The control of voulunteer potatoes in the autumn in cereal stubbles.

The emergence of volunteer potatoes and their regrowth after the cereal harvest were studied in four barley crops. Cutting the shoots of the potato plants before or during cereal harvest did not prevent regrowtth of many of them afer harevet. There was more regrowth (i) after winter barley, (ii) after barley grown at above normal seed rates and (iii) when the early growth of the potatoes in May an June ws suppesed by dry conditions. In one experiment the number of emerged plants on 12 May was negatively correlated with the number of emerged plants on 12 May was negatiely correlated with the number regrowing in September. These studies suggest that control of volunteer potatoes may be possible with foliar applied herbicides after cereal harvest.     

Effects of boron fertilization on `Conference' pear tree vigor, nutrition, and fruit yield and storability

The aim of the study was to examine the response of pear (Pyrus communis L.) trees to soil and foliar applications of boron (B). The experiment was carried out during 2000–2001 in a commercial orchard in Central Poland on mature `Conference' pear trees grafted on Pyrus communis var. caucasica seedlings planted at a spacing of 4 × 2.5 m on a sandy loam soil with a low hot water-extractable B status. Annually, foliar sprays with B were applied. (i) before full bloom (at green and white bud stage, and when 1–5% of flowers was at full bloom), (ii) after flowering (at petal fall, and 7 and 14 days after the end of flowering), or (iii) postharvest in fall (approximately 6 weeks before leaf fall). Spray treatments involved application of B at a rate of 0.2 kg ha^–1 in spring or 0.8 kg ha^–1 in fall. Additionally, other trees were supplied with soil-applied B at the bud break stage at a rate of 2 kg ha^–1. Trees untreated with B served as the control. The results revealed that foliar applications of B before full bloom or after harvest increased fruit set and fruit yield. Tree vigor, mean fruit weight, firmness, soluble solids concentration and titratable acidity of fruits at harvest were not affected by B treatments. Foliar B sprays before full bloom or after harvest increased B concentrations in flowers, and both leaves and fruitlets at 40 days after flowering. Only the foliar treatments after flowering and soil fertilization with B increased the content of this microelement in fruit and leaves at 80 and 120 days after full bloom. Foliar B application before full bloom or after harvest increased calcium (Ca) in fruitlets at 40 days after full bloom, in fruit, and in leaves at 80 and 120 days after full bloom. Nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg) in plant tissues were not affected by B fertilization. After storage, and also after the ripening period, fruits from the trees sprayed with B before full bloom or after harvest had higher firmness and titratable acidity than those from the control trees. After the ripening period, fruits from the trees sprayed with B before full bloom or after harvest had lower membrane permeability and were less sensitive to internal browning than the control fruits. These findings indicate that prebloom and postharvest B sprays are successful in increasing pear tree yielding and in improving fruit storability under the conditions of low B availability in the soil.     

Field control of brown leaf rust (Puccinia recondita) of wheat with a triazole compound in north India

RH-124 (4-n-butyl-i,2,4-triazole) when applied as one or two foliar applications (at the rate of i-6 1 a.i./ha) or given by watering soil (at the rate of 0–8 1 a.i./ha) controlled brown leaf rust ( Puccinia recondita ) of wheat in microplot experiments. In north India where the rust appears 80–90 days before harvest, one foliar or soil application was sufficient to mitigate loss in yield. Seed treatment was not found useful when tested in one trial.     

Reproduction and feeding behavior of Myzus persicae on four cereals

Green peach aphid, Myzus persicae (Sulzer), does not overwinter outdoors in Minnesota; it arrives each spring on low-level jet streams from the south. After arrival, anholocylic reproduction occurs on numerous herbaceous species, including many common weeds, before movement to potato, Solanum tuberosum L. In investigating aphid feeding behavior on barrier crops, we observed winter wheat, Triticum aestivum L., colonized by green peach aphid. The Northern Great Plains grows 94,000 ha of potatoes and 20.5 million ha of small grain cereals each year, the latter potentially providing an early emerging and widely distributed green peach aphid host to influence early season potato colonization. Life tables statistics indicated green peach aphid had its highest reproductive potential among cereals on winter wheat, with rye (Secale cereale L.) > barley (Hordeum vulgare L.) > oats (Avena sativa L.). Green peach aphid was found to colonize barley, rye, and winter wheat, but not oats. Mean generation time, net reproductive rate, doubling time, and finite rate of increase were significantly different between host plants. Electrical penetration graph technique indicated mean nonpenetration duration by green peach aphid was significantly different among plant species, and significantly longer on winter wheat than on the other cereals. Mean xylem phase duration was not significantly different among plant species but sieve element salivation was of longest duration on potato. Phloem sap ingestion (E2) was also significantly different among plant species with longest E2 duration on winter wheat. This study demonstrates that this aphid can effectively use key cereals at the vegetative stage.     

