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1.
Rainfed crop production in northern China is constrained by low and variable rainfall. This study explored the effects of tillage/crop residue and nutrient management practices on maize (Zea mays L.) yield, water use efficiency (WUE), and N agronomic use efficiency (NAE) at Shouyang Dryland Farming Experimental Station in northern China during 2003–2008. The experiment was set-up using a split-plot design with 3 tillage/crop residue methods as main treatments: conventional, reduced (till with crop residue incorporated in fall but no-till in spring), and no-till (with crop residue mulching in fall). Sub-treatments were 3 NP fertilizer rates: 105–46, 179–78 and 210–92 kg N and P ha−1. Maize grain yields were greatly influenced by the growing season rainfall and soil water contents at sowing. Mean grain yields over the 6-year period in response to tillage/crop residue treatments were 5604, 5347 and 5185 kg ha−1, under reduced, no-till and conventional tillage, respectively. Grain yields under no-till, were generally higher (+19%) in dry years but lower (−7%) in wet years. Mean WUE was 13.7, 13.6 and 12.6 kg ha−1 mm−1 under reduced, no-till, and conventional tillage, respectively. The no-till treatment had 8–12% more water in the soil profiles than the conventional and reduced tillage treatments at sowing and harvest time. Grain yields, WUE and NAE were highest with the lowest NP fertilizer application rates (at 105 kg N and 46 kg P ha−1) under reduced tillage, while yields and WUE tended to be higher with additional NP fertilizer rates under conventional tillage, however, there was no significant yield increase above the optimum fertilizer rate. In conclusion, maize grain yields, WUE and NAE were highest under reduced tillage at modest NP fertilizer application rates of 105 kg N and 46 kg P ha−1. No-till increased soil water storage by 8–12% and improved WUE compared to conventional tillage, thus showing potentials for drought mitigation and economic use of fertilizers in drought-prone rainfed conditions in northern China.  相似文献   

2.
Isolated and purified endosperm cell walls (CW), used in this study, were derived from a Canadian malting barley variety, AC Metcalfe, grown in three different environments in Canada in 2003, and varying in grain protein and β-glucan contents, as well as in grain hardness. The CW were initially extracted with water at 45 °C and subsequently digested with barley malt crude enzyme extract resulting in two fractions designated CW-WE45 and CW-MD, respectively. The remaining non-digested cell wall material (CWND) was further fractionated by sequential extraction with water at 95 °C (CWND-WE95), saturated barium hydroxide (CWND-BaE), and 1 N sodium hydroxide (CWND-NaE) at 25 °C. Composition and molecular structure analyses were carried out for all fractions including the remaining cell wall residue (CWRES). Extraction of CW with water followed by digestion with malt crude enzyme extract solubilized the majority of β-glucans (∼55–70%) and glucomannans (∼60–80%) but only a small portion of arabinoxylans (∼20–30%) present in the intact CW. The CW-WE45 and CWND-WE95 fractions consisted mostly of β-glucans exhibiting high average molecular weights (Mw) (2–3 × 106), whereas the CWND-BaE consisted mainly of arabinoxylans with Mw about 1–1.5 × 106. The CWND-NaE contained almost equal amounts of β-glucans and arabinoxylans and a small amount of glucomannans, whereas the CWRES contained approximately equal proportions of β-glucans, arabinoxylans and glucomannans. β-Glucans in CWND-WE95, CWND-NaE, and CWRES exhibited a higher ratio of 3-O-β-d-cellobiosyl-d-glucose to 3-O-β-d-cellotriosyl-d-glucose (DP3/DP4) compared to β-glucans in CW-WE45 and CW-MD. β-Glucans in CWND-NaE showed the highest level of long cellulosic oligosaccharides with DP ≥ 5, whereas those in the CWRES had the highest DP3/DP4 ratio. The CW-MD was fractionated by ultrafiltration into high (CW-MDHMW) and low-molecular weight (CW-MDLMW) sub-fractions, with weight-average Mw of ∼150–350 × 103 and <10 × 103, respectively, as confirmed by size-exclusion chromatography. The monosaccharide composition of the sub-fractions indicated a more extended enzymic degradation of β-glucans and glucomannans than arabinoxylans. Some differences in composition and molecular structure of the cell wall constituents among the three barley samples were related to their solubility and enzymic digestibility.  相似文献   

