首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 54 毫秒
1.
To investigate the interactive effects of drought, heat and elevated atmospheric CO2 concentration ([CO2]) on plant water relations and grain yield in wheat, two wheat cultivars with different drought tolerance (Gladius and Paragon) were grown under ambient and elevated [CO2], and were exposed to post‐anthesis drought and heat stress. The stomatal conductance, plant water relation parameters, abscisic acid concentration in leaf and spike, and grain yield components were examined. Both stress treatments and elevated [CO2] reduced the stomatal conductance, which resulted in lower leaf relative water content and leaf water potential. Drought induced a significant increase in leaf and spike abscisic acid concentrations, while elevated [CO2] showed no effect. At maturity, post‐anthesis drought and heat stress significantly decreased the grain yield by 21.3%–65.2%, while elevated [CO2] increased the grain yield by 20.8% in wheat, which was due to the changes of grain number per spike and thousand grain weight. This study suggested that the responses of plant water status and grain yield to extreme climatic events (heat and drought) can be influenced by the atmospheric CO2 concentration.  相似文献   

2.
This study investigated trade-offs between parameters determining water use efficiency of wheat under elevated CO2 in contrasting growing seasons and a semi-arid environment. We also evaluated whether previously reported negative relationships between nutrient content and transpiration efficiency among wheat genotypes will be maintained under elevated CO2 conditions. Two cultivars of wheat (Triticum aestivum L.), Scout and Yitpi, purportedly differing in water use efficiency related traits (e.g. transpiration efficiency) but with common genetic backgrounds were studied in a high yielding, high rainfall (2013), and in a low yielding, very dry growing season (2014) under Free-Air CO2 Enrichment (FACE, CO2 concentration of approximately 550 μmol mol−1) and ambient (approximately 390 μmol mol−1) CO2. Gas exchange measurements were collected diurnally between stem elongation and anthesis. Aboveground biomass and nutrient content (sum of Ca, K, S, P, Cu, Fe, Zn, Mn and Mg) were determined at anthesis. Yield, yield components and harvest index were measured at physiological maturity. Cultivar Scout showed transiently greater transpiration efficiency (measured by gas exchange) over cultivar Yitpi under both ambient and elevated CO2 conditions, mainly expressed in the high yielding but not in the low yielding season. Nutrient content was on average 13% greater for the lower transpiration efficiency cultivar Yitpi than the cultivar with higher transpiration efficiency (Scout) in the high yielding season across both CO2 concentrations. Elevated CO2 stimulated grain yield to a greater extent in the high yielding season than in the low yielding season where increased aboveground biomass earlier in the season did not translate into fertile tillers in cultivar Yitpi. Yield increased 27 and 33% in the high yielding and 0 and 19% in the low yielding season for cultivars Yitpi and Scout, respectively. Intraspecific variation in CO2 responsiveness related mechanisms of grain yield were observed. These results suggest CO2-driven trade-offs between traits governing water use efficiency are related to both growing season and intraspecific variations, and under very dry finishes, the trade-offs may even reverse. The negative relationship between nutrient content and transpiration efficiency among wheat genotypes will be maintained under elevated CO2 conditions.  相似文献   

3.
Despite its economic and environmental importance, information about effects of future atmospheric carbon dioxide (CO2) enrichment on aboveground biomass production and tuber yield of potato is still rare. Responses of potato (Solanum tuberosum L. cv. Bintje) were thus investigated in two full growing seasons under 380, 550 or 680 μmol mol?1 CO2 in open-top chambers (OTCs). When averaged over both years, aboveground stem biomass at canopy maturity was negatively related to CO2 enrichment. Aboveground-to-belowground biomass ratio was negatively related to CO2 enrichment as there was a positive relationship between CO2 and total dry yield of potato tubers. The stimulation was mainly related to an increase in the tuber size fraction for commercial yield (tubers > 35 mm). For the largest size class (tubers > 50 mm), which is important for industrial processing, large CO2-induced impacts were observed too, although these effects were not significant. Elevated CO2 concentrations will thus affect biomass allocation of potato plants and result in improvements concerning the market value of the commercial tuber yield.  相似文献   

