Wachstumsanalytische Untersuchungen an Knaulgras (Dactylis glomerata L.) unter besonderer Berücksichtigung des phänologischen Entwicklungsstadiums bei der Nutzung im ersten Aufwuchs

Regrowth characteristics of a cocksfoot (Dactylis glomerata L.) sward after initial defoliation at different stages of development Over 2 two-year period (1984-1985) the productivity of Dactylis glomerata (cv. Baraula) swards as influenced by variations in time of the initial defoliation was studied. The stages at which the initial cuts were taken were: (a) before stem apices were raised to defoliation level (5 cm), (b) about two weeks later, when the reproductive tillers reached ear emergence, (c) about 4 weeks after (a), when the reproductive tillers reached flowering stages. Subsequent production was measured by weekly harvesting of representative sward samples over a 6-7 weeks lastening growth period. Furtheron patterns of growth in a second regrowth in August and a third regrowth in September/October were studied. The growth behaviour in the investigation was described by calculations of curves concerning mainly the development of dry matter yield (DM), leaf area index (LAI), crop growth rate (C), relative growth rate (R) and net assimilation rate (E) during the growth period. The leaf area ratio (F) and leaf weight ratio (LWR) were derived from fitted curves. The highest dry matter yield and the highest growth rate (more than 20 g m^?2day^?1) was estimated in the spring growth and in the earliest regrowth (a). About 30 % of the tillers in these swards became reproductive. The main difference between regrowths of primary defoliations at successively later dates was between the earliest, after cutting on 8.-13. May, on the one hand, and, on the other hand, the two later regrowths after primary cuts from 31. May to 12. June. The two latter and the second regrowth in August were in most respects very similar: no reproductive development; herbage yield of about 400-500 g m^?2; highest C of about 15-20 g m^?2day^?1; maximum LAI- values from 8-9. In respect to the E there were some differences between the stands. The E was at the time when C was highest somewhat higher in the reproduction stands (spring growth and first regrowth) compared with the vegetative regrowths. The relationship between C and LAI could in all stands be described by an relatively optimum curve, which means that C did not differ much within a wide range of LAI.     

The Persistence of Tetraploid Perennial Ryegrass in a Mixture with Diploid Perennial Ryegrass

An investigation was carried out into the survival of two tetraploid varieties of perennial ryegrass ( Lolium perenne L.), sown in a mixture with a diploid and very intensively grazed for over five years.
Mixture M1 consisted of the late heading varieties Meltra and Vigor , and mixture M2 of the early heading varieties Merlinda and Melino.
The ploidy was determined by microscopic analysis.
The share of the tetraploid component decreased in both mixtures. The decrease was more pronounced in the early heading mixture. Information was also sought on the technique of sampling such swards.     

Assessment of Cattle Preference for Perennial Ryegrass Varieties in Association with White Clover. Does White Clover Content Interfere?

There is a need to evaluate grass varieties under grazing management to allow selection of varieties to increase animal performance. However, the evaluation of animal performance under grazing with each variety is arduous and time-consuming. An alternative is to describe the preference by grazing animals when given a choice of different varieties. Indeed, there is some indications that preference is related to variety characteristics such as leaf content or digestibility, characteristics having also an impact on the level of intake of this variety. However, preference for grass varieties, when sown alone, may not reflect agricultural practice as grasses often occur in mixed swards, associated with white clover. So, the aim of the present work was to determine whether, under grazing management, cattle expressed selections when given a choice of mixed swards in which different perennial ryegrass varieties were grown in association with a common white clover variety at two levels of fertilizer application (60 or 160 kg N ha⁻¹ annum⁻¹). The preference for perennial ryegrass variety per se was then assessed after taking white clover content into consideration. The results show that there were significant differences in preference for perennial ryegrass varieties, per se, even for varieties with the same heading date and ploidy. The effect of white clover cover on sward selection was more marked in swards which received the higher level of nitrogen fertilizer application which may have been related to a more variable white clover content between swards. This suggests that, under low nitrogen fertilizer application, differences in perennial ryegrass varieties preference can be determined in the same experiments as are used to determine ryegrass varieties persistence in association to white clover. Nevertheless, before such ‘variety preference’ tests can be applied in practice, a validation of the possible correlation between ‘variety preference’ and ‘variety intake’ will be necessary.     