3.
Success in “super” rice breeding has been considered a great progress in rice production in China. This study aimed to test the hypothesis that an improved root system may contribute to better shoot growth and consequently to higher grain yield in “super” rice. Two “super” rice varieties Liangyoupeijiu (an indica hybrid) and Huaidao 9 (a japonica inbred) and two elite check varieties Yangdao 6 (an indica inbred) and Yangfujiang 8 (a japonica inbred) were field-grown at Yangzhou, China in 2006 and 2007. Root and shoot dry weight (DW) was significantly greater in “super” rice varieties than in check ones throughout the growth season in both years, so was the root length density. Root oxidation activity (ROA) and root zeatin (Z) zeatin riboside (ZR) content, in per plant basis, were significantly greater in “super” rice than check varieties before and at heading time. However, both ROA and root Z + ZR content, either in per plant basis or per unit root DW basis, were significantly lower in ‘super’ rice than in check varieties at the mid- and late grain filling stages. Grain yield of the two ‘super’ rice varieties, on average, was 10.2 t ha−1 in 2006 and 11.4 t ha−1 in 2007, and was 13% and 21% higher than that of check varieties, respectively. The high grain yield was mainly due to a larger sink size (total number of spikelets) as a result of a larger panicle. The percentage of filled grains of the two “super” rice varieties, on average, was 72.9% in 2006 and 79.0% in 2007, and was 19.4% and 12.9%, respectively, lower than that of the check varieties. The mean ROA and root Z + ZR content during the grain filling period significantly correlated with the percentage of filled grains. Collectively, the data suggest that an improved root and shoot growth, as showing a larger root and shoot biomass and greater root length density during the whole growing season and higher ROA and root Z + ZR content per plant at early and mid-growth stages, contributes to the large sink size and high grain yield in the “super” rice varieties. The data also suggest the yield of “super” rice varieties can be further increased by an increase in filled grains through enhancing root activity during grain filling.  相似文献   

4.
CIMMYT hexaploid spring wheat (Triticum aestivum L.) germplasm has played a global role in assisting wheat improvement. This study evaluated four classes of CIMMYT germplasm (encompassing a total of 273 lines), along with 15 Australian cultivars (Oz lines) for grain yield, yield components and physiological traits in up to 27 environments in Australia's north-eastern region, where terminal drought frequently reduces grain yield and grain size.Broadly-adapted CIMMYT germplasm selected for grain yield had greater yield potential and improved performance under drought stress, being up to 5% greater yielding in High-yielding (mean yield 429 g m−2) and 4-10% greater yielding than adapted Oz lines in Low-yielding environments (mean yield 185 g m−2). Whilst maintaining statistically similar harvest index and spikes m−2 compared to broadly-adapted Oz lines across all environments, sets of selected CIMMYT lines had greater canopy temperature depression (0.18-0.27 °C), dry weight stem−1 (0.20-0.37 g), increased grains spike−1 (0.8-3.4 grains), grain number m−2 (ca. 20-800 grains), and maturity biomass (56-83 g m−2). Compared to selected Oz lines, broadly-adapted CIMMYT lines had a smaller reduction in Low compared to High-yielding environments for these traits, especially dry weight stem−1, such that CIMMYT lines had ca. 25% and 10% greater dry weight stem−1 than the Oz lines in Low- and High-yielding environment groups, respectively. Broadly-adapted CIMMYT germplasm also had slightly higher stem water soluble carbohydrate concentration at anthesis (ca. 6 mg g−1), which contributed to their higher grain weight (ca. 0.5 mg grain−1), and maintained an agronomically appropriate time to anthesis and plant height. Thus current CIMMYT germplasm should be useful donor sources of traits to enrich breeding programs targeting variable production environments where there is a high probability of water deficit during grain filling. However, as multiple traits were important, efficient introgression of these traits in breeding programs will be complex.  相似文献   

5.
Content, structure and molecular dimensions of arabinoxylan in rye grains influence dramatically the bakery process and the quality of products. Under this aspect, relationships between rye grain quality and properties of arabinoxylan fractions are very important. For detailed information about molecular characteristics, water extractable (WEAX) and water unextractable (WUAX) arabinoxylan fractions from three different varieties of rye during 3 seasons were investigated. Moreover, our research focused on establishing relations of grain quality, indicated by mass of 1000 kernels, to quantity and structure of arabinoxylans. These results help to predict water binding capacity of rye flour in relation to grain quality.  相似文献   

