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181.
南方建筑非透明围护结构热工与节能设计 总被引：1，自引：0，他引：1
如何兼顾冬夏两季建筑供暖空调负荷和能耗,保证室内热环境质量,确定最适宜的热工特性,是长期困扰中国南方建筑围护结构热工与节能设计的难点。通过对夏热冬冷和夏热冬暖地区建筑在采暖、空调与自然通风条件下动态热过程的分析,研究了这一地区围护结构热特性与能耗的制约关系,以及对室内热环境与建筑热稳定性的作用机理。在兼顾冬季保温与夏季隔热的情况下,将建筑全年能耗作为控制目标,从室内热环境质量、节能效果、围护结构的安全性、可靠性、经济性和实用性等角度评价目前所采用的围护结构节能技术存在的问题,提出一种适宜南方气候的建筑围护结构热特性指标及构造形式。 相似文献
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Y. M. Guo N. C. Turner S. Chen M. N. Nelson K. H. M. Siddique W. A. Cowling 《Journal of Agronomy and Crop Science》2015,201(4):267-279
Brassica rapa L. is a genetically diverse parent species of the allotetraploid species, oilseed rape (B. napus) and a potential source of drought tolerance for B. napus. We examined the effect of a 13‐day drought stress period during the early reproductive phase, relative to a well‐watered (WW) control, on subsequent growth and development in nine accessions of B. rapa and one accession of Brassica juncea selected for their wide morphological and genetic diversity. We measured leaf water potential, stomatal conductance, water use, and leaf and bud temperatures during the stress period and aboveground dry weight of total biomass at maturity. Dry weight of seeds and reproductive tissue were not useful measures of drought tolerance due to self‐incompatibility in B. rapa. The relative total biomass (used as the measure of drought tolerance in this study) of the 10 accessions exposed to drought stress ranged from 47 % to 117 % of the WW treatment and was negatively correlated with leaf‐to‐air and bud‐to‐air temperature difference when averaged across the 13‐day stress period. Two wild‐type (B. rapa ssp. sylvestris) accessions had higher relative total and non‐reproductive biomass at maturity and cooler leaves and buds than other types. We conclude that considerable genotypic variation for drought tolerance exists in B. rapa and cooler leaves and buds during a transient drought stress in the early reproductive phase may be a useful screening tool for drought tolerance. 相似文献
184.
J. Li L.‐Q. Wu W.‐Y. Zheng R.‐F. Wang L.‐X. Yang 《Journal of Agronomy and Crop Science》2015,201(5):379-388
MicroRNAs (miRNAs) are known to play important roles in plant growth and stress response. Heat stress is a severe abiotic stresses by adversely affecting plant growth and yield. To identify heat‐responsive miRNAs at the genome‐wide level in rice (Oryza sativa), we constructed two small RNA libraries from young panicles treated or not with heat conditions. Ion torrent sequencing of the two libraries identified 294 known miRNAs and 539 novel miRNAs. Differential expression analysis showed that 26 miRNAs were downregulated and 21 miRNAs were upregulated in response to heat stress. Among them, five heat‐responsive miRNAs, including miR162b, miR529a‐p5, PC‐5P‐62245‐9, miR171b and miR169n, were validated by quantitative real‐time polymerase chain reaction. A total of 44 target genes of the differentially expressed miRNAs were predicted. These target genes are most significantly overrepresented in the cell growth process. The results demonstrated that rice miRNAs play critical roles in the heat stress response. This study opens up a new avenue for understanding the regulatory mechanisms of miRNAs involvement in the heat stress response in rice. 相似文献
185.
