Effect of supplemental nitrogen on true potato seed weight

The effect on true potato seed (TPS) weight of supplemental nitrogen (N) applied during seed development was investigated using crosses DTO-33 × R128.6 (“A” produced in the field) and Atzimba × R128.6 (“B” produced in the field and in a screenhouse). Dry weights of tops and tubers of the mother plants were also measured in the screenhouse. The response to supplemental N (0-240 kg/ha) in 100-TPS weight of cross A and B from the field was positive and linear. In the screenhouse, where higher total N (0-1200 kg/ha) was applied, the responses in 100-TPS weight and dry weight of tops and tubers were curvilinear, with maximum levels at 800, 1000 and 400 kg/ha, respectively. The 100-TPS weight of cross B was 40% higher in the field than in the screenhouse. In the field, increased frequency of supplemental N applications increased 100-TPS weight of large and medium berries of cross B, but had no effect on seed from small berries nor on seed from any berries of cross A. In the screenhouse, increased application frequency decreased tuber dry weight and increased dry weight of tops, but had no effect on 100-TPS weight. It was concluded that supplemental N must be applied during seed development and at higher total levels than those required for optimum tuber yields in order to maximize 100-TPS weight. The lower seed weight from the screenhouse suggests that other environmental factors (e.g., temperature) present during growth of the mother plant can affect the weight of the resultant TPS.     

不同药剂拌种对花生地下害虫的防治试验

采用药剂拌种,筛选防治花生地下害虫的药剂。结果表明,在花生果实膨大期,三种药剂各处理对花生田地下害虫的防治效果达60％以上,20％氯虫苯甲酰胺SC450g/hm2、22％吡虫·辛硫磷EC6750g／hm2。的防治效果达70％以上,但各处理差异不显著;花生果实收获期,20％氯虫苯甲酰胺SC450g/hm2、22％吡虫·辛硫磷EC6750g/hm2、地鹰20kg种子／100g的防治效果达60％以上。表明20％氯虫苯甲酰胺SC、22％毗虫·辛硫磷EC、地鹰在花生播种时拌种可用来防治地下害虫。     

Nitrogen studies in Lolium perenne grown for seed. IV. Response of amenity types and influence of a growth regulator

In field trials in 1979–81, perennial ryegrass cultivars Royal and Majestic (amenity) and Morenne (agricultural) produced maximum seed yields at levels of applied N ranging from 40 kg ha⁻¹ to 160 kg ha⁻¹. Available soil N levels were estimated at 55 kg ha⁻¹; hence maximum seed yields were obtained at total nitrogen levels of 95–135 kg ha⁻¹ in Royal, 95–215 kg ha⁻¹ in Morenne, and 175–215 kg ha⁻¹ in Majestic.
Applied N at rates above 120 kg ha⁻¹ either reduced or did not significantly increase seed yield, decreased seed numbers per unit area and decreased spikelets per tiller and seeds per spikelet.
The use of a growth regulator increased seed yields by preventing lodging, but did so irrespective of nitrogen application rate. It is suggested that failure to increase seed yield at high N rates is a result not of poor pollination because of lodging, but seed abortion as a consequence of competition for assimilate supply by secondary vegetative tillers.     

Influence of treatment of soil with carbofuran on the subsequent performance of insecticides against cabbage root fly (Delia radicum) and carrot fly (Psila rosae)

A sandy loam soil was treated with 2·5 kg carbofuran/ha on each of five occasions between May and October 1984. In 1985, the field performance of benfuracarb, carbofuran, carbosulfan, chlorfenvinphos and furathiocarb against cabbage root fly (Delia radicum) and carrot fly (Psila rosae) was studied in this soil and in identical but previously untreated soil by applying exponentially increasing doses of granular formulations to radish and carrots at drilling. Chlorfenvinphos reduced numbers of larvae of both pests by >90% in both soils but the performance of all the carbamates was significantly worse in the previously treated soil than in the previously untreated soil. Dazomet, a partial soil sterilant, was applied to part of the experimental area in October 1985 and the performance of aldicarb, carbofuran, carbosulfan, chlorfenvinphos and thiofanox against cabbage root fly was assessed in 1986. The efficiency of aldicarb and chlorfenvinphos was not affected by any of the pre-treatments but that of carbofuran and carbosulfan was reduced in all the pre-treated soils, including the soil treated with dazomet. Carbofuran residues in radish were detectable only in plants grown in previously untreated soil. In laboratory incubations, a dustless base formulation of carbofuran was degraded more quickly in pre-treated than in untreated soils but a granular formulation was degraded more slowly and at a similar rate in both soils.     

