Effects of waterlogging and drought on winter wheat and winter barley grown on a clay and a sandy loam soil

Summary The effects of winter waterlogging and a subsequent drought on the growth of winter barley and winter wheat have been examined. We used lysimeters containing soil monoliths with facilities to control the water table and a mobile shelter to control rainfall. Winter wheat was grown on a clay and on a sandy loam, but winter barley only on the clay soil. Lysimeters were either freely-drained during the winter or waterlogged with the water table 10 cm below the soil surface from 2 December until 31 March (that could occur by rainfall with a return period of 2 to 3 years). The lysimeters then were either irrigated so that the soil moisture deficit did not exceed 84 mm, or subjected to drought by limiting rainfall (equivalent to a 1 in 10 dry year in the driest area of England) so that the deficits reached maximum values of 150 mm in the clay and 159 mm in the sandy loam by harvest.Winter waterlogging restricted tillering and restricted the number of ears for all crops; grain yield of the winter barley was decreased by 219 g/m² (30%), and that of winter wheat by 170 g/m² (24%) and 153 g/m² (21% on the clay and sandy loam respectively.The drought treatment reduced the straw weight of winter barley by 75 g/m² (12%) but did not significantly depress the grain yield. For winter wheat on the clay, where the soil was freely-drained during the winter, drought depressed total shoot weight by 344 g/m² (17%) and grain weight by 137 g/m² (17%), but after winter waterlogging, drought did not further depress total or grain weight. In contrast, the winter wheat on the sandy loam was not significantly affected by drought.From these results, which are discussed in relation to other experiments in the United Kingdom, it seems that winter waterlogging is likely to cause more variation in the yield of winter barley and winter wheat than drought.     

Weather and landscape influences on pollinator visitation of flowering winter oilseeds (field pennycress and winter camelina)

Flowers of field pennycress (Thlaspi arvsense L.) and winter camelina (Camelina sativa (L.) Crantz.) produce abundant pollen and nectar in early spring and thereby may be valuable for pollinators. Insects observed in field plots of these flowers were classified into seven easily identifiable groups (bumblebee, honeybee, solitary bee, butterfly/moth, beetle, fly and other) and monitored for 2 years at three sites in the Upper Midwest region of the USA. Average seasonal observations across years and sites varied from 1.6 to 5.3 total insects/min for field pennycress and 1.4 to 4.5 insects/min for winter camelina. Lowest visitation rates occurred in central Iowa and highest rates in south-eastern Minnesota for both crops. Multiple regressions showed that visitation rates for specific insect groups were correlated poorly but significantly (p < .10) with select variables. For example, in field pennycress, visitation by combined bumblebees and honeybees (Apidae) increased with greater air temperature at sampling time and annual site precipitation, whereas fly (Diptera) visitation was related to sampling date and flower cover. Similarly, in winter camelina, solitary bees were linked to increasing air temperature at sampling time and annual site precipitation, whereas flies were correlated with wind speed and flower cover at sampling. Field pennycress and winter camelina are reliably attractive to beneficial pollinating insects across a wide geographic region, but visitation rates and proportional representation of various insect groups depended on a range of site and weather characteristics.     

The effects of phenotypic plasticity on photosynthetic performance in winter rye, winter wheat and Brassica napus

