Factors influencing biocontrol of jimsonweed (Datura stramonium L.) with the leaf-spotting fungus Alternaria crassa

In greenhouse tests, Alternaria crassa (Sacc.) Rands killed > 80% of inoculated jimsonweed (Datura stramonium L.) seedlings within 14 days following a 9-h dew period at 25°C with 1 × 10⁵ spores/ml, and after 8 h of dew at 1 × 10⁶ spores/ml. At least 10 h of dew with 1 × 10⁵ spores/ml and 9 h of dew with 1 × 10⁶ spores/ml were required to obtain 100% mortality of fungus-inoculated plants. Growth stage and inoculum concentration studies revealed that higher concentrations of inoculum were required to obtain 100% mortality of larger plants. Weed control was significantly reduced by day/night air temperatures of 35°C and 24°C, respectively, at all inoculum concentrations as compared to the controls at lower air and dew temperature regimes. The results of these studies indicate that A. crassa has potential as a biological herbicide for the control of jimsonweed.     

Susceptibility of Heliothis zea larvae to Nomuraea rileyi at various temperatures

Laboratory studies were conducted to determine the susceptibility of various larval instars of Heliothis zea to different spore doses of Nomuraea rileyi at constant and variable temperatures. The fungus was most effective at 20° and 25°C, with a mortality of 80% and 71%, respectively. At 15°C the disease progressed very slowly with larval mortality occurring in 12–28 days post-treatment. Conversely, at temperature ranges above 15°C, the mortality of the larvae occurred in 6–12 days. Three different combinations of variable temperatures included 20–30°, 25–30°, and 20–35°C, but mortality did not exceed 46%. Larvae in the third to fifth instars were more susceptible to infection than were those in the first and second instars.     

Haliphthoros milfordensis isolated from black tiger prawn larvae (Penaeus monodon) in Vietnam

A marine fungus was isolated from the black tiger prawn Penaeus monodon at Nha Trang, Vietnam, on March 20, 2001 and named isolate NJM 0131. The fungus was identified as Haliphthoros milfordensis from the characteristics of asexual reproduction, and its physiological characteristics were investigated. Although the optimum temperature for growth of the isolate was 25°–30°C, the fungus grew at a wide range of temperatures (15°–40°C). H. milfordensis grew well in 50%–100% seawater, but poorly in PYG agar containing 1.0%–5.0% NaCl and KCl. The fungus grew at a wide range of pH (4.0–11.0) with the optimum pH value of 7.0–9.0. The isolate also showed pathogenicity to swimming crab larvae (Portunus trituberculatus) by artificial infection, but mortality was not high. This is the first report of disease in the black tiger prawn P. monodon in Vietnam caused by H. milfordensis.     

Dracaena Leaf Proliferosis, a Newly Recorded Disease Affecting Dracaena sanderiana in Egypt

Dracaena leaf proliferosis is a newly reported disease affecting Dracaena sanderiana in Egypt. A cause and effect relationship between this disease and the fungus,Fusarium proliferatum var. minus has been established. In addition to D. sanderiana the fungus was found to be pathogenic, when tested in the laboratory, to several other members of the family Liliaceae. While the in vitro growth of the fungus is optimum at 25 °C, symptom expression is best at 30°C. Twelve fungicides were tested for their in vitro effect on fungal growth. Benlate, Rubigan, Saprol, Cercobin and Vitavax-200 came first on the list and inhibited growth at 2.5, 12.0, 55.0, 75.0, and 94.0 μg/ml, respectively. Although, Benlate was the most effective fungicide in this respect it failed to demonstrate similar effect on disease development when applied to plants artificially inoculated with the fungus. Fungal growth was completely inhibited on PDA medium by a bacterium belonging to Bacillus sp. but when the bacterium at a concentration of 1 × 10¹¹ cell/ml was applied 24 h before, at the same time with, or 24 h after inoculation no control of the disease was achieved. Naturally-infected plants could, however, be freed from infection when subjected to a hot air treatment at 35 ± 5 °C during day time and 25 ± 5° C at night for 3 months.     