臂形草属牧草种子生产试验

采用L25(5^6)正交表，进行了提高臂形草牧草种子产量的试验研究。以臂形草品种、施尿素、抽穗期施硼砂，初花期施硼砂为影响因子，各因子5个水平，作正交试验和统计分析。结果表明：通过2a试验,杂交臂形草种子产量最高。第1年为868．6kg／hm，第2年为303．1kg／hm，第1年氮肥不同处理水平间的种子产量差异不显著，但第2年种子产量随着尿素施肥量的增加而提高。抽穗期施硼砂不论在第1年，还是在第2年均可提高种子产量。抽穗期喷施质量分数1．0％硼砂，产量最高第1年为385．3kg／hm，第2年为208．1kg／hm。初花期施硼砂对种子产量效果不显著。     

丁硫克百威原药和制剂对蚯蚓的毒性及其降解产物克百威的动态变化

为了解蚯蚓急性毒性试验过程中丁硫克百威降解产物克百威的动态变化。采用固相萃取高效液相色谱柱后衍生荧光检测法检测土壤中克百威的动态变化，比较不同浓度的90％丁硫克百威原药和20％丁硫克百威乳油制剂在土壤主要代谢产物克百威中的动态变化及其对蚯蚓的毒性。结果表明：当90％丁硫克百威原药的浓度为42.74、85.47、170.94、341.88、512.82 mg/kg时，试验第7天，土壤中克百威的浓度分别为12.941、25.272、56.652、104.984、143.870 mg/kg；而当20％丁硫克百威制剂的浓度为42.74、85.47、170.94、341.88、512.82 mg/kg时，试验第7天，克百威的浓度分别18.445、41.793、67.709、119.515、144.538 mg/kg。第7天时丁硫克百威原药和制剂在土壤中对蚯蚓的LC50分别为170.514、113.757 mg/kg，实际测得的丁硫克百威对土壤中蚯蚓的毒性已演变成丁硫克百威及其降解产物的联合毒性。土壤中克百威的浓度，与添加丁硫克百威的浓度、时间呈正相关，20％丁硫克百威乳油制剂在土壤中的代谢能力及其对土壤中蚯蚓的毒性均高于原药。     

内蒙古西部区马铃薯脱毒种薯快速繁育的研究——Ⅱ.脱毒种薯生产技术及其良种繁育体系的研究

在内蒙古乌兰察布盟后山地区武川原种基地，对各级种薯生产技术及其良繁体系进行了系统的研究。现已明确：在开放条件下生产脱毒小薯（原原种），产量可达８０７３～９４６５ｋｇ／ｈｍ２，种薯产量和质量不低于温、网室生产的脱毒小薯；不同薯重的脱毒小薯旱坡地直播效果，以１０ｇ和８～１０ｇ薯重的效果好，产量和商品率均高；１级种薯在不同旱地类型种植的增产效果，以旱滩地的产量最高，其次为旱坡地，分别比对照（未脱毒）增产７１．２８％、１７１．２８％；８月上旬为有翅桃蚜迁飞盛期，从７月上旬迁飞初期开始喷药防蚜，防治效果显著；在乌盟后山半农半牧地区以原原种、原种、１、２级种薯建立的３级脱毒良种繁育体系符合该地区的生产实际，能达到留种和保种的快速、优质、高产、低成本的效果。经过６年示范推广，现已在武川等３个旗县普及，累计各级种薯种植面积达到２．３２万ｈｍ２，平均单产３万ｋｇ／ｈｍ２左右，生产出各级种薯及商品薯６９８５万ｋｇ，累计创造社会财富７１５０万元。     

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.     

Grass weed control in sunflower in the spring and kharif (summer) seasons under barani (rainfed) conditions in Pakistan

In field trials conducted at the National Agricultural Research Centre (NARC) near Islamabad and in farm fields, control of grass weeds including Cynodon dactylon (bermudagrass), Sorghum halepense (johnsongrass), Echinochloa colonum (junglerice) and Dactyloctenium aegyptium (crowfootgrass) increased yields of sunflower by 25–100%. The trials were conducted in the spring (February–May) and kharif (July–October) seasons in 1985 and 1986. Hand weeding generally resulted in the greatest yield response but this method was highly labour intensive and considered to be impractical by local farmers. The average time required to maintain 1 ha weed free in the spring and kharif seasons was 41 and 90 eight-hour man-days, respectively. In three of four trials conducted in the spring season, fluazifop-butyl at 0·25 and 0·5 kg/ha did not provide satisfactory control of grass weeds and did not result in significant increases in sunflower seed yields. The performance of fluazifop-butyl in these trials was adversely affected by hot dry conditions causing severe moisture stress after treatment. In contrast, in the fourth spring trial at NARC in 1986 and in all kharif season trials, fluazifop-butyl at 0·25 kg/ha effectively controlled both annual and perennial grasses and resulted in seed yields comparable to those obtained by hand weeding. Value/cost ratios indicate that, in the spring season under drought stress conditions, application of the herbicide would not be profitable; however, in the kharif season, herbicide treatment to control actively growing grass weeds would provide a cost-effective alternative to hand weeding.     