Increasing use efficiency of boron fertilisers by rescheduling the time and methods of application for crops in India

Boron-deficiency is prevalent in light-textured acidic soil regions receiving high precipitation. Crop use efficiency of fertiliser B is also low under such B-leaching environments. For high leaching regimes, we hypothesised that the optimal timing and method of B application would vary with the crop sensitivity to B-deficiency and periods of peak demand for B. The aim of the present experiment was to vary the timing and method of B application to increase use efficiency on typical B-deficient Entisols. Mustard (Brassica campestris L.), wheat (Triticum aestivum L.) and potato (Solanum tuberosum L.) were the test crops. There were seven treatment combinations of B, applied either to soil or as foliar sprays at different doses and growth stages of the crops. Biomass and yield related characters of the crops at harvest, B concentration in plants and its uptake increased with B application being highest in mustard, followed by potato and wheat. Foliar application, in general had higher economic benefits than soil application. Split application of B either to soil (as basal and 25 days after sowing) or foliar sprays (at 25 and 40 and 25 and 45 days after sowing for mustard and potato, respectively) had an edge over a single application. For wheat, a single late application of B (at 45 or 60 days after sowing through soil or foliar spray, respectively) was more effective than the early or split application in increasing yields. Better use efficiency of B can thus be achieved if it is applied late for wheat but in splits over a longer period for mustard and potato with higher economic benefits.     

Role of thiourea in improving productivity of wheat (Triticum aestivum L.)

The role of thiourea (TU), a sulfhydryl compound, was assessed in wheat via soil and foliar treatments. Results showed that at 30 days after flowering, soil-applied TU treatments did not influence dry matter accumulation or its distribution in leaves, stems, and ears, but foliar-applied treatments brought about significant effects varying with the timing of spray. At harvest, however, soil-applied treatment of 10 kg/ha TU increased the number of ears, grains/ear, weight/grain, biological yield (total above ground biomass), grain yield, and harvest index. Grain yield increased by 17.3% over control. Soil-applied 20 kg/ha TU increased the grain yield by 1.6% over control. Foliar applied treatment of 0.5 kg/ha TU at tillering increased the number of ears, grains/ear, weight/grain, biological yield, grain yield, and harvest index. Grain yield increased by 15.2% over control. Foliar spray of 0.5 kg/ha TU at flowering tended to improve only weight/grain, but biological yield and grain yield increased significantly. Grain yield increased by 6.6% over control. TU spray at both tillering and flowering increased the number of ears, grains/ear, weight/grain, biological yield, grain yield, and harvest index. Grain yield increased by 23.9% over control, and when compared with spray at tillering there was a significant increase of 7.5%. Thus, two foliar sprays of thiourea, at tillering and at flowering, at 1 kg/ha can be recommended for improving wheat productivity.Abbreviations TU thiourea - DMA dry matter accumulation - DMD dry matter distribution     

Fertilizer placement experiments

Summary The results are given of an investigation in the Netherlands, made over a number of years, on placement of fertilizers. This new method of application has been tested in field trials, in which placement has been compared with the usual method of broadcasting at certain increasing levels of fertilizer. The experiments relate to nitrogen, phosphate and potash on different kinds of crops and soils.Generally speaking, it would appear that placement is better than broadcasting. The difference between the two methods of application can be represented by a factor indicating the ratio between the amounts of fertilizer giving the same yield for both. Nitrogen applied in bands is about 1.20 times as effective as broadcasting for cereals, potatoes and beets; phosphate for pulse crops 7.50, for maize 2.90, for cereals 2.45, for potatoes 1.90 and for beets 1.20; potash on river clay for cereals 3.65, for potatoes 1.00 at low pH and 1.60 at high pH and for beets 1.00. There are indications that the prevention of fixation and a better early growth as a result of the localisation of the fertilizer near the seed at an adequate depth are reasons why placement is successful.The conclusions of de Wit with regard to the effect of placement are not corroborated. It appears that placement gives higher yields at light dressings, and at heavy dressings yields as high as broadcasting, whereas, according to de Wit, a favourable effect would be attained, as a rule, with light dressings and an unfavourable effect with heavy dressings.     