不同基因型水稻镉积累动态差异分析

探讨镉(Cd)在籽粒Cd积累量差异较大的2个常规籼型水稻品种‘黄华占’（Cd低积累）和IR68144（Cd高积累）各器官中的分布差异和积累动态,分析了在大田栽培条件下2个品种全生育期和生殖生长期各组织器官的Cd积累动态过程。结果表明：成熟期两品种植株的大部分Cd都集中于根系和茎部,IR68144各器官的Cd含量都高于‘黄华占’。在整个生育期中,‘黄华占’根和茎中的Cd含量都呈缓慢上升趋势,IR68144根系Cd含量先上升后下降,最后于灌浆后期快速上升,其茎部Cd含量则先下降后上升;两品种叶片Cd含量在抽穗前变化趋势表现一直,而在抽穗后却截然相反。抽穗后,‘黄华占’剑叶和穗轴Cd含量先持续上升,后于黄熟期有所下降,而IR68144的剑叶和穗轴都呈持续上升趋势,两品种的颖壳和糙米的Cd含量也都整体上升,且同品种的两器官表现趋于一致。籽粒发育过程中,两品种糙米Cd积累量都不断地提高,但它们超过一半的Cd由抽穗后的第21~28天积累完成。     

Contribution of White Clover Varieties in High-Productivity Systems under Grazing and Cutting

Two medium leaf size varieties of white clover (Trifolium repens L.) were grown in mixture with a range of grass species and varieties in a field experiment conducted over 4 years. The clovers were grown singly or as a blend in swards with a tetraploid perennial ryegrass (Lolium perenne L.), a diploid Italian ryegrass (Lolium multiflorum L.) or tetraploid hybrids between these two species (Lolium x boucheanum Kunth). These grasses were also grown in monoculture. Swards were managed in a regime involving two periods of sheep grazing, two periods of cattle grazing and a silage cut in the same year for 4 years. The objectives of this experiment were 3‐fold: (1) to examine the yield and persistency of white clover in highly productive systems with modern perennial, hybrid and Italian ryegrasses; (2) to compare the performance of white clover varieties grown singly in mixture with grasses with their performance together as a blend, and (3) to examine the persistency of new Italian ryegrass varieties, exemplified by AberComo. The clover content of the sward remained high throughout the experiment, with a mean of 31 % overall. Differences in clover yield between plots were largely attributable to the effects of companion grasses. Total yields were very similar in plots containing different clover varieties and in plots where these varieties had been grown singly or as a blend. Grass yields in mixture were greater than those in monoculture but showed similar relative rankings. The diploid Italian ryegrass variety AberComo showed an unexpectedly high yield in the 4th year of the experiment. The implications of these results for strategies for productive, sustainable agriculture using modern white clover and ryegrass varieties are discussed.     

高温刈割时期对非秋眠紫花苜蓿再生的影响

为探讨高温期非秋眠紫花苜蓿的生长状态以及高温期刈割对紫花苜蓿再生产量及品质的影响。采用双因素随机区组设计,3 个非秋眠紫花苜蓿品种在8 月上中旬分别进行4 次刈割试验。结果表明：‘WL656’、‘WL712’和‘WL903’在高温条件下保持较好生长状态,植株高度、鲜重显著增长;高温期刈割后可正常生长,但刈割当天气温会影响再生植株长势;8 月1 日和8 月5 日刈割处理的紫花苜蓿再生速度显著慢于8 月10 日和8 月15 日刈割处理;品种间再生速度趋势基本一致。刈割时期和苜蓿品种对苜蓿粗蛋白、酸性洗涤纤维和中性洗涤纤维含量均有显著或极显著影响。总体来看,‘WL656’、‘WL712’和‘WL903’属于较耐热型品种,夏季产量和品质可维持在较好的状态。     