4.
The increase in atmospheric CO2 concentration [CO2] has been demonstrated to stimulate the growth of C3 crops. However, little information exists about the effect of elevated [CO2] on biomass production of sugar beet, and data from field experiments are lacking. In this study, sugar beet was grown within a crop rotation over two rotation cycles (2001, 2004) at present and elevated [CO2] (375 μl l?1 and 550 μl l?1) in a free air CO2 enrichment (FACE) system and at two levels of nitrogen supply [high (N2), and 50% of high (N1)], in Braunschweig, Germany. The objective of the present study was to determine the CO2 effect on seasonal changes of leaf growth and on final biomass and sugar yield. Shading treatment was included to test whether sugar beet growth is sink limited under elevated [CO2]. CO2 elevation did not affect leaf number but increased individual leaf size in early summer resulting in a faster row closure under both N levels. In late summer CO2 enrichment increased the fraction of senescent leaves under high but not low N supply, which contributed to a negative CO2 effect on leaf area index and canopy chlorophyll content under high N at final harvest. Petioles contained up to 40% water-soluble carbohydrates, which were hardly affected by CO2 but increased by N supply. More N increased biomass production by 21% and 12% in 2001 and 2004, respectively, while beet and sugar yield was not influenced. Concentration of α-amino N in the beet fresh weight was increased under low N and decreased under high N by CO2 enrichment. The CO2 response of total biomass, beet yield and white sugar yield was unaffected by N supply. Averaged over both N levels elevated [CO2] increased total biomass by 7% and 12% in 2001 and 2004, respectively, and white sugar yield by 12% and 13%. The shading treatment in 2004 prevented the decrease in leaf area index under elevated [CO2] and high N in September. Moreover, the CO2 effect on total biomass (24%) and white sugar yield (28%) was doubled as compared to the unshaded conditions. It is concluded that the growth of the storage root of sugar beet is not source but sink limited under elevated [CO2], which minimizes the potential CO2 effect on photosynthesis and beet yield.  相似文献   

5.
Elevated CO2 stimulates crop yields but leads to lower tissue and grain nitrogen concentrations [N], raising concerns about grain quality in cereals. To test whether N fertiliser application above optimum growth requirements can alleviate the decline in tissue [N], wheat was grown in a Free Air CO2 Enrichment facility in a low‐rainfall cropping system on high soil N. Crops were grown with and without addition of 50–60 kg N/ha in 12 growing environments created by supplemental irrigation and two sowing dates over 3 years. Elevated CO2 increased yield and biomass (on average by 25%) and decreased biomass [N] (3%–9%) and grain [N] (5%). Nitrogen uptake was greater (20%) in crops grown under elevated CO2. Additional N supply had no effect on yield and biomass, confirming high soil N. Small increases in [N] with N addition were insufficient to offset declines in grain [N] under elevated CO2. Instead, N application increased the [N] in straw and decreased N harvest index. The results suggest that conventional addition of N does not mitigate grain [N] depression under elevated CO2, and lend support to hypotheses that link decreases in crop [N] with biochemical limitations rather than N supply.  相似文献   

6.
Location specific adaptation option is required to minimize adverse impact of climate change on rice production. In the present investigation, we calibrated genotype coefficients of four cultivars in the CERES-Rice model for simulation of rice yield under elevated CO2 environment and evaluation of the cultivar adaptation in subtropical India. The four cultivars (IR 36, Swarna, Swarn sub1, and Badshabhog) were grown in open field and in Open Top Chamber (OTC) of ambient CO2 (≈390 ppm) and elevated CO2 environment (25% higher than the ambient) during wet season (June–November) of the years 2011 and 2012 at Kharagpur, India. The genotype coefficients; P1 (basic vegetative phase), P2R (photoperiod sensitivity) and P5 (grain filling phase) were higher, but G1 (potential spikelet number) was lower under the elevated CO2 environment as compared to their open field value in all the four cultivars. Use of the calibrated model of elevated CO2 environment simulated the changes in grain yield of −13%, −17%, −4%, and +7% for the cultivars IR 36, Swarna, Swarna sub1, and Badshabhog, respectively, with increasing CO2 level of 100 ppm and rising temperature of 1 °C as compared to the ambient CO2 level and temperature and they were comparable with observed yield changes from the OTC experiment. Potential impacts of climate change were simulated for climate change scenarios developed from HadCM3 global climate model under the Intergovernmental Panel on Climate Change Special Report on Emission Scenarios (A2 and B2) for the years 2020, 2050, and 2080. Use of the future climate data simulated a continuous decline in rice grain yield from present years to the years 2020, 2050 and 2080 for the cultivars IR 36 and Swarna in A2 as well as B2 scenario with rising temperature of ≥0.8 °C. Whereas, the cultivar Swarna sub1 was least affected and Badshabhog was favoured under elevated CO2 with rising temperature up to 2 °C in the sub-tropical climate of India.  相似文献   