The contributions of phenotypic plasticity to photosynthetic performance in winter (cv Musketeer, cv Norstar) and spring (cv SR4A, cv Katepwa) rye (Secale cereale) and wheat (Triticum aestivum) cultivars grown at either 20°C [non‐acclimated (NA)] or 5°C [cold acclimated (CA)] were assessed. The 22–40% increase in light‐saturated rates of CO₂ assimilation in CA vs NA winter cereals were accounted for by phenotypic plasticity as indicated by the dwarf phenotype and increased specific leaf weight. However, phenotypic plasticity could not account for (1) the differential temperature sensitivity of CO₂ assimilation and photosynthetic electron transport, (2) the increased efficiency and light‐saturated rates of photosynthetic electron transport or (3) the decreased light sensitivity of excitation pressure and non‐photochemical quenching between NA and NA winter cultivars. Cold acclimation decreased photosynthetic performance of spring relative to winter cultivars. However, the differences in photosynthetic performances between CA winter and spring cultivars were dependent upon the basis on which photosynthetic performance was expressed. Overexpression of BNCBF17 in Brassica napus generally decreased the low temperature sensitivity (Q₁₀) of CO₂ assimilation and photosynthetic electron transport even though the latter had not been exposed to low temperature. Photosynthetic performance in wild type compared to the BNCBF17‐overexpressing transgenic B. napus indicated that CBFs/DREBs regulate not only freezing tolerance but also govern plant architecture, leaf anatomy and photosynthetic performance. The apparent positive and negative effects of cold acclimation on photosynthetic performance are discussed in terms of the apparent costs and benefits of phenotypic plasticity, winter survival and reproductive fitness.     

Analysis of spatial and yearly variation in winter survival of winter wheat

 Four years of winter survival data for winter wheat (Triticum aestivum L.) were collected on a loam soil located on the Central Experimental Farm at Ottawa, Ontario (45° 23′N, 75° 43′W). The site was low-lying and subject to frequent winter flooding and ice sheet formation. It appeared level although there was microtopographic variation with a range in elevation of approximately 0.15 m. The objective of the study was to gain insight into factors which might affect winter survival. Two varieties, a soft white and a hard red winter wheat, were planted in September. Crop establishment was measured in late fall and the percentage survival was measured in April of the following year. We assumed the large spatial differences in survival were not totally random, but rather were affected by spatial variation in environmental factors such as snow and ice depth, soil moisture and temperature. Hourly measurements of soil temperature at a depth of 0.05 m were recorded throughout the fall, winter and spring. Fall and spring soil moisture at the same depth were measured on the plot, as well as snow and ice depth at selected times throughout the winter. Measurements were taken on a grid covering the plot to help explain spatial variation in survival. In addition, detailed measurements of elevation were taken on a grid. Meteorological data were available from the nearby weather site. While soil temperatures were never low enough to kill plants according to the CERES model, the spatial variation in winter survival was associated with differences in elevation and the resulting surface drainage patterns. Received: 23 March 1998/Accepted: 21 October 1998     

Effect of excess boron on summer and winter squash

The boron tolerance of two summer squash cultivars (Cucurbita pepo L. Aristocrat Zucchini and Peter Pan Scallop) and one winter squash cultivar (Cucurbita moschata Poir. Butter boy) was determined in large, outdoor sand cultures. Boron treatments were imposed by irrigation with culture solutions that contained 1.0, 3.0, 6.0, 9.0, 12.0, or 15.0 mg B L^-1. Relative fruit yields of Zucchini, Scallop, and Butter boy were reduced 5.2%, 9.8%, and 4.3% with each unit (mg L^-1) increase in soil solution B (B_sw)>2.7, 4.9, and 1.0 mg B L^-1, respectively. Reduced yields of all cultivars were attributed to a reduction in fruit number and not fruit size. Boron concentrations in leaves and fruit were directly correlated to B_sw.     

Counting birds on farmland habitats in winter

Capsule Perimeter counts underestimate the number of birds using agricultural fields.

Aims To determine the degree to which farmland birds may be undercounted on field surveys and the factors influencing this.

Methods In a study of 96 fields, birds in the field were counted during a walk of the perimeter. Afterwards transects were walked across the field to determine the number of birds missed. Additionally in a national survey we looked at the birds seen in field transects expressed as a proportion of the total seen in the transect and on perimeter counts.

Results To obtain an accurate count of birds on a field requires the use of the whole-area search methodology especially for species such as Grey Partridge Perdix perdix, Snipe Gallinago gallinago, Skylark Alauda arvensis and Meadow Pipit Anthus pratensis. However, for a large number of species, including thrushes, flocking finches and buntings, over 90% of individuals can be recorded using the much less time-consuming perimeter count method.

Conclusions Perimeter counts are likely to be reliable for most species but special efforts may be required for a few cryptic species.     

