A World-Wide Organization to Promote the Development of Biological Control

Abstract

Three experiments were conducted to evaluate the efficacy of metribuzin in tea fields. These were a field trial in plots infested with a wide range of weeds, a pot experiment using Paspalum conjugatum and a microplot experiment with 100 Ageratum conyzoides plants/plot. Metribuzin at 0.70, 1.05, 1.40 and 2.10 kg a.i./ha was applied in 450 l water/ha. All rates were satisfactory after 1 week but residual activity increased with application rate; metribuzin at 2.10 kg a.i./ha was significantly superior after 6 weeks. Control after 8 weeks was reduced due to the presence of resistant species. Against Paspalum conjugatum metribuzin at 1.40 kg/ha gave good control for 8 weeks but 2.10 kg/ha was necessary for 12 weeks control. All rates compared favourably with dalapon (4.48 kg a.i./ha). Against Ageratum conyzoides metribuzin at all rates gave good control for up to 12 weeks and significantly better than 2, 4-D at 1.12 kg a.i./ha. Most other grass and broadleaved weeds were satisfactorily controlled at 1.40 kg a.i./ha. Metribuzin with its marked post-emergent effect and prolonged soil residual activity from 6-12 weeks after application, depending on weed species, may become an important tool in pre-monsoon weed control programmes in tea fields. It did not induce any phytotoxic symptoms on mature tea.     

Impact of 2,4-D on Ceuthorhynchidius horridus (Coleoptera: Curculionidae) and their compatibility for integrated control of Carduus thistles

Acute and chronic effects of spring application of 2,4-D on adult C. horridus (Panzer) were examined by determining dose-mortality response and adult vitality. LC₅₀ values for males (70.2 kg/ha) and females (61.4 kg/ha) corresponded to 41.7 and 36.6 times, respectively, the recommended application rate of 1.68 kg/ha. Survival of weevils treated with 1.68 kg/ha was not different from untreated controls, but higher doses (16.8–147.8 kg/ha) caused significantly greater mortality. Adult vitality, measured by number of feeding marks per weevil and rate of weight change. was unaffected by the herbicide. When thistle infested fields were sprayed with 1.68 or 2.24 kg/ha of 2,4-D the host plants died, but the survival, reproduction, and population increase of C. horridus were not affected.     

Weed and fertility management using maize/soyabean intercropping in the north‐western Himalayas

Abstract

In a field experiment conducted on a moderately fertile silty clay loam soil in the north‐western Himalayas, growing one or two rows of soyabean (Glycine max L.) as an intercrop in maize (Zea mays L.) reduced weed numbers and weights significantly and increased maize yields. Sowing two rows of soyabean had a better effect than one row, with maize at a constant sowing density. The maize equivalent yield increased significantly with intercropping in the ratio 1:2 (maize:soyabean rows) as compared to maize alone or maize + soyabean in alternate rows, when all these trials were supplied with the full recommended amount of fertilizer. The maize yield in trials with half the recommended fertilizer amount in the intercropped system was similar to that of maize alone supplied with the full fertilizer dose. The weeds were effectively controlled and yields of maize and soyabean were increased with pre‐emergence application of alachlor at the rate of 2.5 kg a.i./ha or with three hand weedings.     

Assessment of Losses of Hybrid Sorghum ‘CSH-1’ to Earhead Caterpillars,and Comparison of Insecticidal Controls

Abstract

In hybrid sorghum ‘CSH-1’ severe infestation of the earhead caterpillars Cydia sp., Ectomyelois sp., Eublemma sp. nr. gayneri Roths., Heliothis armigera Hub., and Euproctis limbata Wlk, was recorded at Jabalpur (Madhya Pradesh) during 1968. The first two were relatively more serious. The loss in grain yield was estimated to be 18.26 per cent, i.e. about 717 kg/ha.

Among different insecticides tested, carbaryl 0.2 per cent spray proved most effective, followed by endosulfan 0.05 per cent spray. Dichlorvos 0.05 per cent gave good initial kill, but showed little persistent effect.     

