Short Growth Period Research Articles

Analysis of factors related to varietal differences in the yield of rice (Oryza sativa L.) under Free-Air CO2 Enrichment (FACE) conditions

ABSTRACTEnhancing crop traits that increase grain yield under elevated CO2 concentrations is an important option for increasing the future productivity of rice. Here, we compared the growth and yield of five varieties with different genetic background under Free-Air CO2 Enrichment (FACE) conditions to identify traits responsible for varietal differences in yield increase under elevated CO2. Three high-yielding and two standard rice varieties grown under FACE conditions commonly had (1) shorter growth periods, (2) higher dry matter production, (3) higher numbers of spikelets (sink capacity) and panicles; and (4) higher yield than those grown under ambient CO2. Yield enhancement by elevated CO2 (FACE/Ambient), however, differed significantly among varieties, ranging from 1.10 to 1.25. The greater response of the sink capacity, defined as the product of spikelet number and single grain mass, was the main factor involved in yield increase. Three high-yielding varieties (Momiroman, Takanari, and Hokuriku 193) had greater sink capacity than two standard varieties and the sink capacity of these varieties significantly increased under FACE condition. However, yield enhancement in elevated CO2 was lower in Hokuriku 193 than in Momiroman and Takanari. In Hokuriku 193, sink production was relatively low while dry matter production was similar to the others. Therefore, larger increase in sink production efficiency per unit of dry matter production under FACE was found to be a particularly important varietal trait, suggesting that efforts to develop varieties suited to the predicted elevated CO2 condition should focus on this and the related traits.

Evaluation of stability and adapbility of heat-tolerant rice lines in Mekong delta

In two crop seasons of 2018, Winter-Spring and Summer-Autumn, in Long An, Can Tho, Hau Giang, An Giang and Tra Vinh provinces, an assessment of stability and adapability of heat-tolerant rice lines (HTL) was conducted. The experiment was performed as a randomized complete block design (RCBD) with 3 replicates. The quantity of fertilizers was equally applied for all treatments, including 100 kg N, 40 P2O5 and 30 kg K2O/ha. The results showed that HTL1, HTL2, HTL5, HTL7, and HTL8 were promising hybrid lines as they had short growth periods and high yields with good heat-tolerance. These rice lines were adapted well to both Winter-Spring and Summer-Autumn crops as indicated by the analysis of rice line and environment interaction.

Modeling the sensitivity of wheat yield and yield gap to temperature change with two contrasting methods in the North China Plain

Wheat productivity in the North China Plain (NCP) is highly sensitive to climate change and varies greatly in spatial-temporal scale. Contrasting responses of wheat productivity to climate change were reported with different assessment methods. In this study, the impacts of climate warming (+ 2 °C) on wheat yields and yield gaps in the NCP were compared under rainfed, irrigated, and potential conditions using climatic resource utilization model (CRUM) and APSIM. Average potential yield increased 289 kg ha−1 per decade (P < 0.01) simulated by CRUM but decreased 219 kg ha−1 per decade (P < 0.01) simulated by APSIM across the NCP during 1961–2010. Under the + 2 °C scenario compared with current climate (1961–2010), wheat yields under potential, two irrigations, one irrigation, and rainfed conditions increased 27%, 23%, 28%, and 13% simulated by CRUM but decreased 7%, 8%, 10%, and 17% simulated by APSIM. Simulated yield gaps between potential yield and yields under rainfed and one and two irrigations by CRUM increased 33%, 27%, and 32%, respectively. Simulated yield gap between potential and rainfed yields by APSIM increased 9% while the gaps between potential yield and yields under one and two irrigations by APSIM decreased 12% and 10%. Without cultivar change, simulated shortened growth period by APSIM due to increased temperature would decrease wheat yields. By contrast, increased temperature under a constant growth period assumed by CRUM would increase yields especially potential yield. This suggested that wheat yields could be maintained by effective utilization of crop growth duration, such as breeding new cultivars under warming climate in the NCP.

