significantly reduced the dry weight of wheat and triticale, but not that of barley. N fertilization (150 kg N ha⁻¹ regardless of application time) slightly increased the dry weight of wheat and triticale grown without weed competition compared with that of control (0 kg N). On the contrary, the presence of wild mustard, until harvest, reduced dry weight of wheat and triticale by 31 and 26 %, respectively, while the corresponding reduction for barley was only 1.5 %. Furthermore, N fertilization (150 kg N ha⁻¹) increased dry weight of wild mustard grown with wheat and triticale by 10 and 16 %, respectively, compared with that of control (0 kg N). Grain yield of wheat and triticale was reduced to 26 and 27 % by the competition of wild mustard, respectively, while the corresponding reduction for barley was only 3.5 %. Moreover, the wild mustard presence reduced total N content of wheat and triticale by 20 and 19 %, respectively, but this was not the case for barley.     

The Influence of Row Spacing and Seeding Rate on Seed Yield and Yield Components of Forage Turnip (Brassica rapa L.)

The effects of four row spacings (17.5, 35.0, 52.5 and 70.0 cm) and five seeding rates (50, 100, 200, 400 and 800 viable seeds m^?2) on seed yield and some yield components of forage turnip (Brassica rapa L.) were evaluated under rainfed conditions in Bursa, Turkey in the 1998–1999 and 1999–2000 growing seasons. Plant height, stem diameter, pods/terminal raceme, total pods/plant, seeds/pod and primary branches/plant were measured individually. The number of plants per unit area was counted and the lodging rate of the plots was scored. The seed yield and 1000‐seed weight were also determined. Row spacing and seeding rate significantly affected most yield components measured. The number of plants per unit area increased with increasing seeding rate and decreasing row spacing. Plant height was not greatly influenced by row spacing and seeding rate, but higher seeding rates reduced the number of primary branches and the stem diameter. The number of pods/main stem was affected by row spacing and but not by the seeding rate. Also, the number of seeds per pod was not affected by either the row spacing or the seeding rate. In contrast, the number of pods per plant clearly increased with increasing row spacing, but decreased with increasing seeding rate. The plots seeded at narrow row spacings and at high seeding rates were more sensitive to lodging. Seeding rate had no significant effect on seed yield in both years. Seed yield was similar at all seeding rates, averaging 1151 kg ha^?1. However, row spacing was associated with seed yield. The highest seed yield (1409 kg ha^?1) was obtained for the 35.0‐cm row spacing and 200 seeds m^?2 seeding rate combination without serious lodging problems.     

Maturity Class and P Effects on Soya Bean Grain Yield in the Moist Savanna of West Africa

Field trials were replicated at four sites in the moist savanna ecological zone of West Africa to study the effect of maturity class and phosphorus (P) rate on grain yield and total protein yield (TPY) of some new soya bean varieties. Grain yield and TPY averaged 1.43 Mg ha^?1 and 587 kg ha^?1, respectively. Without P application grain yield and TPY were not significantly different among the varieties. In addition, at zero P treatment, grain yield and TPY were not significantly different among three sites where available P was 6.2 mg kg^?1 or less. P application depressed grain yield and TPY at a site where the available soil P was high (16.2 mg kg^?1). With P application grain yield and TPY were in the range of 1.2–2.28 Mg ha^?1 and 505–948 kg ha^?1, respectively, for the varieties compared with 0.99–1.12 Mg ha^?1 and 454–462 kg ha^?1 when P was not applied. The response of grain yield to 30 kg P ha^?1 was substantial at Gidan Waya (113 %), Kasuwan Magani (63 %) and Fashola (60 %), three sites where available soil P was low. The application of 30 kg P ha^?1 increased grain yield by 21 % in early, 26 % in medium and 58–70 % in the late varieties. Significant variety by P rate interaction effects were observed on grain yield and TPY but not on grain protein concentration (GPC). TPY showed greater response to P in the late varieties than in the early or medium. While seed size correlated significantly and positively with GPC, P application had no significant effect on GPC.     

