Cm In November Research Articles

Soil organic carbon accumulation and carbon dioxide emissions during a 6-year study in irrigated continuous maize under two tillage systems in semiarid Mediterranean conditions

Aim of study: To evaluate the effects of conventional tillage (CT) and no tillage (NT) systems on the soil organic carbon (SOC) changes, CO2 emissions and their relation with soil temperature and grain yield in a monoculture of irrigated maize during six years.Area of study: In Zamadueñas experimental field in the Spanish province of Valladolid, from 2011 to 2017.Material and methods: The SOC content was determined by collecting soil samples up to 30 cm in November at two years interval. Short-term CO2 emissions were measured simultaneously with soil temperature using a respiration chamber and a hand-held probe immediately before, after every tillage operation and during the maize cycle.Main results: The SOC stock of the top 30 cm soil layers was 13% greater under NT than CT. Short-term CO2 emissions were significantly higher under CT ranging from 0.8 to 3.4 g CO2 m-2 h-1 immediately after tillage while under NT system, soil CO2 fluxes were low and stable during this study period. During the first 48 h following tillage, cumulative CO2 emissions ranged from 0.6 to 2.4 Mg CO2 ha-1 and from 0.2 to 0.3 Mg CO2 ha-1 under CT and NT systems, respectively. Soil temperature did not show significant correlation with CO2 emissions; however, it depended mostly on the time of measurement.Research highlights: No tillage increased the SOC accumulation in the topsoil layer, reduced CO2 emissions without decreasing maize grain yield and minimized the impact on climate change compared to CT system.

The effect of some environmental variables on the abundance and distribution of aquatic macrophytes in Al-Hawizeh marsh, Iraq

Aquatic macrophyte communities and environmental factors were studied at four Al-Hawizeh marsh sites from December 2017 until November 2018. Quantitative data from thirty species of aquatic plants were collected to investigate density, vegetation cover, biomass and their relationship to the environmental factors. For emerging plants, relative abundance reached the highest values (36%) than submerged and wet species, while free-floating plants produced the lowest value (17%).Physical and chemical properties have been studied including water temperature ranging from 11.3 ° C in January to 31.4 ° C in August, dissolved oxygen (DO)ranging from 1.88 mg/L in September to 10.5 mg / L in April, pH varied from 7.2 in June to 8.4 in December, electrical conductivity (EC μ.S/cm) differs from 2257 μ.S/cm in November to 6859 μ.S/cm in April. The results identified the highest percentages of vegetation cover reported during the summer, the lowest percentages revealed during the winter for all plant groups. The highest annual vegetation cover rates for submergent species achieved 52.54% by C.demersum, for free-floating plants 66.67% of S. polyrrhiza, for emergent plants 85.5% of P. australis, 41.62% of P. paspaloide for wet plants. Total mean biomass of plant groups showed the highest value of 844.02 (gm dry weight/m2) reported by emerging plants, the lowest value of 47.25 (gm dry weight / m2) by the wet plants. Thus, biomass values were correlated with the vegetation cover values for all plants.

Seed longevity and seedling emergence behavior of wild oat (Avena fatua) and sterile oat (Avena sterilis ssp. ludoviciana) in response to burial depth in eastern Australia

