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1.
Previous results with red clover ( Trifolium pratense ) leaflets, leaf petioles and stems indicated that the epidermis continued to impose a barrier to water loss at low water contents. Further experiments with red clover leaf petioles and stems suggest that cuticular wax is the epidermal component concerned and that treatments which remove or merely modify this will also increase drying rate. However, when treatments to reduce epidermal resistance were applied to pseudostems and flowering stems of Italian ryegrass ( Lolium multiflorum ) the initial increase in drying rate produced was not sustained at low water contents. The pseudostems consisted of three layers of leaf material rolled one within the other and the true flowering stems were surrounded by one leaf sheath. Their pattern of response to treatments suggested that these affected only the outer sheath, which produced an initial acceleration in drying rate, but that this was not sustained after the outer sheath was dry because the lower untreated layers dried in a similar way to untreated controls.
The results suggest the possibility of devising practical treatments to increase drying rate at low water contents with crops containing a high proportion of leaf or stem not surrounded by leaf sheath. Devising such treatments for crops with a high proportion of grass pseudostem or flowering stem surrounded by leaf sheath will be considerably more difficult. 相似文献
The results suggest the possibility of devising practical treatments to increase drying rate at low water contents with crops containing a high proportion of leaf or stem not surrounded by leaf sheath. Devising such treatments for crops with a high proportion of grass pseudostem or flowering stem surrounded by leaf sheath will be considerably more difficult. 相似文献
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《Field Crops Research》1999,62(1):35-52
A field study was conducted to investigate the effect of intermittent soil drying on resulting non-hydraulic and hydraulic root signals, leaf gas exchange, leaf growth, day of heading, leaf osmotic adjustment and yield of wheat grown in sand and loam soils in lysimeters. A 40-day-drought treatment was imposed when the flag leaf started to emerge and was terminated close to maturity. Soil water content and soil water potential of various soil layers were measured using the neutron moderation method and tensiometers, respectively. Soil drying in the top soil layers induced increase in both xylem and bulk-leaf abscisic acid (ABA) content and reduced the stomatal conductance and leaf growth even before a measurable change in leaf water potential could be detected in droughted plants when compared with fully watered plants. Further, heading and flowering occurred 4 days earlier in the droughted than in the well-watered plants before any loss in leaf water potential had occurred as compared with the fully watered plants. When more severe drought reduced the leaf water status, further accumulation of leaf ABA occurred and transpiration decreased in addition to gradual osmotic adjustment and senescence of older leaves. The osmotic adjustment sustained leaf turgor pressure during soil drying. At severe drought, the osmotic adjustment at full turgor in the flag leaves was 0.85 MPa. In sand, the kernel dry weight increased and as a result similar grain yield was obtained in both the treatments. In loam which had more water available than sand, no significant reduction in the final yield was induced by the drought. It is concluded that (1) non-hydraulic root signals caused early drought adaptation at mild water stress by reducing leaf growth and stomatal conductance and hastening of heading and flowering; (2) osmotic adjustment sustained turgor maintenance and hence the yield-forming processes during moderate and severe water stress. 相似文献
4.
稻田水分管理方式对水稻光合速率和水分利用效率的影响 总被引：30，自引：2，他引：30
以超级杂交稻两优培九和中优6号为材料, 设3个不同水分管理措施,在穗分化期、开花期和花后20 d分别测定叶片光合速率和水分利用率。结果表明:不同水分管理方式影响水稻地上部干物重、叶面积指数、光合速率、蒸腾速率和水分利用效率。水分好气灌溉管理地上部干物重和水分利用效率明显增加;水分低水位管理蒸腾速率、地上部干物重和叶片水分利用效率下降。淹水灌溉地上部干物重、叶面积指数、叶片光合速率和水分利用率较低。因此,水稻好气灌溉有利于光合物质积累,显著增产和提高水分利用效率。试验还表明这3种水分管理对稻米蛋白质含量的影响不显著。 相似文献
5.