Chemical Control of Phalaris minor and Avena ludoviciana in Wheat

Abstract

In field experiments conducted at the Punjab Agricultural University, Ludhiana during 1973–74 and 1974–75, pre-emergence application (one day after sowing) of methabenzthiazuron (1.05 kg a.i./ha), metoxuron (1.6 kg a.i./ha) and chlortoluron (0.75 kg a.i./ha) gave effective control of Phalaris minor and Avena ludoviciana in wheat without any phytotoxic effect on the crop. Methabenzthiazuron, metoxuron and chlortoluron gave 1410, 1420 and 1090 kg/ha, respectively, more grain than the unweeded crop and 590, 600 and 270 kg/ha more than the crop hand-weeded twice. Nitrofen (1.25 kg a.i./ha) applied pre-emergence was effective against P. minor only and gave substantial increase in grain yield. Terbutryne, dichlormate and linuron, while effective against P. minor, also had a phytotoxic effect on the crop.     

：氮肥和有机肥配施对盐碱地酿酒高粱生长、氮素利用效率及土壤N2O排放的影响

采用田间小区试验,依照等氮替换原则,设不施氮肥处理,优化氮肥施用量180 kg·hm^-2单施化肥、40%有机肥替代化肥、60%有机肥替代化肥,常规氮肥施用量240 kg·hm^-2单施化肥、40%有机肥替代化肥、60%有机肥替代化肥共7个处理,探究河套灌区盐渍土氮肥与有机肥配施对酿酒高粱生长特性、氮素利用效率及土壤N₂O排放的影响。结果表明：(1)相同施氮量下,60%有机肥替代化肥处理成熟期土壤全氮、碱解氮和有机质含量较单施化肥处理分别增加10.52%～12.77%、36.36%～50.64%、41.58%～51.33%。(2)相同施氮量下,40%有机肥替代化肥处理高粱产量均高于其他施肥处理,增产6.63%～15.72%。(3)施氮量180 kg·hm^-2 40%有机替代处理较其他施肥处理氮肥利用率提高1.98%～22.84%,氮肥偏生产力提高3.49～17.19 kg·kg^-1;施氮量240 kg·hm^-2 40%有机替代处理较其他施肥处理氮肥农学利用率提...     

Investigations on avian pests of oil palm,Elaeis guineensis Jacq. in India†

Abstract

The common myna Acridotheres tristis Linn., the jungle crow Corvus macrorhynchus Wagner and the house crow Corvus splendens Viellot are the major pests of oil palm in India. Other birds like crow pheasant Centropus sinensis Stresmann, parrot Loriculus sp. and pariah kite Milvus migrans Sykes also feed on oil palm fruits. These birds feed on the fleshy mesocarp of the ripe fruits resulting in heavy fruit loss, significantly reducing oil yield. Gizzard and intestinal content analysis indicated that oil palm fruits are the major source of food for these birds. Observations on 1657 oil palm fruit bunches during 1985–86 revealed that 76% of the ripe bunches and 5.6% of the unripe bunches were damaged by birds. The damage by birds was either ‘partial’ or ‘complete’, where 40–50% and 80–100% respectively, of the individual fruit weight was lost. The partial fruit damage was more common in 130–160 day‐old bunches and the complete fruit damage increased after 150 days of fruit set. Fruit loss due to bird damage was higher in palms in the border area of the plantation (2.3 kg/bunch) than in the interior (1.3 kg/bunch). It is estimated that around 2.8 tonnes of fresh fruits/ha/yr, equivalent to 420 kg of palm oil, are lost due to bird damage.     

Weed Control in Berseem using Stale Seed-bed,EPTC, and MCPB

Abstract

A field experiment was conducted in 1973 and 1974 at Udaipur, India to evaluate the selective weed control efficacy of stale seed-bed prepared with paraquat (1 kg/ha) or by cultivation, pre-planting incorporation of EPTC (1.5 kg/ha), and post-emergent application of MCPB (0.5 kg/ha). Two crop protectants, NA and activated carbon, were also field tested as seed treatments against injury by EPTC. It was found that stale seed-bed prepared by desiccation of weed seedlings with paraquat a day before planting berseem (Trifolium alexandrinum L.) and pre-planting incorporation of EPTC were both effective in significantly reducing weed growth and boosting yields of berseem. Berseem seeds coated with activated carbon before planting provided appreciable protection to the crop against EPTC, but NA stunted berseem growth. A combination of stale seed-bed and EPTC caused maximum reduction in weed growth. Post-emergent MCPB, though efficient in controlling weeds, was highly phytotoxic to the crop. Chenopodium spp. and Phalaris minor were lower in net energy content than berseem.     