AbstractWeed emergence time and the longevity of weed seeds within the soil play an important role in implementing a timely and effective weed control program. In this study, the seed longevity and emergence pattern of wild oat (Avena fatua L.) and sterile oat [Avena sterilis ssp. ludoviciana (Durieu) Gillet & Magne] were monitored in field conditions. Fresh seeds of A. fatua and A. ludoviciana were placed into nylon bags (50 seeds per bag in three replications for three locations in eastern Australia: Gatton, Narrabri, and St George) and buried at depths of 0, 2, and 10 cm in November 2017. Bags were exhumed at 6-mo intervals over 30 mo to evaluate seed germination, viability, and decay components. The seed decay component of A. fatua and A. ludoviciana followed an exponential pattern. On both the surface and at the 10-cm burial depth, 50% of the seeds of A. fatua and A. ludoviciana had decayed by 6 mo. The seeds of A. fatua persisted longer at 2-cm depth than at other depths, particularly at St George, where 90% of the seeds decayed after the 30-mo study. However, at Gatton and Narrabri, 90% of the seeds of A. fatua at this depth had decayed after 18 mo of burial in the soil. In the emergence pattern experiment (2017 to 2019), the emergence of A. fatua and A. ludoviciana from different burial depths was also studied. The emergence of A. fatua and A. ludoviciana was greater from 2-cm (29% to 36%) and 5-cm (18% to 43%) soil depths compared with the surface (5% to 10%) and 10-cm (3-9%) soil depth. Avena ludoviciana emerged earlier (2,253 growing degree days [GDD]; March 14, 2018) than A. fatua (3,364 GDD; May 23, 2018). Both species exhibited high emergence between May to June 2018, and the last cohort of each species was observed in October 2018. The highest seedling emergence occurred at the start of the winter season (May), which emphasizes the need for early PRE weed control such as tillage, herbicide application, and cover crops to ensure crops are planted in a clean seedbed. The continued emergence of these weeds into the spring season (October) emphasizes the need for extended periods of A. fatua and A. ludoviciana management. The results also suggest that management strategies that can control all emerged seedlings over 2 yr and restrict seed rain in the field could lead to complete control of Avena spp. in the field.

68 Effects of Plant Growth-Promoting Rhizobacteria on Fall-Stockpiled Bermudagrass

Abstract Forage production practices have been greatly affected by the increasing cost of N fertilization. Therefore, supplemental and alternative N sources are needed to ensure the economic viability of these systems. A 2-yr, small plot study was designed to evaluate plant growth-promoting rhizobacteria (PGPR) as an alternative form of N fertilizer for fall-stockpiled bermudagrass (Cynodon dactylon). Eighteen 1-m2 ‘Coastal’ bermudagrass plots were treated with a synthetic N fertilizer, DH44 (PGPR strain), DH44+fertilizer, Blend 20 (PGPR blend), Blend 20+fertilizer, and a control, then stockpiled through the fall. Two PGPR applications were applied in late-August and again 30 d later. Fertilizer and PGPR+fertilizer plots received (NH4)2SO4, at a rate of 56 kg N/ha. One-third of each plot was clipped to 2.5 cm in November, December, and January, respectively. Forage DM yield, CP, NDF, ADF, and ADL were determined via wet chemistry at the Auburn University Ruminant Nutrition Laboratory (Auburn, AL). Data were analyzed using PROC MIXED (SAS 9.4, SAS Inst., Cary, NC) as a completely randomized design. Yield was greatest (P ≤ 0.0318) for Blend 20+fertilizer, but it was not different (P = 0.2552) from that of the synthetic fertilizer (1,914 kg ha-1, 1,768 kg ha-1, respectively). Concentration of CP was least (P ≤ 0.0437) for DH44 and Blend 20 treatments (90 g kg-1 and 92 g kg-1, respectively). Concentrations of NDF for the control were different (P ≤ 0.0045) for all treatments except synthetic fertilizer (P = 0.1092). Concentrations of ADF were not different (P ≥ 0.1613) excluding the control (P ≤ 0.0525; 342.8 g kg-1and 358.0 g kg-1, respectively). In vitro true digestibility (IVTD) was not different (P = 0.0947) among all treatments (463.1 g kg-1). All yield and nutritive value parameters were greater (P ≤ 0.0246) in Year 2. These results indicate that PGPR is a viable option for biofertilization of fall-stockpiled bermudagrass; however, further investigation into the effects of PGPR inoculants at a field scale are needed.

