Cool Spring Conditions Research Articles

Effects of Temperature on Development and Survival of Nymphal Lycorma delicatula (Hemiptera: Fulgoridae).

Lycorma delicatula (White), an invasive planthopper originally from Asia, is an emerging pest in North America. It is important to understand its phenology in order to determine its potential range in the United States. Lycorma delicatula nymphs were reared on Ailanthus altissima (Miller) (Sapindales: Simaroubaceae) at each of the following constant temperatures: 5, 10, 15, 20, 25, 30, 35, and 40°C. The time spent in each instar and survival was recorded. Developmental rate increased with temperature from 15 to 30°C for all instars, then declined again at higher temperatures. Nymphal survival was lower at 35°C than between 15 and 30°C for all instars, and first instars placed at 5, 10, and 40°C all died without molting. This suggests that L. delicatula survival and development may be affected in the Southern United States by high temperatures and developmental delays will occur under cool spring conditions. The lower developmental threshold was found to be 13.00 ± 0.42°C for first instars, 12.43 ± 2.09°C for second instars, 8.48 ± 2.99°C for third instars, and 6.29 ± 2.12°C for fourth instars. The degree-day (DD) requirement for nymphs in the previous instar to complete development to reach the second instar, third instar, fourth instar, and adult was 166.61, 208.75, 410.49, and 620.07 DD (base varied), respectively. These results provide key data to support the development of phenology models and help identify the potential range of L. delicatula in North America.

Heterogeneous causal relationships between plant growth variables for biofertilized field-grown hard red spring wheat (Triticum aestivum [L.

The experimental hard red spring wheat (Triticum aestivum [L.]) cultivars AC Barrie, Cardale, Superb, and Vesper are adapted to the wheat-growing regions of the Canadian Prairies. They were bred to resist diseases, but their response to a biofertilizer that is a consortium of bacteria (Bacillus subtilis, Candida utilis, Lactobacillus casei, L. helveticus, L. plantarum, L. rhamnosus, Lactococcus lactis, Rhodopseudomonas palustris-1, and R. palustris-2), filamentous fungi (Aspergillus oryzae and Candida utilis), and yeast (Saccharomyces cerevisiae) was not known. The objectives of this research were to model the structures of causal relationships between plant variables using a member of the family of structural-equation modelling tools, called path analysis; to calculate the rate of “biofertilization” that would optimize wheat grain yield; and to model the effect of the experimental treatments on wheat yield over sites in Québec, Manitoba, Saskatchewan, and Alberta (Canada). The path models, presented in diagrams depicting heterogeneous structures, indicated that the variability of the wheat harvest index in Ste-Anne-de-Bellevue, Québec, depended on the experimental biofertilizer and dry weight at maturity in 2015; and biofertilizer and dry weight at the vegetative stage in 2016. The variability of plant height at maturity in Ste-Anne-de-Bellevue, Québec, depended on the biofertilizer, dry weight at the vegetative stage and dry weight at maturity in 2015, and dry weight at the vegetative stage and yield in 2016. The covariance between seedling emergence and the height of the primary stem at the vegetative stage of plant development was consistently zero, meaning structural independence for these variables. The ultimate effect of the biofertilizer on yield was positive in Manitoba and Saskatchewan, and positive and statistically significant in 2015 on Chateauguay clay loam at the Québec site. Results also indicated that a biofertilizer formulation free of cellular material inhibited yield from T. aestivum cv. Superb in Alberta. A quadratic model indicated that at the 2016 Québec site, the optimal application rate of the experimental biofertilizer was 356 mL ha−1, in addition to 2 L of commercially available nutrient fertilizer ha−1. These rates of biofertilization and nutrient fertilization are based on results with AC Barrie that was grown under cool spring conditions.

Improving Growth and Productivity of Early-season High-tunnel Tomatoes with Targeted Temperature Additions

In northern climates where the growing season is shortened by cool spring conditions, high tunnels make it possible to plant and produce tomatoes (Solanum lycopersicum L.) at least 1 month earlier than in the field. However, limited high-tunnel research has been performed in arid high-elevation regions that experience extreme diurnal temperature fluctuations. High tunnels are designed to be passively heated; therefore, additional protection from frost may be warranted if growers wish to plant significantly earlier than normal. Low tunnels built within a high tunnel reduce the energy requirement by concentrating heat around the plants, particularly when a heat source is placed inside the low tunnel. ‘Sunbrite’ tomatoes were transplanted through black plastic mulch in four high tunnels in North Logan, UT (lat. 41.73° N, long. 111.83° W, 1382 m elevation) on 17 Mar., 30 Mar., and 7 Apr. in 2009 and on 19 Mar., 30 Mar., and 9 Apr. in 2010. Low tunnels were constructed over each row, and three supplemental heat treatments (unheated, soil-warming cables, and soil-warming cables plus 40-W incandescent lights) were tested to improve plant performance. The highest total marketable yield was achieved for earliest planting dates in both 2009 and 2010. In 2009, early-season yield was significantly greater when both the soil + air were heated, but only for the earliest planting date. In 2010, soil heat alone and in conjunction with air heat significantly improved early-season yield. Information gathered in this study on planting dates, yield, and energy costs provides valuable production and economic information to growers in arid high-elevation climates who desire the benefits of growing early-season tomatoes in high tunnels.