Etiology and control of durian foliar blight and dieback caused by Rhizoctonia solani

Foliar blight and dieback of durian seedlings and trees in Peninsular Malaysia was found to be caused by Rhizoctonia solani (teleomorph - Thanatephoms cucumeris) The fungus grew well and produced abundant sclerotia at temperatures higher than 24°C with an optimum at 28°C. It grew poorly at 35°C and did not grow at 10°C. The strains studied were found to belong to the anastomosis group AG-1. They were pathogenic on durian, papaya, cucumber, long bean, Mikania weed, padi, musk melon, mung bean, Zoysia grass, Bermuda grass, and St Augustine grass. They were mildly pathogenic on groundnut, and non-pathogenic on maize, guava and Brassica‘pak choy’. The disease was effectively controlled by foliar sprays of pencycuron and benomyl; triadimefon and an antagonistic bacterium suspension treatment were less effective and quintozene-etridiazole mixture gave poor disease control.     

Impact of temperature on olive (Olea europaea L.) pollen performance in relation to relative humidity and genotype

Olive varieties ‘Koroneiki’, ‘Kalamata’, ‘Mastoidis’ and ‘Amigdalolia’ were employed in two experiments for 3 years to assess the effect of temperature on olive pollen germination and tube growth in relation to relative humidity and genotype. Pollen samples were subjected to pre-incubation at 10, 20, 30 or 40 °C in combination with decreased air relative humidity – 80, 40, 30 or 20%, respectively – for 24 h to simulate temperature stress that is observed during pollen dispersal; and subsequently in vitro cultured. In the second experiment, pollen was exposed at 15, 20, 25 and 30 °C for 24 h in vitro to evaluate pollen response in conditions of water and nutrients availability and to determine the optimum pollen germination and tube growth temperatures for each cultivar. The highest pre-incubation temperature treatment (40 °C) prevented pollen germination in ‘Koroneiki’ and ‘Mastoidis’, with the less affected varieties (‘Amigdalolia’ and ‘Kalamata’) having average germination percentages of only 7.6 and 2%, respectively. Pre-incubation at 30 °C had a negative impact on pollen germination in ‘Koroneiki’ (?65%), ‘Kalamata’ (?20%) and ‘Amigdalolia’ (?72%) compared to the control (20 °C). Pollen pre-incubation at 40 °C decreased significantly the pollen tube length in ‘Kalamata’ (?50%) and ‘Amigdalolia’ (?52%). In the second experiment, in vitro pollen germination increased after incubation at 25 °C for ‘Koroneiki’ (+6%), ‘Mastoidis’ (+52%), ‘Kalamata’ (+10%) and ‘Amigdalolia’ (+10%) compared to the control (20 °C). At 30 °C germination percentages for ‘Mastoidis’, ‘Kalamata’ and ‘Amigdalolia’ were 8, 6 and 14% higher, respectively, compared to the control (20 °C). Pollen tube length also increased with incubation temperature for all of the studied cultivars. Based on the cumulative stress response index (CSRI) that was calculated for high temperature stress the varieties were classified: ‘Mastoidis’ and ‘Kalamata’ as tolerant and ‘Koroneiki’ and ‘Amigdalolia’ as intermediate at 30 °C while all studied cultivars were sensitive at 40 °C. The observed strong genotype-differentiated response in high and low temperature stress could be exploited by plant breeders towards producing new tolerant olive varieties.     

