End Of Growing Season Research Articles

Influence of Mulch Type and Fertilization System upon the Percentage of Fruits Set and Yield in Strawberry

In recent years, organic strawberry culture is becoming more and more important butknowledge concerning best practice is still contradictory. Behavior of ten strawberry cultivars -‘Alba’, ‘Kimberly’, ‘Korona’, ‘Elliany’, ‘Elsanta’, ‘VimaZanta’, ‘Viktoriana’, ‘Virena’, ‘VimaXima’,‘Premial’ under three different types of mulch (agro-textile, 0,04 mm thick black polyethylene andstraw) and two fertilizer systems (poultry manure and liquid NPK 24:8:16, Mg 2.2%, S 2%, B 0.03%,Fe 0.1%, Mn 0.05% and Zn 0.025%) has been studied in climatic conditions from Cluj-Napoca,Romania in 2012. The control cultivar was ‘Premial’. Observation were made on number of trusses,number of flowers, percent of fruits set, and yield at end of first growing season. There were varietiesscattered compact trusses, with flowers arranged at or above the leaves. In the trusses, each flower issolitary or terminal and opens upward. The flowers are large, medium or small depending on thespecies and their position on the plant. The size of the fruit is related to the rank of the flower fromwhich the fruit developed. The best behavior in the experimental conditions proved ’Viktoriana’ and‘VimaXima’ because of their high productivity. It was noted that organic fertilization has a highinfluence on number of inflorescence ‘VimaXima’ and ‘Virena’ and the percentage of fruits set.

Spatiotemporal variation in alpine grassland phenology in the Qinghai-Tibetan Plateau from 1999 to 2009

Plant phenology is the most salient and sensitive indicator of terrestrial ecosystem response to climate change. Studying its change is significantly important in understanding and predicting impressively changes in terrestrial ecosystem. Based on NDVI from SPOT VGT, this paper analyzed the spatiotemporal changes in alpine grassland phenology in Qinghai-Tibetan Plateau from 1999 to 2009. The results are enumerated as follows: (1) The spatial distribution of the average alpine grassland phenology from 1999 to 2009 is closely related to water and heat conditions. Accompanying the deterioration in heat and water conditions from southeast to northwest, the start of growth season (SOG) was delayed gradually, the end of growth season (EOG) advanced slowly, and the length of growth season (LOG) shortened gradually. Elevation played an important role in the regional differentiation of phenology, but a dividing line of approximately 3500 m existed. Below this line, the phenology fluctuated irregularly with altitude change, whereas above the line, the phenology is closely related to altitude change. (2) From 1999 to 2009, SOG of the alpine grassland came earlier by six days per decade (R 2 =0.281, P=0.093), EOG was late by two days per decade (R 2 =0.031, P=0.605), and LOG lengthened by eight days per decade (R 2 =0.479, P=0.018). The early SOG, the late EOG, and the extended LOG mainly occurred at the center and east of the Plateau. SOG in most of the Plateau advanced significantly, especially in the eastern Plateau. (3) The inter-annual phenology changes of the alpine grassland in the Qinghai-Tibetan Plateau exhibited significant differentiation at different elevation and natural zones. The inter-annual changes at high altitude were more complicated than that at low altitude. The most significant phenology changes were found in the eastern Qinghai-Qilian montane steppe zone, and non-significant changes occurred in the Southern Tibet montane shrub-steppe zone. Qinghai-Tibetan Plateau, alpine grassland, phenology, spatiotemporal variation

Effect of soil acidification on growth indices and microelements uptake by greenhouse cucumber

Based on the climate condition of Iran and most of its soils that are calcareous, it is important to prepare the nutritional requirements of cucumber and decrease the growth and development limitations of greenhouse cucumber. In this way, notation to pH properties is essential. Optimum pH for plants production is slightly acidic such that it is necessary to correct soil pH to a more suitable range in order to increase nutrients availability for plants. The goal of this research is to assess the effect of irrigation water pH changes on yield and nutrient uptake especially on micro nutrients by plant. The experiment consisted of three treatments of pH (5.5, 6.5 and 7.5). The experiment was carried out in a factorial design in the research greenhouse of Khorasgan University. During growth season, Ca and micronutrients were not used. After sampling different nutrients, concentrations were measured. At the end of growth season, growth indices were measured. The evidences provided by this experiment indicated that pH changes did not have significant effect on fruit yield and dry weight of plant shrub. Also, irrigation water pH did not have effect on chlorophyll amounts, LAI and stem diameter, significantly. However, the highest amount of LAI was achieved in pH = 5.5. The pH changes in irrigation water had significant effect on nutrients uptake, though micronutrients uptake was increased and the optimum concentration of nutrients was extracted in plant leaves and fruits by decreasing the pH to 5.5. The maximum uptake of Ca and Mg was obtained when the pH = 7.5 and the maximum uptake of N, P and K was obtained when the pH = 6.5.