Influence of climate on seasonal patterns of stem increment of balsam fir in a boreal forest of Québec, Canada

It is important to develop a better understanding of the climatic factors controlling the growth of boreal forests. Dendrometer measurements were used to characterize inter-annual variation in seasonal patterns of stem diameter increment of balsam fir trees (n=3) over seven growing seasons (2004–2010) in a boreal forest of Québec, Canada. For the period studied, cumulative seasonal growth ranged from 1.1mm to 2.9mm. Cumulative seasonal growth was a function of the timing of tree growth initiation and cessation along with the maximum growth rate observed throughout the growing season. The start and finish of diameter growth showed variations of 21 and 53 days, respectively, and duration of the growing season ranged from 38 to 107 days while maximum growth rates observed throughout a season ranged from 36.0μmd−1 to 57.6μmd−1. Interestingly, similar cumulative annual growth can be achieved through very different seasonal growth patterns, depending on the inter-annual variation of the three factors mentioned above. Air temperature and photosynthetically active radiation appeared to regulate the initiation of tree growth with high photosynthetically active radiation and cool spring conditions delaying the start of growth. The maximum growth rate within a given season was related to snowpack depth and the timing of snowmelt. Deeper snowpack that melt earlier in spring was associated to higher maximum growth rates during the following season. Apart from exceptional climatic conditions that led to a very early growth cessation in 2006, the timing of growth cessation cannot be explained by climatic variables, suggesting that this phenological event is internally controlled by a physiological mechanism. Overall, the results indicate that the onset of growth as well as the maximum growth rate were regulated by climatic triggers. Consequently, changes in climate seasonality may have considerable effects on both seasonal pattern of growth and tree growth itself.

Organic fertilizers derived from plant materials Part II: Turnover in field trials

AbstractOur aim was to investigate two different organic fertilizers derived from plant materials (OFDP) with respect to their nitrogen (N) and carbon (C) turnover in field trials planted with small radish (Raphanus sativus L. var. sativus) and white cabbage (Brassica oleracea L. convar. capitata var. alba) or fallow. The two fertilizers investigated were coarse seed meal of yellow lupin (Lupinus luteus L.) and coarse meal of castor cake (Ricinus communis L.). Under cool spring conditions, the soil turnover of yellow lupin–seed meal was slightly enhanced compared to castor‐cake meal. During the vegetation period of the vegetables, N added with both fertilizers was metabolized more or less completely by soil microorganisms. Due to similar efficiencies of the fertilizers tested, no significant difference could be found in the N uptake of plants. From this point of view, yellow lupin–seed meal, which can be produced by farmers themselves, has the potential to replace the widely used castor‐cake meal. Considerable amounts of N may remain in the field after fertilization with OFDPs either as mineral N or as easily mineralizable organic N. This N should be utilized immediately by a succeeding crop to avoid leaching losses.

Landscape Resources for the Territorial Nymphalid Butterfly Inachis io: Microsite Landform Selection and Behavioral Responses to Environmental Conditions

We investigate the use of landforms at different scales by males of the territorial nymphalid butterfly Inachis io (Linnaeus, 1758) under different weather conditions. They are known to use landforms at two different scales including macroscale, such as valley sides, tops of slopes and wood edges, and mini-landforms, such as molehills produced by the burrowing animal Talpa europaea Linnaeus (Linnaeus, 1758). Here, we demonstrate that they exploit microscale features on the molehills. The butterfly shifts its position in the landscape in relation to changing conditions by flying, and at the microscale, by walking. The links between thermoregulatory behavior and site selection indicate that perches are adopted to maintain body heat in the cool spring conditions when territories are established. Mini-landforms such as the molehills are adopted for their potential shelter and warmth in relation to ambient conditions; microsite selection typically includes warm niches on molehills, such as sunny slopes, sheltered margins and depressions. Shelter is adopted regardless of reduced visibility for territorial males. The importance of non-consumable (mate location) resources at different spatial scales is discussed in the context of habitat and the matrix.