Effects of sowing date and depth on Fusarium wilt development in chick pea cultivars

Fusarium wilt is one of the most prevalent diseases which threaten chick pea production worldwide. The impacts of planting date on Fusarium wilt and yield in chick pea sown at different depths are little understood. Field trials established in Kermanshah province, Iran, during 2009–2011 examined interactions among planting date and depth, and cultivar on Fusarium wilt and chick pea yield. According to Wald test results, disease incidence levels differed among test planting dates and depths, cultivars and years. In 2009–2010, disease levels on November-planted Arman, Hashem and ILC482 for all test depths were often lower than those for the March date. For the 9 cm and 13 cm depths, often greater disease levels were observed in cvs Arman and ILC482 than in cv. Hashem. In 2010–2011, disease levels on 5-cm-March-planted Arman and Hashem were greater than those planted at the depth of 5 cm in November and December. Lowest 100-seed weight was found on March-planted Hashem in 2010–2011. Highest yields were observed on November-planted ILC482 in 2010–2011. Lowest yields were detected on March-planted Hashem in both years. From principal component analysis, three factors accounting for 69.4% of the total variance demonstrated that the development of Fusarium wilt epidemics corresponded mainly to planting date and yield (factor 1), cultivar (factor 2), and planting depth (factor 3).

An Update on the Invasion of Weakfish Cynoscion regalis (Bloch & Schneider, 1801) (Actinopterygii: Sciaenidae) into Europe

New information on weakfish introduction vectors, its invasive status, distribution, and use as a fishing resource arose after the publication of “The transatlantic introduction of weakfish Cynoscion regalis (Bloch & Schneider, 1801) (Sciaenidae, Pisces) into Europe” by Morais and Teodósio (2016). Currently, the first known report of weakfish in Europe dates back to September 2009, with a specimen captured in the Schelde estuary (Belgium/The Netherlands). This fact suggests that weakfish could have been introduced into Europe via multiple and independent ballast water introduction events, and not through a point-source introduction event with subsequent dispersion as previously hypothesized. It is also unlikely that Schelde weakfish migrated southwards to colonize Iberian aquatic ecosystems. Weakfish have established a population in the Gulf of Cádiz region and have already reached an invasive status in the Sado estuary (Portugal). Weakfish were also captured in several other locations along the Portuguese coast, including the Tagus and Mira estuaries at least since 2013 or 2014, and the Ria Formosa lagoon in 2017. Tagus anglers caught weakfish specimens of ~1 kg and ~40 cm in November 2016, which corresponds to fish of 3+ years of age in the native range. The presence of weakfish in the Tagus estuary is still fairly unknown to local anglers. Sado weakfish has already been sold in local fish markets in southern Portugal for 3 to 10 € kg−1. However, we consider that the weakfish sale price is underrated in comparison with other wild species (e.g., meagre, seabass, gilthead seabream). Increasing sale price will convince fishers to use weakfish as a new fishing resource; however, it is necessary to promote the species among consumers and evaluate consumers’ preference in respect to other species. A putative biological threat might turn into a new valuable fishing resource by implementing adequate management solutions.

Residual soil nitrate content and profitability of five cropping systems in northwest Iowa.