Effects of a new-type inner-canopy illuminant and light quality on spring wheat growth in CELSS

Traditional plant illumination in Controlled Ecological Life Support System (CELSS) has been generally roof illumination (RI). In order to improve the utilization efficiency of light energy for cultivating plants, a new-type inner-canopy illuminant (ICI), which was embedded among the stems and leaves of spring wheat, was applied in the research. The experimental group was 50% ICI+ 50% RI, while the control group was 100% RI, both of which consumed the same total electric power. For each of the two groups, six different qualities of light were separately used to study the effects of red, blue and green light under simulated CELSS conditions. By comparing the two groups, it was found that the PPFD (Photosynthetic Photon Flux Density) on the leaf surface was increased in the experimental group, resulting in a shortened growth period, higher net photosynthetic rate (Pn), lower plant height, larger leaf area index (LAI), higher biomass and seed yield. The increased percent of PPFD across the leaf surface under the experimental group on average reached 8.6%–14.6% within 30 days, while PPFD increased by 3.9%–8.0% in 70 days after sowing. An increased seed yield as large as 19.6% per day was achieved in the experimental group. In addition, Red, blue and green light contributed differently to photosynthetic efficiency. Firstly, red light promoted the shortening of growth period, while blue and green light had no significant effect on it. For example, reducing 20% red light caused a 12- or 13-day prolongation of the growth period. Secondly, increasing the ratio of red/blue could increase Pn, plant height, leaf area index, total biomass and seed yield. Thirdly, it can be seen that the green light did not contribute to photosynthesis directly, but it still had an important role in spring wheat growth. Green light significantly increased the tiller number and LAI, as well as total biomass and seed yield, but daily seed yield was not increased under 10% or more green light. The total seed yield was the highest in combination of 80% red +10% blue +10% green light, but the highest daily seed yield was achieved under 90% red +10% blue light for a shorter growth period. The above results should provide a useful reference for choosing the suitable plant lighting method in CELSS.

Recombinant vector vaccine evolution.

Replicating recombinant vector vaccines consist of a fully competent viral vector backbone engineered to express an antigen from a foreign transgene. From the perspective of viral replication, the transgene is not only dispensable but may even be detrimental. Thus vaccine revertants that delete or inactivate the transgene may evolve to dominate the vaccine virus population both during the process of manufacture of the vaccine as well as during the course of host infection. A particular concern is that this vaccine evolution could reduce its antigenicity—the immunity elicited to the transgene. We use mathematical and computational models to study vaccine evolution and immunity. These models include evolution arising during the process of manufacture, the dynamics of vaccine and revertant growth, plus innate and adaptive immunity elicited during the course of infection. Although the selective basis of vaccine evolution is easy to comprehend, the immunological consequences are not. One complication is that the opportunity for vaccine evolution is limited by the short period of within-host growth before the viral population is cleared. Even less obvious, revertant growth may only weakly interfere with vaccine growth in the host and thus have a limited effect on immunity to vaccine. Overall, we find that within-host vaccine evolution can sometimes compromise vaccine immunity, but only when the extent of evolution during vaccine manufacture is severe, and this evolution can be easily avoided or mitigated.

Bone histology of two pareiasaurs from Russia (Deltavjatia rossica and Scutosaurus karpinskii) with implications for pareiasaurian palaeobiology

Abstract Pareiasaurs were one of the main clades of large herbivorous tetrapods in Middle–Late Permian continental ecosystems. Despite abundant pareiasaur material, many aspects of their biology remain poorly known. This paper provides a description of ontogenetic changes in long-bone and rib microanatomy/histology of two Upper Permian pareiasaurs from Russia, Deltavjatia rossica and Scutosaurus karpinskii. Analysis of a growth series of bones of Deltavjatia and Scutosaurus revealed rapid and cyclical growth early in ontogeny (as indicated by fast-growing fibrolamellar bone with lines of arrested growth). This was followed by a change in the growth pattern (as indicated by an outer avascular layer of lamellar bone in the cortex) and a decrease in the growth rate after 50% of maximum body size was reached in Deltavjatia and 75% in Scutosaurus (larger body sizes in Scutosaurus were attained through an extended initial period of fast skeletal growth). The study confirms that the bones of all pareiasaurs are histologically and microanatomically uniform [spongious (porous) microstructure and a very thin compact cortex] and indicate a similar growth strategy (a short initial period of rapid and cyclical growth followed by a long period of slow growth). The microanatomical characteristics of pareiasaurs do not provide a clear indication of their lifestyle.