6.
Productivity and resource-use efficiency in corn (Zea mays L.) are crucial issues in sustainable agriculture, especially in high-demand resource crops such as corn. The aims of this research were to compare irrigation scheduling and nitrogen fertilization rates in corn, evaluating yield, water (WUE), irrigation water (IRRWUE) and nitrogen use (NUE) efficiencies. A 2-year field experiment was carried out in a Mediterranean coastal area of Central Italy (175 mm of rainfall in the corn-growing period) and corn was subjected to three irrigation levels (rainfed and supply at 50 and 100% of crop evapotranspiration, ETc) in interaction with three nitrogen fertilization levels (not fertilized, 15 and 30 g (N) m−2). The results indicated a large yearly variability, mainly due to a rainfall event at the silking stage in the first year; a significant irrigation effect was observed for all the variables under study, except for plant population. Nitrogen rates affected grain yield plant−1 and ear−1, grain and biomass yield, HI, WUE, IRRWUE and NUE, with significant differences between non-fertilized and the two fertilized treatments (15 and 30 g (N) m−2). Furthermore, deficit irrigation (50% of ETc) was to a large degree equal to 100% of the ETc irrigation regime. A significant interaction “N × I” was observed for grain yield and WUE. The effect of nitrogen availability was amplified at the maximum irrigation water regime. The relationships between grain yield and evapotranspiration showed basal ET, the amount necessary to start producing grain, of about 63 mm in the first and 206 mm in the second year. Rainfed crop depleted most of the water in the 0–0.6 m soil depth range, while irrigated scenarios absorbed soil water within the profile to a depth of 1.0 m. Corn in a Mediterranean area can be cultivated with acceptable yields while saving irrigation water and reducing nitrogen supply and also exploiting the positive interaction between these two factors, so maximizing resource-use efficiency.  相似文献   

7.
Plant responses to water deficit need to be monitored for producing a profitable crop as water deficit is a major constraint on crop yield. The objective of this study was to evaluate physiological responses of cotton (Gossypium hirsutum) to various environmental conditions under limited water availability using commercially available varieties grown in South Texas. Soil moisture and variables of leaf gas exchange were measured to monitor water deficit for various varieties under different irrigation treatments. Lint yield and growth variables were also measured and correlations among growth parameters of interest were investigated. Significant differences were found in soil moisture, leaf net assimilation (An), stomatal conductance (g), transpiration rate (Tr), and instantaneous water use efficiency (WUEi) among irrigation treatments in 2006 while no significant differences were found in these parameters in 2007. Some leaf gas exchange parameters, e.g., Tr, and leaf temperature (TL) have strong correlations with An and g. An and WUE were increased by 30–35% and 30–40%, respectively, at 600 μmol (CO2) m−2 s−1 in comparison with 400 μmol (CO2) m−2 s−1. Lint yield was strongly correlated with g, Tr, WUE, and soil moisture at 60 cm depth. Relative An, Tr, and TL started to decrease from FTSW 0.3 at 60 cm and FTSW 0.2 at 40 cm. The results demonstrate that plant water status under limited irrigation management can be qualitatively monitored using the measures of soil moisture as well as leaf gas exchange, which in turn can be useful for describing yield reduction due to water deficit. We found that using normalized An, Tr, and TL is feasible to quantify plant water deficit.  相似文献   