7.
Atmospheric CO2 enrichment affects C3 crops both directly via increased carbon gain and improved water use efficiency and indirectly via higher temperatures and more frequent climatic extremes. Here we investigated the response of spring wheat (Triticum aestivum L. cv. Triso) to CO2 enrichment (550 vs. 380 µmol/mol) and heat, applied as a constant +4°C increase or a typical heat wave either before or after anthesis, or as two typical heat waves before and after anthesis. We applied a climate chamber approach closely mimicking ambient conditions. CO2 enrichment increased above‐ground biomass and yield by c. 7 and 10%, but was not able to compensate for adverse heat stress effects, neither before nor after anthesis, with few exceptions only. Yield depression due to heat stress was most severe when two heat waves were applied (?19%). This adverse effect was, however, compensated by CO2 enrichment. Applying heat stress before or after anthesis did not exert different effects on yield for both +4°C warming and heat wave application. However, +4°C depressed yield more than a heat wave at ambient CO2, but not so at elevated CO2. Thus, the interactive effects were complex and prediction of future wheat yield under CO2 enrichment and climate extremes deserves more attention.  相似文献   

8.
Anthropogenic increases in atmospheric carbon dioxide concentration [CO2], and subsequent increases in surface temperatures, are likely to impact the growth and yield of cereal crops. One potential means for yield reduction is for climate parameters to increase the occurrence of lodging. Using an in situ free-air CO2 enrichment (FACE) system, two morphologically distinct rice cultivars, KH (Koshihikari) and SY (Shan you 63), were grown at two [CO2]s (ambient and ambient + 200 μmol mol−1) and two soil temperatures (ambient and ambient ± 1.8 °C) over a two year period to assess and quantify lodging risk. Elevated [CO2] per se had no effect on lodging resistance for either cultivar. However, elevated [CO2] and higher soil temperature increased the lodging risk for SY, due to a relatively higher increase in plant biomass and height at the elevated, relative to the ambient [CO2] condition. Elevated soil temperature per se also increased lodging risk for both cultivars and was associated with longer internodes in the lower portion of the tillers. These findings illustrate that lodging susceptibility in rice, an important cereal crop, can be increased by rising [CO2] and soil temperature; however, variation observed here between rice cultivars suggests there may be sufficient intraspecific variability to begin choosing rice lines that minimize the potential risk of lodging.  相似文献   

9.
张磊  吕金印  贾少磊 《作物学报》2013,39(8):1514-1519
为明确干旱胁迫对小麦穗部花前同化物合成和转运的影响,选用旱地品种西农928和水分敏感品种郑引1号,通过14CO2标记技术研究了水分亏缺下穗部光合特性及穗部花前同化物的转运和分配规律。水分亏缺条件下,西农928灌浆前期、中期的穗部净光合速率、颖壳中叶绿素含量及可溶性总糖含量略有下降,而郑引1号显著下降。成熟期西农928的水分利用效率上升1.7% (P>0.05),籽粒中14C-同化物分配率略降3.2% (P>0.05);而郑引1号水分利用效率下降16.9% (P<0.05),籽粒中花前14C-同化物分配率上升7.8% (P<0.05)。试验表明,水分亏缺对西农928穗部光合的影响有限; 适度水分亏缺促进了水分敏感品种郑引1号颖壳及内外稃中花前14C-同化物向籽粒的转运, 相对提高了其穗部花前光合同化物对籽粒灌浆的贡献率。  相似文献   