Temperature controls on the spatial pattern of tree phenology in China's temperate zone

We used Ulmus pumila leaf unfolding and leaf fall data collected at 46 stations during the 1986–2005 period to construct and validate daily temperature-based spatial phenology models. These models allowed simulation of the 20-year mean and yearly spatial patterns of U. pumila growing season beginning and end dates. This work was undertaken to explore the ecological mechanisms driving tree phenology spatial patterns and examine tree phenology spatial responses to temperature across China's temperate zone. The results show that spatial patterns of daily temperatures within the optimum spring and autumn length periods control spatial patterns of growing season beginning and end dates, respectively. Regarding 20-year mean growing season modeling, mean growing season beginning date correlates negatively with mean daily temperature within the optimum spring length period at the 46 stations. The mean spring spatial phenology model explained 90% of beginning date variance ( P < 0.001) with a Root Mean Square Error (RMSE) of 4.6 days. In contrast, mean growing season end date correlates positively with mean daily temperature within the optimum autumn length period at the 46 stations. The mean autumn spatial phenology model explained 82% of end date variance ( P < 0.001) with a RMSE of 5.6 days. On average, a spatial shift in mean spring and autumn daily temperatures by 1 °C may induce a spatial shift in mean beginning and end dates by −3.1 days and 2.6 days, respectively. Similarly, a significant negative and positive correlation was detectable between beginning date and spring daily temperature and between end date and autumn daily temperature at the 46 stations for each year, respectively. In general, the explained variances for yearly spatial phenology models are less than those of mean spatial phenology models, whereas the RMSEs of yearly models are greater than those of mean models. On average, a spatial shift in spring and autumn daily temperatures by 1 °C in a year may induce a spatial shift in beginning and end dates between −4.28 days and −2.75 days and between 2.17 days and 3.16 days in the year, respectively. Moreover, both mean and yearly spatial phenology models perform satisfactorily in predicting beginning and end dates of the U. pumila growing season at external stations. Further analysis showed that the negative spatial response of yearly beginning date to spring daily temperature was stronger in warmer years than in colder years. This finding suggests that climate warming in late winter and spring may enhance sensitivity of the growing season's spatial response due to the relationship of beginning date to temperature.

Effect of polyethylene mulching on the spatial variability of soil physical properties and growth parameters of taro (Colocasia esculantum)

The objective of this study was to investigate the spatial variability of soil physical properties and growth of taro (Colocasia esculantum) in an unfertilized 42 m ridge covered with black plastic mulch. The study was conducted at the National Agriculture Research Centre Tsukuba (Japan). The experimental field was made of 3 adjacent ridges of 42 m long and 0.90 m width each. Uniform taro corms were planted in the middle of each ridge at 0.30 m spacing. At the end of growing season, soil samples were taken for measurements of air content (¦a), bulk density (rb), gravimetric (qg) and volumetric water contents (qv), total pore space (TPS), pore tortuosity (t), gas diffusion coefficient (DSDO) and water-filled pore space (WFPS). Taro plants were harvested, separated into leaves (LFW), petioles (PFW), corms (CFW), roots (RFW) and tubers (TFW). All autocorrelation functions (r(h)) for soil properties and taro growth dropped sharply after one lag. Except forqg, (r(h) for qa, rb, Ds/Do and WFPS dropped below zero at about 16 lags, which revealed that these soil properties could be sampled at 4.8 m for independent observations. For taro growth parameters, only PFW, TFW and RFW could be sampled together at 14 lags or 4.2 m for uncorrelated observations. Except for RFW, all taro growth parameters significantly correlated among themselves and with qg, ¦a, rb, Ds/Do, WFPS and t with correlation coefficients ranging from 0.16 to 0.99. Plastic mulch improved soil properties which in turn improved the relationship between these properties and taro growth parameters. Key words: Soil physical properties, taro growth parameters, plastic mulch, volcanic ash soil.