Harvesting in seasonal environments

Most harvest theory is based on an assumption of a constant or stochastic environment, yet most populations experience some form of environmental seasonality. Assuming that a population follows logistic growth we investigate harvesting in seasonal environments, focusing on maximum annual yield (M.A.Y.) and population persistence under five commonly used harvest strategies. We show that the optimal strategy depends dramatically on the intrinsic growth rate of population and the magnitude of seasonality. The ordered effectiveness of these alternative harvest strategies is given for different combinations of intrinsic growth rate and seasonality. Also, for piecewise continuous-time harvest strategies (i.e., open / closed harvest, and pulse harvest) harvest timing is of crucial importance to annual yield. Optimal timing for harvests coincides with maximal rate of decline in the seasonally fluctuating carrying capacity. For large intrinsic growth rate and small environmental variability several strategies (i.e., constant exploitation rate, linear exploitation rate, and time-dependent harvest) are so effective that M.A.Y. is very close to maximum sustainable yield (M.S.Y.). M.A.Y. of pulse harvest can be even larger than M.S.Y. because in seasonal environments population size varies substantially during the course of the year and how it varies relative to the carrying capacity is what determines the value relative to optimal harvest rate. However, for populations with small intrinsic growth rate but subject to large seasonality none of these strategies is particularly effective with M.A.Y. much lower than M.S.Y. Finding an optimal harvest strategy for this case and to explore harvesting in populations that follow other growth models (e.g., involving predation or age structure) will be an interesting but challenging problem.     

Effects of Break Crops on Yield and Grain Protein Concentration of Barley in a Boreal Climate

Rotation with dicotyledonous crops to break cereal monoculture has proven to be beneficial to successive cereals. In two fields where the soil had been subjected to prolonged, continuous cereal production, two 3-year rotation trials were established. In the first year, faba bean, turnip rape and barley were grown, as first crops, in large blocks and their residues tilled into the soil after harvest. In the following year, barley, buckwheat, caraway, faba bean, hemp and white lupin were sown, as second crops, in each block and incorporated either at flowering stage (except barley) or after harvest. In the third year, barley was grown in all plots and its yield and grain protein concentration were determined. Mineral N in the plough layer was determined two months after incorporation of crops and again before sowing barley in the following year. The effect of faba bean and turnip rape on improving barley yields and grain protein concentration was still detectable two years after they were grown. The yield response of barley was not sensitive to the growth stage of second crops when they were incorporated, but was to different second crops, showing clear benefits averaging 6-7% after white lupin, faba bean and hemp but no benefit from caraway or buckwheat. The effect of increased N in the plough layer derived from rotation crops on barley yields was minor. Incorporation of plants at flowering stage slightly increased third-year barley grain protein concentration but posed a great potential for N loss compared with incorporation of crop residues after harvest, showing the value of either delayed incorporation or using catch crops.     

Supplementary foliar N, P and K, applied individually or in combinations, and the tolerance of potatoes to infection by the potato cyst nematodes Globodera rostochiensis and G. pallida