Rhodes grass breeding in Kenya I. Intra-variety variation and character relationships

Summary Spaced swards of 3000 plants and a selected subpopulation of 750 plants of 3 commericial Rhodes varieties, Mbarara, Masaba and Pokot, were studied between 1969 and 1975. Intra-variety variation was large in heading date, vigour of growth, seed (PGS) yield, persistence, drought tolerance and in vitro digestibility.There were on average 6 weeks between the heading date of the first and the last 5% of the plants within a variety. Variation in heading date was largely accounted for by variation in vigour and vice versa. Vigorous plants tended to be early heading and only few plants were found to possess a combination of high vigour and late heading.Among plants equally selected for high vigour from within a variety, early-heading plants were higher in PGS yield, persistence, drought tolerance and digestibility.     

Effects of elevated CO2 and cutting frequency on the productivity and herbage quality of a semi-natural grassland

Monoliths of a fertile, although N limited, C₃ grassland community were subjected (or not) to an atmospheric CO₂ enrichment (600 μmol mol⁻¹), owing to the Mini-FACE system from August 1998 to June 2001, at two contrasting cutting frequencies (3 and 6 cuts per year). The present study reports the effects of elevated CO₂ on the above-ground productivity and on the herbage quality. Elevated CO₂ did not affect the dry matter (DM) yield of the swards in 1999. In 2000, the second year, there was a positive CO₂ effect (+26%) both on the DM and on the nitrogen yields (+30%). With the frequently cut monoliths, the DM of the legume component of the sward was strongly increased by elevated CO₂. This effect became also significant in July 2000 for the low cutting frequency treatment. These results are in good agreement with the concept of an increased legume development and symbiotic N₂ fixation triggered by an increased ecosystem scale demand of N under elevated CO₂. At a low cutting frequency, the DM of the forbs was strongly increased in elevated compared with ambient CO₂. This increased development of the forbs apparently led to a competitive decline of the grasses. Therefore, the total DM yield response to CO₂ was smaller at a low (+15%) compared with a high (+36%) cutting frequency in 2000. An increase in the water soluble sugar content of the bulk forage under elevated CO₂ and a corresponding decline in cell wall contents (NDF) were observed. In June 1999, the decline in NDF was correlated with an increased in-vitro DM digestibility. The forage quality was also indirectly affected by elevated CO₂ through changes in leaf:stem ratio and in botanical composition. At a low cutting frequency, the increased forb content favoured the herbage quality because of a higher digestibility of the forb shoots and, indirectly, through the reduction in the mass of the grass stems. These results emphasise the role of species dynamics for elevated CO₂ impacts on semi-natural grassland productivity and herbage quality.     

不同秋眠类型苜蓿品种的生产性能研究

通过对国内外42个秋眠级为2~9级的紫花苜蓿品种4个生产年的研究, 探讨苜蓿秋眠级与生产性能的关系。结果表明: (1)不同秋眠级苜蓿的干物质产量均呈第4年≈第3年＞第1年＞第2年的趋势, 其中第2生长年(2003年)天气温度较低和降雨过量是其低产的直接原因; (2)在郑州地区, 4、2秋眠级苜蓿干物质产量显著高于非秋眠品种, 其他秋眠或半秋眠苜蓿产量也程度不同地高于非秋眠苜蓿; (3)不同秋眠级的苜蓿品种第1茬产量最高, 其次为第2、3、4茬, 第5茬产量最低; (4)苜蓿的秋眠级与年干物质产量、粗蛋白质(CP)含量呈负相关, 与粗纤维(CF)呈正相关, 认为郑州地区不宜选用非秋眠品种。     

Influence of cutting frequency on the morphology and the C and N reserve status of two cultivars of white clover (Trifolium repens L.)