Studies on Pure and Mixed Stands of Wheat and Barley Under Dryland Agriculture Conditions

Grain yield and yield components were studied in wheat and barley grown in pure and 2:1,1 : 1 and 1 : 2 mixed stands (Wheat : barley row ratio) as well as a 1 : 1 seed blend mixture under dryland agriculture conditions of the Indian Agricultural Research Institute, New Delhi. Wheat as well as barley produced significantly longer and more ears/m and higher grain yield in mixed stands than in their pure stands. The 2 : 1 wheat : barley mixed stand gave the highest grain yield; 35 % relative yield advantage over mid-monoculture yield. The 1 : 1 seed blend mixture was inferior to 1 : 1 (Wheat : barley row ratio) mixed stand.     

Nitrogen and Phosphorus Effects on Faba Bean Yield and Some Yield Components

The faba bean is among the major grain legumes cultivated in Ethiopia and is used extensively as a break crop in the highlands. Although a blanket application of DAP (diammonium phosphate) at the rate of 100 kg · ha^?1 has been practised in faba bean production in the country, this was not based on research results. In addition, little information is available on the response of the crop to N and P fertilizers under diverse environmental conditions. Hence, field experiments were carried out at three locations in 1991, seven locations during 1992 and 1993 and at one location in both 1993 and 1995 to determine faba bean response to N and P fertilization. Five levels of N (0, 9, 18, 27 and 36 kg N · ha^?1 as urea) in factorial combinations with four levels of P (0, 23, 46 and 69 kg P₂O₅ · ha^?1 as TSP [triple super phosphate]) were studied in a randomized complete block design with four replications in the first year. In the remaining years four levels of N (0, 18, 27 and 36 kg N · ha^?1 as urea) in factorial combinations with four levels of P (0, 23, 46 and 92 kg P₂O₅ · ha^?1 as TSP) were used in a randomized complete block design with three and four replications at one and seven locations, respectively. Results indicated that a positive linear response of faba bean seed yield was noted at all locations (except Debre Zeit and Burkitu) to P fertilization, while a significant quadratic response was also found at Holetta. In addition, plant height, above ground biomass and number of pods per plant were positively influenced by P application while the effect of N on these was mostly nonsignificant. Faba bean seed yield response to N was noted at only two out of eight locations; in most cases, nonsignificant and inconsistent seed yield responses to N fertilization were obtained. There was nonsignificant N × P rate interaction. In conclusion, we do not recommend supplemental N application to faba bean at six out of eight locations but we recommend the application of P fertilizer to faba bean at almost all locations (with the exception of Debre Zeit) and for other soils deficient in available P. Further work is recommended on the determination of critical levels for soil-available P, below which P fertilization should be practised for optimum faba bean seed yield.     

Effects of Time and Rate of Nitrogen and Phosphorus Application on the Growth and the Seed and Oil Yields of Canola (Brassica napus L.)

A field study was conducted to investigate the influence of variable rates of application of N and P fertilizers in splits at various times on the growth and the seed and oil yields of canola (Brassica napus L.) during 1995–97. Rates of fertilizer application were 0 and 0 (F0), 60 and 0 (F1), 0 and 30 (F2), 60 and 30 (F3), 90 and 60 (F4) and 120 and 90 (F5) kg N ha^?1 and kg P₂O₅ ha^?1. All the P was applied at sowing while N was applied in splits, i.e. all at sowing, half at sowing and half with first irrigation, or half at sowing and half at flowering. The responses of growth, seed yield and components of yield were consistent in both years. Increasing the rate of fertilizer application from F4 (90/60 kg N/P₂O₅ ha^?1) to F5 (120/90 kg N/P₂O₅ ha^?1) increased the leaf area index (LAI) relative to the control and to lower rates of fertilizer application. For both crops, application of 90/60 kg N/P₂O₅ ha^?1 significantly enhanced total dry matter (TDM) and seed yield. Seed yield increased mainly due to a greater number of pods per plant and seeds per seed‐pod. The time of fertilizer application did not significantly affect seed yield or components of yield in either season. Oil yield generally followed seed yield, increasing with increasing rate of fertilizer application up to 90/60 kg N/P₂O₅ ha^?1. The maximum oil contents were obtained from the control. The results show that seed and oil yields of canola were maximized at the F4 (90/60 kg N/P₂O₅ ha^?1) rate of application under the agro‐ecological conditions of Faisalabad, Pakistan.     