Phenological responses of Ulmus pumila (Siberian Elm) to climate change in the temperate zone of China

Using Ulmus pumila (Siberian Elm) leaf unfolding and leaf fall phenological data from 46 stations in the temperate zone of China for the period 1986-2005, we detected linear trends in both start and end dates and length of the growing season. Moreover, we defined the optimum length period during which daily mean temperature affects the growing season start and end dates most markedly at each station in order to more precisely and rationally identify responses of the growing season to temperature. On average, the growing season start date advanced significantly at a rate of -4.0 days per decade, whereas the growing season end date was delayed significantly at a rate of 2.2 days per decade and the growing season length was prolonged significantly at a rate of 6.5 days per decade across the temperate zone of China. Thus, the growing season extension was induced mainly by the advancement of the start date. At individual stations, linear trends of the start date correlate negatively with linear trends of spring temperature during the optimum length period, namely, the quicker the spring temperature increased at a station, the quicker the start date advanced. With respect to growing season response to interannual temperature variation, a 1°C increase in spring temperature during the optimum length period may induce an advancement of 2.8 days in the start date of the growing season, whereas a 1°C increase in autumn temperature during the optimum length period may cause a delay of 2.1 days in the end date of the growing season, and a 1°C increase in annual mean temperature may result in a lengthening of the growing season of 9 days across the temperate zone of China. Therefore, the response of the start date to temperature is more sensitive than the response of the end date. At individual stations, the sensitivity of growing season response to temperature depends obviously on local thermal conditions, namely, either the negative response of the start date or the positive response of the end date and growing season length to temperature was stronger at warmer locations than at colder locations. Thus, future regional climate warming may enhance the sensitivity of plant phenological response to temperature, especially in colder regions.

Extracting vegetation phenology metrics in Changbai Mountains using an improved logistic model

Remotely sensing images are now available for monitoring vegetation dynamics over large areas. In this paper, an improved logistic model that combines double logistic model and global function was developed. Using this model with SPOT/NDVI data, three key vegetation phenology metrics, the start of growing season (SOS), the end of growing season (EOS) and the length of growing season (LOS), were extracted and mapped in the Changbai Mountains, and the relationship between the key phenology metrics and elevation were established. Results show that average SOS of forest, cropland and grassland in the Changbai Mountains are on the 119th, 145th, and 133rd day of year, respectively. The EOS of forest and grassland are similar, with the average on the 280th and 278th, respectively. In comparison, average EOS of the cropland is relatively earlier. The LOS of forest is mainly from the 160th to 180th, that of the grassland extends from the 140th to the 160th, and that of cropland stretches from the 110th to the 130th. As the latitude increases for the same land cover in the study area, the SOS significantly delays and the EOS becomes earlier. The SOS delays approximately three days as the elevation increases 100 m in the areas with elevation higher than 900 m above sea level (a. s. l.). The EOS is slightly earlier as the elevation increases especially in the areas with elevation below 1200 m a. s. l. The LOS shortens approximately four days as the elevation increases 100 m in the areas with elevation higher than 900 m a. s. l. The relationships between vegetation phenology metrics and elevation may be greatly influenced by the land covers. Validation by comparing with the field data and previous research results indicates that the improved logistic model is reliable and effective for extracting vegetation phenology metrics.

اکولوژی فردی گون قشلاقی Kar. & Kir) (Astragalus arpilobus، گونه ای امیدبخش برای اصلاح مراتع شمال شرق ایران