土壤干旱对小粒种咖啡有关生理参数的影响 总被引：1，自引：0，他引：1
对塑料袋一年生咖啡苗定期停止淋水，使土壤遭受不断加剧的干旱胁迫，以检测水分供应对咖啡生理状况的影响。试验结果表明：轻度水分胁迫，如１ｄ不淋水，即导致咖啡光合速率、蒸腾速率、可溶性蛋白质和叶绿素、类胡萝卜素含量以及含水量、气孔开张率、水势等生理参数开始下降；而过氧化物酶活性、脯氨酸和丙二醛含量以及细胞透性等生理参数开始上升，且随土壤水分胁迫的逐步加剧，上述各生理参数呈渐进性恶变。光合速率对土壤水分的反应属敏感参数之一，轻度干旱即使光合速率明显下降。高温间歇干旱期，常规管理的田间含水量能使咖啡光合速率受到抑制，灌水可促使光合速率提高。 相似文献
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The effects of variety, cutting interval and nitrogen application on the morphology and development of stolons and leaves of white clover 总被引：1，自引：0，他引：1
Six varieties of white clover, each grown with perennial ryegrass, four intervals between cuts and two levels of applied nitrogen in all combinations, were compared in a field experiment during the first 27 months after sowing. Information about yields, crop fractions, heights and ryegrass tillers has been presented in an earlier paper (Wilman and Asiegbu, 1982). The present paper is concerned with the more detailed studies of white clover, which help to explain the yield results and contribute to the understanding of the response of this species to management when grown in competition with grass. Increasing the interval between harvests increased the length of clover stolon per unit area of ground and increased stolon diameter, petiole length, weight per leaf and number of leaves harvested as a proportion of the number present in the sward while only slightly reducing the rate of leaf emergence, helping to explain the positive effect of increasing the interval on clover yield noted in the earlier paper. During regrowth, successive leaves had longer petioles and the length of individual petioles increased beyond the stage at which the leaflets were fully opened. Weight per leaf in clover increased considerably from April to June and declined to below the April value by October. It was shown that weight per leaf can be greatly increased by increasing the interval between harvests without reducing the number of leaves harvested per unit area per year. The stolon length measurements provided some support for the view that medium large-leaved varieties of white clover can with advantage be defoliated rather less frequently than small-leaved varieties. Stolon length was less adversely affected by applied N in the medium large- than in the small-leaved varieties. The small-leaved varieties had thinner stolons than the medium large-leaved varieties but about twice the stolon length when no N was applied, and a relatively high proportion of leaves which escaped defoliation. The application of N reduced stolon diameter, increased petiole length and had little or no effect on weight per clover leaf. 相似文献
7.
水钾耦合对大豆光合特性及其产物积累运转的影响 总被引：2，自引：0，他引：2
盆栽条件下,研究了不同生育时期水钾耦合对大豆光合特性及水分利用效率的影响,并对光合速率与各器官干物重进行相关分析。结果表明：苗期与花期控水时,土壤水分及水钾互作极显著影响光合速率（Pn）;结荚期控水时,水分极显著影响Pn。花期与荚期控水后测定的Pn要高于苗期的Pn。水钾耦合对光合速率（Pn）、蒸腾速率（Tr）和气孔导度（Gs）的影响趋势相似,即水分效应要优于钾肥,且一般而言同一钾肥水平下,土壤水分的影响表现为：W4>W3、W5>W2>W1。只有当土壤水分供应适宜（W3）时,钾肥的施用提高了植株的Pn、Tr和Gs。水分对植株水分利用效率（WUE）的影响要优于钾肥,且水分为正效应。苗期及开花期控水条件下,植株的Pn与根、茎、叶干物重呈极显著正相关（p<0.01）,且Pn与各器官的相关程度表现为茎>叶>根;结荚期植株Pn与根、茎、叶干物重仍呈极显著正相关（p<0.01）,与荚粒干物重呈显著正相关（p<0.05）。 相似文献
8.
以免耕平作为对照,研究不同垄作覆盖模式对夏玉米耕层土壤含水量、干物质积累与分配以及产量的影响效应。结果表明,垄作和覆盖栽培的保水效果在玉米生育后期尤其是干旱时更为显著。相同条件下宽窄行垄作栽培处理的增产效果明显优于等行距垄作处理,无覆盖条件下等行距垄作处理的实际产量较平作处理提高0.5%,宽窄行垄作处理提高8.91%;覆盖条件下等行距垄作处理与宽窄行垄作处理的实际产量较平作处理分别提高3.62%和11.59%。相关及通径分析表明,子粒实际产量与开花至成熟期耕层土壤平均含水量、大喇叭口期叶片干重以及成熟期叶片干重呈显著正相关。提高开花至成熟期耕层土壤平均含水量、降低开花期茎鞘干重、促进叶片的干物质积累是垄作覆盖模式下玉米获得高子粒产量的主要原因。 相似文献
9.