Nitrogen fertilization and yield losses of tea to red crevice mite (Brevipalpus phoenicis geijskes) in the Eastern Highlands of Kenya

A field trial using a mite-susceptible clone 11/4 of tea whose yield potential is over 3 t ha^-1 year^-1 was conducted to determine how yield losses due to infestation by red crevice mite (Brevipalpus phoenicis Geijskes) relate to nitrogen nutrition. This was done over a 3 year period in plots either receiving 0, 100, or 200 kg N ha^-1 year^-1. For determining the losses due to mites, an acaricide check method of yield loss assessment was used. Mites were controlled in the plots by spraying flucythrinate. The yield varied considerably between seasons with mean yields in the 3 year period ranging from 2.0 to 2.4 t ha ^-1 without fertilizer and 2.4 to 2.6 t ha^-1 year^-1 at 100 kg N and 2.5 to 2.7 t ha^-1 year^-1 at 200 kg N. Application of the acaricide decreased the mite population by 60-74%. Yield loss between sprayed and unsprayed treatments was 12-22% without fertilizer but this was reduced to 5-6% when fertilizer was supplied at 100-200 kg N ha^-1. The reduction in yield losses in fertilized plots indicate the beneficial effects of nitrogen in inducing tolerance to mites and possibly increasing plant vigour. Protecting the tea from mite attack resulted in yield advantage and a net benefit of $US 0.3, 0.2 and 0.2 per kg made tea at 0, 100 and 200 kg N ha^-1 respectively. Application of 100 kg N ha^-1 had higher net cost benefit than the 200 kg N application rate. The strategy for control of mites would be to integrate spraying with use of fertilizer.     

Study on the effect of four herbicides with and without applied phosphorus on weed control and seed yield of fenugreek (Trigonella foenum‐graecum L.)

Abstract

Field experiments were conducted at Jobner (Rajasthan) during the winter seasons of 1982 and 1983 to evaluate certain physical and chemical weed control systems in fenugreek at two levels of applied phosphorus. The experiments comprised four herbicides (fluchloralin, pendimethalin, thiobencarb, and chloramben) at two levels each, manual weeding at three levels; and an unweeded check. The second factor, namely, application of phosphorus was evaluated at 0 and 40 kg P₂O₅/ha. The soil of the experiment site was loamy sand, containing 0.16% organic carbon. The results showed that amongst the herbicides, preemergent pendimethalin at 0.75 kg/ha controlled the weeds most effectively and gave 8.91 q/ha fenugreek seed yield, which was more than twice the seed yield obtained from the unweeded check plots. The twice hoed plots were found to give 1.32 q/ha higher seed yield than the pendimethalin herbicide treatment, but the benefit‐cost ratio was found higher for the herbicidal treatment. Application of phosphorus at 40 kg P₂O₅/ha was found to bring about significant increase in the seed yield of fenugreek by 59 kg/ha over control, without any interaction with the weed control treatments.     

Herbicides in Cotton—Combinations of Trifluralin with Other Products

Abstract

Results are given of a trial in which trifluralin, incorporated in the soil, at rates of 0.5 and 0.75 kg/ha, was combined with fluometuron at 1.6 kg/ha, and with prometryne at 1.0 kg/ha, both incorporated, pre- and post-em. and with noruron + MSMA (1.0:2.2) at 1.7 kg/ha post-em.

Best results were given by incorporated treatments of trifluralin + fluometuron (0.5 + 1.6) kg/ha, or by trifluralin incorporated at 0.5 or 0.75 kg/ha + fluometuron applied pre-em. at 1.6 kg/ha, or by trifluralin incorported at 0.75 kg/ha + prometryne applied pre-em. at 1.0 kg/ha.

It is recommended that noruron + MSMA (1.0:2.2) at 1.7 kg/ha be applied post-em. as a complementary treatment to trifluralin at 0.5 kg/ha in fields where Cyperus spp. are a problem.     