10.
Thermometry and thermography are alternative methods used for measuring stomatal conductivity via transpirative cooling. However, the influence of mixed soil–plant information contained in thermal images compared to thermometric spot measurements on the measurement quality and relationships to agronomic traits remains unclear. To evaluate their respective influence, canopy temperature was measured simultaneously by two infrared thermometers (thermometry), which were oriented oblique to the plant canopy and mounted on a tractor, and a hand‐held, nadir oriented thermal camera (thermography) in irrigated and drought‐stressed spring barley cultivar trials in 2011. Canopy temperatures were separated from soil temperatures and extracted from the thermal images by matching thermal and RGB images. Thermometric measurements conducted at the beginning of shooting during a stable period of high radiation were more closely related to total plant biomass and straw yield at harvest than thermography under both irrigated and drought‐stressed conditions. Taking into account the results of this evaluation, thermometry was used for assessing the agronomic importance of stomatal sensitivity, the earliness of stomatal closure, of spring barley cultivars subjected to different water supply in 2013. In this year, 16 spring barley cultivars were grown under mild drought stress and rainfed conditions. A stomatal sensitivity index was derived relating canopy temperatures of the cultivars grown under rainfed and drought‐stressed conditions to each other. Under rainfed conditions, stomatal sensitivity was negatively related to grain protein yield with a coefficient of determination of R2 = .43. Under increasing terminal drought stress, positive regression slopes of stomatal sensitivity to grain yield, biomass yield and culms/m2 were observed with coefficients of determination amounting to R2 = .22, .31 and .36, respectively. Stomatal sensitivity negatively impacts agricultural production under well‐watered conditions, but maintains productivity under conditions of terminal drought.  相似文献   

11.
The leaf subtending to a cotton boll (LSCB) is vital to boll development and biomass, but few studies have examined the effects of drought on the source capacity of LSCBs on different fruiting branches (FBs). To investigate the response of LSCB photosynthesis on different FBs and the relationship of boll biomass to drought, a drought experiment was performed with three treatments: well‐watered (WW, soil water relative content [SRWC] 75 ± 5%), mild drought (MD, SRWC 60 ± 5%), and severe drought (SD, SRWC 45 ± 5%). Despite photosynthetic active radiation increasing under drought conditions, the pre‐dawn leaf water potential, net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and maximum quantum yield in PSII (Fv/Fm) under MD and SD significantly decreased when compared with WW, with a more pronounced decrease observed on upper FBs. Additionally, the maximum sucrose and hexose levels in LSCBs increased under drought conditions, whereas the maximum starch content decreased on FB10–11, but showed a varied trend on FB2–3 and FB6–7. Although carbohydrate levels in the LSCBs increased, biomass per cotton boll decreased. More importantly, the ratio of cotton boll biomass was significantly correlated to the maximum sucrose content ratio on each FB, indicating that sucrose allocation was important to cotton boll biomass. Cotton boll biomass notably decreased on upper FBs, but was maintained on lower FBs, indicating that drought promoted carbon allocation in older bolls. Thus, LSCBs and cotton bolls on upper FBs were more affected under drought conditions due to decreased photosynthesis and carbohydrate allocation.  相似文献   

12.
Atmospheric CO2 concentrations ([CO2]) are predicted to increase from current levels of about 400 ppm to reach 550 ppm by 2050. The direct benefits of elevated [CO2] (e[CO2]) to plant growth appear to be greater under low rainfall conditions, but there are few field (Free Air CO2 Enrichment or FACE) experimental set-ups that directly address semi-arid conditions. The objectives of this study were to investigate the following research questions: 1) What are the effects of e[CO2] on the growth and grain yield of lentil (Lens culinaris) grown under semi-arid conditions under FACE? 2) Does e[CO2] decrease grain nitrogen in lentil? and 3) Is there genotypic variability in the response to e[CO2] in lentil cultivars? Elevated [CO2] increased yields by approximately 0.5 t ha−1 (relative increase ranging from 18 to 138%) by increasing both biomass accumulation (by 32%) and the harvest index (by up to 60%). However, the relative response of grain yield to e[CO2] was not consistently greater under dry conditions and might depend on water availability post-flowering. Grain nitrogen concentration was significantly reduced by e[CO2] under the conditions of this experiment. No differences were found between the cultivars selected in the response to elevated [CO2] for grain yield or any other parameters observed despite well expressed genotypic variability in many traits of interest. Biomass accumulation from flowering to maturity was considerably increased by elevated [CO2] (a 50% increase) which suggests that the indeterminate growth habit of lentils provides vegetative sinks in addition to reproductive sinks during the grain-filling period.  相似文献   