The use of supplementary foliar N, P and K to ameliorate the reduced nutrient uptake of potato plants infected by potato cyst nematode (PCN) were investigated. The potato cv. Pentland Dell achieved yields in plots not treated with oxamyl similar to those found in plots treated with oxamyl when supplementary foliar N or N plus K was applied to plots infested with 13 eggs g^-1 soil of Globodera pallida. Yield improvements from foliar N applications were attributed to increased leaf area index but the reason for yield increases from foliar N plus K applications could not be clarified. In a second experiment, where PCN infestation was 76 eggs g^-l soil, the potato cv. Sante gave yields up to 19% higher than a standard fertiliser practice when supplementary foliar N was applied to plots not treated with oxamyl. Nutrient analysis showed that without oxamyl there were significantly lower concentrations of N, P and K in whole plant dry matter at 58 days after planting (DAP) but higher levels of N in the fourth leaf dry matter at 98 DAP. Emergence was significantly advanced by the use of oxamyl in both experiments. Sante dramatically reduced populations of Globodera rostochiensis from an average of 76 eggs g^-1 soil to 7 eggs g^-1 soil. Foliar application of nutrients is a promising method of ameliorating the effects on potatoes of PCN invasion but the nutrient concentrations and timing of individual sprays need to be more closely matched to crop requirement than was possible in our experiments     

Treating potato ridges in spring with aldicarb, D-D or dazomet to control potato cyst-nematode, Heterodera rostochiensis, in sandy clay and peat loam soils

Applied to potato ridge soil in spring, before potatoes were planted, small amounts of aldicarb (10-3 kg/ha or less) controlled potato cyst-nematodes (Heterodera rostochiensis Woll.) better than large amounts of dazomet (110–466 kg/ha) or D-D (102–439 kg/ha). Applied in spring 1968 and 1969 to heavily infested sandy clay soil 466 kg dazomet/ha allowed Majestic potatoes to grow and yield well in both years without increasing the number of nematodes in the soil after harvest, but in peaty loam dazomet was toxic to potato plants and, when applied in autumn, killed fewer nematodes. D-D in potato ridges in spring controlled nematodes less well than dazomet or aldicarb, but 896 kg D-D/ha injected in sandy clay soil in autumn increased potato yield the following year without increasing the number of nematodes after harvest.     

Boron foliar supplementation as a strategy to attenuate drought stress in soybean

Drought is the major abiotic stress that limits growth, development and yield of crops worldwide. In this scenario, mineral nutrients, such as boron (B), have been promising for increasing the tolerance of plants to abiotic stresses because of their physiological roles in plants. We aimed to evaluate the benefits of foliar supplementation of B in either relieving or reducing the physiological damages caused by water stress in soybean (Glycine max L.). A greenhouse trial was carried out in a 2 × 3 factorial scheme, with two water conditions (well-watered and drought stress) and three doses of B (0, 150 and 300 mg B L⁻¹). Foliar application of B was before inducing the water stress, which remained for 20 days during vegetative stage. Plants were evaluated at three moments, according to the water conditions: maximum stress, rehydration and just before harvesting. The levels of hydrogen peroxide and lipid peroxidation increased in soybean leaves and roots under water stress, resulting in impaired plant growth. However, the foliar supplementation with B before the stress increased activities of the antioxidant enzymes and reduced the levels of stress markers. Furthermore, B applied foliar increased the nutrient concentration in the leaves of plants and stimulated root growth, which resulted in higher harvest index related to yield. The foliar application of B has shown as an alternative management to mitigate the damages caused by drought stress in soybean.     

绿色食品生产中土壤作物系统铅的积累与迁移研究

研究了Pb在土壤-作物生态系统中的积累和迁移,并结合水稻绿色食品生产,进行了无机肥、有机肥和生物菌肥及其配比试验．结果表明,土壤全Pb含量随土层的加深而逐渐递减,收获后土壤全Pb含量在0～15和15～30cm分别为11．14和9．37mg·kg^-1．水稻根从土壤中吸收Pb,并向茎、叶和籽粒中迁移．在同一生长期,水稻植株不同部位全Pb累积态势为：根>茎叶>籽粒．在不同生长期,随水稻生长发育,全Pb含量缓慢增加,至收获时,606—14和辽粳294籽粒中全Pb含量分别为0．008和0．007mg·kg^-1,均低于绿色食品标准．方差分析表明,品种间产量差异显著;不同处理间产量差异不显著．试验结果表明。可以用有机肥或生物菌肥来代替无机肥进行水稻生产．     

Survival of soft rot coliforms, Erwinia carotovora subsp. carotovora and E. carotovora subsp. atroseptica in soil in Scotland