Physiological Basis of Yield Variation in Short-duration Pigeonpea Grown in Different Environments of the Semi-Arid Tropics1

Five short-duration pigeonpea (Cajanus cajan (L.) Millsp.) genotypes were grown at three plant populations in three locations during the 1986 and 1988 rainy seasons, to determine the physiological basis of observed variations in yield. Significant differences were found in seed yield (Y), crop growth rate (C), and the durations of vegetative (Dv) and reproductive (Dr) growth, and partitioning (P). These were attributable to genotypes and their interactions with environments (except for C). Variation in C, Dr, and P together explained 78 % of the observed variation in Y due to different genotypes and environments. Crop growth rate alone contributed about 71 % of the variation in Y, and reached an optimum value of around 6.5 kg ha^?1°Cd^?1. Crop growth rates increased with the duration of the vegetative period and with plant population. However, a negative relationship between C and P resulted in plant population having little effect on seed yield. The maximum-yielding genotype, ICPH 8 had the highest C and an intermediate P.     

Productivity and Sustainability of Cotton (Gossypium hirsutum L.)–Wheat (Triticum aestivum L.) Cropping System as Influenced by Prilled Urea, Farmyard Manure and Azotobacter

Field experiments were conducted at Indian Agricultural Research Institute, New Delhi, during 2001–2002 and 2002–2003, to study the effect of inorganic, organic and Azotobacter combined sources of N on cotton (Gossypium hirsutum L.) and their residual effect on succeeding wheat (Triticum aestivum L.) crop. The results indicated considerable increase in yield attributes and mean seed cotton yield (2.33 Mg ha^?1) with the combined application of 30 kg N and farmyard manure (FYM) at 12 Mg ha^?1 along with Azotobacter (M₄). The treatment in cotton that included FYM, especially when fertilizer N was also applied could either improve or maintain the soil fertility status in terms of available N, P and K. Distinct increase in yield attributes and grain yield of wheat was observed with the residual effect of integrated application of 30 kg N ha^?1 + FYM at 12 Mg ha^?1 + Azotobacter. Direct application of 120 kg N ha^?1 resulted 67.4 and 17.7 % increase in mean grain yield of wheat over no N and 60 kg N ha^?1, respectively. Integrated application of organic and inorganic fertilizer is therefore, recommended for higher productivity and sustainability of the cotton–wheat system.     

Effect of Deep Placement of Slow-release Fertilizer (Lime Nitrogen) Applied at Different Rates on Growth, N2 Fixation and Yield of Soya Bean (Glycine max [L.] Merr.)

A new fertilization method with deep placement of slow‐release N fertilizers, such as coated urea and lime nitrogen (LN) (calcium cyanamide) at 20 cm depth was found to promote soy bean seed yield. In the present study, the effect of deep placement of LN was investigated on different parameters such as growth, N accumulation, N₂ fixation activity and yield of soy bean by applying LN at different rates in the rotated paddy field of Niigata, Japan. In addition to the basal fertilizer, ammonium sulphate (16 kg N ha^?1), deep placement of LN was conducted by applying various amounts such as 50 kg N ha^?1 (A50), 100 kg N ha^?1 (A100) and 200 kg N ha^?1 (A200) at 20 cm depth in separate plots. A ¹⁵N‐labelled LN fertilizer was also employed for each of the above treatments to calculate N utilization from LN in separate plots. Soya bean plant growth and N₂ fixation activity were periodically analysed. Both plant growth and N accumulation were found to increase with LN treatment compared with control plants. An increase in N₂ fixation activity was found in the A100 plots. The total seed yield was the highest in the deep placement of LN with A100 (73 g per plant) compared with other treatments. The visual quality of harvested seeds also showed that A100 enhanced the quality of seeds compared with other treatments. Thus, it is suggested that N fertilization management with particular reference to optimum amount of fertilizers is important for maximum growth, N₂ fixation and enhancement of seed yield of soy bean.     