Common Leafspot of Alfalfa: Ascospore Germination and Disease Development in Relation to Moisture and Temperature

In a moist chamber Pseudopeziza medicaginis ascospores infected alfalfa (Medi sativa L.) moderately to abundantly within 6–10 h at 10–20 °C and within a longer time-span outside this temperature range. Approximate limits of the range were 2.5 and 28 °C; no infection took place at 30 °C. At 14°C ascospores infected alfalfa abundantly at 98 %relative humidity (RH) and above, moderately at 97%, sparsely at 95 and 96%, but not at 94% and below. Ascospores were hydrophilic, germinating best at or near 100%, RH but did not germinate at or below 93 % RH. After infection was established, tiny leafspots became visible within 6–7 days at constant temperatures of 15–25°, 10 days of 10°C, 13 days of 5 °C, and 25 days of 2.5 °C. They failed to develop into normal size spots within 4 weeks at constant temperatures near 30 °C, or near 10 °C and lower. Temporary exposure of incipiently diseased plants 1–6 days to 30–38 °C adversely affected subsequent leafspot development at 20–24°C. Inhibition depended on temperature and on the extent of post-infection disease development.     

Screening Diverse Fungi for Laccases of Varying Properties

Qualitative screening of 295 fungi for laccases yielded 125 laccase positive ones, mostly basidiomycetes. Fifty of these were tested for laccase activity at pH 3.0, 4.5 and 6.0. Most showed maximum activity at pH 4.5, a few showed a broad activity range, two were optimal at pH 3.0 and only the mitosporic fungus Beltraniella sp. was best at pH 6. Most of the 25 fungi assayed at three different temperatures had an optimum at 45°C. The basidiomycete Auricularia sp. acted best at 30°C, while three others showed best activity at 60°C. This study shows the potential of screening diverse fungi for laccase with varying pH and temperature preferences for different applications.     

Influence of arbuscular mycorrhiza on the growth and antioxidative activity in cyclamen under heat stress

The influence of the arbuscular mycorrhizal (AM) fungus, Glomus fasciculatum, on the growth, heat stress responses and the antioxidative activity in cyclamen (Cyclamen persicum Mill.) plants was studied. Cyclamen plants (inoculated or not with the AM fungus) were placed in a commercial potting media at 17–20 °C for 12 weeks in a greenhouse and subsequently subjected to two temperature conditions in a growth chamber. Initially, plants were grown at 20 °C for 4 weeks as a no heat stress (HS?) condition, followed by 30 °C for another 4 weeks as a heat stress (HS+) condition. Different morphological and physiological growth parameters were compared between G. fasciculatum-inoculated and noninoculated plants. The mycorrhizal symbiosis markedly enhanced biomass production and HS + responses in plants compared to that in the controls. A severe rate of leaf browning (80–100 %) was observed in control plants, whereas the mycorrhizal plants showed a minimum rate of leaf browning under HS + conditions. The mycorrhizal plants showed an increase activity of antioxidative enzymes such as superoxide dismutase and ascorbate peroxidase, as well as an increase in ascorbic acid and polyphenol contents. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity also showed a greater response in mycorrhizal plants than in the control plants under each temperature condition. The results indicate that in cyclamen plants, AM fungal colonisation alleviated heat stress damage through an increased antioxidative activity and that the mycorrhizal symbiosis strongly enhanced temperature stress tolerance which promoted plant growth and increased the host biomass under heat stress.     

A new method to determine the energy saving night temperature for vegetative growth of Phalaenopsis