13.
In semi‐arid areas of north‐west China, grain yields of wheat (Triticum aestivum L.) are higher in recently bred cultivars than those released six decades earlier. The gas exchange, chloroplast activity and yield of six spring wheat cultivars grown in the 1950s, Hst and Gs96 (early), in the 1970s, Gy602 and Dx24 (intermediate), and in the 1990s, Gc20 and Lc8275 (modern) were compared with adequate water (WET) and drought stress (DRY) to determine the effects of drought stress among the cultivars. The results showed that in the WET treatment, the modern cultivars had significantly higher rates of leaf gas exchange, photosystem 2 (PS2) maximal photochemical efficiency, actual quantum yield of PS2 (ФPS2), photochemical quenching of chlorophyll (qp) and lower non‐photochemical quenching (NPQ) than early cultivars, but had significantly lower gas exchange rates, intercellular CO2 concentration, ФPS2, qp and NPQ in the DRY treatment. In the WET treatment, the grain yield of early cultivars was significantly lower (10 %) than intermediate cultivars, but was significantly higher (17 %) than intermediate cultivars in the DRY treatment. The modern and intermediate cultivars had more sensitive stomata to water shortage, but the decreased activity of the PS2 reaction centre helped avoid damage from photoinhibition in these cultivars.  相似文献   

14.
One of the major goals of the European Stress Physiology and Climate Experiment (ESPACE-wheat) was to investigate the sensitivity of wheat growth and productivity to the combined effects of changes in CO2 concentration, ozone and other physiological stresses. Experiments were performed at different sites throughout Europe, over three consecutive growing-seasons using open-top chambers. This paper summarizes the main experimental findings of the effects of CO2 enrichment and other factors i.e. ozone (O3), drought stress or nitrogen supply on the biomass and yield of spring wheat (Triticum aestivum cv. Minaret). Final harvest data from different sites and seasons were statistically analysed: (1) to identify main effects and interactions between experimentally controlled factors; and (2) to evaluate quantitative relationships between environmental variables and biological responses. Generally, ‘Minaret’ wheat did not respond significantly to O3, suggesting that this cultivar is relatively tolerant to the O3 levels applied. The main effect of CO2 was a significant enhancement of grain yield and above-ground biomass in almost all experiments. Significant interactions between CO2 and other factors were not common, although modifications in different N- and water supplies also led to significant effects on grain yield and biomass. In addition, climatic factors (in particular: mean air temperature and global radiation) were identified as important co-variables affecting grain yield or biomass, repectively. On average, the yield increase as a result of a doubling of [CO2] was 35% compared with that observed at ambient CO2 concentrations. However, linear regressions of grain yield or above-ground biomass for individual experiments revealed a large variability in the quantitative responses of ‘Minaret’ wheat to CO2 enrichment (yield increase ranging from 11 to 121%). Hence, CO2 responsiveness was shown to differ considerably when the same cultivar of wheat was grown at different European locations. Multiple regression analyses perfomed to evaluate the relative importance of the measured environmental parameters on grain yield indicated that although yield was significantly related to five independent variables (24 h mean CO2 concentration, 12 h mean O3 concentration, temperature, radiation, and drought stress), a large proportion of the observed variability remained unexplained.  相似文献   