8.
A pot and a field experiment were conducted to assess the effects of root/shoot ratio (R/S) on the water use efficiency (WUE) and grain yield of winter wheat. The R/S was regulated by pruning the roots during the stem elongation stage, resulting in reduced root systems of the plants. At the heading stage, the root dry weight of root-pruned plants was less than that of intact-root plants, but their R/S was similar to that of intact-root plants under both experimental conditions. After tiller pruning, the R/S of root-pruned plants was significantly lower than that of intact-root plants (p < 0.05). Root pruning reduced the rate of leaf transpiration and lowered the number of tillers per plant (p < 0.05) during the vegetative stage. As a result, root-pruned wheat showed reduced water use when compared to intact-root plants before heading (p < 0.05). At anthesis, there was no significant difference in transpiration between plants with intact roots and those with pruned roots in the pots. However, under field conditions, transpiration of root-pruned plants was significantly higher than that of intact-root plants at anthesis. Additionally, at anthesis root-pruned plants had a higher rate of leaf photosynthesis and lower rate of root respiration, which resulted in a significantly higher grain yield at maturity when compared to plants with intact roots. Under both experimental conditions, there were no significant differences in shoot dry weight per plant between root-pruned and intact-root plants grown in monoculture. When root-pruned plants were grown with intact-root plants, the root-pruned wheat was less productive and had a lower relative shoot dry weight (0.78 and 0.86, respectively) than the intact-root plants (1.24 and 1.16, respectively). These results suggest that plants with pruned roots had a lower ability to compete and to acquire and use the same resources in the mixture when compared with intact-root plants. Root pruning improved the WUE of winter wheat under both experimental conditions. This suggests that appropriate management for the root system/tillers in wheat crops can be used to increase grain yield and water use efficiency. Specifically, lowering the R/S improved the grain yield and WUE of winter wheat significantly by lowering its competitive ability and improving root efficiency. Therefore, drought-resistance breeding to improve the grain yield and WUE, at least for wheat, should be made by targeted selection of less competitive progeny with a small R/S for cultivation in arid and semiarid areas.  相似文献   

9.
The association of specific target traits for drought resistance (early flowering, high accumulation of stem water soluble carbohydrate (WSC) reserves, presence of awns and high green flag-leaf area persistence) with yield performance under late-season drought was analyzed utilizing two doubled-haploid (DH) populations derived from crosses between Beaver × Soissons and Rialto × Spark in two seasons 2000/2001 and 2001/2002. The aim was to quantify associations between target traits and yield responses to drought, and to prioritize traits for drought resistance. Flowering time variation had a neutral effect on the absolute yield loss under drought, suggesting there may be a trade-off between water-saving behaviour in the shorter pre-flowering period with early flowering and a reduced capacity to access water associated with a smaller rooting system. The presence of awns also had a neutral effect on yield loss under drought amongst lines of the Beaver × Soissons population. The potential advantages of awns for increasing water-use efficiency and sensible heat transfer responsible for a cooler canopy appeared to be of less significance under moderate droughts in the UK than under severe droughts in other regions worldwide. The value of large stem soluble carbohydrate reserves for drought environments alone could not be confirmed in the UK environment. Stem WSC was positively associated with grain yield under both irrigation and drought. The genetic trait which showed the clearest correlation with the ability to maintain yield under drought was green flag-leaf area persistence. Averaged across years, the positive phenotypic correlation of this trait with yield under drought amongst DH lines of the Beaver × Soissons population (r = 0.49; p ≤ 0.001) indicated the potential use of this trait as a selection criterion for yield under drought. It is suggested that screens for this trait including marker-assisted selection would have value in future breeding programmes aimed at improving yields in high yielding, rainfed environments, but where drought can also be a problem, such as the UK.  相似文献   

10.
The crop-soil simulation model CropSyst was used to simulate growth, water- and N-uptakes of irrigated winter wheat (Triticum aestivum L. cv. Kupava) in Khorezm, in the dry lands of northwest Uzbekistan, Central Asia. CropSyst was calibrated using the findings of field experiments of 2005/06 and 2006/07 and validated for the 2007/08 season. A relative root mean squared error of 11% proved the accuracy between simulated and observed aboveground biomass and grain yield in 2007/08. Scenario analyses showed that N-leaching was high and ranged from 63 to 106 kg ha−1 when irrigated between 749 and 869 mm during the first two cropping seasons. The simulated N-leaching was lowest and ranged from 7 to 15 kg ha−1 when irrigation was only 148–395 mm during 2007/08. The considerable N losses during leaching and high N-uptakes by wheat together resulted in a negative N-balance even during applications of 180 and 240 kg ha−1 of N-fertilizer. N scarcity in the N-balance was reduced with increasing N-fertilizer amounts and ranged from −29 to −153 kg N ha−1 in 2005/06 and 2006/07. Despite a common shallow groundwater table in the region during some time of the year, scenario analysis revealed that only full irrigation water (580 mm) and N supply according to crop demand (180 kg ha−1) guaranteed high grain yields, unless the water table is permanently shallow to overcome irrigation deficits. Limited irrigation and N application (40% and 55% of ‘optimal’, respectively) in combination with a groundwater table below 3 m resulted in a 55% yield decline. The CropSyst wheat model proved a robust tool for assessing the influence of water and N dynamics under conditions of varying irrigation and shallow groundwater tables. It thus has potential as a decision support not only in northwest Uzbekistan, but also in comparable regions of Central Asia.  相似文献   