CHEMICAL CONTROL OF IMPERATA CYLINDRICA (L.) BEAUV. IN MALAYSIA*

Summary. Paraquat-based treatments were evaluated for the control of Imperata cylindrica (L.) Beauv., a perennial grass with extensive rhizomes of great regenerative power. Single applications of 0–5 lb/ac paraquat gave good initial control, but regeneration was rapid. Increases up to 2–0 lb/ac had little effect on the duration of control, nor did the volume rate from 40 to 120 gal/ac. When an initial application of 05 lb/ac was followed by two further applications of 0–25 lb/ac, when the level of control had decreased to 50%, lasting control was obtained. Application of 6–8 lb/ac dalapon followed by 0–25 lb/ac paraquat also gave good control, comparable with that achieved by the conventional treatment of dalapon alone at 15–20 lb/ac. La lutte chimique contre Imperata cylindrica (L.) Beauv. en Malaisie Résumé. Des traitements utilisant le paraquat ont étè essayés pour lutter contre Imperata cylindrica (L.) Beauv., graminée pérenne avec des rhizomes importants qui manifestent un pouvoir de régénération élevé, Des applications uniques de paraquat à la dose 0,56 kg/ha ement un bon eifel initial mais la régéneration fut rapide. L'accroissement de la dose jusquà 2,2 kg/ha n'eut qu'une faible incidence sur la durée de l'action herbicide, l'augmentation du volume de traitement de 450 à 1350 1/ha ne provoqua pas non plus d'augmentation de I'efficacité. Une seule application de paraquat à 0,56 kg/ha, quand le niveau de I'efficacité eut décru jusquà 50%, suivie de deux applications supplémen-taires à 0,275 kg/ha, donna une efficacité plus durable. Des applications de dalapon de 6,7 à 9,0 kg/ha suivies de traitements au paraquat à 0,275 kg/ha donnèerent un résultat aussi bon que celui obtenu par les traitements habituels au dalapon seul, à la dose dc 16 à 22 kg/ha. Chemisehe Bekampfung von Imperata cylindrica (L.) Beauv. in Malaysia Zusammenfassung. Es erfolgten Untersuchungen zur Bekämpfung von Imperata cylindrica (L.) Beauv., einem mehrjährigen Gras mit einem ausgedehnten Rhizomsystem und starker Regenerationskraft, mit Paraquat, Einmalige Applikation von 0,56 kg/ha Paraquat hatte zwar eine gute Anfangswirkung, doch erfolgte rasche Regeneration. Eine Erhöhung bis auf 2,2 kg/ha war ebenso wie eine Änderung der Spritzbrühmenge von ca 450–1350 I/ha von geringem Einfluss auf die Nachhaltigkeit der Bekämpfungs-massnahmen. Eine einmalige Anwendung von 0,56 kg/ha Paraquat gefolgt von zwei weiteren Applikationen von 0,28 kg/ha, wenn die Regeneration ungelahr 50% erreicht hatte, ergab nachhaltige Wirkung. Behandlungen mit 6,7-9 kg/ha Dalapon gefolgt von 0,28 kg/ha Paraquat hatten ebenfalis eine gute Wirkung, die mit der einer konven-tionellen Behandlung mit 16,8-22 kg/ha Dalapon vergleiehbar war.     

Response of transplanted rice to nitrogen fertilization under different weed management practices

Abstract

Rice yield increased significantly and consistently up to 120 kg N/ha when weeds were not controlled. But when weeds were effectively controlled by two hand weedings (20 and 40 days after transplanting) or by use of thiobencarb at 1–0 kg a.i./ha rice yield increased significantly up to 80 kg N/ha. The optimum dose of N for transplanted rice under mid‐hill conditions of Himachal Pradesh (Palampur) was 82 kg/ha when two hand weedings were done and 86 kg/ha when weeds were managed using thiobencarb. The yield response per kg of N in the respective treatments was 20 and 24 kg of grain. The weed dry weight was significantly lower in thiobencarb and hand weeded plots compared with unweeded check though the difference in weed dry weight due to the former two treatments was not significant.     

Correspondence

Abstract

Twenty-seven different herbicides were tested at the AUB Agricultural Research and Education Center in the Beqa'a, Lebanon, to determine their effects on weeds in wheat, barley, maize, onion and sugar beet. Each herbicide was tested at three different rates as pre-emergence and post-emergence applications. Unweeded and hand-weeded check plots were included. Data on yield, quality and other agronomic characteristics of the crops tested were recorded.

Concentrations of 1,000 and 10,000 ppm of 2, 4–D caused a significant decrease in the height and grain yield of wheat and barley when sprayed at the 3-leaf stage. At the 5-leaf stage, injury to wheat and barley occurred only when sprayed at 10,000 ppm, whereas an increase in the grain yield was obtained at 1,000 ppm of 2, 4–D acid equivalent (1 kg a.i./ha).

