Fertilizer management impacts on stand establishment, disease, and yield of Irish potato

Summary Excessive fertilizer application in North Carolina, USA results in high residual soil levels of P, K and total soluble salts in potato fields. Our objectives were to determine the salt sensitivity of three common cultivars (Atlantic. Snowden and Superior), and the effects of planting density and fertilization on stand establishment, soilborne disease, and yield. Greenhouse results suggest that potato growth and emergence, but not shoot initation, are reduced by high salinity. On a Portsmouth fine sandy loam, high fertilizer rates did not reduce stands of cv. Atlantic in the field in 1996 or 1997. Excess N resulted in moreRhizoctonia stem canker in 1996, and lower yields at the lower planting density in 1997. Yield compensation for reduced plant density occurred in 1997 at the lower N rates (56 and 112 kg N ha⁻¹) and at the high PK rate (49 kg P and 139 kg K ha⁻¹).     

The effect of physiological age and planting date on the response of potatoes to applied nitrogen and on levels of residual nitrogen post-harvest

Summary Experiments were conducted on sandy and deep silty soils to assess the effect of physiological age of seed tubers and planting date on the response of potatoes to nitrogen fertiliser. Nitrogen optima commonly had large standard errors which made interpretation of the data difficult. On the sandy soil with cv. Record, early planting increased yield in two years but had no effect on mean N optimum (303 kg ha⁻¹, NOpt). Mean NOpt was less on the silty soil where the cv. Pentland Squire was grown, and was reduced from 273 kg ha⁻¹ to 241 kg ha⁻¹ when planting was delayed by 4 weeks. Physiological age had no effect on NOpt. On the sandy soil, residual soil mineral nitrogen (RSMN) increased by 0.05 kg ha⁻¹ per kg N fertiliser applied; on the silty soil the increase was four times as large. RSMN was larger following the late planted crop on the silty soil in one year.     

不同土壤背景下秸秆全量还田对水稻产量及稻米品质的影响

为了探明北方地区不同土壤背景下水稻秸秆全量还田对水稻产量及稻米品质的影响,以辽粳2501为材料,通过盆栽试验,比较分析了在总施纯氮200 kg/hm²条件下不同处理（砂壤土、砂壤土+秸秆、盐碱土、盐碱土+秸秆、棕壤黏土、棕壤黏土+秸秆）辽粳2501的产量结构和品质表现。结果表明,与秸秆不还田处理相比,棕壤黏土背景下秸秆全量还田处理产量提高4.45%,而在砂壤土和盐碱土背景下秸秆全量还田处理表现为显著减产,减产幅度分别为2.20%和3.84%;秸秆全量还田均能显著提高不同土壤背景下的每穗颖花数,尤其是二次枝梗颖花数,但降低了盐碱土和砂壤土背景下的有效穗数;秸秆全量还田显著增加了稻米胶稠度和米饭食味值,但降低了盐碱土和砂壤土背景下稻米的垩白粒率和垩白度。     

土壤质地对玉米产量的影响

采用空间位移法,将砂土、砂质黏壤土、砂质壤土3种不同质地土壤移到同一地点的水泥池小区上,研究土壤质地对玉米产量的影响。结果表明,无论是免耕还是翻耕,玉米产量均表现为砂质黏壤土>砂质壤土>砂土。不同质地的土壤玉米产量均表现为翻耕比免耕高,但差异不显著。根据玉米产量构成因素分析,不同土壤质地条件下玉米产量的差异主要由单穗粒重和千粒重的变化引起。     

The effect of irrigation and nitrogen on powdery scab and yield of potatoes

Summary Powdery scab, caused by the fungusSpongospora subterranea, has developed in the Cappodocia region of Turkey because of changes in agronomic practices, such as excessive irrigation and nitrogen fertilizer use and growth of highly susceptible cultivars. The most suitable irrigation and nitrogen application levels were established to maintain powdery scab at minimum levels without affecting potato yield. Three irrigation levels were used in 1998 (673, 897, 1121 mm) and five in 1999 (329, 494, 658, 823, 987 mm). Nitrogen levels were applied 150, 300, 450, 600 kg N ha⁻¹. In 1998, least powdery scab occurred with 673 mm irrigation, which yielded 41 t ha⁻¹ potatoes. The lowest disease severity occurred in 1999 with 494 mm irrigation and 150 kg N ha⁻¹. At these levels, tuber yield was 34 t ha⁻¹ which was not significantly different from the highest yield measured. In 1999 and at two of the three irrigation levels inl998, nitrogen increased disease severity.     