11.
Grain growth in wheat depends on current photosynthesis and stem water-soluble carbohydrates (WSC). In semiarid regions with terminal drought, grain filling in wheat crops may depend more on stem WSC content than on current assimilates. Reduction in grain yield under drought is attributed to shorter duration of linear grain growth despite increased contribution of stem reserves to grain yield. The amount of stem reserves is measured either by changes in stem dry weight (indirect method) or by stem WSC content (direct method). Genotypic variation in the rate and duration of linear grain growth and in percent contribution of stem reserves to grain yield has not been evaluated in wheat. The objectives of this study were: (i) to quantify the relationship between the direct and indirect measurement of stem reserves during and across the grain-filling period and (ii) to measure the extent of genotypic variation in rate and duration of linear grain growth and in percent contribution of stem reserves to grain yield. Dry weight, WSC content and grain yield of the main stem were measured at 10-day intervals in 11 diverse wheat genotypes under well-watered and droughted-field conditions across 2 years. Drought reduced stem WSC content from 413 to 281 mg and grain yield from 4.6 to 2.5 t ha−1. Stem WSC content and dry weight were positively correlated. Genotypic differences in linear rate of grain growth were significant in well-watered (ranging from 48.9 to 72.4 mg spike−1 day−1) and in droughted-field (ranging from 33.2 to 59.9 mg spike−1 day−1) conditions. Drought, on average, reduced the linear rate and duration of grain growth by 20 and 50%, respectively. Reduction in linear rate ranged from 13 to 43%. The amount of current assimilates and stem reserves contributed to grain yield was reduced, respectively, by 54 and 11% under drought. Genotypic differences in percent contribution of stem reserves to grain yield were significant in well-watered (ranging from 19.1 to 53.6%) and in droughted-field (ranging from 36.6 to 65.4%) conditions. The wheat genotypes responded differently to drought. Main spike grain yield was reduced by 43% under drought due to 26 and 11% reduction in grain weight and number of grains, respectively. Grain yield was correlated with linear grain growth under well-watered (r = 0.96) and droughted (r = 0.83) conditions. The genotypic variation observed indicates that breeding for a higher rate of linear grain growth and greater contribution of stem reserves to grain yield should be possible in wheat to stabilize grain yield in stressful environments.  相似文献   

12.
Rice (Oryza sativa L.) ratooning is the production of a second rice crop from the stubble left behind after the main-crop harvest. Lowering the main-crop stubble height by harvesting the main crop at a lower than traditional height is believed to alter growth parameters and increase ratoon yields. The objectives of this study were to evaluate the effect of main-crop stubble height on ratoon grain yield, agronomics, and cumulative/weekly panicle growth parameters (density, point of origin, and weight). Main-crop ‘Cocodrie’ and ‘Trenasse’ rice cultivars were harvested to leave either a 40- or 20-cm stubble height. When the main-crop stubble was harvested at 20 cm, ratoon rice grain yield in 2007 was increased by 375 and 190 kg ha−1 for Cocodrie and Trenasse, respectively. Yield was not improved in 2006 using the low (20 cm) harvest height. The yield advantage in 2007 was associated with the increased weight of the basal panicles when the main crop was harvested at 20 cm. When the main-crop stubble was 20 cm, basal and axial panicle points of origin were numerically similar 5 weeks after main-crop harvest (WAH), while panicles originating from basal nodes were predominant 6 WAH and beyond. In contrast, when the main-crop stubble was 40 cm, approximately 75% of the emerged panicles originated from axial nodes 5 WAH, panicles from both axial and basal points of origin were nearly identical 6 WAH, and basal panicles were dominant thereafter. Results from this study indicate that when the initial stubble height is reduced from 40 to 20 cm the growth of the ratoon crop is altered by shifting panicle point of origin during the early growth period and delaying maturity.  相似文献   