Many communities in the Midwestern United States obtain their drinking water from shallow alluvial wells that are vulnerable to contamination by NO3-N from the surrounding agricultural landscape. The objective of this research was to assess cropping systems with the potential to produce a reasonable return for farmers while simultaneously reducing the risk of NO3-N movement into these shallow aquifers. From 2009 to 2013 we conducted a field experiment in northwest Iowa in which we evaluated five cropping systems for residual (late fall) soil NO3-N content and profitability. Soil samples were taken annually from the top 30 cm of the soil profile in June and August, and from the top 180 cm in November (late fall). The November samples were divided into 30 cm increments for analysis. Average residual NO3-N content in the top 180 cm of the soil profile following the 2010 to 2013 cropping years was 134 kg ha-1 for continuous maize (Zea mays L.) with a cereal rye (Secale cereale L.) cover crop, 18 kg ha-1 for perennial grass, 60 kg ha-1 for a three year oat (Avena sativa L.)-alfalfa (Medicago sativa L.)-maize rotation, 85 kg ha-1 for a two year oat/red clover (Trifolium pratense L.)-maize rotation, and 90 kg ha-1 for a three year soybean (Glycine max (L.) Merr.)-winter wheat (Triticum aestivum L.)-maize rotation. However, residual NO3-N in the 90 to 180 cm increment of the soil profile was not significantly higher in the oat-alfalfa-maize cropping system than the perennial grass system. For 2010 to 2013, average profit ($ ha-1 yr-1) was 531 for continuous corn, 347 for soybean-winter wheat-maize, 264 for oat-alfalfa-maize, 140 for oat/red clover-maize, and -384 (loss) for perennial grass. Considering both residual soil NO3-N and profitability data, the oat-alfalfa-maize rotation performed the best in this setting. However, given current economic pressures widespread adoption is likely to require changes in public policy.

FARMER’S PARTICIPTION ON APPLICATION OF LAND REHABILITATION AND SOIL CONSERVATION ENGINEERING ON MICRO WATERSHED

This study aims to determine the level of farmers participation in the implementation of land rehabilitation and soil conservation (LRSC) techniques where appropriate to the micro watershed through PRA and PAR approaches. The techniques of LRSC both mechanical and vegetative methods have been built in a participatory manner in the demonstration plots of 2 ha in Datara micro watershed and of 2.5 ha in Mararin also micro watershed, South Sulawesi. Gully plug equipped with stick-scale and V-notch weir were constructed in Datara micro watershed and concrete tank of mud and runoff was built in Mararin micro watershed to monitor the impact of LRSC actvities to sedimentation and runoff level. The results showed the level of farmers participation at both locations fluctuated in the category of low ( 80%) against targets LRSC activities that have been agreed at a meeting of the group. The level of participation is determined from the condition of the microhydro electric power who have built together. Participation of farmers on the application of LRSC on both plots are: willing to lend of their land for the location of demonstration plots, planting and maintaining trees for timber production, building and maintaining contour terraces and channel of water drainages, maintaining grass and gliricidia as reinforcement terraces for soil conservation techniques. Activities of LRSC impact plots show that layers of sedimentation and runoff volume decreased in the research sites. Demonstration plots in Datara, high sedimentation layer in the second year (2011) in gully plug average of 32.72 cm decline to 7.14 cm in the fourth year (2013), as well as runoff discharge 44.47 liter/sec in 2010 down to 22.8 liter/sec in November 2013. in Mararin plots the average height of a layer of mud in the tank in 2011 from 4.89 cm decline to 1.99 cm in November 2013 and the runoff volume 8.5 liter/sec down to 5.6 liter/sec at the same time.

Seasonal changes in properties of abandoned terraced paddy field soil incubated under different water content conditions

The chemical properties of soil samples collected in August and November from an abandoned terraced paddy field dominated by reeds were examined by in vitro incubation under normal moisture and flooded conditions. Soil pH extracted with water [pH(H2O)] was higher in soil samples collected from a depth of 0–10 cm in November than in samples collected in August; a high pH(H2O) was maintained even during nitrification under normal moisture conditions. When soil samples collected in August from a depth of 0–10 cm were incubated under flooded conditions, a significant decrease in reduction potentials (Eh) and an increase in total Fe2+ concentrations were observed. Reductive conditions during sampling were strong in soil samples collected in August from a depth of 40–50 cm. Moreover, under normal moisture conditions, soil samples collected in August showed significant decreases in pH(H2O) and significant production of water-soluble SO42− than those collected in November. Glucose addition to soil samples collected from a depth of 0–10 cm caused nitrogen immobilization under normal moisture conditions, increases in exchangeable Fe2+ and Mn2+, and decreases in exchangeable bases (Ca2+, Mg2+, K+, and Na+) under flooded conditions. Seasonal changes in soil properties were probably due to microbial activity and vegetation phenology; thus, the timing of soil sampling influenced incubation experiment results. When abandoned terraced paddy fields are created as biotopes, seasonal changes in reductive soil conditions and slope position must be considered to prevent soil acidification and base cation elution.