The effect of seed-and soilborne inoculum ofColletotrichum coccodes on the incidence of black dot on potatoes

Summary Soil in a potato field naturally infested with black dot (Colletotrichum coccodes) was fumigated with methyl bromide at 126 g m⁻² or left unfumigated. Potato seed tubers (cv. BP1) uninfected, lightly infected (1–25% surface affected), severely infected (26–100% surface affected) and severely infected withC. coccodes but dusted with prochloraz manganese chloride as Octave 2.5% DP at 750 g per 100 kg seed were planted in fumigated and unfumigated soil. When harvested, the incidence of black dot on the progeny of infected seed planted in unfumigated soil was twice that of progeny in fumigated soil, with progeny of uninfected seed having a 68.5 times higher disease incidence in unfumigated soil. Black dot on progeny tubers was reduced by pre-treatment of seed with prochloraz in fumigated soil only. With black dot infested fields, planting disease-free seed or treating seed with fungicides would not decrease disease on progeny tubers.     

Differential susceptibility of potato cultivars to four herbicides

Greenhouse and field studies were conducted to evaluate the susceptibility of six potato (Solatium tuberosum L.) cultivars to injury by four herbicides. The White Rose cultivar was the most susceptible to injury, especially from metribuzin {4-amino-6-tert-butyl-3-(methylthio)-s-triazin-55 (4H) one}, and linuron {3-(3,4-dichlorophenyl)-l-methoxy-l-methyl-urea}. Injury was attenuated by decreasing the rate of herbicide in the range of 4.5 to 0.5 kg/ha (4 to 0.5 1b/A) and by increasing the seed piece size. Injury seemed to be associated with soil texture and was greater in a sandy loam than in a sandy clay loam soil. Greenhouse studies provided valuable leads on cultivar susceptibility to herbicides but reductions in foliar weight of 15 to 20% are required to justify any suspicion that field injury will occur.     

Spatial variation of infiltration rate and compactness in paddy fields

Percolation loss of water in rice fields is a major cause of low water use efficiency. Variation of infiltration rate and soil compactness in four paddy fields (with clay, silty clay, clay loam, and loam textures) was investigated in northern Iran. In each field, in longitudinal and transverse directions, points located 0.5, 2.5, 6.5, 12.5, … m from the bunds were selected and water infiltration rate and resistance to penetration of a pocket penetrometer were measured. The results showed that in clay soil, average final infiltration rate (f _c) in longitudinal direction, transverse direction, and center of the field was 0.216, 0.136, and 0.08 cm day⁻¹, respectively. The f _c for loamy soil was 2.77, 2.32, and 0.409 cm day⁻¹, respectively. Similar differences were observed in the other two soil textures. In general, effect of direction of the field for measuring infiltration rate was not statistically significant. Loam and clay loam soils, with resistance to penetration of 0.37 and 0.33 kg cm⁻², were not significantly different. But, clay and silty clay soils with resistance to penetration of 0.25 and 0.14 kg cm⁻² were significantly different (P < 0.05). Resistance to penetration of the penetrometer was not affected significantly (P < 0.05) by direction of measuring this parameter in the field. The conclusion is that if measured soil physical properties in a paddy field are going to be representative of the whole field, they should be measured at different locations, especially near the bunds. Another strategy for obtaining a representative infiltration rate or compactness for a paddy field is uniform puddling of the field.     