13.
Opium poppy (Papaver somniferum L.) is an important medicinal plant produces more than 80 alkaloids belonging to various tetrahydrobenzylisoquinoline derived classes. These alkaloids are obtained from the capsules and straw of the plant. Information on the nature and magnitude of gene effects are required for genetic improvement. Therefore, the continuous assessment of newer breeding materials is mandatory on part of breeders. The objective of this study was undertaken to understand the particular gene action involved in the inheritance of yield and component traits. Two families (VG26 × VG20 and SG35II × VE01) of opium poppy were analyzed to study the gene actions involved in the inheritance of yield and component traits (plant height, leaves per plant, capsules per plant, peduncle length, capsule index, seed and straw yield per plant and morphine content). Simple additive, dominance, and epistatic genetic components were found to be significant. Dominance effect (‘h’) was higher than additive effect (‘d’) for capsule index and morphine content. Digenic interaction indicated the prevalence of dominance × dominance (‘l’) followed by additive × dominance (‘j’) type epistasis. The opposite sign of dominance (‘h’) and dominance × dominance (‘l’) indicated duplicate epistasis for all the traits. Biparental mating followed by recurrent selection involving desired recombinants may be utilized to improve the component traits.  相似文献   

14.
The accumulation of KCl-soluble/methanol-insoluble albumins and globulins was investigated in the endosperm of developing wheat (Triticum aestivum, L. cv. Butte 86) grain produced under a moderate (24 °C/17 °C, day/night) or a high temperature regimen (37 °C/28 °C) imposed from 10 or 20 days post-anthesis (dpa) until maturity. Proteins were separated by 2-DE and developmental profiles for nearly 200 proteins were analyzed by hierarchical clustering. Comparison of protein profiles across physiologically equivalent stages of grain fill revealed that high temperature shortened, but did not substantially alter, the developmental program. Accumulation of proteins shifted from those active in biosynthesis and metabolism to those with roles in storage and protection against biotic and abiotic stresses. Few proteins responded transiently when plants were transferred to the high temperature regimens, but levels of a number of proteins were altered during late stages of grain development. Specific protein responses depended on whether the high temperature regimens were initiated early or mid development. Some of the heat responsive proteins have been implicated in gas bubble stabilization in bread dough and others are suspected food allergens.  相似文献   

15.
Kalmegh (Andrographis paniculata Wall. ex Nees) is a medicinal herb of tropical south east Asia and native to India and Sri Lanka. It has been used herb for liver ailment in all prevailing systems of medicine viz. Ayurvedic, Unani, Homeopathic and modern throughout most of the south East Asian countries viz. China, India, Sri Lanka, Indonesia, Thailand, Burma, and Vietnam, etc. Commercially cultivation of Kalmegh is done through seeds. Optimal germination potential, temperature and first as well as final count day are three primary parameters for developing the seed quality standards. Germination of Kalmegh variety ‘CIM-Megha’ was carried out at six constant temperatures at an interval of every ‘5 °C’ from ‘15 to 40 °C’ temperatures coupled with 16 h light and 8 h dark photo period. The temperature of ‘25 °C’ was found optimally suitable with ‘94.6’ and ‘23.6’ percentage of germination and germination energy, respectively, while the temperature at ‘40 °C’ was deleterious with no germination. Significant decrease in percentage of germination and germination energy was observed at ‘15 °C’, ‘20 °C’, ‘30 °C’ and ‘35 °C’ of temperature in comparison to ‘25 °C’. The study further revealed that days 5-6 and days 7-9 after seed sowing were the ideal for first and final count, respectively for seed germination of Kalmegh.  相似文献   

16.
不同基因型玉米冠层温度与产量和水分利用效率的关系   总被引：3，自引：0，他引：3  
2007年在甘肃陇东旱塬利用红外测温仪研究了19个基因型玉米冠层温度与产量、水分利用效率的关系。结果表明,不同基因型玉米在子粒灌浆期存在着冠层温度高度分异的现象,其差异可反应在产量和水分利用效率的不同上。无论灌浆初期还是中期或后期,旱地玉米产量、水分利用效率与冠层温度呈极显著的负相关(R2= 0.445～0.634),并且随着灌浆期推移,相关性增大。表明灌浆期冠层温度偏低的品种具有较高产量和水分利用效率,冠层温度可作为高产节水品种田间筛选的指标。  相似文献   