Variations of Fatty Acids During the Sulphidization Process in the Authie Bay Sediments (8 pp)

Background, Aim and Scope The sulphidization process in relatively clean sediments sampled in a mudflat of the Authie estuary (located in Northern France) has been studied by coupling geochemical expertise and the use of fatty acids (FAs) as biochemical markers. Materials and Methods: Three sediment cores have been sampled in September 2003, November 2003 and May 2004, and cut every 2 cm in the field under nitrogen atmosphere so as to prevent any oxidation of reduced species. In the solid phase, reduced sulphur compounds, e.g. AVS (Acid Volatile Sulphides) and CRS (Chromium Reducible Sulphur) [including also the calculation of the degree of sulphidization (DOS) and the degree of pyritization (DOP)], and fatty acids have been carried out. Eh, pH, metal species (mostly iron and manganese), dissolved S(-II) and sulphate have also been determined in the porewaters. Results: The sediment cores display a lot of differences due to the high sedimentation rate and the seasonal evolution as well. The presence of Mn2+, Fe2+, S(-II) and the decrease of the redox potential and the concentration of sulphates clearly indicate early diagenetic transformations promoted by the bacterial activity. Acid Volatile Sulphides are produced in the first cm and are stabilized with depth. A rapid decrease of FAs concentrations in September and May has also been pointed out owing to a rapid consumption of the labile organic matter. Several categories of FAs have been separated and most of them belong here to the saturated and monounsaturated groups. In the saturated group, branched chain FAs, iso and anteiso C15:0 are predominant and represent the bacterial imprint in the sediments. Maximum proportions are observed between 5 and 10 cm in September, and between 13 and 17 cm in November and May. Discussion: As sulphate concentrations remain high in the porewater, the limitation of the sulphidization process in our sediments must be due to a lack of labile organic matter input. The presence of pyrite in our sediment is bound to its formation at the water-sediment interface, where partial reoxidation may take place. However, at deeper depths, pyritization processes does not continue any more. Presence of maximum, dissolved S(-II) concentrations have been observed, simultaneously with maximum proportion relative to total FAs of iso and anteiso C15:0, and, in September, with an increase in proportions of C18:1ω7. This indicates the presence of sulphate-reducing bacterial activity at the time when the sediments were sampled. However, no close correspondence between bacterial FAs concentrations and S(-II) concentrations has been found. Conclusions: In each core, the sulphidization process is not complete, and this is probably due to the lack of biodegradable organic matter, which appears as the limiting factor from a qualitative point of view. S(-II) production in porewaters is linked with the activity of sulphate-reducing bacteria. Seasonal effects have also been pointed out and, especially, a more important input of diatom organic matter in May when compared to September and November. Recommendations and Perspectives: Fatty acid analyses represent an original and a useful tool for a better understanding of an early diagenetic process in the first cm of the sediments. More studies should be carried out associating inorganic chemical parameters and chemical biomarkers for pointing out stronger and more reproducible relations. Moreover, the use of microcosms in our group is on the way to take into account the kinetics of the organic matter degradation during the early diagenesis.