15.
Translocations of the short arm of rye (Secale cereale L.) chromosome 1 (1RS) in wheat (Triticum aestivum L. cv. Pavon 76) are known to increase root biomass. Such an increase enhances water and nutrient uptake and may improve grain yield. Two greenhouse experiments and a field experiment were carried out at the University of California, Riverside, in 2012 and 2013 under well‐watered and terminal drought treatments to evaluate phenotypic characters associated with varying dosages of 1RS, including grain yield. The genotypes used were cultivar Pavon 76 (R0), Pavon 76/Pavon1RS.1AL (F1 hybrid) with a single dosage of 1RS (R1A), Pavon 1RS.1AL with two dosages of 1RS (R2A), Pavon 1RS.1DL (R2D) also with two dosages of 1RS and Pavon 1RS.1AL‐1RS.1DL (R4AD) with four dosages of 1RS. There was a significant positive correlation between number of dosages of 1RS and root biomass. However, no correlation was found between root biomass and grain yield per plant. Drought in the field experiment reduced grain yield significantly. Under well‐watered field conditions, grain yield of R2A (215.9 g plant?1) was significantly greater than those of R2D (191.8 g plant?1) and R4AD (161.7 g plant?1). Also, grain yield of R4AD was significantly less than those of F1, Pavon 76 and R2D under well‐watered conditions. Under drought field conditions, no significant differences were found among the genotypes for grain yield was found between F1 (14.7 g plant?1) and R4AD (12.4 g plant?1). Harvest index was significantly greater in well‐watered (44.2 %) than in drought (34.6 %) field conditions. On average, genotypes F1 (42.3 %) and R2A (40.6 %) had higher harvest index than R2D (38.3 %) and R4AD (35.5 %) in the field. Also, Pavon 76 (40.2) and R2D (38.3) had higher harvest index than R4AD. Drought tolerance was lowest for R4AD due to its relatively lower grain yield potential. In general, Pavon 1RS.1AL carrying two dosages of 1RS showed higher grain yield under wet treatments. Pavon 1RS.1AL‐1RS.1DL carrying four dosages of 1RS produced the largest shoot and root biomasses, but the least grain yield.  相似文献   

16.
普通菜豆抗旱生理特性   总被引：6，自引：1，他引：5  
采用盆栽试验,以抗旱性较好的品种跃进豆、260205和敏感品种奶花芸豆为试材,设置干旱和正常供水2种处理,测定产量、产量构成因素及相关生理生化指标,分析干旱胁迫下参试品种各性状及生理指标的变化及对干旱胁迫的生理响应。结果表明,干旱处理36 d,跃进豆和260205的根干重为总生物量的20.2%和20.6%,荚干重为总生物量的30.0% 和28.9%,而奶花芸豆的根干重和荚干重仅为总生物量的10.6%和17.1%,光合产物向根系和籽粒的有效分配与普通菜豆抗旱性关系密切;跃进豆在干旱胁迫后期的水分利用效率较对照增加 230.5%,而奶花芸豆的增幅仅为84.3%,较高的水分利用效率有利于CO2的有效扩散和高效固定;其他生理特性分析表明,抗氧化酶与光呼吸共同作用有效降低了膜脂过氧化程度,减少了叶片的损伤;脯氨酸和可溶性糖是普通菜豆主要的渗透调节物质,能够较好地保持自身叶片的水分平衡。普通菜豆抗旱性是多种生理调节机制协同作用的结果,主要包括形态调节、气孔调节、渗透调节以及抗氧化能力的调节等。  相似文献   

17.
Earlier studies showed that the ratio of the weight of the wheat ear to stem at anthesis (ear:stem ratio) may give a better indication of potential yield than harvest index because it is determined early in the life cycle and is not affected by post anthesis stress. These studies concluded that selection for high ear:stem ratio at anthesis may lead to further improvement in grain yield of wheat. The present work was undertaken in the field to identify lines varying in ear:stem ratio in breeding populations and to study its implications for yield improvement.At anthesis stem length, ear length, tiller number, dry weight of stem and ear and ear:stem ratio were measured in 14 crosses on F2 single plants and F2 derived lines grown in the F3, F4, and F5 at three locations in Western Australia over four seasons. In addition, biomass, grain yield and yield components were measured on selected crosses at two locations on F2 derived lines grown in the F4 and F5. There was a considerable range of ear:stem ratio between and within the crosses studied. Although ear:stem ratio was strongly correlated with stem length, there was substantial variation within stem length classes. Ear:stem ratio had a high mean broad sense heritability (82%), whereas HI, grain yield and above ground biomass had lower heritabilities, 68, 55 and 35% respectively. Ear:stem ratio was strongly correlated between generations and sites indicating stability of this character. Ear:stem ratio had a significant positive correlation with grain yield, HI, grains per ear and per m2. The correlation of grain yield with HI was equal or slightly higher than that of grain yield with ear:stem ratio.Ear:stem ratio offers promise as a predictor of HI and yield potential where post-anthesis moisture stress can influence HI. Ear:stem ratio measurement is unlikely to be adopted for selection purposes in routine breeding programs, as it is laborious and time consuming. However, ear:stem ratio could be used to identify superior parental genotypes and early generation selections from special crosses in terms of its ability to partition assimilate.  相似文献   