Knowledge of the energy saving night temperature (i.e. a relatively cool night temperature without affecting photosynthetic activity and physiology) and a better understanding of low night temperature effects on the photosynthetic physiology of Phalaenopsis would improve their production in terms of greenhouse temperature control and energy use. Therefore, Phalaenopsis‘Hercules’ was subjected to day temperatures of 27.5°C and night temperatures of 27.0°C, 24.2°C, 21.2°C, 18.3°C, 15.3°C or 12.3°C in a growth chamber. A new tool for the determination of the energy saving night temperature range was developed based on temperature response curves of leaf net CO₂ exchange, chlorophyll fluorescence, organic acid content and carbohydrate concentrations. The newly developed method was validated during a complete vegetative cultivation in a greenhouse environment with eight Phalaenopsis hybrids (i.e. ‘Boston’, ‘Bristol’, ‘Chalk Dust', ‘Fire Fly’, ‘Lennestadt’, ‘Liverpool’, ‘Precious’, ‘Vivaldi’) and day/night temperature set points of 28/28°C, 29/23°C and 29/17°C. Temperature response curves revealed an overall energy saving night temperature range for nocturnal CO₂ uptake, carbohydrate metabolism, organic acid accumulation and photosystem II (PSII) photochemistry of 17.1°C to 19.9°C for Phalaenopsis‘Hercules’. At the lower end of this energy saving night temperature range, a high malate‐to‐citrate ratio switched towards a low ratio and this transition seemed to alleviate effects of night chilling induced photoinhibition. At night temperatures of 24°C or higher, the degradation of starch, glucose and fructose indicated an increased respiratory CO₂ production. During the greenhouse validation experiment, the differences between the eight Phalaenopsis hybrids with regard to their response to the warm day/cool night temperature regimes were remarkably large. In general, the day/night temperature of 29/17°C led to a significantly lower biomass accumulation and less leaves which were in addition shorter, narrower and smaller in size as compared to the day/night temperature regimes of 28/28°C and 29/23°C. During week 25 of the cultivation period, plants matured and flower initiation steeply increased for all hybrids and in each day/night temperature regime. Before week 25, early spiking was only sufficiently suppressed in the 29/23°C and 29/17°C temperature regimes for three hybrids (‘Boston’, ‘Bristol’ and ‘Lennestadt’) but not in the other five hybrids. Although a considerable biochemical flexibility was demonstrated for Phalaenopsis‘Hercules’, inhibition of flowering after exposure to a combination of warm days and cool nights appeared to be largely hybrid dependent.     

Differential protein expression for geothermal Agrostis scabra and turf-type Agrostis stolonifera differing in heat tolerance

Heat stress is a major factor limiting the growth of cool-season grasses in warm climatic regions by affecting many physiological processes, including protein metabolism. Protein degradation often occurs with increasing temperatures, but certain specific proteins such as heat shock proteins (HSPs) may be induced or enhanced in their expression under supraoptimal temperatures. The objectives of this study were to determine the critical temperature that causes protein induction or degradation in two Agrostis grass species differing in heat tolerance and to compare protein profiles between the two species under different temperature regimes. Plants of heat-tolerant Agrostis scabra and two cultivars of heat-sensitive Agrostis stolonifera (‘L-93’ and ‘Penncross’) were exposed to constant day/night temperatures of 20, 30, 35, 40, or 45 °C for 14 d. Leaf photochemical efficiency (Fv/Fm), chlorophyll and carotenoid contents, and soluble protein content declined with increasing temperatures. The decreases were the least severe for A. scabra, intermediate for ‘L-93’, and the most severe for ‘Penncross’, indicating interspecific and intraspecific variations in heat tolerance in Agrostis species. Protein degradation was observed at 30–45 °C in both cultivars of A. stolonifera, and at 40–45 °C in A. scabra.HSPs were induced or enhanced at 35–45 °C in ‘L-93’ and A. scabra, and at 40–45 °C in ‘Penncross’. Immunoblotting also revealed stronger expressions of HSP60 and HSP70 in A. scabra or ‘L-93’ than in ‘Penncross’ at 35–45 °C after 3 d. The results suggested the superior heat tolerance of Agrostis grass species and cultivars could be attributed to the early induction of HSPs, particularly small molecular weight (23 kDa), at a lower level of heat stress and the maintenance of protein thermostability, particularly high-molecular weight proteins (83 kDa and large units of Rubisco).     