Pre-emergence treatments of atrazine and simazine at 2.5 kg a.i./ha caused a significant increase in the forage and grain yields of maize as compared to unweeded check plots. Wheat, oats, vetch and sugar beet were injured when planted after triazine-treated maize, whereas onions and soyabeans were tolerant. Other promising herbicides tested on maize were C 3095 (N–3–trifluoromethylphenyl–N'–methyl–N'–methoxyurea) and BV– 201 (1–(3′, 4′–dichlorophenyl)–3–methylpyrrolidin–2–one) applied as a pre-emergence spray at 1 and 2 kg/ha respectively.

Pre-planting treatment of EPTC and pre-emergence treatment of pebulate at 2 kg/ha gave a slight increase in the yield of roots of sugar beet. BV–201 and BV–207 (1–(3–chloro–4–methylphenyl)–3–methylpyrrolidin–2–one) were phytotoxic to beet.

In onions, nitrofen, BV–201 and BV–207 at 1–2 kg/ha were promising as pre-emergence and post-emergence sprays. DNOC and dinoseb at 1.5 kg/ha and ioxynil at 0.5 kg/ha sprayed post-emergence increased the yield of onions significantly over the check. No significant effects of these herbicides were observed on the bulb index, moisture content and total soluble solids of onions.     

The effects of combining modified sowing methods with herbicide mixtures on weed interference in wheat crops

In India, wheat is prone to being heavily infested with weeds, which cause considerable yield losses. Agronomic practices, including sowing method, influence weed interference in wheat growth. A herbicide mixture is usually more effective than a single herbicide for controlling a broad-spectrum of weeds. It may prevent weed species shift and delay resistance development in weeds. This study attempted to develop an integrated approach, combining a modified sowing method with applying a herbicide mixture for efficient weed management in wheat. We found that flat bed missing-row sowing resulted in significant reductions in: (i) the three-year mean population densities of grassy, broad-leaved and total weeds at 40 days after sowing (d.a.s), (ii) total weed population density and biomass (dry weight) at 60 d.a.s., compared to a mainly, furrow-irrigated raised bed system. Applying a tank-mix of fenoxaprop-p-ethyl at 0.08 kg/ha and isoproturon at 0.4 kg/ha applied 30 d.a.s. resulted in significant reductions in total weed population density and biomass, leading to a significant improvement in wheat growth and yield compared to either a weedy check or a regime of fenoxaprop-p-ethyl applied at 0.10 kg/ha. However, a combination of the flat bed missing-row sowing and tank-mix application of fenoxaprop-p-ethyl 0.08 kg/ha and isoproturon 0.4 kg/ha 30 d.a.s. resulted in higher wheat yield through better management of weeds compared with other sowing/ weed control combinations.     

Possible Methods for Controlling Ischaemum afrum (J. F. Gamel) Dandy,in Fallow

Abstract

Different mechanical cultivations and herbicide treatments were compared for controlling Ischaemum afrum in a heavily infested fallow area. Of the mechanical cultivations, disc ploughing to a depth of more than 15 cm, following removal of tufts and watering, was found very effective (83% reduction). Incorporated pre-emergence triluralin (1.90 kg a.i./ha) alone or in tank mixtures with oxadiazon (0.95 + 0.95 kg a.i./ha) was also found promising (79 and 76% reduction respectively). Three applications of dalapon (8.09 kg a.i./ha), as post-emergence, at two weekly intervals or two applications followed by another application at 4.05 kg a.i./ha gave almost complete eradication of Ischaemum afrum seedlings for about 12 weeks (99% reduction).     

Effects of Herbicides on Horticultural Characteristics,Yield and Quality of Onions

Abstract

Seven different herbicides were tested in 1967, and two of these chemicals were further evaluated in 1969 for their efficacy in onions grown in Lebanon. Chloroxuron at 6 kg a.i./ha and Sindone at 1.5 kg/ha gave a significant increase in the bulb weight and yield of onions over unweeded plots. Significant reductions in yield were observed from pre-em. applications of chlorbromuron at 3 kg/ha, propachlor at 6 kg/ha, Sindone at 0.5 kg/ha, and prometryne at 1 and 1.5 kg/ha. Good weed control was obtained as a result of pre-em. application of all herbicides tested.