بررسی های اکولوژی فردی گیاهان مرتعی، اطلاعات پایه ای را در خصوص نیازمندی های اکولوژیک، روش کاشت و واکنش آنها به محیط در دسترس قرار می دهد که برای مدیریت صحیح مراتع قابل استفاده است. در این تحقیق برخی خصوصیات اکولوژیک گونه گون قشلاقی (Astragalus arpilobus Kar. & Kir.) در مراتع قشلاقی استان خراسان شمالی مورد بررسی قرار گرفت. این گونه در بخش جرگلان بجنورد، دامنه ارتفاعی 600 - 500 متر از سطح دریا، شیب های 20 تا 100 درصد و متوسط بارندگی سالانه 85/236 میلی متر پراکندگی داشت. خاک های عرصه رویش دارای بافت لومی، مقدار ماده آلی متوسط (1.2%)، حاصل خیزی کم، اسیدیته 32/7 و هدایت الکتریکی معادل 30/2 dS.m-1 (شوری کم) بود. رشد رویشی گیاه اوایل اسفندماه، زمان ظهور گل ها اوایل اردیبهشت ، بذردهی خرداد و ریزش بذر تیر بود. ارزش غذایی و کیفیت علوفه این گونه در مراحل اولیه رشد در بیشترین مقدار بود که با افزایش سن کاهش یافت و در مرحله بذردهی به کمترین مقدار خود رسید. پروتئین خام و خاکستر تحت تاثیر مرحله فنولوژی رشد کاهش یافت، اما درصد دیواره سلولی منهای سلولز (ADF)، همی سلولز و لیگنین (NDF) و ماده خشک با افزایش سن گیاه افزایش یافت. استقرار اولیه گیاه در شرایط کشت گلدانی با موفقیت انجام شد، ولی درصد جوانه زنی آن پایین (24%) بود که با تیمار خراش دهی با سمباده تا 51% افزایش یافت. به طور کلی سهولت استقرار، ارزش غذایی بالا، تطبیق فنولوژی با زمان حداکثر نیاز دام ها به علوفه (فروردین و اردیبهشت)، این گیاه را به عنوان گونه امیدبخش برای اصلاح مراتع قشلاقی شمال شرق کشور معرفی می کند.

Ecophysiological Aspects of the Interactions between Bromus kopetdaghensis and Two Nurse Shrubs, Astragalus meschedensis and Acantholimon raddeanam in a Semiarid Rangeland

Plant-plant interactions are known as the main biotic drivers of the vegetation dynamics. Therefore, understanding such processes is beneficial for the applied vegetation management. The aim of this research was to investigate the type and intensity of plant-plant interaction during the time course of a growth season. We studied ecophysiological aspects of facilitation and competition between two aridland shrubs, A. meschedensis Bunge and A. raddeanam Czernjak and one perennial grass, B. kopetdaghensis Krasch. Soil and plant sampling were carried out for shrubs and the grass that were either growing alone or the grass was growing under the canopy of shrubs. In Spring (May), soil humidity weight was higher under the shrubs+grass than the grass-only site. By the beginning of Summer (July) grass consumed the common soil water and rapidly terminated its yearly growth. Therefore, in August and September, soil humidity weight was lower under the shrubs+grass than shrub-only sites. Photosynthesis rate of B. kopetdaghensis was sharply reduced from the beginning towards the end of growth season, but was not varied between the different plant combinations. Leaf proline measurement in July indicated higher stress for B. kopetdaghensis that were growing under shrubs than those of open areas. In conclusion, we found facilitation effects of shrubs on the grass at the early times of growth season, but it shifted into the competition for water during summer times. The outcome of plant interaction was positive for the grass but negative for the shrubs, especially A. meschedensis.

Mild salinity improves sugar beet (Beta vulgaris L.) quality

Sugar beet (Beta vulgaris L.) is cultivated mainly on saline soils. Low levels of salinity stimulate growth of this crop plant possibly due to production of broader leaves as sources of assimilates. In this work, six cultivars were studied under mild salinity (EC = 5.5 dS m−1) in a field experiment to analyse its effect on growth parameters and yield of storage root and sugar accumulation. An attempt was also made to determine the contributing role of photosynthetic gas exchange in response of sugar beet plants to salinity. Production of greater leaf area in salinized plants occurred only transitionally in the early growth period; in progression of the growing season it was decreased, and at 3rd harvest (100 days after treatment) it was significantly lower compared with control plants without cultivar differences. Leaf chlorophyll fluorescence, net photosynthesis rate, and stomatal conductance did not change by salinity significantly. Although, at the end of growth season, leaf area and potential photosynthesizing component of salinized plants on the basis of leaf area (LAR) or weight (LWR) were significantly lower than for control plants, weight of storage root and sugar content were up to 90 and 37% higher than in control plants, respectively. Consequently, a considerable higher yield under mild salinity conditions in sugar beet is not attributable to higher leaf area or, therefore, higher photosynthetic capacity of whole plants. Indeed, the storage roots benefit from lower dry matter and surface production of shoot during the late growing season (because of lower nitrogen assimilation and a slight drought stress of salinized plants) and a change in dry-matter partitioning in favor of roots takes place. However, a possible special effect of Na on carbon allocation for storage and structure and involvement of growth regulators in the change of root-shoot allometry could not be excluded.