The influence of cutting frequency was studied on white clover (Trifolium repens L.) cultivars (giant-Aran and dwarf-Rivendel) during two experiments set up under field conditions. Clover morphological and biochemical characteristics were measured prior to regrowth in response to various cutting interval treatments (1, 2, 3, 6 and 8 weeks of regrowth between two successive defoliations). The morphology of the aerial parts of the plant was described through the residual leaf area (RLA), the number of total growing points (TGP), stolon length and stolon and root dry matter productions per unit of cultivated area, as well as stolon dry weight per unit length. C and N reserve status was assessed by starch and vegetative storage proteins (VSP) concentration and amount measurements. Cutting frequency largely influenced the different variables. RLA and TGP increased in response to frequent cuttings while all other morphological and biochemical parameters decreased, with the exception of the soluble protein concentrations and protein amounts. Nevertheless, a significant difference in morphology and C and N reserve accumulation was shown between the two clover cultivars. In spite of a few number of leaves and growing points, the giant cultivar Aran showed higher C and N reserves, compared with the dwarf type Rivendel. However, the genetic expression of these differences was tightly linked to the cutting frequency applied to the sward, and was at its maximum in response to the most frequent treatments. Subjected to severe cuttings, both genotypes showed an increase in RLA and TGP, the greater effect of the treatment was obtained with the dwarf-type Rivendel. Frequent defoliations strongly reduced organic reserves but the cutting-induced decreases observed in starch and VSP contents were similar for each cultivar. Overall results confirmed that the morphological development of clover, partly defined by genetic performance, should also be controlled by cutting frequency, and highlighted a tight relationship between morphogenesis, reserve accumulation and sward management. Results are also discussed in terms of the use of C and N reserve contents as a further characterisation of white clover cultivars.     

双季水稻叶片温度变化规律及其与产量关系的研究

为了研究水稻叶片温度与产量关系,以双季早晚稻12个品种为材料,2008-2009年应用红外测温仪记录叶片温度,并分析大气温度、气叶温差与产量的关系。结果表明,水稻叶片温度的日变化呈单峰曲线,变化幅度小于气温;在不同生育阶段品种间气叶温差存在明显差异。各生育时期14:00点的气叶温差与产量呈正相关关系,抽穗期的相关程度最高;抽穗期和抽穗后的剑叶日平均温度与产量呈负相关,剑叶的日平均气叶温差与产量呈正相关;超级稻的气叶温差高于非超级稻。     

Unravelling the relationship between a seasonal environment and the dynamics of forage growth in grazed swards

It is well reported in the scientific literature that pastures can have similar net forage accumulation when managed with contrasting structures. However, we hypothesized that the dynamics of forage accumulation in grazed swards is linked to seasonal-environmental conditions. Marandu palisadegrass (Brachiaria brizantha [Hochst. ex A. Rich.] was used as the forage species model. The experimental treatments were four grazing heights (10, 20, 30 and 40 cm) allocated to experimental units according to a randomized complete block design with four replicates and evaluated throughout four contrasting environmental seasons (summer, autumn, winter–early spring and late spring). Under rainy and warm periods, greater net forage accumulation was observed in pastures maintained taller; on the contrary, during the mild and dry periods, net forage accumulation rate reduced as grazing height increased. Such patterns of responses were related to compensations between tiller population density and tissues flows during summer and late spring and the reduced capacity of taller canopies to compensate lower population with greater growth rates during autumn and winter–early spring. Grazed swards changed their patterns of forage growth as they transitioned from favourable to more abiotic stressful conditions, suggesting that seasonal adjustments in grazing intensities are necessary in order to maximize forage production.     