With post-em. application, weed control was not effective. With the exception of prometryne at 1.5 kg/ha which injured the onions and reduced the yield, the post-em. applications of herbicides tested gave no significant effect on onion yield.

None of the treatments, in both pre-em. and post-em. applications, had any significant effect on leaf length, bulb index, bolting and splitting percentages, dry matter content, total soluble solids, or pungency of onions.     

土壤添加生物质炭和施肥对褐飞虱生长发育和生殖的协同效应

为评价土壤添加生物质炭控制褐飞虱Nilaparvata lugens的应用潜力是否受到施肥的影响,在室内按析因设计进行添加生物质炭和施肥的盆栽试验,观察在生物质炭(0、10、50 g/kg)×施肥(不施肥、尿素、复合肥)处理后的水稻上取食的褐飞虱生长发育和生殖表现。结果表明,添加生物质炭对褐飞虱若虫发育历期的影响不因施肥而变化,少量(10 g/kg)和足量(50 g/kg)生物质炭处理下的若虫发育历期分别为13.7 d和13.9 d,但均比不添加生物质炭对照(12.9 d)显著延长。添加生物质炭对若虫存活率的影响与施肥有关,在施复合肥条件下生物质炭处理不影响存活率,而在施氮肥条件下足量生物质炭处理使若虫存活率(69.9%)比少量生物质炭处理(88.8%)显著降低。添加生物质炭对成虫长翅型比例的影响取决于施肥,虽然不施肥条件下添加足量生物质炭可使长翅型比例从少量处理的10.9%增至足量处理的40.2%,但在施复合肥或氮肥条件下,生物质炭不影响长翅型比例。添加生物质炭对褐飞虱生殖力的影响与施肥有关,在施复合肥条件下生物质炭对其生殖力影响不显著,在施氮肥条件下足量生物质炭处理的产卵量平均为170.6粒,较不添加生物质炭对照(290.3粒)和少量生物质炭处理(309.3粒)显著减少。研究结果表明,土壤添加生物质炭对褐飞虱存活和生殖的不利影响因施肥种类不同而有一定的变化。     

Influence of methyl bromide soil fumigation method on fungicidal efficacy and bromide residues

Highest inorganic bromine residues (30 ppm) were found when soil was fumigated with liquid methyl bromide (MB) introduced by conventional means into evaporating dishes. With preheated (vaporized) MB or injection of MB/chloropicrin (CP) mixtures, bromide concentrations were reduced by 50%. They were uniform throughout the soil (0 to 60 cm) except after MB/CP injection, when larger residues were found in the 30-60 cm layer. Leaching with 2000 m^p3/ha (20 cm) of water always reduced bromide content to 7.5 and 10 ppm at the 0-30 and 30-60 cm depth, respectively. Organic amendments to soils substantially increased bromide levels up to 118 ppm, most of which was found in the upper soil layers; two teachings with 2000 m^p3 /ha water were required to return the soils to their normal state.Sclerotium rolfsii andFusarium oxysporum f. sp.dianthi cultures buried in soil were eliminated from the upper 30 cm with MB applied either conventionally or preheated. At 50 cm, 500 kg/ha of the preheated gas was superior to 1000 kg/ha of the cold gas. All MB fumigations suppressed carnation flower yields compared with CP alone but were superior to no treatment. After leaching, MB-fumigated soils yielded the highest number of flowers.     

旱作条件下施肥对老芒麦和冰草种子产量及构成的影响I-氮、磷、钾对牧草种子产量及构成的影响

对老芒麦和诺丹冰草种子生产田的施肥试验表明 ,N肥、P肥单施及 N、P和 N、P、K混施可使老芒麦实际种子产量及各产量构成因子指标有显著提高 ,但 N、P、K及 N、P混施效果优于 N肥、P肥单施。 N肥、P肥、K肥单施对诺丹冰草种子增产效应不明显 ,但 N、P、K混施对提高诺丹冰草种子产量及各产量构成因子指标有显著效应。在老芒麦种子生产中每公顷施用 1 2 0 kg的 N和 90 kg的 P可获得较高的产量 ;而在诺丹冰草种子生产中每公顷施用1 2 0 kg的 N和 60 kg的 P可获得较高的产量。施肥试验的结果亦提示 ,在旱作条件下 ,干旱年份施肥可能并不是一种较经济的提高产量的措施