An enrichment method was used to monitor Erwinia carotovora in soil or the rhizosphere of different crops and weeds in 17 fields with different cropping histories on three farms. The bacteria were detected in all fields not cropped with potatoes, although not consistently, and the mean annual frequency of detection was generally low (< 10%). Fields in which potatoes were grown were extensively contaminated after harvest in September but contamination declined over the winter to very low levels by early summer in the following year. Contamination level tended to rise in some fields without potatoes regardless of their cropping history but for only a short time during autumn and winter. The bacteria were no more frequent in rhizosphere soil of any of the weeds or crops examined, with the exception of brassicas, than in bare soil. In fields where more than 16 months had elapsed since cropping with potatoes, 91% of erwinia isolates obtained were E. carotovora subsp. carotovora , the remainder being E. carotovora subsp. atroseptica. The bacteria were shortlived in soil and in the rhizospheres of inoculated field and pot grown crop and weed plants. Longevity was greater in dry (10% moisture) than in wet (21% moisture) soil and decreased as temperatures rose, particularly above 25°C. Survival was best in association with brassica plants, moderate on grasses and cereals, and least on potatoes and weeds. E.c. carotovora survived better than E.c. atroseptica. Because survival of the bacteria in soil is apparently restricted, their presence in fields could be attributed to recurrent introductions from different sources.     

Stimulating effects of foliar K-fertilizer applied at the appropriate stage of development of maize: A new way to increase yield and improve quality

A series of eight experiments was conducted using large pots to (1) find the most effective date, site, concentration of K-solution and K-salt for foliar K-fertilization of maize plants (Zea mays, L.) grown with sufficient K-supply in soil, (2) explain why maize responded to the K-treatment, and (3) examine the influence of various levels of N and P supplies on the effectiveness of K-fertilizer via the leaves. A single spraying on sweet maize and field maize on any day between 50% tasselling date to 10 days after tasselling shortened maturity date, increased grain yield, stover yield, grain-stover ratio, absorption of N, P, K, Ca and Mg, sweetness of young grain (of sweet maize), and crude protein content of grain. However spraying on the third day after 50% tasselling was most effective. The second application later than 7 days after the 50% tasselling date suppressed the effects of spraying on the most effective date. In application of many repetitive sprayings covering the most effective date, a spraying program with late spraying could reduce grain yield. KNO₃, 2.5% KNO₃-solution, and applications on all aerial parts were found to be the most effective. Increases in grain yield for spraying on all aerial parts, spraying on ear leaf only, spraying on all leaves above ear leaf and applying K to soil were 74%, 51%, 41% and 23%, respectively. The foliar K-fertilization affected maize by stimulating chlorophyll synthesis and not by increasing leaf area. A balance in N and K supplies was determined to be effective for the K-fertilization.     

Population dynamics of the potato tuber moth on processing tomatoes in Israel

The potato tuber moth (PTM),Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is a major pest of processing tomatoes,Lycopersicon esculentum Mill. (Solanaceae), in Israel. The larvae penetrate the tomato fruit through the stem end and present a serious threat to crop quality. Foliage and fruit samples were taken in nine commercial tomato fields located in Israel's three main tomato growing areas, two of which are potato growing areas as well. PTM was not found where potatoes were absent. Potato harvest in nearby fields was found to be the most significant factor affecting seasonal trends in PTM population density in tomatoes. All four larval instars were found in foliage on all sampling dates. Significantly higher proportions of first instars were found during the population density increase which followed potato harvest. Damaged fruits did not contain first instar larvae, indicating that PTM never undergoes complete development within tomato fruit. Fruit damage levels at harvest were positively correlated to the peak mean population densities on foliage and the date they were observed. In tomato fields not adjacent to potatoes, infestation was first observed at the edge of the field. Both before and after the potato harvest in nearby fields, population density at the edge of the field was significantly higher than at the center. In tomato fields adjacent to potatoes, no significant differences were found between population densities at the edge and center before the potatoes were harvested. After the potato harvest, population density at the center of tomato fields was higher than at the edge. Deceased, October 1988     