Selection and characterization of an improved strain ( ST‐2 ) of Pyropia haitanensis by 60 Co‐γ ray irradiation

Although the improved strain HR-5 of Pyropia haitanensis has improvement in yield and quality, it shows earlier maturation and shortened growth period. In this study, blades of HR-5 strain were treated with 60Co-γ ray irradiation, and a mutant strain ST-2 was selected and characterized. The blade length of ST-2 strain was 401.4 cm on day 70 post-culture, which was 1.9-fold longer than that of the parental strain HR-5. The blades of HR-5 strain matured earlier and most were matured on day 55, while the ST-2 strain was not matured until day 90. When blades of HR-5 and ST-2 strains were firstly cultured at 23°C for 40 days and their blade discs cultured at 29°C for another 30 days, the mean length of ST-2 strain was 2.0-fold longer than that of HR-5 strain. Besides, the contents of Chl. a and phycobiliprotein and the conchospore numbers in ST-2 were comparable to that in HR-5 strain. In summary, compared with HR-5, we observed delayed maturation, increased length, weight and high-temperature resistance of the blades, high content of photosynthetic pigments, and high production of conchospores in ST-2, suggesting it might be a better strain for large-scale production.

Transcriptome Analysis Reveals Key Cold-Stress-Responsive Genes in Winter Rapeseed (Brassica rapa L.).

Low ambient air temperature limits the growth and selection of crops in cold regions, and cold tolerance is a survival strategy for overwintering plants in cold winters. Studies of differences in transcriptional levels of winter rapeseed (Brassica rapa L.) under cold stress can improve our understanding of transcript-mediated cold stress responses. In this study, two winter rapeseed varieties, Longyou-7 (cold-tolerant) and Lenox (cold-sensitive), were used to reveal morphological, physiological, and transcriptome levels after 24 h of cold stress, and 24 h at room temperature, to identify the mechanism of tolerance to cold stress. Compared to Lenox, Longyou-7 has a shorter growth period and greater belowground mass, and exhibits stronger physiological activity after cold stress. Subsequently, more complete genomic annotation was obtained by sequencing. A total of 10,251 and 10,972 differentially expressed genes (DEG) were identified in Longyou-7 and Lenox, respectively. Six terms closely related to cold stress were found by the Gene Ontology (GO) function annotation. Some of these terms had greater upregulated expression in Longyou-7, and the expression of these genes was verified by qRT-PCR. Most of these DEGs are involved in phenylpropanoid biosynthesis, plant hormone signal transduction, ribosome biogenesis, MAPK signaling pathway, basal transcription factors, and photosynthesis. Analysis of the genes involved in the peroxisome pathway revealed that Longyou-7 and Lenox may have different metabolic patterns. Some transcription factors may play an important role in winter rapeseed tolerance to cold stress, and Longyou-7 is slightly slower than Lenox. Our results provide a transcriptome database and candidate genes for further study of winter rapeseed cold stress.

تاثیر کمآبیاری بر عملکرد و اجزای آن در هیبریدهای ذرت دانهای (Zea mays L.)