云南杜果果肉象甲、果实象甲发生危害及其熏蒸处理

杧果象是杧果的重要害虫,该类害虫的为害严重影响杧果的产量和质量,对杧果产业造成巨大的经济损失.调查发现杧果果肉象和果实象在云南发生为害严重,发生程度不一,早熟品种较晚熟品种受害重.采用溴甲烷对采后的丰亡果鲜果及新鲜果核进行熏蒸处理,结果表明:在20～25℃,常压下使用72/m~3,溴甲烷熏蒸鲜果、新鲜果核3 h或使用24、36 g/m~3溴甲烷进行熏蒸鲜果6 h,可100%杀死果肉及果核内的杧果象且果实外观、风味未发生改变,种子发芽率与对照差异不显著.     

Impact of non-corrosive forage stabilizer on chemical composition and storage characteristics of lucerne hay

Three trials examined the impact on chemical composition, leaf-stem ratio and bale temperature of applying a low-acid stabilizer and a Lactobacillus fermentation product at baling lo moist (20–25% moisture) lucerne Medicago saliva L.) hay. Treatments evaluated were lucerne baled at: 17–20% moisture (dry control); 20–25% moisture with addition of 200 g or 400 g 100kg^-1 of a low-acid stabilizer, with 4·1 ml or 8·1 ml 100kg^-1 of a Lactobacillus fermentation product; and 20–25% moisture with no treatment (wet control). In trial 1, low-concentration acid treatment was effective in limiting the increase in bale temperature of moist hay. In trials 2 and 3, bale temperature for low-concentration acid and Lactobacillus fermentation product-treated hay was similar to untreated moist hay In trial 3, higher application rates of either product were not effective in further reducing bale temperature. In trials 1 and 3, levels of neutral detergent fibre, acid detergent fibre, acid detergent lignin and acid detergent insoluble nitrogen were higher for moist hay than dry control. Nitrogen levels tended to be higher for moist hay. Leaf-stem data from trial 2 suggest that more leaves can be retained by baling relatively high-quality (late bud maturity) legumes at 20–25% moisture. In some circumstances use of a low-acid forage stabilizer for preservation of high-quality lucerne can minimize increases in temperature during storage of hay baled while moist (20–25%).     

Developing nominal threshold levels for Phyllotreta cruciferae (Coleoptera: Chrysomelidae) damage on canola in Montana,USA

The flea beetles Phyllotreta cruciferae (Goeze) and Phyllotreta striolata (F.) (Coleoptera: Chrysomelidae) are serious pests infesting canola (Brassica napus L.; Brassicales: Brassicaceae) in the Northern Great Plains of the United States. In Montana, P. cruciferae is the only flea beetle species that attacks canola during the crop growing stage. Management of P. cruciferae is usually focused on treating adults feeding on canola seedlings, which is the stage most vulnerable to flea beetle damage. In the Golden Triangle area in Montana, canola growers traditionally use seed treatments or calendar based spraying to control P. cruciferae. Here, we compared calendar-based spraying with seed treatment and threshold-based treatment. The experiment treatments included threshold levels (15–20, 25, 45% of leaf area damaged), calendar based sprays (15, 30 and 45 day intervals after plant emergence), seed treatments (imidacloprid), and untreated controls. The trials were done at two locations (Conrad and Western Triangle Agricultural Research Center). We found that calendar-based spraying at a 15-day interval did not differ significantly in yields from threshold-based treatment at 15–20% leaf damage. Also, the seed treatment did not give significantly higher yields compared to calendar-based sprays. A negative correlation was detected between leaf damage and yield in each treatment. Overall, calendar-based and threshold-based treatments were most effective in improving yields. However, treatment made at the threshold of 15–20% leaf area damage is recommended in order to reduce the number of chemical applications and also to reduce the possibility of selecting for resistance in flea beetles.     