Performance of Dimethomorph + Mancozeb Applied to Seed Potatoes in Early Management of Late Blight (<Emphasis Type="Italic">Phytophthora infestans</Emphasis>)

Treating seed potatoes with contact fungicides prevents infection of Phytophthora infestans from tuber to tuber during handling but does not prevent field infections in the young plant. Dimethomorph (DMM) 9% + mancozeb 60% (Acrobat MZ, BASF) can cover both aspects due to the contact and systemic action of mancozeb and DMM, respectively. Experiments were performed under greenhouse and field conditions (three seasons and two locations) with cvs Kennebec, Shepody, Spunta, Russet Burbank, and Ranger Russet. Immediately after cutting, seed pieces were treated with Acrobat MZ at doses equivalent to 2, 3, and 4 kg ha⁻¹. At any dose, Acrobat MZ protected healthy seed tubers against P. infestans infections. Acrobat MZ (4 kg ha⁻¹) also protected the foliage of all cultivars against artificial inoculation of P. infestans, assessed by the detached-leaf method. These effects were observed up to 30 days after emergence in greenhouse experiments and up to 28 days after crop emergence under field conditions in two growing seasons. In cv Spunta, significant foliage protection was observed up to 35 days after field emergence whereas in seed tubers of cv Kennebec planted in sandy soils, significant foliage protection persisted longer. Additional evidence for acropetal translocation of Acrobat MZ in field crops was also found. With this strategy, there is no need to apply contact or systemic fungicides early in the season, and spraying costs and environmental risks are also reduced.     

土壤质地对铬胁迫下小麦灌浆期形态与旗叶光合特性的影响

为了探讨铬(Cr)胁迫条件下土壤质地对小麦植株形态及旗叶光合特性的影响,采用盆栽试验方法,研究了3种土壤质地(壤土、粘土、砂土)下灌浆期小麦的根长、分生根数、干物质量等形态指标及旗叶的净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)、蒸腾速率(Tr)、水分利用率(WUE)、叶绿素相对含量等光合特性指标的差异。结果表明,随着Cr胁迫浓度的升高,小麦根长在粘土中呈逐渐变短的趋势,在壤土和砂土上则呈先升高后降低趋势,且根长达到最大值的Cr浓度为100 mg·kg-1;小麦分生根数在3种质地土壤上均呈逐渐减少趋势;Cr胁迫使不同器官的干物质量及干物质总重都有不同程度下降;旗叶的Pn在壤土上也随Cr浓度的升高逐渐降低,在粘土和砂土上则先升高后降低,且当Cr浓度分别为100和200 mg·kg-1时达到最大值;小麦旗叶Gs、Ci、Tr和叶绿素相对含量均呈先升高后降低趋势,且在壤土和粘土上达到最大值的Cr浓度均为100 mg·kg-1,在砂土上为200 mg·kg-1;旗叶WUE在粘土上呈先升高后降低趋势,砂土上则呈现升高趋势,壤土上波动不大。整体来说,Cr胁迫对小麦灌浆期各项光合指标起到了低促高抑或抑制作用,尤其当Cr浓度≥200 mg·kg-1时,Cr对小麦表现出明显的胁迫效应,导致根长降低,分生根数减少,旗叶Gs、Ci、Tr和叶绿素相对含量降低,各器官干物质量减少。此外,在3种质地土壤上,小麦灌浆期旗叶光合指标在Cr胁迫下不同程度下降,砂土的下降趋势比壤土和粘土明显。     

The influence of tuber position on periderm calcium content and its relationship to soft rot susceptibility

Summary Calcium levels in the periderm of tubers (cv. Sebago) growing in irrigated sands were influenced by the stem position at which the tuber grew, but the effect was not consistent over two seasons. Calcium levels were increased at all tuber positions by addition of calcium to soil; combined treatments of gypsum (1400 kg Ca²⁺/ha) pre-plant and calcium nitrate (37 kg Ca²⁺/ha) side dressings gave the greatest response. Percentage incidence of soft rot lesions caused byErwinia chrysanthemi pv.zeae was not influenced by periderm calcium content. The severity of infection (weight of tissue macerated within 48 h at 30°C) was significantly reduced only by the pre-plant gypsum treatment, but there was no correlation with calcium content of the periderm. Calcium levels in periderm tissue (60–208 mg Ca²⁺/100g) are within the range of published data for other cultivars and results support previous reports that the correlation between tuber susceptibility toErwinia spp. and periderm calcium content is inconsistent.     