Switchgrass and milkvetch intercropping under 2:1 row-replacement in semiarid region, northwest China: Aboveground biomass and water use efficiency

An experiment was conducted to investigate the aboveground biomass and water use characteristics of switchgrass ( Panicum virgatum) and milkvetch ( Astragalus adsurgens Pall.) in solecropping and 2:1 row-replacement intercropping in semiarid region on the Loess Plateau of China. Field experiments were conducted during the growing seasons from 2001 to 2005. The aboveground biomass production, considering the sum of dry litter and standing parts, was measured every year at the end of growth season. The aboveground biomass, soil water content dynamics, water use efficiency (WUE), actual yield loss (AYL), land equivalent ratio (LER) and aggressivity (A) were compared under sole and intercropping. Intercropping reduced the biomass production of the two component plants, compared with their respective pure stands. Milkvetch was the dominant species in the intercropping in 2001–2004, however its aggressivity to swichgrass decreased gradually as the growth years progressed, and in 2005 it became the dominant in the mixture. The equivalent biomass production under intercropping and whole WUE of mixture were significantly lower than their respective solecropping, although LER of the mixture was equal or bigger than 0. It is concluded that there was no advantage of growing switchgrass and milkvetch under 2:1 row-replacement in semiaird hilly-gully region of Loess Plateau if total biomass production is the primary purpose.

Application of Trichoderma to Prevent Phaeomoniella chlamydospora Infections in Organic Nurseries

Summary. In order to prevent or reduce infection in grapevine nurseries, greenhouse and nursery trials were carried out to evaluate the effects of Trichoderma harzianum (Rootshield ® ) on the morpho-physiological characteristics of grapevine and on Phaeomoniella chlamydospora artificially inoculated on potted cuttings. The long-distance activity of Trichoderma against Botrytis cinerea was also examined. The study was performed in a commercial nursery where plants were grown organically. Results greatly depended on the vine-growth stage at which Trichoderma was applied. Treatment at rooting was the most effective, whilst callusing-box application or treatments at both rooting and callusing gave inconsistent but generally negative results. Treatment at rooting further improved the quantitative and qualitative characteristics of the root system, and increased the percentage of certifiable vines produced. Moreover, Trichoderma application also reduced the necrotic area caused by B. cinerea inoculated on the leaves collected from Trichoderma-treated plants and the extent of necrosis of P. chlamydospora-inoculated cuttings. This reduction in necrosis was significantly higher 15 months after inoculation. On the other hand, Trichoderma increased vine mortality at the end of the growing season compared with untreated plants. On the whole, only when it was applied at rooting did Trichoderma produce positive effects on the morpho-phisiological characteristics of grapevine and increased its tolerance to stress–related diseases, such as forms of esca found in the nursery.

Aboveground biomass production and soil water dynamics of four leguminous forages in semiarid region, northwest China

The study evaluated the forage productivity and water use of four leguminous grasses namely alfalfa (Medicago sativa L.), vetch (Astragalus adsurgens Pall.), sainfoin (Onobrychis viciaefolia Scop.) and Lespedeza davurica grown in semiarid region on the Loess Plateau of China. The experiments were conducted in the years 2001–2004 where each grass was grown on four 7 m×6 m experimental plots. The aboveground biomass production considered the sum of dry litter and standing parts was measured every year at the end of growth season. Soil water measurements were made from soil drill (Ø4 cm cores) every month for soil extending to a depth of 300 cm in the first and second year and up to 500 cm in the rest of the period.The yearly biomass production, soil water storage volume as well as its change, monthly rainfall and water consumption of each grass were statistically analyzed. A linear correlation was used to analyze the biomass production and total water used in evapo-transpiration. Stepwise regression was performed to evaluate the relationship between biomass production and monthly rainfall and soil water storage to explain the differences among grasses. The analysis showed that biomass production of both the vetch and L. davurica were significantly (P<0.05) correlated with total precipitation of April to June while that of sainfoin and alfalfa was significantly (P<0.05) correlated with total precipitation of the growth season (April to October). All four grasses exhibited positive (P<0.05) aboveground biomass production response to soil water usage, but there is difference among. Alfalfa, vetch and sainfoin had a drying effect at a depth less than 2.0 m and consistently showed profiles with the lowest soil water content. Profiles with the lowest soil water content also had greater herbage growth and greater depths of water extraction.