The relationship between rate of water loss of Italian ryegrass (Lolium multiflorum) and crop properties, weather conditions and mechanical treatments were studied on a field scale, as was the importance of the variables and their combined effects on influencing the wilting process. Eleven forage-drying experiments were performed between 1992 and 1994 on diploid and tetraploid cultivars cut at different growth stages, ranging from early elongation to flowering, under environmentally variable conditions. The rate of drying was measured until a moisture content of 1 g water g?1 dry matter (DM) (500 g kg?1) was reached, or for a maximum of 2 days by calculating the rate of water loss from two consecutive hourly weights of swath portions placed on trays. Multiple regression analysis was used to correlate the drying rate (k) with crop properties and with meteorological and mechanical treatment variables. The interaction between potential evapotranspiration (ET0) and the moisture content of grass at cutting (Mgrass appeared to be the most important variable, from the twenty-one tested, in influencing K. This variable shows that the same quantity of energy available for evaportaion acts in different ways when the water content of the crop at cutting differs. The rate of water loss is also influenced by the Mgrass itself, surgacae density of the swath, tedding and the weather conditions on the first day of drying. The value of Mgrass at cutting is greatly greatly dependent on crop maturity and ploidy. The tetraploid cultivars, with a higher inital moisture content, lost water more slowly than diploid cultivars did. Because the date of cutting cannot be delayed, owing to the decline in nutrive value, it is helpful to select for cultivars with low moisture contents at cutting, as well as applying mechanical treatment (spreading and tedding), in order to keep the wilting period as short as possible. A validated drying model can be useful for operational purposes to understand the drying process and to assess technological choices for forage drying. 相似文献
10.
R. A. ARNOTT 《Grass and Forage Science》1984,39(4):305-310
White clover swards were grown in a freely ventilated glasshouse during August and September 1979. The uninterrupted growth of these swards, which were grown in Perlite with either nitrate or biologically fixed nitrogen, was studied from 5 weeks after sowing until peak dry weights of the live sward components occurred. The dry weight of leaf laminae, petioles, stolons, roots, nodules and dead material was determined weekly together with live leaf numbers and leaf lamina area. The pattern of dry matter accumulation of the yield components of the swards (live leaf laminae plus petioles) was characterized by an initial period of more or less exponential growth up to 6 weeks from sowing dominated by leaf lamina development. This was followed by a linear phase, when petiole weight increased rapidly and a final slowing down period terminated by peak yields of live DM 12 weeks after sowing.
The weight of stolons, roots and nodules increased slowly during the period dominated by leaf lamina growth compared with the rapid increase thereafter, which resulted in a two- to three-fold increase in the weight of stolons, roots and nodules by the time the weights peaked. It is assumed that after the leaf area index of the sward had reached a plateau there was a limit to the assimilate supply to the sward components at a stage when they were all apparently competing for photosynthates. There was a progressive slowing down in the rate of dry matter accumu- 相似文献
The weight of stolons, roots and nodules increased slowly during the period dominated by leaf lamina growth compared with the rapid increase thereafter, which resulted in a two- to three-fold increase in the weight of stolons, roots and nodules by the time the weights peaked. It is assumed that after the leaf area index of the sward had reached a plateau there was a limit to the assimilate supply to the sward components at a stage when they were all apparently competing for photosynthates. There was a progressive slowing down in the rate of dry matter accumu- 相似文献
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不同花生品种对稻田镉富集及转运的研究 总被引：1，自引：0，他引：1