Yield and Quality Response of Two Potato Cultivars to Nitrogen Fertilization

Potatoes require high nitrogen (N) fertilizer rates because of their poor N efficiency. Better understanding of N dynamic in potato crops could improve N efficiency and thus enhance crop profitability and reduce N losses. A similar field experiment was conducted in Switzerland in 3 years, from 2009 to 2011, to investigate the yield and quality response to N fertilization of two commercial potato cultivars with different tuber qualities, Bintje and Laura. Five doses of ammonium nitrate were tested: 0, 80, 120, 160 and 200 kg N ha^?1. Aboveground and belowground biomass evolution, total yield, starch concentration and tuber sizes were measured annually. In 2011, the total N uptake and the soil mineral N content were also measured during the growing season and at harvest.The study showed that N fertilization had a positive effect on yield and the percentage of large tubers (>?70 mm) and a negative effect on starch concentration. Both cultivars presented the same potential yield, although cv. Laura’s yield was more affected by N fertilization deficiency and more responsive to the late N fertilizer application. At harvest, both cultivars had a similar N uptake efficiency and N utilization efficiency. However, they differed with respect to N uptake dynamics. Nitrogen uptake was slower for cv. Laura than for cv. Bintje due to a longer period required for the development of the belowground biomass. The results provide useful recommendations for improvement of N fertilization practices (e.g. rate and time of application) of these two cultivars in Swiss conditions.     

Effect of soil salinity on the wheat and bean root respiration rate at low matric suctions

Water logging and salinity often occur together because rising water table brings salt to the surface. We studied the effects of a range of low soil matric suctions (or nearly paddy condition) (2–33 kPa) and salinity (EC = 0.7–8 dS m^?1 for bean and 2–20 dS m^?1 for wheat) on the root respiration (Rr) in two sandy loam and clay loam soils at greenhouse condition. Results showed that the aeration porosity mainly controls Rr especially at 2 kPa matric suction. As matric suction increases, soil aeration rises and consequently the Rr reaches maximum values (7.9 μmol m^?3 s^?1 for bean and wheat) at 6 and 10 kPa suctions in clay loam and sandy loam soils, respectively. Using a mechanistic soil respiration model reveals that these matric suctions, h, are corresponded to the aeration porosities of 0.18 m³ m^?3 in sandy loam and 0.16 m³ m^?3 in clay loam soils. Bean and wheat Rr remains nearly constant at higher suctions (h > 10 kPa) in sandy loam and decreases slightly in clay loam soil. Gas diffusivity and the root surface area may explain the variation of the Rr between the sandy loam and the clay loam soils. Results showed that the salinity (EC = 6–8 dS m^?1 for bean and EC = 16–20 dS m^?1 for wheat) amplifies the effect of aeration stress at 2 kPa matric suction in both soils. We also observed a strong correlation between root surface area, Rs, and the Rr for all experiments. We concluded that the aeration deficit is not only major factor determining differential plant respiration under adverse stress conditions, and the salinity has a pronounced impact on differences in crop physiological responses.     

Grain cadmium and zinc concentrations in wheat as affected by genotypic variation and potassium chloride fertilization