Aphidicidal activity of a novel botanical insecticide made by alkalization of bamboo tar

Bamboo tar is a water-insoluble semi-solid waste generated from bamboo charcoal processing, and its increasing accumulation threatens environment and sustainability of the charcoal industry that enhances the economic value of bamboo forestry in southern China. Here we converted bamboo tar to a completely water-soluble sodium salt through full alkalization with NaOH and evaluated its insecticidal activity against the cotton aphid Aphis gossypii, the soybean aphid Aphis glycines and the green peach aphid Myzus persicae in laboratory bioassays and field trials. The tar salt LC₅₀s against the three global aphid pests decreased to 35–93 μg/ml on day 7 from 246 to 486 μg/ml on day 3. In three field trials, the tar salt at the application rates of 338–675 g/ha controlled the aphid pests as efficaciously as but more persistently than pymetrozine (a synthetic aphidicide) at the recommended rate. Our results highlight an easy approach to converting bamboo tar to a promising botanical aphidicide but extensive further work to determine its toxicity and environmental and crop safety is needed.     

Herbage intake and milk production by grazing dairy cows 2. The effects of level of winter feeding and daily herbage allowance

Two experiments are described in which two levels of winter feeding and three levels of herbage allowance during the grazing season were imposed upon March/April calving British Friesian dairy cows. The winter treatments resulted in differences in live weight and milk yield at turnout of 35 and 53 kg and 3·4 and 3·2 kg d^-1 for the two trials. Subsequently, when grazed at generous herbage allowances, the cows were able to compensate for much of this difference but when herbage was restricted the milk yield differences were accentuated. Groups of cows from each winter treatment were offered 25, 50 or 75 (Experiment 1) and 30, 50 or 70 (Experiment 2) g herbage DM per kg LW daily during the grazing season. Daily herbage intakes on the three allowances in each trial were 14·1, 13·3, 10·7 and 12·5, 12·1, 11·5 kg OM and milk yields were 16·0, 15·3, 12·5 and 15·2, 14·3, 11·8 kg SCM respectively. Both intake and milk production were depressed once the cows were forced to consume more than 50% of herbage on offer or to graze the sward down to a mean height of less than 8–10 cm. Grazing behaviour observations indicated that under rotational managements the cows did not compensate for restrictions in available herbage by grazing longer. Highest levels of milk production per unit area were observed in both trials when production per cow was depressed by 20–25%.     

Treatment of seed potatoes with prochloraz for simultaneous control of silver scurf and black dot on progeny tubers

Summary Potato seed tubers infected withHelminthosporium solani andColletotrichum coccodes were treated with prochloraz (as Omega 450 g a.i. l⁻¹ EC) and/or prochloraz managanese chloride (as Octave 25 g/kg DP), and planted in two separate fields not previously cultivated with potatoes. Dipping seed 28 d prior to planting in 2,4 or 6 g a.i. l⁻¹ Omega, and dusting with 500 or 750 g Octave per 100 kg seed significantly reduced the incidence of silver scurf and black dot on progeny tubers. In one field, the higher concentrations of Omega and Octave gave slightly better control than the lower Omega concentrations. At the second site, postharvest application of 4 g a.i. l⁻¹ Omega or 750 g Octave per 100 kg seed limited development of both diseases on progeny tubers, with slightly better control when an additional Octave dusting was applied 14 d before planting. None of the prochloraz treatments adversely affected plant stand or tuber yield.     

湖北省油菜磷肥施用效果 与土壤速效磷分级标准研究

近两年在湖北省油菜主产区布置27个油菜大田施磷试验。试验统计结果表明,油菜施用磷肥具有明显 的增产和增收效果, 25 个试验施磷增产效果在5%以上,施磷增产油菜籽产量15 ～1 783kg/hm2 ,平均增产量 558kg/hm2 ,平均增产率为53. 0% ,每千克P2O5 平均增收油菜籽6. 2kg;施磷的纯利润平均为831. 6元/hm2 ,产投比 平均为3. 10。油菜施磷增产幅度与土壤速效磷含量呈极显著负相关。按照不施磷对照处理产量占施磷处理产量 的50%、75%和90%作为判断土壤缺磷标准,则土壤速效磷极度缺乏、严重缺乏和缺乏的指标分别为9. 9mg/kg、 14. 3mg/kg和20. 2mg/kg;以施磷产投比2. 0和1. 0作为土壤缺磷标准时,土壤速效磷严重缺乏和缺乏的指标分别 为16. 2mg/kg和20. 2mg/kg。     

Seed flavonoids and anthocyanins as markers of enhanced plant defence in nodulated cowpea (Vigna unguiculata L. Walp.)