M. Rokebul Anower M. D. Peel I. W. Mott Y. Wu 《Journal of Agronomy and Crop Science》2017,203(6):506-518
We previously reported an alfalfa half‐sib family, HS‐B, with improved salt tolerance, compared to parental plants, P‐B. In this study, we conducted additional experiments to address potential physiological mechanisms that may contribute to salt tolerance in HS‐B. Vegetatively propagated HS‐B and P‐B plants were treated with a nutrient solution (control) or a nutrient solution containing NaCl (EC = 12 dS/m). Shoots and roots were harvested at various time points after treatment for quantification of proline, soluble sugar, and H2O2 using spectrophotometers. Subcellular localization and quantification of Na in roots were conducted using a Na+‐specific dye under a confocal microscope. HS‐B produced 86 and 89% greater shoot and root dry biomass, respectively, compared to parental plants, P‐B, under salinity in the greenhouse. Under saline conditions the HS‐B shoots accumulated 115% and roots 55% more soluble sugars than P‐B counterparts. The non‐saline HS‐B shoots, however, showed 72% less soluble sugars than the non‐saline P‐B plants. Under saline conditions HS‐B accumulated 39% less proline in shoots, while roots accumulated 56% more proline, compared to their P‐B parents. HS‐B plants also showed a greater reduction of stomatal conductance under mild saline stress. HS‐B shoots and roots contained 3–4 times less reactive oxygen species (H2O2) after salt treatment compared to P‐B plants. Sodium localization and distribution analysis using Na+‐specific dye revealed HS‐B plants accumulated 88% and 48% less Na+ in stele and xylem vessels compared to P‐B. The study provides insights into the potential mechanisms that may contribute to salt tolerance in HS‐B: maintaining RWC by accumulating soluble sugars while reducing transpiration, maintaining healthy status by reducing oxidative stresses, and preventing salt toxicity by reducing accumulation of Na+ inside root cells and xylem. 相似文献
186.
J.-D. Lee J. G. Shannon Y.-S. So D. A. Sleper R. L. Nelson J.-H. Lee M.-G. Choung 《Plant Breeding》2009,128(1):97-100
Lutein is a major carotenoid in soybean [ Glycine max (L.) Merr.] seed, and has been shown to be beneficial for eye health in humans. Development of soybeans high in lutein is a goal of some breeding programmes. Little is known about how different growing environments affect lutein content. The objective of this study was to determine the variation of lutein and its relationship to seed protein, oil and individual fatty acids in soybean seed. Fifteen soybean genotypes were planted at four environments. There was no effect of year and planting date on lutein content in soybean seed. However, genotype × year, genotype × planting date and genotype × year × planting date were significant for lutein content. Although each genotype showed similar response across environments, lutein content varied significantly across the four growing environments in 14 of the 15 genotypes evaluated. Lutein content was not correlated with seed protein or oil and palmitic or stearic acid concentrations. However, lutein was positively correlated with oleic acid content and negatively correlated with linoleic and linolenic acids content. 相似文献
187.
Compared with hexaploid wheat, tetraploid durum is more susceptible to Fusarium crown rot (FCR) infection. The feasibility of enhancing FCR resistance in durum wheat by introgressing chromosome segments of hexaploid wheat was investigated by generating and analysing a backcross population derived from a susceptible durum wheat variety ??Bellaroi?? (recurrent parent) and a resistant hexaploid genotype ??CSCR6?? (donor parent). Together with a few scattered segments on various chromosomes, segments of a large section of the donor chromosome 6B showed a significant effect in enhancing FCR resistance in the durum background. However, a known major locus on the donor 3BL conferring high level of resistance to FCR in hexaploid wheat failed to provide any improvement in resistance than that of the genome average once it was introduced into the durum wheat. A small proportion of the backcross population gave similar resistance to the bread wheat variety ??Kennedy??, a level of FCR resistance acceptable to durum growers. These lines share a 4B segment from the hexaploid donor, although the segment was not among those with the largest individual effect across the whole population. These results show that it is feasible to improve FCR resistance of durum wheat by exploiting hexaploid chromosome segments, although resistance loci of the hexaploid wheat may not function properly in durum backgrounds. 相似文献
188.
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190.
CS‐B14Sh and CS‐B22Sh are cotton interspecific chromosome substitution (CS)‐B lines, in which a pair of short arms of chromosome 14 and chromosome 22 were introgressed from Gossypium barbadense doubled‐haploid line 3‐79 with the background of Gossypium hirsutum line TM‐1, respectively. These two CS‐B lines were crossed with TM‐1, and segregating progenies (F2 and F2:3, respectively) were obtained. Phenotypic data of lint yield, yield‐related traits and fibre‐quality traits were collected from two trials. In the cross CS‐B14SH X TM‐1, QTL for boll weight (BW), lint percentage (LP), fibre upper half mean length (UHML), micronaire reading (MIC), and fibre breaking tensile strength (STR) were repeatedly detected. Alleles from 3‐79 decreased BW and MIC, but increased UHML and STR. In the cross CS‐B22Sh X TM‐1, QTL for BW, LP, UHML, MIC, STR, fibre elongation (EL),seed weight(SW), node of first fruiting branch (NFB) and fibre uniformity index (UI) were repeatedly detected, and alleles from 3‐79 decreased UHML, UI and STR, but increased NFB, SW, MIC and EL. QTL clusters were found in both populations. 相似文献