Evaluation of the Effect of SoyaSignal Technology on Soybean Yield [Glycine max (L.) Merr.] under Field Conditions Over 6 Years in Eastern Canada and the Northern United States

Previous studies showed that inoculation of soybean [Glycine max (L.) Merr] with Bradyrhizobium japonicum preactivated with plant‐to‐bacteria signal molecules increased nodule number, particularly at low root zone temperatures, thereby improving plant seasonal nitrogen fixation and final grain and protein yield under cool spring conditions. Two products carrying this technology, SoyaSignalTM and Affix+TM, were designed and tested at 127 locations in Canada and the United States from 1994 to 1999. A summary of the field test results shows that preincubation of B. japonicum with genistein and daidzein, as well as directly increasing the genistein and daidzein concentration in the soybean root rhizosphere, gave an average final grain yield increase of 7 %. The success of SoyaSignal technology was temperature dependent. The plants responded better to the SoyaSignal products when grown under cool soil conditions. Application of SoyaSignal to early planted soybean (before the soil temperature rose above 17.5 °C) increased yields by an average of 10 %. The responses declined with delayed planting dates. Soybean genotypes with high yield potential had greater yield increases than those with low yield potential. As the ratio of return to cost for SoyaSignal technology was 5.3 : 1 over the 127 site‐years, SoyaSignal technology can be used as a tool to improve soybean yield in production areas with cool springs.

Variability in yield and yield component responses to genistein pre-incubated Bradyrhizobium japonicum by soybean [Glycine max (L.) Merr] cultivars

The sub-tropical legume, soybean [Glycine max (L.) Merr.], has lower grain yields at low temperatures, mainly due to reduced nitrogen fixation. The isoflavone genistein has been identified as one of the major compounds in soybean seed and root extracts responsible for inducing the expression of the B. japonicum nod genes. A 2-year field study was conducted in 1997 and 1998 with 11 soybean cultivars recommended for Quebec, and representing a range of yield potentials and maturity groups. The objective of this study was to assess the variability among soybean cultivar maturity groups in terms of response to genistein application under Canadian short season and cool-spring conditions. The experiments were organized in a randomized complete block design with three replications. The two genistein treatments included B. japonicum inoculant pre-incubated with 20 μm genistein and B. japonicum inoculant only. The inoculants were applied into the furrow at the time of planting. The results of this study showed that genistein pre-incubated B. japonicum increased soybean grain yield and protein content over two years. In 1998, pod number per plant−1 and seed number plant−1 were also clearly increased. When 20 μm genistein was applied in 1998, cultivars in the late maturity group had 28 and 70% more shoot and total protein content, respectively, than the early maturity groups with or without genistein, or the late maturity without genistein, in 1998. There was no interaction between genistein application and soybean cultivar in this study, indicating that both early and late maturing cultivars responded similarly to genistein pretreated inocula. Pre-incubation of B. japonicum with genistein can increase N2 fixation potential in short season areas. Key words: Soybean, cultivars, genistein, yield, and yield components

Early seedling and seasonal N2-fixing symbiotic activity of two soybean [Glycine max (L.) Merr.] cultivars inoculated with Bradyrhizobium strains of diverse origin

In areas with a short growing season the poor adaptability of soybean [Glycine max Meer. (L.)] to cool soil conditions is considered the primary yield limiting factor. Soybean requires temperatures in the 25 to 30°C range for optimum N2-fixation and yield. Field studies were conducted in 1990 and 1991 at Montreal, Quebec to determine whether adaptability to cool soil conditions, with respect to earlier symbiosis establishment and function, existed among either Bradyrhizobium strains or soybean genotypes. An early maturing isoline of the soybean cultivar Evans and the cultivar Maple Arrow were inoculated with one of four strains isolated from the cold soils of Hakkaido, northern Japan, or the commercially used strains 532C or USDA110, at two planting dates. Plot biomass and nodulation were assessed at seedling (V2), and flowering(R2) growth stages and harvest maturity. Soybean genotypes did not differ for pre-flowering nodulation or N2-fixation in the cool spring conditions of the first year. Seasonal N2-fixation rates were also determined at the final harvest by the N-balance and 15N-isotope dilution methods. Significantly higher symbiotic activity was found for two of the four Hakkaido strains and was reflected in higher final soybean seed yield and total N2-fixation for the growing season, as compared to the two commercial strains. Planting 14 days earlier resulted in greater early vegetative and total seasonal N2 fixation and yield in the second year when soil temperatures were warmer, emphasizing the need for the development of soybean-Bradyrhizobium combinations superior in nodule development and function under cool soil conditions.