با توجه به کمبود آب و مصرف زیاد آب در هیبریدهای دیررس ذرت، بررسی رشد، عملکرد و مصرف آب در هیبریدهای این گیاه ضروری می باشد. از این رو به‌منظور بررسی اثرات کم‌آبیاری بر عملکرد و اجزای عملکرد هیبریدهای ذرت دانه‌ای، آزمایشی به صورت کرت‌های خردشده در قالب طرح بلوک کامل تصادفی با سه تکرار، طی دو سال زراعی 4-1393 اجرا شد. کرت‌های اصلی به سطوح آبیاری (100، 80 و 60 درصد نیاز آبی) و کرت‌های فرعی به هیبریدهای ذرت (شامل دو هیبرید دیررس(KSC705, KSC704)، دو هیبرید متوسط‌رس (KSC500, KSC400) و دو هیبرید زودرس((DC370, KSC260) تخصیص داده شدند. نتایج نشان داد که عملکرد و اجزای عملکرد همه هیبریدها در مواجهه با شرایط کم-آبی، به طور معنی‌داری کاهش یافت، به‌طوری که در سال اول در هیبرید KSC705 (دیررس) و هیبرید KSC400 (متوسط‌ رس)، کاهش آبیاری از 100 به 60 درصد نیاز آبی، کاهش حدود 20 درصدی عملکرد را به دنبال داشت. در صورتی که در هیبرید زودرس کاهش آبیاری از 100 به 60 درصد نیاز آبی کاهش چندانی در عملکرد ایجاد نکرد. در سال دوم کاهش آبیاری از 100 به 60 درصد نیاز آبی در هیبرید KSC705 (دیررس)، KSC400 (متوسط‌ رس) و DC370 (زودرس) به ترتیب منجر به کاهش 24، 28 و 24 درصدی عملکرد شد. برتری عملکرد در هیبریدهای دیررس متاثر از برتری صفاتی مانند ارتفاع بوته، تعداد ردیف بلال، تعداد دانه در ردیف، وزن 300 دانه، شاخص برداشت و عملکرد زیست‌توده بود، با وجود این با اعمال کم‌آبیاری شدید، این برتری در بین هیبریدها معنی‌دار نبود. لذا به نظر می رسد که بتوان هیبریدهای دیررس را برای مناطق بدون محدودیت آب و هیبریدهای متوسط‌رس را برای شرایط با محدودیت آب استفاده کرد.

Characterization of Two Growth Period QTLs Reveals Modification of PRR3 Genes During Soybean Domestication.

Soybean yield is largely dependent on growth period. We characterized two growth period quantitative trait loci, Gp11 and Gp12, from a recombinant inbred population generated from a cross of wild (W05) and cultivated (C08) soybean. Lines carrying Gp11C08 and Gp12C08 tend to have a shorter growth period and higher expression of GmFT2a and GmFT5a. Furthermore, multiple interval mapping suggests that Gp11 and Gp12 may be genetically interacting with the E2 locus. This is consistent with the observation that GmFT2a and GmFT5a are activated by Gp11C08 and Gp12C08 at ZT4 in the recessive e2 but not the dominant E2 background. Gp11 and Gp12 are duplicated genomic regions each containing a copy of the soybean ortholog of PSEUDO RESPONSE REGULATOR 3 (GmPRR3A and GmPRR3B). GmPRR3A and GmPRR3B from C08 carry mutations that delete the CCT domain in the encoded proteins. These mutations were selected during soybean improvement and they alter the subcellular localization of GmPRR3A and GmPRR3B. Furthermore, GmPRR3A and GmPRR3B can interact with TOPLESS-related transcription factors, suggesting that they function in a transcription repressor complex. This study addresses previously unexplored components of the genetic network that probably controls the growth period of soybean and puts these loci into context with the well-characterized growth period-regulating E loci.

Tending of wild Heterosmilax yunnanensis

To minimize the predatory harvest of Heterosmilax yunnanensis and maintain the sustainable utilization of its resources, a study on the tending technology of wild H. yunnanensis was carried out. The results showed that the tuber tending model had a higher seed emergence rate, shorter growth period and easier control of male and female ratios than other tending models; by removing shrubs, topping, bending pruning, controlling insects and pests and other effective technical measures, the growth period of H. yunnanensis was shortened; the average annual net income of the tending area was 1 086 yuan/mu (1 mu≈666.67 m²), which was 86.9% higher than before. This study was conducive to increasing the yield and quality of H. yunnanensis in Karst landform area, and instructive for the tending of other wild traditional Chinese medicinal herbs in this area.