The early vascular ageing of long-term RRT patients: endoprosthetic repair of an aortic aneurysm in a young patient on RRT for over 20 years

Keywords: aortic aneurism; atherosclerosis; endo-prothesis; daily haemodialysis; long-term RRTThe impressive calcifications seen in the computedtomography (CT) reconstruction of an aortic aneur-ysm of the abdominal aorta in Figure 1 belong to a 48-year-old male, on renal replacement therapy (RRT)from the age of 22. His end-stage renal diseasewas membrano-proliferative glomerulonephritis withsevere and prolonged nephrotic syndrome. In 1981,3 years after diagnosis, he started RRT on peritonealdialysis; he was switched to haemodialysis in 1985 dueto functional exhaustion of the peritoneum, and acadaveric graft was performed in 1993. Haemodialysiswas resumed in 1996 after graft failure due to recurrentmembranous and proliferative glomerulonephritis,again with severe nephrotic syndrome. He hadhypertension, usually well controlled by multipledrug therapy, parathyroidectomy because of severehyperparathyroidism unresponsive to conservativetreatment (1993) and a coronary by-pass (1997). Theaortic aneurysm shown in Figure 1 was first diagnosedin 1991: at that time, the maximum diameter was4.2cm. The diameter was stable until March 2000,when it increased to 4.6cm and further to 4.8cmin November 2000, despite a daily haemodialysisschedule (started in 1999), minimizing weight lossper dialysis and with a good blood pressure controlwithout need for drug therapy.Balancing the young age of the patient and thesurgical risks due to the diffuse arterial calcificationstypical of uraemic patients (Figure 2), a percutaneousendoluminal approach was chosen and successfullyperformed in January 2001, employing a modular

Cultivar Influences Cranberry Response to Surface Sanding

Surface sand application to cranberry (Vaccinium macrocarpon Ait.) is commonly practiced for a combination of vine and insect management. However, the efficacy of sanding on crop production has been poorly documented. This study determined the effect of three rates of sand application using a barge sanding technique on two different cultivars—`Early Black' and `Stevens'. Beds were sanded to a depth of 0, 1.3, or 2.5 cm in November and monitored at the end of the following three growing seasons for yield, berry weight, and upright distribution. The 2.5-cm sanding rate adversely affected yield in `Early Black' during the first two growing seasons. In `Stevens' yields were not reduced until the third season and then only by the 2.5-cm rate. Although the 2.5-cm sanding rate increased vegetative upright density in both cultivars in the first growing season, yield and number of fruiting uprights were not significantly influenced the next year. Application of 1.3 cm of sand could improve insect pest management without negatively impacting yields of `Early Black' and `Stevens'.

頬部に発生した隆起性皮膚線維肉腫

Dermatofibrosarcoma protuberance (DFSP) is a fibrohistiocytic tumor which frequently tends to relapse locally, but it has been rarely reported on the face. We reported a case of DFSP on right cheek.A 30-year-old man noticed a tumor on his right cheek 2 years ago. The tumor grew gradually. He visited to our clinic with a subcutaneous tumor measuring 5×4.5cm in November, 1992. Histologically, the tumor was composed of spindle-shape cells which formed a storiform pattern around vessels, and showed positive staining with anti CD34. Wide excision of the lesion and skin grafting were performed in January, 1993, and the lesion was reconstracted using free vasculized Rectus abdominal MC flap.

Synthesis mapping of a solar type I storm simultaneously at 90 and 20 centimeters with the VLA

A type I radio storm was observed simultaneously at 20 and 90 cm in November 1986. The characteristic signatures of the storm are detected at 90 cm only. The results indicate that the noise storm is unambiguously associated with an active region at the sun center, and that the distribution of energetic electrons responsible for the storm emission reaches low coronal heights. Polarization measurements and storm source location results suggest that the 90-cm emission is fundamental plasma radiation and that the 20-cm measurements are characteristic of free-free emission.

Occurrence of Trichoderma in a Douglas-fir Soil

Trichoderma species were isolated to a depth of 100 cm in soil supporting a Douglas-fir stand in western Oregon. Isolation from Mueller-Durrell (M-D) tubes was rare below 33 cm in May and August and did not occur below 53 cm in November. Most common species were T. viride, T. hamatum, and T. polysporum. Trichoderma viride accounted for 72% of November isolates while T. hamatum dominated May (54%) and August (34%) isolates. Soil dilution plates from 25–30-cm depth produced only one colony of Trichoderma in nearly 2000 observations whereas it was isolated at a frequency of 10% from M-D tubes at that depth.