Spatial and temporal variation of phenological growing season and climate change impacts in temperate eastern China

AbstractUsing phenological and normalized difference vegetation index (NDVI) data from 1982 to 1993 at seven sample stations in temperate eastern China, we calculated the cumulative frequency of leaf unfolding and leaf coloration dates for deciduous species every 5 days throughout the study period. Then, we determined the growing season beginning and end dates by computing times when 50% of the species had undergone leaf unfolding and leaf coloration for each station year. Next, we used these beginning and end dates of the growing season as time markers to determine corresponding threshold NDVI values on NDVI curves for the pixels overlaying phenological stations. Based on a cluster analysis, we determined extrapolation areas for each phenological station in every year, and then implemented the spatial extrapolation of growing season parameters from the seven sample stations to all possible meteorological stations in the study area.Results show that spatial patterns of growing season beginning and end dates correlate significantly with spatial patterns of mean air temperatures in spring and autumn, respectively. Contrasting with results from similar studies in Europe and North America, our study suggests that there is a significant delay in leaf coloration dates, along with a less pronounced advance of leaf unfolding dates in different latitudinal zones and the whole area from 1982 to 1993. The growing season has been extended by 1.4–3.6 days per year in the northern zones and by 1.4 days per year across the entire study area on average. The apparent delay in growing season end dates is associated with regional cooling from late spring to summer, while the insignificant advancement in beginning dates corresponds to inconsistent temperature trend changes from late winter to spring. On an interannual basis, growing season beginning and end dates correlate negatively with mean air temperatures from February to April and from May to June, respectively.

Forest phenological patterns of Northeast China inferred from MODIS data

The role of remote sensing in phenological studies is increasingly regarded as a key to understand large area seasonal phenomena. This paper describes the application of Moderate Resolution Imaging Spectroradiometer (MODIS) time series data for forest phenological patterns. The forest phenological phase of Northeast China (NE China) and its spatial characteristics were inferred using 1-km 10-day MODIS normalized difference vegetation index (NDVI) datasets of 2002. The threshold-based method was used to estimate three key forest phenological variables, which are the start of growing season (SOS), the end of growing season (EOS) and growing season length (GSL). Then the spatial patterns of forest phenological variables of NE China were mapped and analyzed. The derived phenological variables were validated by the field observed data from published papers in the same study area. Results indicate that forest phenological phase from MODIS data is comparable with the observed data. As the derived forest phenological pattern is related to forest type distribution, it is helpful to discriminate between forest types.

Nitrogen fixation and soil nitrate interactions in field-grown chickpea (Cicer arietinum) and fababean (Vicia faba)

Soil in which nodulated legumes are growing often contains more nitrate nitrogen (N) than soil in which unnodulated legumes or non-legumes are growing. There is conjecture, however, as to whether the extra or ‘spared’ N is due to reduced use of soil N by the legume or to net mineralisation of legume root and nodular N. We report results of a field experiment to quantify and compare, at different levels of soil-N supply, N2 fixation, and soil-N use by chickpea (Cicer arietinum) and fababean (Vicia faba). Wheat (Triticum aestivum) was included as a non-N2-fixing control. Plants of the 3 species were grown on a low-nitrate Vertosol with fertiliser N rates of 0, 50, and 100 kg/ha (0N, 50N, and 100N), applied 6 weeks before sowing. Samples were collected at sowing and at 64, 100, 135, and 162 days after sowing (DAS) for analysis of soil nitrate, root, and grain dry matter (DM) and N and shoot DM, N, and 15N. The latter was used to estimate the percentage (%Ndfa) and total N fixed by the 2 legumes. Soil nitrate levels to a depth of 1.8 m at sowing were 11–17 kg N/ha (0N), 41–55 kg N/ha (50N), and 71–86 kg N/ha (100N). Grain yields of the 2 legumes were unaffected by soil-N supply (fertiliser N treatment), being 2.0–2.4 t/ha for chickpea and 3.7–4.6 t/ha for fababean. Wheat grain yields varied from 1.6 t/ha (0N) to 4.8 t/ha (100N). Fababean fixed more N than chickpea. Values (total plant including roots) were 209–275 kg/ha for fababean and 146–214 kg/ha for chickpea. Corresponding %Ndfa values were 69–88% (fababean) and 64–85% (chickpea). Early in crop growth, when soil N supply was high in the 100N treatment, fababean maintained a higher dependence on N2 fixation than chickpea (Ndfa of 45% v. 12%), fixed greater amounts of N (57 v. 16 kg/ha), and used substantially less soil N (69 v. 118 kg/ha). In this situation, soil N sparing was observed, with soil nitrate levels significantly higher in the fababean plots (P &lt; 0.05) than under chickpea or wheat. At the end of growth season, however, there were no crop effects on soil nitrate levels. Soil N balances, which combined crop N fixed as inputs and grain N as outputs, were positive for the legumes, with ranges 80–135 kg N/ha for chickpea and 79–157 kg N/ha for fababean, and negative for wheat (–20 to –66 kg N/ha). We concluded that under the starting soil nitrate levels in this experiment, levels typical of many cropping soils in the region, high-biomass fababean and chickpea crops will not spare significant amounts of soil N. In situations of higher soil nitrate and/or smaller biomass crops with less N demand, nitrate sparing may occur, particularly with fababean.