Growth,pigments, and biochemical composition of marine red alga Gracilaria crassa

The marine red alga Gracilaria crassa was investigated for its proximate composition, minerals, fatty acids, amino acids, and agar content to decipher its nutritional implications. The growth performance and pigments were studied under different combinations of temperature and salinity. On a dry weight basis the total lipid content was 1.30?±?0.05 %, protein was 5.18?±?0.64 %, carbohydrate was 42.0?±?1.2 %, ash was 43.18?±?1.15 %, and agar content was 21.52?±?0.73 %. Appreciable amounts of macro-, micro-nutrients (K?>?Na, Ca, Mg, and Fe), and essential amino acids (Ileu, His, Thr, Leu, and Lys) were found. Palmitic, stearic acid, and arachidonic acid were major fatty acids detected. The alga showed maximum daily growth rate (DGR %) 5.8?±?0.09 % at 25 °C, 35 ‰ salinity. The highest content of pigment R-phycoerythrin (444.7?±?1.9 μg g^?1 fresh weight (FW) basis) was obtained at 25 ‰ salinity at 35 °C while that of R-phycocyanin (476.3?±?2.3 μg g^?1 DW) at 30 ‰ salinity at 30 °C. This study revealed that this alga can be utilized as a potential source for food and feed. The data generated on best growth conditions will be very useful for farming of G. crassa in open sea. This alga could be used for production of natural colorants at defined control condition.     

Ecophysiological differences between saprotrophic and clinical strains of the microscopic fungus Aspergillus sydowii (Bainier & Sartory) Thom & Church

A number of ecophysiological differences were shown for saprotrophic and clinical strains of the potentially pathogenic microscopic fungus Aspergillus sydowii. The colony growth rates were determined for four saprotrophic and five clinical fungus strains on Czapek medium within the ranges of temperature (5, 10, 15, 20, 30, 35, 37, 40, 42°C) and humidity (0.8, 0.85, 0.9, 0.95, 099 a_w), as well as on media with other sources of organic matter (Sabouraud medium, Hutchinson medium with cellulose, and water agar). The capacity for growth of A. sydowii strains on a broad spectrum of organic substrates was determined with the EKOLOG method for multisubstrate testing. The clinical and saprotrophic strains of A. sydowii differed in the colony growth rates under the same temperature and humidity combinations, as well as in the capacity for growth on different organic substrates. At decreased water activity (0.90–0.85 a_w), the temperature interval for growth of the saprotrophic strains was narrower (30 ± 2°C) than for the clinical strains (25–30°C). Comparison of growth on different media revealed the highest growth rates of the clinical strains on Sabouraud protein-containing medium. The method of multisubstrate testing showed that the saprotrophic strains grew on sugars better than the clinical ones.     

Effects of drought stress on seed germination of ornamental sunflowers

The response to drought stress on germination was investigated on three hybrids of ornamental sunflower, ‘Hadar’, ‘Pazit’, and ‘Zohar’. Different levels of water potential [Ψ: 0.0 (control), ?0.15, ?0.30, ?0.45, ?0.60, ?0.75, and ?0.90 MPa] were adopted using polyethylene glycol-6000 (PEG6000) at four germination temperatures (15, 20, 25, and 30 °C). Final germination percentage, mean germination time, germination index, germination rate index, and germination stress tolerance index were used to evaluate the genotype response to PEG-induced water stress. Shoot and root length and fresh and dry weight were measured on seeds germinated at 20 °C under the different levels of water potentials. During germination, the three ornamental sunflowers showed to be more sensitive to suboptimal temperature than to supraoptimal. Decreasing water potential of imbibition solution progressively inhibited and delayed seed germination. Among cultivars, ‘Hadar’ and ‘Pazit’ performed better at temperature lower than 30 °C. ‘Zohar’ showed a lower sensitivity to PEG-induced water stress at all temperature conditions. Water stress during seed germination depressed the following seedling growth under favourable conditions. As a result, shoot and root length and fresh and dry weight was significantly lower in seedlings from seed germinated at ψ ≤ 0.45 MPa.     