北方茶区茶树短穗扦插繁育技术研究

研究旨在提出适宜北方茶区茶树的扦插繁育技术,为抗寒茶树品种的选育和推广提供技术支撑。以无性系茶树品种‘中茶108’为试验材料,采用L₉(3⁴)正交试验设计,研究激素种类、插穗状态、浸蘸浓度和时间等因子对茶苗发育和扦插成活率的影响。正交试验结果显示,最优组合为A₁B₃C₃D₃,即插穗清水浸泡,扦插前浸蘸200 mg/L IBA 30 min,成活率达81.3%;4个扦插因素产生的效应由主到次依次为激素种类、插穗处理方式、激素的浸蘸时间、激素浓度。不同激素种类处理下,地上部发育指标显示IBA+NAA处理有利于叶片数量和干重增长;由茶苗根系发育情况表型观测可知,IBA+NAA处理根类组成较合理,有利于根系中一级侧根、延长根和吸收根的协同生长;由根系发育指标分析可知,IBA+NAA处理最大程度地促进了根系总根长、总表面积、根体积、根尖数和生物量的增长。由此确立最优扦插组合为插穗斜削后立即清水浸泡,扦插前用激素组合IBA(200 mg/L)+NAA(200 mg/L)浸蘸30 min后迅速插入基质。在此扦插组合下,27个茶树品种的扦插繁育特性差异较大,扦插成活率最高为91.1%,最低仅为12.17%,高于80%的有11个。研究结果在北方茶树扦插中具有较强的应用性,能够为茶树品种的选育和推广提供技术支撑。     

抽穗后冬小麦旗叶光合特性的变化对产量的影响

为了探讨不同小麦品种之间的光合特性的差异及光合作用与经济产量的关系,本研究选取4个不同冬小麦品种分别在6个生育时期进行了光合特性的测定。结果表明：小麦旗叶6项光合特性指标随发育进程变化的趋势、变化程度基本相同,但不同品种在不同发育时期内光合特性指标的数值、变化程度不同;6项光合特性指标均与籽粒产量正相关;相关程度表现为绿叶面积>气孔导度>胞间CO₂浓度>净光合速率>叶绿素含量>蒸腾速率;不同时期光合特性与籽粒产量的相关性顺序为灌浆中期>灌浆前期>灌浆后期>开花期>抽穗期>灌浆末期;在开花期至灌浆后期,维持和提高旗叶的绿叶面积、叶绿素含量、净光合速率、气孔导度、胞间CO₂是提高小麦产量的基础。因此,在开展小麦高光效育种时,对种质资源材料进行光合特性测定和比较对育种工作具有非常重要的参考价值和指导意义。     

Phenological and physiological evaluation of first and second cropping periods of sorghum and maize crops

Environmental conditions influence phenology and physiological processes of plants. It is common for maize and sorghum to be sown at two different periods: the first cropping (spring/summer) and the second cropping (autumn/winter). The phenological cycle of these crops varies greatly according to the planting season, and it is necessary to characterize the growth and development to facilitate the selection of the species best adapted to the environment. The aim of this study was to characterize phenological phases and physiological parameters in sorghum and maize plants as a function of environmental conditions from the first cropping and second cropping periods. Two parallel experiments were conducted with both crops. The phenological characterization was based on growth analyses (plant height, leaf area and photoassimilate partitioning) and gas exchange evaluations (net assimilation rate, stomatal conductance, transpiration and water-use efficiency). It was found that the vegetative stage (VS) for sorghum and maize plants was 7 and 21 days, respectively, longer when cultivated during the second cropping. In the first cropping, the plants were taller than in the second cropping, regardless of the crop. The stomatal conductance of sorghum plants fluctuated in the second cropping during the development period, while maize plants showed decreasing linear behaviour. Water-use efficiency in sorghum plants was higher during the second cropping compared with the first cropping. In maize plants, in the second cropping, the water-use efficiency showed a slight variation in relation to the first cropping. It was concluded that the environmental conditions as degree-days, temperature, photoperiod and pluvial precipitation influence the phenology and physiology of both crops during the first and the second cropping periods, specifically cycle duration, plant height, leaf area, net assimilation rate, stomatal conductance and water-use efficiency, indicating that both crops respond differentially to environmental changes during the growing season.     