Thirteen bread wheat (Triticum aestivum L.) and two durum wheat (Triticum turgidum L. var. durum) cultivars were grown over six site-years to identify differences in grain Cd and Zn concentrations, as affected by genotypic variation and soil application of potassium chloride (KCl) fertilizer. Application of KCl fertilizer did not consistently affect grain Cd concentration of wheat cultivars, but increased average grain yield and decreased average grain Zn in 4 of 6 site-years. However, soil type and year had significant effects on grain Cd and Zn, indicating a strong environmental effect on grain quality. Grain concentrations of Cd and Zn were generally lower for the clay loam (CL) than the fine sandy loam (FSL) soils. The wheat cultivars showed significant genotypic differences in grain concentrations of Cd and Zn, suggesting the potential of breeding to reduce Cd and increase Zn concentrations in grain. The two durum cultivars contained high concentrations of Cd but not Zn compared to the bread wheat. The interaction between cultivars and site-years was significant for grain Zn, but not for grain Cd, suggesting that grain Cd is a more stable trait than grain Zn across environments. Grain Zn and Cd were not related to each other but they both correlated negatively with grain yield. The lack of relationship between Zn and Cd suggests that breeding for enhanced Zn concentration can be attained without necessarily affecting grain Cd concentration. The negative relationship between Cd and Zn concentration and dry matter yield was likely the result of biological dilution, suggesting that genetic improvement leading to increased yield may concurrently decrease mineral concentration. Results of this study are useful to improve the mineral composition of wheat used for human consumption through the development of cultivars and use of agronomic management practices that increase Zn and/or reduce Cd concentrations in wheat grain.     

The effect of potato seed tuber age and soil temperature on the phenomenon of non-emergence

Summary In three experiments seed tubers of cvs Jaerla, Bintje and Alpha, stored at 12 °C in the dark, were planted in glasshouses on various dates at soil temperatures varying from 8 °C to 28 °C to study the phenomenon of ‘non-emergence’ with ageing seed tubers. In general the tubers were desprouted before planting. At all plantings cv. Alpha produced normal plants. The cvs Jaerla and Bintje, however, showed high proportions of the ‘little potato’ phenomenon when planted in cold soil, and high proportions of decayed tubers more frequently in warm soil. When using physiologically older seed at later planting dates, both the range of soil temperatures became wider and the proportions of seed tubers experiencing both ‘little potato’ and decay increased.     

滴灌条件下不同土壤质地对水稻苗期根系生长和分布的影响

【目的】研究滴灌条件下不同土壤质地对水稻苗期根系生长和分布的影响,揭示土壤质地对滴灌水稻苗期生长的重要作用,阐明滴灌水稻苗期生长发育机理。【方法】在石河子大学试验场采用盆栽土柱试验,设置重壤土、轻壤土、砂土共3个处理,每个处理重复3次,在播后10、20、30、40 d取样,对比不同处理出苗率、根系形态、生物量、根系活力、根系分布等指标,分析不同土壤条件对滴灌水稻苗期根系生长及分布的影响。【结果】砂土平均出苗率比重壤土、轻壤土分别高15.21和4.6个百分点;计算各项指标40 d平均值可知,重壤土处理根数比轻壤土、砂土处理分别高26.73%和15.67%;重壤土处理平均根长比轻壤土、砂土处理分别高4.52%和13.92%;重壤土处理根系体积比轻壤土、砂土处理分别高18.53%和43.15%;砂土处理最长根长比重壤土、轻壤土处理分别高38.44%和12.69%;重壤土处理总生物量比轻壤土、砂土处理分别高19.76%和41.48%。重壤土处理根系生物量比轻壤土、砂土处理分别高14.98%和35.83%。苗期根系活力表现为重壤土>轻壤土>砂土,重壤土处理40 d内平均根系活力比轻壤土、砂土处理分别高3.54%和13.91%;滴灌水稻苗期根系分布情况表现为前期水稻根系集中在0-5 cm土层中,后期根系开始逐渐分布于0-20 cm土层。【结论】不同的土壤质地对滴灌水稻出苗率、根系形态、生物量、根系活力和根系分布影响显著。因此,滴灌水稻的种植推广过程中,不同土壤质地应采取不同的播种量和相应的栽培措施,才能达到滴灌水稻的优质、高产和高效的目标。     

Successive annual applications of organic manures for cut grass: short-term observations on utilization of manure nitrogen