Usefulness of 10 genomic regions in soybean associated with sudden death syndrome resistance

Sudden death syndrome (SDS) is an important soybean [Glycine max (L) Merrill] disease caused by the soilborne fungus Fusarium virguliforme. Currently, 14 quantitative trait loci (QTL) had been confirmed associated with resistance or tolerance to SDS. The objective of the study was to evaluate usefulness of 10 of these QTL in controlling disease expression. Six populations were developed providing a total of 321 F2-derived lines for the study. Recombinant inbred lines (RIL) used as parents were obtained from populations of ‘Essex’ × ‘Forrest’ (EF), ‘Flyer’ × ‘Hartwig’ (FH), and ‘Pyramid’ × ‘Douglas’ (PD). Disease resistance was evaluated in the greenhouse at three different planting times, each with four replications, using sorghum infested with F. virguliforme homogeneously mixed in the soil (Luckew et al., Crop Sci 52:2215–2223, 2012). Four disease assessment criteria—foliar disease incidence (DI), foliar leaf scorch disease severity (DS), area under the disease progress curve (AUDPC), and root rot severity—were used. QTL were identified in more than one of the disease assessment criteria, mainly associated with lines in the most resistant categories. Five QTL (qRfs4, qRfs5, qRfs7, qRfs12, and Rfs16) were associated with at least one of the disease assessments across multiple populations. Of the five, qRfs4 was associated with DI, AUDPC, and root rot severity, and Rfs16 with AUDPC and root rot severity. The findings suggest it may be possible for plant breeders to focus on stacking a subset of the previously identified QTL to improve resistance to SDS in soybean.     

Nitrogen utilization by Typha latifolia L. as affected by temperature and rate of nitrogen application

Greenhouse and growth chamber studies were conducted to evaluate growth and N utilization by Typha latifolia L. in flooded organic soil under varying temperatures and rates of N additions. Elevation of temperature from 10 to 25°C increased shoot biomass yields by 275%. Root biomass yields were lowest at 10°C and increased linearly as a function of temperature. Shoot/root ratios were low (0.72–0.82) at lower temperatures (10–15°C) and ratios increased by about three times at higher temperatures (20–30°C). Biomass yields were increased by addition of N fertilizers, while the shoot/root ratios were directly related to plant-available N present in the soil.Fertilizer ¹⁵N uptake (expressed as % of applied N) by the whole plant was 5.3% at 10°C, 37.5% at 20°C and at 30°C decreased to 20.8%. Fertilizer N accumulation in shoots was 2.1–29.8% of applied N, while roots accumulated 3.2–7.7%. Under greenhouse conditions, N uptake by T. latifolia was found to increase with increased rate of N application. Fertilizer N uptake by both shoots and roots was in the range of 61–77%. Plants cultured in growth chambers were affected by low light conditions resulting in poor growth and low fertilizer ¹⁵N uptake, as compared to plants grown under greenhouse conditions. Added fertilizer N was the major source of N during the early part of the growing season, while soil organic N was the major and perhaps the sole source of N during the latter part of the growing season.     

Cryopreservation of ex-vitro-grown Rosa chinensis ‘Old Blush’ buds using droplet-vitrification and encapsulation-dehydration

Axillary buds from greenhouse-grown plants of Rosa chinensis ‘Old Blush’ were successfully used to establish cryopreservation protocols using both droplet-vitrification and encapsulation-dehydration methods. In droplet vitrification, regrowth occurred after exposure to liquid nitrogen even without pre-culture in the loading solution (LS) before immersion in the plant vitrification solution 2 (PVS2). However, a 20–80 min LS step followed by a short immersion in PVS2 for 3 or 15 min, at 0 °C gave the best regrowth rates (82–86 %). In encapsulation dehydration, the level of dehydration significantly influenced shoot regrowth. The best regrowth rate, 60 %, was obtained at a bead water content of 0.35 g water per g dry weight. These results demonstrate the possibility of using greenhouse plants of rose for cryopreservation by droplet vitrification and encapsulation dehydration.     