Helium and Argon Isotopes in the Fe-Mn Polymetallic Crusts and Nodules from the South China Sea: Constraints on Their Genetic Sources and Origins

In this study, the He and Ar isotope compositions were measured for the Fe-Mn polymetallic crusts and nodules from the South China Sea (SCS), using the high temperature bulk melting method and noble gases isotope mass spectrometry. The He and Ar of the SCS crusts/nodules exist mainly in the Fe-Mn mineral crystal lattice and terrigenous clastic mineral particles. The results show that the 3He concentrations and R/RA values of the SCS crusts are generally higher than those of the SCS nodules, while 4He and 40Ar concentrations of the SCS crusts are lower than those of the SCS nodules. Comparison with the Pacific crusts and nodules, the SCS Fe-Mn crusts/nodules have lower 3He concentrations and 3He/4He ratios (R/RA, 0.19 to 1.08) than those of the Pacific Fe-Mn crusts/nodules, while the 40Ar/36Ar ratios of the SCS samples are significantly higher than those of the Pacific counterparts. The relatively low 3He/4He ratios and high 40Ar concentrations in the SCS samples are likely caused by terrigenous detrital input with high radiogenic 4He and 40Ar contents. The SCS crusts and nodules have shorter growth periods, implying that in situ post-formation radiogenic 3He, 4He and 40Ar produced by decay of U, Th and K have no effect on their isotope compositions. Thus, the SCS crusts/nodules inherited the noble gases characteristics of their sources. Helium and Ar isotope compositions in the SCS Fe-Mn crusts and nodules reflect the product of an equilibrium mixture between air-saturated seawater and radiogenic components during their growth, while the partial 3He excess in some SCS samples may represent a little mantle-derived origin. The different He and Ar isotope compositions of the Fe-Mn crusts and nodules between the South China Sea and the Pacific Ocean are due to their different sources and genetic processes. The characteristics of He and Ar isotope compositions in the SCS polymetallic crusts and nodules are similar to the properties of hydrogenetic Fe-Mn oxide/hydroxide precipitates, which reflects mainly the product of an equilibrium mixture between air-saturated seawater and radiogenic components.

Green light drives photosynthesis in mosses

Temperate forests are characterised by variable light quality (i.e. spectral composition of light) at or near the forest floor. These understory environments have a high concentration of green light, as red and blue light are preferentially absorbed by upper canopy leaves. Understory species may be well-adapted for using green light to drive photosynthesis. Angiosperms have been shown to use green light for photosynthesis, but this ability has not been demonstrated in shade-dwelling bryophytes. In this study, net photosynthetic rate (PN) of three temperate understory species of moss (Dichodontium pellucidum (Hedw.) Schimp., Leucobryum albidum (Brid. ex P.Beauv) Lindb. and Amblystegium serpens (Hedw.) Schimp.) was measured under green, red + blue, and red + blue + green light to assess green light use efficiency. All three species were capable of photosynthesising beyond their respiratory demands using solely green light, with higher green light use efficiency measured in plants collected from areas with greater canopy cover, suggesting growth in a green light concentrated environment increases green light use efficiency. Each species was also collected from sites differing in their degree of canopy cover and grown under three light treatments (high light, low light, and green light). Photosynthetic efficiency (chlorophyll fluorescence), tissue nitrogen and carbon isotope concentrations were assessed after a short growth period. Growth conditions had little effect on leaf chemistry and monochromatic green light did not significantly degrade photosynthetic efficiency. This study provides the first evidence to date of positive net ‘green light photosynthesis’ in mosses.