基因型与环境对小麦品种粉质参数的影响

用陕西省关中小麦品种区域试验所选用的20个小麦品种(品系)在12个试点1996～1997、1997～1998两年度的数据资料,分析了品种、环境及品种×环境互作(GEI)对粉质参数的影响。结果表明:品种与环境对所有粉质参数指标均有显著影响,但由品种决定的粉质参数的变异程度远大于环境引起的变异。基因型×环境互作效应对形成时间、稳定时间、软化度与评价值影响较大,而对吸水率影响较小。品种稳定性分析的回归系数(b值)表明基因型对不同环境的反应存在着显著差异。对每一粉质参数指标大部分品种都具有平均稳定性,只有1至2个品种稳定性显著较好或较差。     

Effects of bathing and hot footbath on sleep in winter

The effects of daily bathing and hot footbath (immersion of feet in hot water) in winter on the sleep behavior of nine healthy female volunteers were studied. Subjects were assigned to three sleep conditions: sleep after bathing (Condition B), sleep after hot footbath (Condition F), and sleep without either treatment (Control). Polysomnograms (consisting of electroencephalograph, electrooculograph, and electromyograph) were obtained, and body movements during sleep were measured while monitoring both the rectal and skin temperatures of subjects. In addition, subjective sleep sensations were obtained with a questionnaire answered immediately by the subjects on awakening. The rectal temperature increased by approximately 1.0 degree C under Condition B, but this elevation was not observed under Condition F compared with Control. In contrast, the respective increases in the mean skin temperature of participants subjected to bathing and hot footbath were greater than those of Control, although these temperature differences became negligible 2 h after subjects went to bed. The sleep onset latency was shortened under both conditions compared with Control. Body movements during the first 30 min of sleep in Control were greater than under the other conditions. Rapid eye movement (REM) sleep decreased under Condition B compared with Condition F, and stage 3 was greater under the latter condition compared with Control. As such, the subjective sleep sensations were better under the two treatment conditions. These results suggest that both daily bathing and hot footbath before sleeping facilitates earlier sleep onset. A hot footbath is especially recommendable for the handicapped, elderly, and disabled, who are unable to enjoy regular baths easily and safely.     

Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes

This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities. The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus-infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL-507 0.2%, SL-509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings.     

干热风天气对冬小麦生理的影响

通过开展干热风气象条件人工模拟,分别在冬小麦灌浆前期和中期进行重度、轻度及无干热风的平行对比试验。结果表明:干热风对冬小麦生理机能的危害为灌浆中期灌浆前期,重度干热风轻度干热风;灌浆中期重度干热风灾害后第2天,小麦旗叶净光合速率(Pn)降低了19.4%~36.6%,蒸腾速率(Tr)降低44.1%~58.0%,气孔导度(Co)降低24.3%~41.7%;其次为灌浆中期轻度干热风,上述各项指标分别减少9.7%~20.2%、28.2%~34.0%和19.9%~31.8%;小麦叶绿素含量(SPAD)和根系伤流量(Gn)也在灌浆中期重度灾害胁迫下降低程度最大,灌浆前期轻度干热风对小麦的胁迫作用不明显;灌浆前期遇干热风天气小麦净光合速率(Pn)和SPAD可在一定程度内修复,其他大部分时段受损的生理机能不可修复。在气孔导度Co0.1 mmol·m-2·s-1条件下,干热风灾害对Tr的胁迫程度大于Pn。     

甘肃省冬小麦生长发育对暖冬现象的响应

运用甘肃省天水、西峰两地1951-2005年的气温资料及天水、西峰农业气象试验站1981-2003年冬小麦物候观测资料,分析探讨了甘肃冬小麦种植区50多年的冬季气温变暖趋势及冬小麦生长发育过程对气候变暖的响应．结果表明：冬季气温升高对冬小麦生长发育产生了较大影响．在最近20多年,冬小麦越冬死亡率下降到2％以下,越冬天数减少了7～8d,整个生育期缩短8～10d,返青一开花期天数延长7d,这有利于冬小麦生产及气候资源的利用-同时,冬季气温升高及降水减少也使冬小麦产量稳定性变差,麦田病、虫危害发生率增加,给冬小麦的安全生产增加了不确定因素．     