The Influence of n-Propanol on the Growth and Conidiation of Pestalotia rhododendri

Pestalotia rhododendri was exposed to vapours from 1 ml propanol solution in water and linear growth, formation of aerial hyphae and production of conidia were determined. A special Petri dish technique was used and maximum stimulation of conidial formation was induced by the vapours from a propanol concentration of 3–4 % (v/v) at 25°C. When propanol was added directly to the medium, a concentration of 1.2 × 10^?2M was optimal for growth and sporulation at 30°C. Sporulation stimulated by propanol was observed at temperatures from 20–32°C, with an optimum at 30°C. Certain observations indicated that an exposure to propanol for 24 hours was enough to induce a stimulated spore production. The stimulation was noticed on different media at 25°C, and was more pronounced at 30°C. One exception was observed. Propanol did not promote sporulation when the fungus was grown on maltagar at 30°C. Propanol 3 ° (v/v) in combination with the standard medium containing (NH₄)₂-tartrate as sole nitrogen source, inhibited the linear growth at 15–20°C, was inactive at 22.5° and 25°C, and stimulated growth at 27.5–31°C. The stimulatory effect was maximal at 30°C. Other media were tested at 25° and 30°C. At both temperatures stimulations of linear growth caused by propanol were observed with a medium containing KNO₃ as sole nitrogen source, and inhibitions with maltagar and another medium containing l -asparaginc as sole nitrogen source. The linear growth could be either inhibited or stimulated while the sporulation was stimulated.     

Temperature interactions with transpiration response to vapor pressure deficit among cultivated and wild soybean genotypes

A key strategy in soybean drought research is increased stomatal sensitivity to high vapor pressure deficit (VPD), which contributes to the ‘slow wilting’ trait observed in the field. These experiments examined whether temperature of the growth environment affected the ability of plants to respond to VPD, and thus control transpiration rate (TR). Two soybean [Glycine max (L.) Merr.] and four wild soybean [Glycine soja (Sieb. and Zucc.)] genotypes were studied. The TR was measured over a range of VPD when plants were growing at 25 or 30°C, and again after an abrupt increase of 5°C. In G. max, a restriction of TR became evident as VPD increased above 2.0 kPa when temperature was near its growth optimum of 30°C. ‘Slow wilting’ genotype plant introduction (PI) 416937 exhibited greater TR control at high VPD compared with Hutcheson, and only PI 416937 restrained TR after the shift to 35°C. Three of the four G. soja genotypes exhibited control over TR with increasing VPD when grown at 25°C, which is near their estimated growth optimum. The TR control became engaged at lower VPD than in G. max and was retained to differing degrees after a shift to 30°C. The TR control systems in G. max and G. soja clearly were temperature‐sensitive and kinetically definable, and more restrictive in the ‘slow wilting’ soybean genotype. For the favorable TR control traits observed in G. soja to be useful for soybean breeding in warmer climates, the regulatory linkage with lower temperatures must be uncoupled.     

Life history parameters of the cattle long‐nosed sucking louse,Linognathus vituli

Cattle sucking lice, Linognathus vituli (L.) (Phthiraptera: Linognathidae), were obtained from naturally infected cattle and maintained within ‘arenas’ affixed to the backs of cattle confined in controlled environment chambers maintained at a constant temperature of 15 °C. Temperatures measured within the arenas at an ambient temperature of 15 °C were constant at about 34 °C and only slightly above the temperature on nearby skin. The effect of temperature on egg development was determined using a gradient of temperatures between 25 °C and 41 °C. Eggs did not develop at temperatures of < 26 °C or > 39 °C. Survival of eggs was highest at temperatures of 30 °C and 35 °C. The earliest hatch was observed at 5 days post‐oviposition (at 33–35 °C). Development was extended to as long as 13 days at the lower temperatures. Kaplan–Meier survival probabilities were compared for lice kept at two densities in the arenas and showed there to be no effect of density on louse survival. Similarly, the mean number of eggs/louse/day over an 8‐day period was not influenced by louse density.