Scratching Stimuli of Mycelia Influence Fruiting Body Production and ROS-Scavenging Gene Expression of Cordyceps militaris

The entomopathogenic fungus Cordyceps militaris is a valuable medicinal ascomycete, which degenerates frequently during subsequent culture. To avoid economic losses during industrialized production, scratching stimuli of mycelia was introduced to improve the fruiting body production. The present results indicated that higher yields and biological efficiency were obtained from two degenerate strains (YN1-14 and YN2-7) but not from g38 (an insertional mutant in Rhf1 gene with higher yields and shorter growth periods). Furthermore, the growth periods of the fruiting bodies were at least 5 days earlier when the mycelia were scratched before stromata differentiation. Three ROS-scavenging genes including Cu/Zn superoxide dismutase (CmSod1), Glutathione peroxidase (CmGpx), and Catalase A (CmCat A) were isolated and their expression profiles against scratching were determined in degenerate strain YN1-14 and mutant strain g38. At day 5 after scratching, the expression level of CmGpx significantly decreased for strain g38, but that of CmSod1 significantly increased for YN1-14. These results indicated that scratching is an effective way to promote fruiting body production of degenerate strain, which may be related at least with Rhf1 and active oxygen scavenging genes.

Natural variation in GmGBP1 promoter affects photoperiod control of flowering time and maturity in soybean.

The present study screened for polymorphisms in coding and non-coding regions of the GmGBP1 gene in 278 soybean accessions with variable maturity and growth habit characteristics under natural field conditions in three different latitudes in China. The results showed that the promoter region was highly diversified compared with the coding sequence of GmGBP1. Five polymorphisms and four haplotypes were closely related to soybean flowering time and maturity through association and linkage disequilibrium analyses. Varieties with the polymorphisms SNP_-796G, SNP_-770G, SNP_-307T, InDel_-242normal, SNP_353A, or haplotypes Hap-3 and Hap-4 showed earlier flowering time and maturity in different environments. The shorter growth period might be largely due to higher GmGBP1 expression levels in soybean that were caused by the TCT-motif with SNP_-796G in the promoter. In contrast, the lower expression level of GmGBP1 in soybean caused by RNAi interference of GmGBP1 resulted in a longer growth period under different day lengths. Furthermore, the gene interference of GmGBP1 also caused a reduction in photoperiod response sensitivity (PRS) before flowering in soybean. RNA-seq analysis on GmGBP1 underexpression in soybean showed that 94 and 30 predicted genes were significantly upregulated and downregulated, respectively. Of these, the diurnal photoperiod-specific expression pattern of three significant flowering time genes GmFT2a, GmFT5a, and GmFULc also showed constantly lower mRNA levels in GmGBP1-i soybean than in wild type, especially under short day conditions. Together, the results showed that GmGBP1 functioned as a positive regulator upstream of GmFT2a and GmFT5a to activate the expression of GmFULc to promote flowering on short days.

On the role of internal defects in the fatigue damage process of a cast Al-Si-Cu alloy

The effect of shrinkage pores and gas pores on the fatigue process of a secondary Al-Si-Cu-Fe alloy was analyzed by micro-computed tomography and scanning electron microscopy. Repeated CT-scans were performed in order to study the damage accumulation process. It was found that there are basically three different failure scenarios. In the first one, lifetime is determined by cracking of the dendritic branches bridging extended pores. This damage process will happen even at moderate load levels as these material bridges are exposed to high local loads. Lifetime in the second case is dominated by crack initiation from complex shaped gas pores followed by a short period of stable crack growth. Crack coalescence then becomes very likely, and failure is imminent. Finally, a two-stage crack growth process was observed for complex shaped shrinkage: fracture of the material bridges is followed by a phase of stable crack extension with the fatigue crack starting from one or several branches of the shrinkage pore. Estimate of the crack growth rate agree with previous results from the literature and confirm that the internal cracks grow much faster than expected long crack vacuum tests.