为研究湖南湘江流域稻田镉（Cd）污染治理方法,筛选稻田替代种植作物,于长沙县和湘阴市受污染稻田 改种花生,选用5个大果品种,设置2种（露地、覆膜）栽培方式,研究品种与栽培方式组合下对稻田Cd吸收、富集及 转运的影响。结果表明：稻田花生营养器官（根、茎、叶）Cd含量较高,生殖器官（果壳、籽仁）Cd含量较低,且品种间有明显差异。5 个花生品种的组织器官中Cd 含量最高的是茎（5.413~8.859mg·kg-1）,果壳和籽仁最少（0.523~ 1.326mg·kg-1）,但是籽仁Cd含量超出NY/T 1067-2006标准的规定值,食用安全存在风险。覆膜栽培尽管降低了花生茎、叶、果针、果壳及籽仁等的Cd含量,但提高了植株干物质重和Cd总积累,其中,营养器官（根、茎、叶）Cd富集系数高于2.5,生殖器官（果壳、籽仁）Cd富集系数为0.8~1.7。不同部位间Cd转移系数大小顺序为：根→茎秆>茎秆 →叶>果壳→籽仁>果针→果壳>茎秆→果针。不同品种的花生油中Cd含量范围在0.012~0.074mg·kg-1,符合标准, 因此花生油食用是安全的。以地上部单株干物质积累量及其Cd含量作为高镉积累筛选指标,5个品种中09-3106 的单株可高积累镉元素。建议在湘阴、长沙等地的Cd污染稻田进行覆膜栽培花生。 相似文献
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Summary ‘Top rot’, a new bacterial disease of potato was found to occur in India. Water-soaked lesions developed on succulent stems,
petioles and leaves. On stems and petioles the lesions enlarged into stripes turning black, which ultimately enveloped the
affected portion and caused a soft rot, resulting in toppling of the stem/leaf. The affected tissues were covered with whitish
bacterial exudates under high humidity but became dried and shrivelled under dry conditions. Leaflet infection occurred through
infected petioles, via mid-rib and veins, or through the margins, resulting in rotting and blighting. The bacterium also caused
soft rot of tubers. The disease was favoured by high humidity and a temperature range of 25–30°C. The causal bacterium was
identified asErwinia carotovora var.carotovora. 相似文献
14.
大豆不同叶位叶柄维管组织的比较研究 总被引：1，自引：0，他引：1
大豆叶柄维管束划分为大、中、小三种类型。植株主茎第三复叶以下叶位叶柄中有五个大型和五个中型维管束并交错排列,第四——十四复叶叶位叶柄则有大、中、小型维管束并交互排列。不同叶位叶柄的大型维管束数目皆为五个,中部叶位叶柄具有较多的中小型维管束。中部叶位叶柄大中型维管束面积大于其他叶位叶柄。新品种比老品种具有较多的维管束数目和较大的维管束面积。维管束组织性状与饱和CO_2同化率具有较大的正相关。 相似文献
15.
White clover seedlings were defoliated when either two, four or six leaves had opened. There were four defoliation treatments, involving removal of younger laminae, older laminae, all laminae or all laminae and petioles, plus a control (no defoliation).
Leaf removal reduced area of subsequently emerging leaves when measured as they became fully opened, though some compensatory expansion occurred after this. Petiole length was also reduced considerably. The magnitude of these effects varied according to severity of the treatment: removal or older laminae had little effect, removal of younger laminae had a similar effect to removing all laminae, but the effect was considerably increased by removing petioles in addition to laminae. The youngest plants showed the greatest reductions in leaf size following leaf removal. Defoliation had little effect on the rate of development of subsequent leaves.
The most severe defoliation treatments reduced plant dry matter but younger seedlings appeared to have a capacity for recovery equal to or greater than that of older seedlings.
It is concluded that white clover seedlings have a considerable ability to recover from leaf removal, especially if only laminae of old leaves are removed, but the growth reduction following removal of petioles as well as laminae appears to be especially severe. 相似文献
Leaf removal reduced area of subsequently emerging leaves when measured as they became fully opened, though some compensatory expansion occurred after this. Petiole length was also reduced considerably. The magnitude of these effects varied according to severity of the treatment: removal or older laminae had little effect, removal of younger laminae had a similar effect to removing all laminae, but the effect was considerably increased by removing petioles in addition to laminae. The youngest plants showed the greatest reductions in leaf size following leaf removal. Defoliation had little effect on the rate of development of subsequent leaves.
The most severe defoliation treatments reduced plant dry matter but younger seedlings appeared to have a capacity for recovery equal to or greater than that of older seedlings.
It is concluded that white clover seedlings have a considerable ability to recover from leaf removal, especially if only laminae of old leaves are removed, but the growth reduction following removal of petioles as well as laminae appears to be especially severe. 相似文献
16.
LEWIS JONES 《Grass and Forage Science》1979,34(2):139-144
The drying of Italian ryegrass (RvP) tillers under controlled conditions at three stages of growth is described. The rate of water loss was dependent on tiller morphology as well as on water content. Leaf laminae dried faster than stems and also aided the loss of water from stems. Drying time was shortest for vegetative tillers despite their high water content, and longest for reproductive tillers shortly before ear emergence. The practical implications in relation to haymaking are discussed. 相似文献
17.