17.
试验在防雨棚中盆栽条件下进行。供试玉米杂交种5个,苗期设置正常供水、轻度干旱胁迫和中度干旱胁迫3种处理,拔节期均复水到正常水平。分别在拔节期、吐丝期和成熟期对相关形态及生理指标进行测定,并与水分利用效率(water use efficiency,WUE)进行多元逐步回归分析。结果表明:在吐丝期,正常供水和中度干旱时散粉至抽丝间隔(anthesis-silking interval,ASI)短的品种WUE高;在成熟期,正常供水时粒叶比高、茎较粗和轻度干旱时粒深的品种WUE高;在正常供水时,拔节期植株矮小、叶片失水率小、成熟期收获指数(harvest index,HI)较高和穗位比较大的品种在轻度干旱胁迫下具有较高WUE;在正常供水时,出籽率较高、行粒数较少的品种在中度干旱胁迫下具有较高WUE。  相似文献   

18.
Measurements of soil physical properties, root growth and the water content in the subsurface layers of a clay Sodosol soil were carried out to determine why the incorporation of organic amendment (20 t/ha) resulted in marked increases in wheat yield in an earlier paper. The incorporation of lucerne or dynamic lifter® pellets at a depth of 30–40 cm resulted in an almost doubling of the macroporosity from <10% to >18%, together with reductions in bulk density and the volumetric water content (θvθv) at −1500 kPa, and a 50-fold increase on saturated hydraulic conductivity in this subsurface layer. These changes in physical properties in the 30–40 cm deep layer were highly correlated (r values 0.69–0.93, P < 0.01) with increased root growth in this layer, and increases in crop yield. The practice of incorporating an organic amendment in the top clay layer of the B horizon in soils where the high density restricts root growth, which is termed ‘subsoil manuring’, shows promise for increasing crop productivity on these soils in the high rainfall zone of southern Australia.  相似文献   

19.
The effect on the viscosity of wheat flour batter following treatments with a crude pentosanase-containing enzyme preparation and an endo-xylanase purified from the same preparation, was studied in relation to changes to the chemical features of the water- and Ba(OH)2-extractable arabinoxylan fractions. Addition to batter of the crude enzyme or the pure xylanase caused a consistent and identical decrease in batter viscosity, demonstrating that the viscosity change was caused by the selective action of the xylanase in the crude enzyme preparation. The lowering of batter viscosity upon addition of enzyme was attributed to partial hydrolysis of the arabinoxylans in the water-extractable fraction which lead to an increase in the proportion of lower molecular weight water-extractable arabinoxylans possessing an increased xylose/arabinose ratio. There was no detectable change in the monosaccharide composition of either the water- or Ba(OH)2-extractable arabinoxylan fraction after enzyme treatment and no indication of any increase in the amount of the water-extractable arabinoxylan fraction at the expense of the Ba(OH)2-extractable fraction. It is concluded that the xylanase can extensively degrade arabinoxylan to small oligosaccharides in vitro. However, such degradation does not take place in situ, in the enzyme treated batters, where only a very small shift in the molecular weight profile of the water-extractable arabinoxylans was necessary to effect major changes to batter viscosity.  相似文献   

20.
Data from on-farm participatory varietal trials are often highly unbalanced. Using statistically robust techniques we showed that such data are amenable to sophisticated analyses. Data from 38 varieties of wheat tested in 44 mother trials (all test varieties compared) and 663 baby trials (single entries compared with local checks) over 6 years in Lunawada, Gujarat, India, were analysed. Two combined analyses for grain yield were performed by using either a fixed effects model within general linear modelling (GLM) or a mixed effects model using the restricted maximum likelihood (REML) procedure. Both analyses made substantial adjustments over the raw means and the estimated mean values from the two analyses for the fixed set of tested varieties were highly correlated (R2 = 0.89) as were the t-value that compared test cultivars with the check variety (R2 = 0.96). The GLM detected 15 varieties and REML detected 12 varieties that were significantly superior to the check cultivar with 11 varieties in common. Both methods were similar in identifying the top-most promising varieties but REML was more conservative (i.e. more subject to Type II error) with larger standard errors (S.E.s) of variety means for n > 17. However, for both procedures the S.E.s increased sharply when the number of trials decreased below 17.  相似文献   

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