Silicon Nanowires as Sensory Material for Surface-Enhanced Raman Spectroscopy

This paper shows steps for silicon nanowires substrates synthesis in detail. The research is focused on experimental techniques optimization while the targeted application was a fabrication of highly sensitive substrates for surface-enhanced Raman spectroscopy (SERS). Horizontal silicon nanowires on top of two-inch wafers were obtained by vapour-liquid-solid growth inside the low-pressure chemical vapour deposition reaction tube. The silicon nanowires morphology was monitored by scanning electron microscope after a short and long growth period which defined an adequate deposition time for SERS applications. Surface-enhanced Raman spectroscopy features were tested on silver nanoparticles decorated substrates and the detection concentration limit of 10− 9 M of rhodamine 6G molecules was reached. Raman spectroscopy showed that the 532 nm laser excitation powers of less than 4 mW (∼0.57 kW/cm2) do not widen the phonon peak or shift its frequency and the nanostructure distribution parameter of 3.7 nm was calculated. The horizontally placed Ag decorated nanowires are proved to be sensitive substrates for surface-enhanced Raman spectroscopy only if the silicon nanowires thickness, length, volume density as well as metal nanoparticle size and distribution are carefully designed.

Primordial Regular Black Holes: Thermodynamics and Dark Matter

The possibility that dark matter particles could be constituted by extreme regular primordial black holes is discussed. Extreme black holes have zero surface temperature, and are not subjected to the Hawking evaporation process. Assuming that the common horizon radius of these black holes is fixed by the minimum distance that is derived from the Riemann invariant computed from loop quantum gravity, the masses of these non-singular stable black holes are of the order of the Planck mass. However, if they are formed just after inflation, during reheating, their initial masses are about six orders of magnitude higher. After a short period of growth by the accretion of relativistic matter, they evaporate until reaching the extreme solution. Only a fraction of 3.8 × 10−22 of relativistic matter is required to be converted into primordial black holes (PBHs) in order to explain the present abundance of dark matter particles.

Assessment of Reproductive Performance and Flock Composition of Small-houlders Sheep and Goat Production Systems Under Assiut Governorate

This study was aimed to recognize the reproductive performance and herd composition of sheep and goat in six studied area located in east and west river Nile at Assiut governorate. A set of semi-structured questionnaire was used to collect information from 300 sheep owners based on single-visit-interviews. The study revealed that farmers keep mixed livestock species. Sheep and goat production are the major livestock activity in located study area. The average farm size of households surveyed in Assiut Governoratewas 8.2 feddan. The farmers cultivated 50.74% and 50.86 % of their lands for green fodder and field crops in winter and summer, respectively. About 50.89 % of the total farm size area cultivated with animal fodder around the year. In summer 25.37%. Of the area was cultivated with field crops. The reproductive and productive performance of sheep and goats were discussed and data showed that, no significant differences were observed in lambing interval and age at first lambing between sheep and goats, while goats were significantly higher in litter size (P<0.01), lambing mortality (p<0.05) weaning weight (p<0.01) and age at marketing (p<0.05) than sheep. Generally, Sheep and goat production in the studied areas was constrained by different problems; where the major ones are availability and cost of feeds, limitation of land for the expansion of production and poor extension services. Sheep and goats are very important smallholder producers due to their biological factors such as short generation interval, twinning, short growth periods, do not require much space and low food requirements. In this domain, reasons of high lamb mortality rates should be identified and reduced in order to make sheep and goat production profitable and sustainable.

Fire tests on full-scale steel portal frames against progressive collapse

This paper presents experimental investigations on the collapse behavior of a full-scale 36 m × 12 m steel portal frame exposed to natural fires. Extensive thermal and structural responses of the frame are measured and presented. The frame collapses after 15-min fire exposure with a critical temperature of about 1100 °C in the heated column. The measured gas temperature history has a short growth period of 3 min, and reaches its peak temperature of 1100 °C within 8 min (400 °C higher than standard fire). It is found that a two-zone model can be assumed with uniform temperature distribution in the lower and upper half region, respectively. The temperature gap of these two zones reaches 200 °C. The gas temperature at top region decreases due to the deformation-induced opening of roof and fire walls. The surface facing the environment has higher gas temperatures than that inside the fire compartment (more than 200 °C). The temperature of rafters beyond the fire compartment reaches 700 °C due to the spread hot smoke. Outward bending of the external unexposed column and pulling out of corner column base are observed, which should be prevented in practical design to mitigate fire spread to adjacent buildings and ensure life safety of fire fighters. Numerical simulation is conducted and compared to experimental results which can be used for calibrating numerical models.