为了探究小麦幼苗生长潜力及其对营养胁迫的适应能力,通过沙培试验,设置了正常生长植株和种子营养物质缺失(仅去除胚乳、仅去除根系、胚乳和根系均去除)处理,考察了小麦苗期叶龄、生长速率、株高、根系、叶绿素含量（SPAD）、叶面积、干物质积累、生理特性的变化。结果显示,萌发36 h的小麦幼苗在营养缺失处理下均已具备独自存活能力。与未去除胚乳（正常植株和仅去除根系）的小麦幼苗相比,去除胚乳（仅去除胚乳以及胚乳和根系均去除）的小麦幼苗发育缓慢,需要更多时间才能达到与正常小麦相同的生长阶段,且在两叶一心时生长速率、株高、根长、SPAD、总叶面积和干重显著下降,长势明显较弱,可溶性蛋白、脯氨酸和丙二醛含量一直维持在较低的水平。与正常生长植株相比,仅去除根系的小麦幼苗能够快速适应营养胁迫,在两叶一心时生长速率、株高、根长和干重与正常植株基本一致,可溶性蛋白和脯氨酸含量显著增加,丙二醛含量显著降低。由此可见,苗期小麦种子营养物质缺失条件下幼苗生长迟缓,适应能力弱,影响小麦后期的生长和发育。 相似文献
18.
To explore the zinc stress response in eddo, plants were grown for 15 d in hydroponic solutions containing 1 (control), 200, and 1000 μM zinc, and the hydathode function and changes in the contents of various elements in these plants were investigated. Under 1000 μM zinc, the dry weights of leaf blades and roots are decreased by 17 and 42%, respectively. The zinc contents in leaf blades, petioles, corms, and roots increased with increasing zinc levels in the solution. The zinc content in roots was 6.57 mg g?1 dry weight, which was 2.8–4.3 times higher than in other plant parts under 1000 μM zinc. These results demonstrate that the severe root damage occurring under 1000 μM zinc is due to higher zinc content in the roots. Under zinc stress, the contents of iron and copper in roots increased, but the contents of magnesium and calcium in petioles, corms, and roots, iron in leaf blades and corms, and manganese in petioles and corms decreased. In the guttation fluid, the concentrations of zinc, magnesium, and potassium increased, while the iron concentration decreased under 1000 μM zinc. Thus, elemental changes occurred in the guttation fluid as well as in different plant parts in eddo. In the 200 and 1000 μM zinc treatments, the amount of zinc eliminated via guttation was 2.8 and 8.5 times higher, respectively, than in the control. The results indicate that guttation partly contributes to the excretion of excess zinc under zinc stress conditions. 相似文献
19.
L. JONES 《Grass and Forage Science》1990,45(1):83-90
The drying rates of grasses and lucerne, following treatment with 1% formic acid, were compared with those of untreated crops. Material was fully exposed to a flow of air in a ventilated laboratory oven set at 23 °C. Treatment with formic acid initially enhanced the rate of drying of grass, but this was followed by retardation. This reduction in the rate of drying was caused by the rapid desiccation of laminae, which reduced their effectiveness in providing a pathway for water loss from the stem. The rate of water loss directly from the stem surface was not increased by formic acid treatment, probably because the enveloping leaf sheaths acted as a protective layer. In contrast, formic acid increased drying rate in lucerne. whose stems have no such protective layer. The results suggest that chemical desiccants. which have a contact action are unlikely to have any application in making hay from grass. 相似文献
20.
缺磷对茶树幼苗养分吸收的影响 总被引：1，自引：0，他引：1
每周3次用含0、40、80、160、400、1000μmol/L磷(P)的营养液浇沙培10月龄扦插"黄观音"茶[Camellia sinensis(L.)O.Kuntze]苗17周。随供P浓度的增加,茶树根P含量呈线性增加,但茎和叶P含量呈曲线增加;在所有供P处理中,根P含量最高,其次是叶P含量,茎P含量最低,高供P处理的植株尤为明显。缺P降低茶树根茎叶K含量,但对根茎叶Ca含量影响不大。缺P降低根Mg含量,增加茎的Mg含量,但对叶Mg含量影响较小。不供P叶有稍高的C含量,较低的N含量和较高的C/N比;供P对根和茎C和N含量及C/N比影响较小。总之,缺P不仅影响茶树根茎叶营养元素的含量,也改变其在根茎叶之间的分配。 相似文献