Occurrence ofTrichodermain a Douglas-Fir Soil

Trichoderma species were isolated to a depth of 100 cm in soil supporting a Douglas-fir stand in western Oregon. Isolation from Mueller-Durrell (M-D) tubes was rare below 33 cm in May and August and did not occur below 53 cm in November. Most common species were T. viride, T. hamatum, and T. polysporum. Trichoderma viride accounted for 72% of November isolates while T. hamatum dominated May (54%) and August (34%) isolates. Soil dilution plates from 25-30-cm depth produced only one colony of Trichoderma in nearly 2000 observations whereas it was isolated at a frequency of 10% from M-D tubes at that depth. Antagonism by species of Trichoderma toward other fungi in soil and in wood has been reported by numerous investigators since 1931 (Garrett, 1956). Species of Trichoderma were found to be the principal invaders of wood colonized by Phellinus weirii (Murr.) Gilbertson when buried in forest soil (Nelson, 1964), but soil dilution plates from the same forest site showed that Trichoderma spp. occurred infrequently over the 2-yr sampling period (Nelson, 1969). In 1972, in conjunction with the International Biological Program, Coniferous Forest Biome, the opportunity to answer the following questions arose: Is Trichoderma uncommon in western Oregon Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] soils, or do the limitations of the dilution plate technique only make it appear so? What is the distribution of Trichoderma in the upper meter of soil? What species of Trichoderma are most common? MATERIALS AND METHODS

Dormancy Changes and Fate of Some Annual Weed Seeds in the Soil

Seeds of common cocklebur (Xanthium pensylvanicumWallr.), jimsonweed (Datura stramoniumL.), ivyleaf morningglory [Ipomoea hederacea(L.) Jacq.], giant ragweed (Ambrosia trifidaL.), yellow foxtail[Setaria lutescens(Weigel) Hubb.], and velvetleaf (Abutilon theophrastiMedic.) were buried in the soil at depths down to 15.2 cm in November 1966. Seeds of jimsonweed, ivyleaf morningglory, giant ragweed, yellow foxtail, velvetleaf, common ragweed (Ambrosia artemisiifoliaL.), and Pennsylvania smartweed (Polygonum pensylvanicumL.) were buried 2.5 and 10.2 cm below the surface in October 1968. Seeds were exhumed for periodic laboratory analyses of dormancy changes. All species except ivyleaf morningglory and common cocklebur germinated better in light than in darkness after at least one winter of burial in the soil. Seeds decayed faster at 2.5 cm below the soil surface than at 10.2 cm, but some viable seeds of all species were recovered from both depths after 3 years. The development or maintenance of hard seeds was considered the principle mechanism for seed survival for 3 years in these species.

Distribution and Activity of the Desert Cockroach Arenivaga Investigata (Polyphagidae) in Relation to Microclimate

Arenivaga investigata is abundant in sand dunes of the Colorado desert at the foot of Mount San Jacinto, California. Measurements of temperature and humidity were made in its habitat at various depths in the sand over 24—h periods at least once each month from July 1967 to July 1968. At the driest and hottest times of the year (surface temperature 72°C, RH < 10%), relative humidities of 82% and above were available only 45 cm below the surface, and temperatures below 40°C occurred at —7.5 cm or lower. Since the insects can absorb water vapor from 82% RH or above, their source of water is assured. Onset of subsurface activity towards nightfall may be correlated with the movement downward of the temperature inversion, but this is not proved. The insects are found much more commonly in the sand near or under shrubs than in open sand. Their vertical distribution shows a maximum at —12.5 cm in July, and at —5 cm in November. In July most insects were found at temperatures between 30° and 35°C, whereas in November they were most frequent from 22° to 26°C. This seasonal difference in distribution, which could be attributed to acclimation, awaits further analysis.