Varietal differences in perennial ryegrass for nitrogen use efficiency in leaf growth following defoliation: performance in flowing solution culture and its relationship to yield under simulated grazing in the field

Varietal differences in rates of NO₃ uptake and remobilization of nitrogen (N) during a cycle of severe defoliation and regrowth were assessed in perennial ryegrass (Lolium perenne L.) varieties Ba11778, Aberelan, Talbot and Gator. Plants were grown in flowing solution culture for 34 days, prior to a 30 d treatment period, including 21 d of regrowth. Net uptake of NO₃ was measured continuously from solutions maintained automatically at 10 mmol m^-3NO₃.¹⁵ N-labelled NO_{3 3} was supplied to the plants in situ for either 21 h immediately prior to defoliation, or for 7-11 days afterwards, to measure remobilization of N from roots and stubble into the regrowing leaves. The four varieties differed only slightly in total dry matter production over 30 d, but varied substantially in post-defoliation specific growth rate by the leaf fraction. Gator was the lowest ( 0.11 g g^-1 d^-1), Ba11778 the highest ( 0.15 g g^-1 d^-1) and Aberelan and Talbot intermediate in leaf regrowth rate. Varieties did not vary significantly in shoot: root dry weight ratio, but the rate of NO₃ uptake per unit of leaf fresh weight during regrowth was 27% lower in Ba11778 than in Gator. Leaves of Ba11778 and Aberelan had a lower organic N concentration in the dry matter at the end of the regrowth period than Talbot, which, in turn, had a lower concentration than Gator. Varieties differed in amount of leaf dry matter produced per unit of N absorbed by the plants after defoliation, the values (g g^-1 N) being Ba11778 (22.6 ), Aberelan (20.7), Talbot (18.3) and Gator (16.7). More N was remobilized from the roots than from the stubble after defoliation. There were no significant differences among varieties in the amount and rate of N remobilization following defoliation. In earlier field experiments employing frequent cutting to simulate grazing, Ba11778 and Aberelan yielded at least 10% more dry matter annually than Talbot which, in turn, outyielded the amenity variety Gator by a similar amount. Thus the present results are consistent with the hypothesis that the efficiency of N use in leaf growth is an important factor determining genetic variation in productivity under frequent defoliation in the field when the herbage produced consists primarily of leaf. This revised version was published online in July 2006 with corrections to the Cover Date.     

Systemic View on Heading and Overwintering: Are They Always Opposed?

The study investigated the cultivars of non‐obligatorily requiring vernalization plant Festulolium braunii and assessed the influence of non‐hardy reproductive and hardy vegetative structures on overwintering effect. The study was conducted taking into account systemic relations between these types of structures. The results show the cultivars differ according to the percentage of headed and overwintered plants, when the cultivars with the most abundant heading – ‘Felopa’ and ‘Sulino’ – are also better at overwintering. The positive correlation between heading and overwintering characteristics was also observed, what seemed to be a rather new finding. It can be explained by systemic effect: non‐hardy later reproductive structures induce the post‐generative regrowth of vegetative shoots, which during shorter days halt development and become potentially hardy. More detailed interpretation is also provided including discussion of causal mechanisms of the detected phenomenon. The authors suppose that these mechanisms constitute a survival strategy for such perennial plants. The observed late heading which represents reproductive structures could be applied in plant breeding as a marker of winter‐hardiness among perennial grass plants which non‐obligatorily demand vernalization.     

Effect of Variety and Seeding Rate on Establishment and Productivity of Alfalfa Sown in Autumn