18.
Rising atmospheric CO2 concentration ([eCO2]) increases the yield of wheat mainly by increasing grain number, but effects on single grain weight are variable. It is discussed whether single grain growth is limited by the sink or the source size under a non-stress environment. This study explores the effect of e[CO2] combined with varying N supply on the source and sink size during grain filling. Source size was defined as the amount of stem reserves per grain (SRG) and the proportion of incident radiation intercepted by the green canopy per grain (fIRG) at anthesis. Data from a 2-year free-air CO2 enrichment experiment with wheat with three N levels (on average 38 [Nd], 190 [Nad] and 320 kg N ha−1 [Nex]) and two CO2 levels (393 and 600 ppm) on SRG, fIRG and grain filling rate (GFR) and duration (GFD) were evaluated. SRG ranged from 2.5 to 12.9 mg and fIRG from 4.0 × 0.001% to 6.8 x 0.001%. Rising N supply or e[CO2] decreased SRG and fIRG via their increases in grain number. Accordingly, there was a negative linear relationship between grain number and SRG (r2 ≥ 0.84) or fIRG (r2 ≥ 0.97). Increasing N supply decreased GFR, but increased GFD, and GFR was increased by e[CO2] under Nad and Nex. For GFR and final grain weight, there was a strong positive (r2 ≥ 0.85), and for GFD, a strong negative linear relationship (r2 ≥ 0.76) with fIRG under Nad and Nex. Under these N levels, fIRG supplied the largest share (>86%) for grain growth and thus single grain growth was possibly source limited under Nad and Nex. Under high grain number such as under Nex and e[CO2], there might be a risk for low final grain weight due to the low SRG that is insufficient for buffering assimilate shortage under unfavourable environmental conditions in early grain filling.  相似文献   

19.
Drought stress is one of the most important abiotic factors which adversely affect growth, metabolism and yield of crops worldwide. The objective of this study was to determine the effects of drought stress on photosynthesis in barley and examine the differential responses of photosynthetic apparatus in relatively tolerant (Yousof) and susceptible (Morocco) barley genotypes. Plants were subjected to different levels of soil water availability including control, mild and severe drought stress. In both genotypes, drought stress led to decrease in chlorophylls, β‐carotene and stomatal conductance accompanied by decrease in CO2 assimilation rate. Significant increase in α‐tochoperol content was only observed in Yousof cultivar under drought stress. Initial slope and plateau phase of CO2 response curve of drought‐stressed plants as well as polyphasic chlorophyll a fluorescence transient curve (OJIP test) and fast fluorescence induction kinetics were influenced by drought stress. These parameters were more affected in Morocco cultivar by drought stress compare with Yousof. Drought stress also resulted in reduction of D1 protein content in both genotypes and accelerated photoinhibition process. Based on our results, stomatal conductance is the main factor limiting photosynthesis in Yousof genotype under mild drought stress. However, in Morocco, in addition to stomatal limitation, damage to photosystem II (PSII), reduced electron transport and carboxylation efficiencies were important parts of limitation in photosynthesis. Severe drought stress resulted in structural and biochemical impairment of light‐dependent reactions as well as carboxylation process of photosynthesis in both genotypes. Alpha‐tocopherol showed an important protective role against drought stress in Yousof cultivar as a relatively drought‐tolerant cultivar.  相似文献   

20.
Abiotic stress tolerance in plants is said to be induced by pre-stress events (priming) during the vegetative phase. We aimed to test whether drought priming could improve the heat and drought tolerance in wheat cultivars. Two wheat cultivars “Gladius” and “Paragon” were grown in a fully controlled gravimetric platform and subjected to either no stress or two drought cycles during the tillering stage. At anthesis, both batches were either subjected to high temperature stress, drought stress or kept as control. No alleviation of grain yield reduction due to priming was observed. Higher CO2 assimilation rates were achieved due to priming under drought stress. Yield results showed that priming was not damage cumulative to wheat. Priming was responsible to alleviated biochemical photosynthetic limitations under drought stress and sustained photochemical utilization under heat stress in “Paragon.” Priming as a strategy in abiotic stress alleviation was better evidenced in the stress susceptible cultivar “Paragon” than tolerant cultivar “Gladius”; therefore, the type of response to priming appears to be cultivar dependable, and thus phenotypical variation should be expected when studying the effects of abiotic priming.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号