Maize Grain Yield Response to Tillage and Fertilizer Nitrogen Rates on a Tara Silt Loam

Effects of tillage on the appropriate fertilizer N applications needed to achieve maximal grain yield are poorly denned. The study objective was determination of relative corn grain yield response to N application rate for four tillage practices: no-tillage (NT), ridge tillage (RT), fall chisel plowing (CP) and fall moldboard plowing (MP). Maize (Zea mays L.) grain yield and N accumulation were monitored over a 6 year period with the same tillage treatment and the same fertilizer N rate applied each year to each plot. Two hybrids, differing in relative maturity rating, were planted each year. Fertilizer N rates ranged from 10 to 190 kg ha^?1 and consisted of 10 kg ha^?1 of liquid starter N applied at planting with varying amounts of fall applied anhydrous ammonia. With only starter fertilizer, grain yields increased with tillage intensity in the order NT ≤ RT ≤ CP ≤ MP. With ≥ 55 kg total applied Nha^?1, 6 year average grain yields were unaffected by tillage. Total N removed in grain annually with only starter fertilizer ranged from 25–85 kg ha^?1 Maximal amounts of N removed, about 145 kg N ha^?1, occurred with 100–145 kg applied N ha^?1 for all tillage treatments under the more favorable climatic conditions. Several interactions affecting grain yield appear climatically sensitive with exception of tillage by fertilizer N interactions. Because of variability in climate, planting dates varied by almost 4 weeks. Relative yield loss due to planting delay were Fertilizer N (mean change ??124 –?275 kg ha^?1 day^?1) > Starter N only and MP (mean ?? 259 kg ha^?1 day^?1) > other tillages in general. Yield loss due to delayed planting ranged from 0.0–275 kg ha^?1 day^?1. Grain yield gains due to early spring soil temperatures were 16.0–21.8 kg ha^?1 index-degree^?1 with MP tillage and averaged 2.7– 16.7 kg ha^?1 index-degree^?1 more than those of other tillage-hybrid combinations.     

Field Pea Seeding Management for Semi-arid Mediterranean Conditions

The effects of seeding rate (30, 60 and 90 seeds m^?2), seeding date (14 January, 28 January and 12 February), seed weight (0.18 and 0.25 g seed^?1), seeding depth (3 and 6 cm), and phosphorus fertilization rate (17.5, 35.0 and 52.5 kg P ha^?1) and placement method (banded or broadcasted) on field pea (Pisum sativum L.) development and seed yields were investigated in irrigated field experiments conducted in northern Jordan in 2000 and 2001. Results and treatment responses were consistent in both years. Seeding rate, seeding date, seed weight and rate and method of phosphorus fertilization had significant effects on most traits measured; planting depth however did not affect any of the traits. Generally a positive correlation was observed between each factor and seed yield and yield components, with the exception of a negative correlation between seeding rate and yield components, and seeding date and yield and yield components. Increase in seeding rate from 30 to 90 seeds m^?2, and increase in P fertilization from 17.5 to 52.5 kg ha^?1 alone increased seed yields by 50 and 41 %, respectively. Each delay of 2 weeks for seeding from mid‐January resulted in reductions of 12 % in seed yields. Overall, the results revealed that a combination of early seeding (14 January), of large seeds at an high seeding rate (90 seeds m^?2), with P fertilizer banding (52.5 kg P ha^?1) maximize field pea yields in irrigated fields in semi‐arid Mediterranean environments. With such management pea seed yields can be as high as 2800 kg ha^?1.     