Rattlesnake denning: theoretical considerations on winter temperatures

Aggregations of over-wintering rattlesnakes are considered as a hypothetical metabolic unit. Estimates of fat consumption are utilized to predict heat production during the denning season. Previously determined temperature heat production curves allow prediction of a mean body temperature for the winter season which is around 15°C above the ambient den site temperature. An estimate from the previously derived relationship between heat production per unit surface area and body temperature predicts a reduction in aggregate effective surface area of 40 % of the summed surface areas of the individual animals constituting the hypothetical aggregation.     

Photoperiod and temperature effects on gametogenesis in winter flounder Pseudopleuronectes americanus

The winter flounder is an in‐shore flatfish living in shallow waters on the east coast of North America from Labrador to Georgia. In the St Lawrence estuary, the reproductive season is May and June. Our objective was to test the effects of winter‐spring photoperiod and temperature conditions on the timing of sexual maturation in both males and females. Groups (16 animals each) of winter flounder breeders were maintained from mid‐January to mid‐May under five different experimental conditions: (1) natural photoperiod and temperature conditions; (2) natural photoperiod, 6° C; (3) 15L : 9D, natural temperature conditions; (4) 15L : 9D, 6° C; (5) accelerated photoperiod increase from winter to spring conditions, 6° C. Natural photoperiod and temperature conditions correspond to a gradual increase in light period from 8L : 16D (January) to 15L : 9D (May) and in temperature from −1° C (January to April) to 6° C (May). GSI and condition factor did not differ among the treatments ( P  > 0·05). In males, milt production occurred simultaneously in the different treatments and histological examination did not indicate any significant effect of either photoperiod or temperature on testes development. In females, seven stages of oocyte development were observed. Both the number of oocytes at the cortical alveoli stage and number of atretic oocytes increased at 6° C (warm temperature conditions). Overall, neither photoperiod nor temperature modified the reproductive period. Warm winter‐spring temperature conditions, however, may decrease egg numbers and egg quality.     

Effects of thermal underwear on thermal and subjective responses in winter

This study was conducted to obtain basic data in improving the health of Koreans, saving energy and protecting environments. This study investigated the effects of wearing thermal underwear for keeping warm in the office in winter where temperature is not as low as affecting work efficiency, on thermoregulatory responses and subjective sensations. In order to create an environment where every subject feels the same thermal sensation, two experimental conditions were selected through preliminary experiments: wearing thermal underwear in 18 degrees C air (18-condition) and not wearing thermal underwear in 23 degrees C air (23-condition). Six healthy male students participated in this study as experiment subjects. Measurement items included rectal temperature (T(re)), skin temperature (T(sk)), clothing microclimate temperature (T(cm)), thermal sensation and thermal comfort. The results are as follows: (1) T(re) of all subjects was maintained constant at 37.1 degrees C under both conditions, indicating no significant differences. (2) (T)(sk) under the 18-condition and the 23-condition were 32.9 degrees C and 33.7 degrees C, respectively, indicating a significant level of difference (p<0.05). (3) Among local skin temperature, trunk part (forehead and abdomen) did not show significant differences. After 90-min exposure, the skin temperature of hands and feet under the 18-condition was significantly lower than that under the 23-condition (p<0.001). (4) More than 80% of all the respondents felt comfortable under both conditions. It was found (T)(sk) decreased due to a drop in the skin temperature of hands and feet, and the subjects felt cooler wearing only one layer of normal thermal underwear at 18 degrees C. Yet, the thermal comfort level, T(re) and T(cm) of chest part under the 18-condition were the same as those under the 23-condition. These results show that the same level of comfort, T(re) and T(cm) can be maintained as that of an environment about 5 degrees C higher in the office in winter, by wearing one layer of thermal underwear. In this regard, this study suggests that lowering indoor temperature by wearing thermal underwear in winter can contribute to saving energy and improving health.