Effect of methyl bromide on the control of Fusarium oxysporum f.sp. dianthi propagules in carnation greenhouse soil and on inoculum increase after one growth cycle of carnation

The effectiveness of methyl bromide (80 g m −2) on the control of Fusarium oxysporum f.sp. dianthi ( F. o. dianthi) was studied at soil depths of 0–60 cm, subdivided into three layers of 0–20, 20–40 and 40–60 cm, in five carnation greenhouses during four successive growth seasons. Each growth season, the number of propagules of F. o. dianthi in the soil was counted before and after fumigation. The efficiency of methyl bromide control was also measured in terms of the viability of F. o. dianthi propagules placed in the soil at depths of 0, 10, 20, 30, 40, 50 and 60 cm. Carnation cultivars ( Dianthus caryophyllus) highly susceptible to Fusarium wilt were planted in four of the five greenhouses studied. Moderately resistant cultivars were planted in one greenhouse during three growth seasons and in a second greenhouse during the last growth season. At the end of each growth season, the largest number of propagules (57–100% of total count) was found in the 0–20 cm layer. More inoculum was found in the 20–40 cm than in the 40–60 cm layer. Methyl bromide reduced the F. o. dianthi propagule count at all soil depths between 0 and 60 cm, but was most effective in the upper 30 cm. A count of F. o. dianthi propagules in the soil in fumigated greenhouses on the ten occasions when their level at the end of the previous growth season was high revealed propagule survival rates of 0% (below detection level) five times, 0.1 % twice, 0.6% once, 1.6% once and 4.6% once. The highest count of viable propagules, when methyl bromide was not successful in reducing propagule count to below detection level, was found in the 20–40 cm layer. At the end of each growth season, both inoculum level in the soil and Fusarium wilt incidence varied in the four greenhouses planted with highly susceptible or susceptible carnation cultivars, irrespective of the propagule counts of F. o. dianthi after fumigation. The correlation between inoculum level in the soil after fumigation and inoculum or Fusarium wilt incidence at the end of that growth season was non-significant ( r 2 = 0.001, p = 0.87 for inoculum; r 2 = 0.19, p = 0.2 for wilt incidence). This indicates that in monocultures of susceptible carnation cultivars, methyl bromide cannot give total protection even for one growth season. In each of the two greenhouses planted with moderately resistant cultivars, the number of propagules in the soil at the end of each growth season remained undetectable, as it was after fumigation.

Long term (100 yr) climatic trends for agriculture at selected locations in Canada

Long term (100 yr) trends of 17 selected annual climatic parameters were studied for 5 locations in Canada. Simple linear correlation coefficients (r) were computed for each variable with time. Temporal variations were not uniform over space, as might be expected over a large continent. Some variables differed significantly with time, while others did not. Forage aridity indices (FAI), or seasonal forage water deficits, had significant negativer values at Agassiz and Ottawa, indicating decreasing aridity over time, but no such trends were evident at the other 3 locations. Stations in western Canada were characterized byr values (mostly significant atP = 0.01) which indicated trends to earlier last spring frost (SF), later growing season end (GSE), later first fall frosts (FF) and increased frost-free period (FFP), growing degree-days (GDD) and Corn Heat Units (CHU). Stations in eastern Canada did not exhibit the same warming trends. No warming trends were observed in January mean temperature (JAN).