播期播量对旱地小麦土壤水分消耗和植株氮素运转的影响

为解决旱地小麦等雨播种的生产现状,明确播量对土壤水分利用和产量形成的调控机制,于2015—2017年在山西闻喜试验基地开展大田试验,以早播(9月20日,EB)、晚播(10月10日,LB)两个播期为主区,以低密度(67.5 kg·hm^-2,LD)、中密度 (90 kg·hm^-2,MD)、高密度(112.5 kg·hm^-2,HD)3个播量为副区,研究播期播量对旱地小麦土壤水分消耗和植株氮素运转的影响.结果表明: 早播较晚播生育期土壤总耗水量增加11～22 mm;随播种密度的增加,生育期土壤总耗水量增加2～20 mm,且早播条件下,花前土壤耗水量增加,晚播条件下,花后土壤耗水量显著增加.早播较晚播在低、中密度条件下花前氮素运转量、花后氮素积累量增加,高密度条件下降低.早播条件下,花前氮素运转量,茎秆+叶鞘、穗轴+颖壳花前氮素运转量对籽粒的贡献率以及花后氮素积累量均以低密度条件下最高;晚播条件下,花前氮素运转量和花后氮素积累量随播种密度增加而增加.早播较晚播产量显著提高163～996 kg·hm^-2,提高幅度达5%～26%,水分利用效率提高幅度达2%～21%,氮素吸收效率提高幅度达3%～36%,氮素收获指数提高幅度最高达11%.早播条件下产量、水分利用效率、氮素吸收效率、氮素收获指数以低密度条件下最高;晚播条件下以高密度条件下最高.此外,花前氮素运转量与花前100～200 cm土壤耗水量显著相关,尤其是茎秆+叶鞘、穗轴+颖壳;花后植株氮素积累量与花后100～300 cm土壤耗水量呈显著相关.总之,旱地小麦9月20日配套播量67.5 kg·hm^-2、10月10日配套播量112.5 kg·hm^-2有利于增产增效.     

Effect on carrot root yield and size distribution of the growth-retardants chlormequat chloride and aminozide

In two experiments, foliar sprays of either chlormequat chloride or aminozide depressed top growth, increased root yield and enhanced leaf and root colour in six carrot cultivars. In the first experiment, a direct correlation between concentration of the two retardants and root yield was apparent within the range 0–2000 mg/1 a.i. applied as run-off sprays to two cultivars. In the second experiment, increases in total root and canning-size yield and root/shoot ratio were obtained with four cultivars, but the magnitude of these effects was dependent on the time at which the retardants were applied and the time of harvest of the crop. The effects of aminozide on root yield were less persistent than those of chlormequat chloride, the yield differences between untreated and aminozide-treated plots decreasing with time after application.     

The analysis of grain yield of wheat in terms of photosynthetic ability and efficiency of translocation

A technique, using ¹⁴CO₂, for measuring the rate of photosynthesis and the distribution of synthesized carbohydrate in the same plant, applied to wheat plants at intervals from 10 days before anthesis until the plants were no longer green, showed that the rate of photosynthesis by the leaves and ears decreased steadily; it was much less for ears than for leaves. The proportion of carbohydrate translocated to the grain was very small at and before anthesis, but increased rapidly afterwards. Integration of these data provided estimates of yield based on physiological components which showed good agreement with measured yields at harvest, though varietal differences in observed yield could not be explained. An experiment in which ears were removed from plants 7 days after anthesis showed that photosynthetic activity was not limited by the size of the ‘sink’ to which photosynthates were translocated.     

Control of pearl millet downy mildew caused by Sclerospora graminicola with systemic fungicides in an artificially-contaminated plot

Among four fungicides, viz. metalaxyl (two formulations), fosetyl-Al, pro-pamocarb and cyomaxanil tested in vitro against sporangial germination inhibition of Sclerospora graminicola, cyomaxanil was found to be most inhibitory. In an artificially contaminated plot, when used as seed treatment or foliar spray for the control of downy mildew of pearl millet, only metalaxyl was effective. Metalaxyl 25 (Ridomil) and metalaxyl 35 (Apron) seed treatments protected the pearl millet plants from downy mildew up to 30 days. As a foliar spray, metalaxyl 25 used once at 20 days or twice after 20 and 38 days of plant growth gave less disease at harvest time. Seed treatment (metalaxyl 25 or 35) followed by one metalaxyl 25 spray was found to be effective in controlling the downy mildew. These treatments improved the growth of plants and yield significantly.