Variation in Food Quality and Temperature Constrain Foraging of Gregarious Caterpillars

We examined the separate and combined effects of changing food quality, thermal environment, and larval behavior on the foraging pattern of a gregarious caterpillar. Hemileuca lucina (Saturniidae), which specializes on the shrub Spiraea latifolia (Rosaceae). First—instar larvae, which encounter only new leaves under field conditions, showed no preference for new leaves over mature ones. In contrast, third—instar larvae, which normally encounter both leaf types, exhibited a preference for new leaves, in both 12—h and instar length choice tests. In laboratory tests, larvae in groups were more likely to survive and exhibited less variation in biomass gained than solitary larvae. An experiment was conducted to determine the interactions of temperature (with daytime temperatures of 20°, 25°, or 30°C), group size (solitary or in groups of 10), and diet (new or mature leaves) on third—instar larvae. The effect of diet and group size on relative growth rate depended on the daytime temperature. At a daytime temperature of 20°, representing overcast and cool spring conditions, growth rates were similar for all group size—diet combinations. Thus, at such a cool temperature, there was no advantage in feeding on new leaves or in larval groups. In contrast, solitary larvae fed mature leaves gained less mass and developed more slowly than the other group size—diet combinations at the mean maximal day temperature (25°) for field conditions. At 30° representing the average temperature reached through basking, larvae eating new leaves grew significantly faster than those on mature leaves, regardless of larval group size. These results indicate that in the absence of predators, in which case larvae eat new leaves, bask, and remain aggregated, the larvae can grow twice as fast and attain more biomass per instar than solitary larvae eating mature leaves in the shade, which is often the case when they avoid predators.

Effect of population design and planting pattern on yield response of grain sorghum

A range of grain sorghum cultivars were grown under irrigation of various population densities and planting pattern in three seasons. Yield responses are interpreted by a method allowing extrapolation to a wider environmental range. High populations (4 and 8 × 105 plant per ha) were always superior or equal to the standard population (2 × 105 plants per ha) generally used under irrigation. Whilst cultivar responses varied, no yield depressions were recorded at high population. Application of these results to other irrigated environments may be made with some confidence. This superiority of high population varied with season, and was related to variability of pre-anthesis growth. Seasonal conditions favouring rapid pre-anthesis growth resulted in a yield plateau at low populations (<2 × 105 per ha) (asymptotic response). In contrast, environments causing slow pre-anthesis growth (e.g. cool spring conditions) led to an increasing yield over the entire population range (hyperbolic response). Most of the yield differences were associated with differences in grain number, and hence with pre-anthesis environmental conditions. Maximum yield appeared to be the result of rapid canopy closure, whether achieved by high rated of growth of individual plants (asymptotic responses), or by high populations, when rates of growth of individual plants slow down (increasing hyperbolic response). These results contrast with responses to increasing population recorded for most species, where clear optimal ranges can be defined (parabolic responses).

Comparative Growth Analysis of Two Spring Wheats and One Spring Barley1

Two cultivars of spring wheat, Triticum aestivum L., cvs. ‘Neepawa’ and ‘Pitic 62’, and one cultivar of spring barley, Hordeum vulgare L., cv. ‘Bonanza’, were compared for grain yield and its relationship to patterns of leaf area development and dry matter accumulation. Each cultivar was planted at an early and a late seeding date at Saskatoon in 1980 and in 1981. Leaf area (cm2/plant) and biological yield (g/m2) were determined at weekly intervals commencing five weeks after seeding. Grain yield, components of grain yield, and final biological yield were measured at maturity. Grain yield was found to be a curvilinear function of final biological yield in Pitic 62 and Bonanza but the relationship appeared to be linear for Neepawa. Within a cultivar, higher biological yield gave higher grain yield.Bonanza barley produced more dry matter and greater leaf area than either wheat cultivar early in the season. This advantage disappeared as the crop approached maturity. Pitic 62, although having greater maximum leaf area index and greater leaf area duration than Neepawa, tended to have a similar pattern of dry matter accumulation early in the season. Pitic 62 had greater final biological yield and grain yield by virtue of its later maturity. Yield of wheat might be increased without delaying maturity by searching for types which grow quickly under cool spring conditions.

The Effect of Methyl Bromide Fumigation on the Germination of Onion Seed and Vigour of the Seedlings

SUMMARYBatches of onion seed were fumigated with dosages of 1,000 or 2,000 mg.hr/1. of methyl bromide at 18°C for the control of stem eelworm (Ditylenchus dipsaci (Kühn) Filipjev). The subsequent effects of these fumigations on germination and seedling vigour were tested under standard laboratory and simulated cool spring conditions. Cool spring conditions lessened germination by up to 12·4 per cent compared with a standard laboratory test, while fumigation at the lower dosage rate caused up to a further 11·5 per cent reduction but had little effect on seedling vigour. The higher dosage rate severely affected percentage germination and caused some loss of vigour.