Five alfalfa varieties (var.) were sown on 26 September, 1983 near Aleppo on clay or heavy clay soils, classified as Vertisols (FAO-system) or Chromoxerertic (Calcic) Rhodoxeralf (USDA-system). Irrigation was applied after planting to ensure uniform germination. Thereafter the study was conducted under supplementary irrigation. The parameters measured to estimate fresh weight (FW) and dry matter (DM) yields; plant height, ground cover and regrowth after cutting, indicated that winter-active var. ( Moapa 69, CUF 101 and Aleppo local ) resulted in better productivity than semi-dormant ( Paravivo ) and dormant ( Lebanon local ) varieties. The 2-years mean average FW yields were 70.2, 68.2, 65.2, 57.1 and 36.9 t/ha, or 16.2, 16.0, 15.5, 13.1 and 8.9 t/ha DM respectively. Forage yields were similar among the 12, 16 and 20 kg/ha seeding rates, indicating little justification for high seeding rates under good establishment conditions, even if a seeding-year yield is desired. In general, seeding rate had also no effect on plant population, which was reduced with time and towards the end of the tested period it became nearly similar and counted 137, 132 and 134 plants/m² according to the seeding rates respectively. Alfalfa yields were positively correlated with plant height, ground cover and regrowth after cutting. The highest yielding combination for FW and DM yields in Moapa 69 with 12 kg/ha seeding rate.     

黑小麦光合特性的变化及对产量的影响

本研究旨在为选育高产黑小麦品种提供理论依据。以5个黑小麦品系和1个普通小麦(CK)为材料,在抽穗期—成熟前期7个生育期探究了旗叶光合特性指数(PCI)的变化及其与籽粒产量(GY)的关系。结果表明：与CK相比,5个黑小麦品系旗叶的叶绿素含量(CC)在抽穗期—灌浆后期均显著较低;绿叶面积(GLA)在灌浆后期较低而在成熟前期则较高,生物学产量(BY)的增长速率在灌浆前—中期均显著较高而在开花期—灌浆前期、灌浆末期—成熟前期则均显著较低;灌浆速度(GFR)在灌浆—中期、灌浆中—后期均显著较低。5项PCI与GY间显著正相关,PCI的变化速率在抽穗期—开花期、开花期—灌浆前期与GY间正相关而在灌浆中—后期、灌浆后—末期、灌浆末期—成熟前期则负相关。PCI的变化速率与GY间相关程度为GLA>Trm>Pn>Gs>CC,Pn>Gs>Trm>CC>GLA。不同时期PCI的变化速率与GY间相关性程度为灌浆中期>灌浆前期>灌浆后期>灌浆末期>抽穗期>开花期>成熟前期,开花期—灌浆前期>抽穗期—开花期>灌浆前—中期>灌浆末期—成熟前期>灌浆后—末期>灌浆中—后期。选育旗叶在抽穗期—灌浆中期具有较高CC、Pn、Gs、GLA的黑小麦品系是提高黑小麦产量的重要手段。     

北方水稻生育后期剑叶可溶性物质含量及植株生产力对CO_2浓度增高的响应

以高产优质粳稻松粳9号和稻花香2号为试材,利用中国北方FACE(free air CO2enrichment)实验平台研究北方水稻生理代谢对CO2浓度增高的响应规律。在水稻抽穗期开始测定剑叶可溶性糖含量、蛋白质含量和总叶绿素含量,收获后实测小区产量及产量构成因素,比较处理间和品种间差异。结果表明,CO2浓度增高显著提高水稻抽穗期、乳熟期和完熟期剑叶可溶性糖含量,松粳9号和稻花香2号最高增幅分别达11.7%和47.5%。CO2浓度增高显著降低抽穗期和完熟期剑叶可溶性蛋白含量,松粳9号和稻花香2号最大降幅分别为16.2%和10.5%。CO2浓度增高使抽穗期和乳熟期剑叶总叶绿素含量显著增加,松粳9号和稻花香2号最大增幅达18.9%和22.5%,之后便逐渐降低。CO2浓度增高使松粳9号单株籽粒产量、生物学产量、经济系数分别提高6.82%、1.50%和12.64%,稻花香2号平均升高2.56%、2.13%和26.05%。研究表明,CO2浓度增高最终提高了水稻植株生产力,对可溶性物质含量的影响在不同生育期存在差异。这可能由于CO2浓度增高促进水稻生长发育,导致水稻提早成熟,叶片衰老促进了可溶性糖分解,也加快了功能叶可溶性蛋白向籽粒运输速率。