Insect pests are a major constraint to cowpea production in Africa. Therefore the aim of this study was to identify cowpea material that exhibit greater pest resistance and grain yield for evaluation by farmers. About 45 cowpea genotypes were assayed for flavonoids and anthocyanins with the objective of quantifying the levels of these phenolics in seed extracts as markers for effective plant defence. The results revealed significant differences in the concentration of flavonoids and anthocyanins in seed extract. Farmer varieties such as Sanzie, Bensogla and Omondaw exhibited much higher levels of phenolics compared with improved genotypes like ITH98-46, TVu1509 and IT93K-452-1. When planted in the field in Ghana and Tanzania, the genotypes that had high concentrations of flavonoids and anthocyanins in seed extracts (e.g. Bensogla, Omondaw and IT86D-2075) showed relatively lower infestation by thrips, pod-sucking bugs, aphids and alcidodes. Providing minimum protection with insecticide spray further showed that, genotypes with low infestation by thrips and pod-sucking bugs produced more grain yield without spraying, an indication of their natural resistance to these insect pests. Furthermore, farmer-selected varieties such as Sanzie, Bensogla, and Omondaw produced more grain yield without protection than their improved counterparts. These results showed that the higher the concentration of flavonoids and anthocyanins in cowpea seed extracts, the lower the insect pest incidence on seedlings raised from those seeds. Correlation analysis further confirmed a direct relationship between high flavonoids/anthocyanins in seed extracts and enhanced insect pest.     

不同处理对柱花草种子的产量和质量的影响

以热研5号柱花草为材料,研究了不同的底肥、种植密度、追肥、灌水次数和采收方式对柱花草种子产量和质量的影响。结果表明,3个底肥(磷肥)水平种子产量和质量均高于未施磷水平,0.07 kg/m2处理磷肥水平产量最高,为358.50 kg/hm2,且3个处理相差不大。净度和千粒重最低的处理是0.13 kg/m2磷肥水平,分别为8.87%和2.42 g。种植密度为0.5 m×1.0 m产量最高,为448.63 kg/hm2,种植密度行距为1 m的种子净度、千粒重和出苗率均高于株行距为0.5 m的,净度为9.12%,千粒重为2.63 g,出苗率为74.33%。未追肥条件种子产量最低,为339.96 kg/hm2,种子净度、千粒重和出苗率变化较小。3个灌溉处理种子产量差异较小,未灌溉处理种子千粒重和出苗率最低,分别为2.48 g和42.44%。铺膜采收种子处理种子产量最高,为370.79 kg/hm2,成熟后刈割收种处理种子产量和千粒重最低,分别为197.42 kg/hm2和2.47 g。试验为云南柱花草生产及草业的发展提供理论依据。     

砜嘧磺隆25%可湿性粉剂在马铃薯中的残留动态

为了制定砜嘧磺隆在马铃薯生产中的安全使用标准,采用田间试验的方法,研究砜嘧磺隆在马铃薯中的残留动态,应用液相色谱法测定砜嘧磺隆在马铃薯中的残留量。试验结果表明:砜嘧磺隆在马铃薯植株和土壤中降解符合一级化学反应动力学方程C=C0e-kt,砜嘧磺隆在土壤中半衰期为(0.02～3.10 d),在植株中的半衰期为(0.93～2.90 d)。该药属易分解农药(T1/2<30 d)。在马铃薯4叶期时喷药1次,按推荐剂量90 g/hm2及1.5倍剂量135 g/hm2施用25%可湿性粉剂砜嘧磺隆。在收获期马铃薯植株和块茎均未检测出,在马铃薯上的砜嘧磺隆安全使用量推荐为90 g/hm2,建议马铃薯上砜嘧磺隆最大残留限量值MRL暂定为0.1 mg/kg。     

A comparison of seed harvesting methods for perennial ryegrass treated with the growth retardant paclobutrazol

Methods of harvesting seed of perennial ryegrass cv. S24 treated with the growth retardant paclobutrazol applied at spikelet initiation at a rate of 2.0 kg active ingredient ha⁻¹ were examined in 1982. The greatest seed yield (2202 kg ha⁻¹) was obtained from swathing the crop at 35% seed moisture content and combining 2 days later, but this was not significantly different from that obtained from swathing at 48% seed moisture content or double direct combining at 35% seed moisture content. Seed yields from a single direct combining at either 35% or 25% seed moisture content were significantly lower than those of other treatments.