Abstract The recovery of nitrogen (N) from, and the fertilizer‐N value of, low dry‐matter (DM) cattle slurry and farm yard manure (FYM), applied annually to perennial ryegrass swards grown at two sites, on sandy loam and shallow calcareous silty clay loam soils, were studied over a 4‐year period. Slurry or FYM, applied at target rates of either 150 kg N ha^?1 or 300 kg N ha^?1 in either October, February or May/June, in combination with 150 kg N ha^?1 inorganic fertilizer‐N (applied as split dressings before the first and second grass cut), were compared with a set of inorganic fertilizer‐N response treatments. DM yield, N offtake, apparent manure‐N recovery (in herbage) and manure‐N efficiency (compared with inorganic fertilizer‐N) were determined at two silage cuts each summer. Soil mineral nitrogen (SMN) measurements in autumn and spring were used to assess potential N leaching loss over winter and to quantify available N residues in the soil in spring. Apparent manure‐N recovery and manure‐N efficiency were usually greater from slurry applications in February than from those in October, but the timing of the application of FYM had a much smaller effect, compared with the timings of the application of slurry, on the utilization of N from manure by grass. Spring assessment of SMN was useful in quantifying available N residues from October slurry applications. Manure‐N recovery for all application timings was, on average, higher from the sandy loam than the shallow calcareous clay loam. The application of slurry to grass in early spring, at a rate of 150 kg total N ha^?1, with the addition of a supplementary 50 kg inorganic fertilizer‐N ha^?1, was the most suitable strategy for utilizing slurry‐N effectively and for supplying the N requirement for first‐cut silage.     

The effect of netted scab (Streptomyces spp.) andVerticillium dahliae on growth and yield of potato

Summary The effect ofStreptomyces spp. (netted scab) on the growth of potato was investigated in three pot experiments, in two of which the effect ofVerticillium dahliae was also assessed. The netted scab organisms attacked all underground plant parts of susceptible potato cultivars early in the growing season; the roots were especially seriously attacked, markedly reducing tuber yield and number but prolonging the duration of the growing season. The nematicide oxamyl had little effect on the incidence of netted scab. Repeated growing of the susceptible cv. Bintje greatly increased soil contamination with the netted scab pathogens. V. dahliae reduced haulm growth before wilt symptoms were evident and it reduced tuber yield but not number. Oxamyl delayed infection byV. dahliae by controlling parasiticPratylenchus nematodes (mainlyP. thornei).     

不同质地土壤对高油玉米产量和品质的影响

采用池栽的方式研究了粘土、壤土、沙土3种质地土壤对高油玉米产量和品质的影响。结果表明:3种质地土壤高油玉米子粒干物质积累动态在灌浆过程中基本相似,而在吐丝35d后差异明显,壤土质地的玉米子粒油分和蛋白质含量较粘土和沙土分别提高8.92%和10.23%,而粘土上玉米子粒产量最高,达176.5g/穗,较壤土和沙土分别提高16.77%和52.63%;油分、蛋白质、淀粉与子粒产量表现趋势相同,表现为粘土>壤土>沙土。高油玉米适宜在粘土上种植。     

Influence of storage temperature on rate of potato tuber tissue infection caused byPhytophthora infestans (mont.) de bary estimated by digital image analysis

Summary Potato tubers were inoculated with two biotypes ofPhytophthora infestans then stored at 3,7, 10 and 15°C. Image analysis quantified average reflective intensity (ARI) of diseased tissue from cut surfaces of sample tubers. Tuber tissue infection and infection rate were measured by calculating Mean ARI of samples. Average tuber tissue infection and infection rate was minimal at 3°C (P.i.-US8 orP.i.-US1). Tuber tissue infection increased at temperatures >3°C, from 220 Mean ARI seven days after inoculation (dai) to 190–150 Mean ARI 50 dai (depending on cultivar and biotype ofP. infestans). Rate of tuber tissue infection caused byP.i.-US1 at 7°C was about zero in cv. Snowden but greater than −0.2 ARI day⁻¹ (cvs Russet Burbank and Superior). Rate of late blight infection in tuber tissue generally increased with temperature from −0.2 ARI day⁻¹ (at 7°C) in all cultivars to a maximum of −0.8 ARI day⁻¹ (10°C).