The Impact of Underseeding Barley (Hordeum vulgare L.) on Timothy (Phleum pratense L.)-Clover (Trifolium pratense L.; Trifolium hybridum L.) Forage Production in a Cool Maritime Climate

Growing barley (Hordeum vulgare L.) in the year of forage establishment is a common agronomic practice in marginal growing regions, but is often not recommended to growers. We examined the effect of silage barley production over an establishing timothy (Phleum pratense L.)‐clover (Trifolium pratense L.; Trifolium hybridum L.) forage sward in a 4‐year study near St. John's, Newfoundland, Canada. The experiment compared two barley varieties differing in plant height (semidwarf Chapais and Leger), three barley seeding rates and the effect of a forage understorey on forage (barley) production in the establishment year and forage (timothy‐clover) production in the subsequent year. The taller Leger yielded similar forage biomass to Chapais in the year of forage establishment, which (when planted at 375 plants m^?2) was roughly twice that of a pure‐stand timothy‐clover mix. Increasing the barley seeding rate from 125 to 375 plants m^?2 resulted in a linear increase in forage yield in the year of planting. The production of barley forage in the establishment year resulted in reduced timothy‐clover forage yield in the year following barley planted at 125 and 375 seeds m^?2, but not for barley planted at 250 seeds m^?2. Companion planting also altered forage species composition in that higher barley seeding rates resulted in 12–18 % less timothy and 2–4 % lower fibre levels in the year following planting. Barley seeded at rates of 250–375 seeds m^?2 and undersown with a timothy‐clover mixture (harvested at mid‐milk) resulted in greater forage yield of poorer quality than pure‐stand timothy‐clover in the planting year, and a barley seeding rate of 250 seeds m^?2 did not impede forage production in the subsequent year.     

Impact of Nitrogen and Plant Growth Promoting Rhizobacteria on yield and yield components of sunflower in a glasshouse environment

The effects of Nitrogen (N) and Plant Growth Promoting Rhizobacteria (PGPR) on growth and development of sunflower (Helianthus annuus L. var. Hysun-33) grown in the greenhouse under a natural environment were studied. The N-use efficiency of a sunflower crop grown under three N rates (N₁ = 0 kg ha^?1, N₂ = 120 kg ha^?1, and N₃ = 240 kg ha^?1) and three PGPR levels (R₁ = 0 kg ha^?1, R₂ = 30 kg ha^?1, and R₃ = 60 kg ha^?1) were investigated. The maximum amount of N resulted in higher total dry matter production per plant and the effect was prominent from 34 days after sowing (DAS). Seed yields differed significantly among different sunflower crops especially at limiting N supply, with significant shifts according to the N level. N uptake was an important parameter for yield at all N rates. The 240 kg N ha^?1 treatments provided the maximum yield, while the oil contents in these treatments of higher yield showed a lower oil content (%). Harvest index was also significantly correlated to yield across N rates; however, its importance depended much on environmental conditions as well. It can be inferred from the study that sunflower crop is well-supplied with respect to growth, development, yield and yield components, to enhance N efficiency and depends very much on the N supply. All the parameters gave maximum results with the increment of N while PGPR regimes had no prominent impact on the sunflower crop, the target environment, and the target yield level grown under a specified controlled glasshouse environment.     

Effects of Rate and Time of Potassium Application on Cotton Yield and Quality in Turkey

Studies were conducted at Adana, in the Çukurova region of southern Turkey, to evaluate the effects of the rate and timing of application of soil‐applied potassium (K) on cotton (Gossypium hirsutum L.) in 1999 and 2000. Potassium rates of 0, 80, 160 and 240 kg K₂O ha^?1 were soil‐applied in single treatments (all at early boll development) or in split treatments (1/2 at first square and 1/2 at first white flower; 1/4 at first square, 1/4 at first white flower and 1/2 at early boll development). Data collected in the two years indicated that application of 160 kg K₂O ha^?1 produced significant differences in seed‐cotton yield, lint yield and boll weight compared with the untreated control. The best combination producing the greatest yield was application of 160 kg K₂O ha^?1 with all of the K soil‐applied at early boll development. Cotton yields did not respond to K fertilization above the rate of 160 kg K₂O ha^?1 under the production practices typically found in the region. For application of K at a rate of 240 kg K₂O ha^?1 there was a marked difference in fibre strength between years in this study, but micronaire and uniformity ratio were not different amongst K rates within each year. When the total amount of K was applied at early boll development, higher yields, boll weights and lint turnouts were obtained compared with split applications, but the single application did not have a large impact on fibre properties.     

低氮密植栽培对超级稻产量和氮素利用率的影响

为了研究低氮密植栽培对水稻分蘖发生及成穗率、干物质积累及其转化、氮素利用率和产量的影响,2012—2013年以超级稻Y两优1号为材料,在湖南长沙和海南澄迈进行了施氮量(75、150、225 kg N hm–2)与栽插密度(68、40、27、19穴m–2),每穴苗数(单、双、三本穴–1)与栽插密度(40、27、19、14穴m–2)的大田栽培试验。结果表明,在基本苗数相同或相近的条件下,减苗增密在齐穗期和成熟期的干物质量及产量分别比增苗减密高10.5%、5.2%和2.9%,有效穗数对产量的贡献最大,达到显著水平;在低氮密植条件下,有效分蘖期缩短6 d左右,分蘖成穗率、表观转化率、氮肥偏生产力和氮素籽粒生产效率分别提高10.9%、21.0%、150.6%和19.6%。在施氮量为75 kg N hm–2的密植(40~68穴m–2)条件下,齐穗期和成熟期的干物质量及长沙点产量分别比中、高氮(150~225 kg N hm–2)常规密度(19~27穴m–2)低3.2%、7.5%和1.2%,但差异不显著,而澄迈点产量在2012年和2013年分别比之低5.2%和高9.1%,且差异均达显著水平。在施氮量为150 kg N hm–2的密植条件下,成熟期干物质量比高氮常规密度低1.7%,但齐穗期干物质量和产量比高氮常规密度高10.3%和3.3%。因此,超级稻采用低氮密植栽培,在100~150 kg N hm–2和40穴m–2条件下提早了够苗期,增加了有效穗数,提高了分蘖成穗率和结实率,加之齐穗期适宜的干物质积累和较高的表观转化率,有利于高产的形成和氮肥利用率的提高。     

Effect of Phosphorus and Nitrogen Fertilization on Sunflower (Helianthus annus L.) Nitrogen Uptake and Yield

Little is known about the effect of combined phosphorus and nitrogen (P‐N) fertilization on the N requirement of sunflower (Helianthus annus L.). This study was carried out to evaluate the effects of varying levels of P and N, as well as the interaction P × N, on the N uptake, yield and N apparent utilization efficiency under field conditions. Split‐plot design experiments were conducted in the mid‐western Pampas in Argentina. Four levels of N (0, 46, 92 and 138 kg N ha^?1) and three levels of P (0, 12 and 40 kg P ha^?1) were applied to two Typic Hapludolls over two growing seasons (1997–98 and 1998–99). N uptake and soil N‐NO₃ contents were determined at the V₇, R₅ and R₉ growth stages. The sunflower yield ranged from 2.5 to 5.0 Mg ha^?1. The total N requirement was around 45 kg N Mg^?1 grain, and this result suggests that it is not necessary to use different N requirements (parameter b) for fertilized crops when a yield response is expected. To achieve a 100 % yield maximum a N supply (soil plus fertilizer) of 181 kg N ha^?1 at P₄₀ was needed. However, at P₀, the highest yield was about 80 % of the maximum yield with a N supply (soil plus fertilizer) of 164 kg N ha^?1. P application increased the apparent use efficiency of the supplied N.