Effects of drought on non-structural carbohydrates and C,N,and P stoichiometric characteristics of Pinus yunnanensis seedlings

To study non-structural carbohydrate character-istics and nutrient utilization strategies of Pinus yunnanen-sis under continuous drought conditions,2-year-old seed-lings were planted in pots with appropriate water,light and moderate and severe drought treatments[(80±5),(65±5),(50±5),and(35±5)%of field water-holding capacity].Non-structural carbohydrates,carbon(C),nitrogen(N),and phosphorus(P)concentrations were measured in each plant component.The results show that:(1)With increasing drought,non-structural carbohydrates gradually increased in leaves,stems,and coarse roots,while gradually decreased in fine roots;(2)C concentrations of all were relatively stable under different stress levels.Phosphorous utilization of each component increased under light and moderate drought conditions,while N and P utilization efficiency of each plant component decreased under severe drought.Growth was mainly restricted by N,first decreasing and then increasing with increased drought;(3)There was a correlation between the levels of non-structural carbohydrates and C,N,and P in each component.Changes in N concentration affected the interconversion between soluble sugar and starch,which play a regulatory role in the fluctuation of the concentration of non-structural carbohydrates;and,(4)Plasticity analysis showed that P.yunnanensis seedlings responded to drought mainly by altering starch concentration,the ratio of soluble sugar to starch in leaves and stems,and further by alter-ing N and P utilization efficiencies.Overall,these results suggest that the physiological activities of all organs of P.yunnanensis seedlings are restricted under drought and that trade-offs exist between different physiological indicators and organs.Our findings are helpful in understanding non-structural carbohydrate and nutrient adaptation mechanisms under drought in P.yunnanensis seedlings.

Irrigation regimes modulate non-structural carbohydrate remobilization and improve grain filling in rice(Oryza sativa L.)by regulating starch metabolism

Recently developed ‘super’ rice cultivars with greater yield potentials often suffer from the problem of poor grain filling, especially in inferior spikelets. Here, we studied the activities of enzymes related to starch metabolism in rice stems and grains, and the microstructures related to carbohydrate accumulation and transportation to investigate the effects of different water regimes on grain filling. Two ‘super’ rice cultivars were grown under two irrigation regimes of well-watered(WW) and alternate wetting and moderate soil drying(AWMD). Compared with the WW treatment,the activities of ADP glucose pyrophosphorylase(AGPase), starch synthase(StSase) and starch branching enzyme(SBE), and the accumulation of non-structural carbohydrates(NSCs) in the stems before heading were significantly improved, and more starch granules were stored in the stems in the AWMD treatment. After heading, the activities of α-amylase, β-amylase, sucrose phosphate synthase(SPS) and sucrose synthase in the synthetic direction(SSs)were increased in the stems to promote the remobilization of NSCs for grain filling under AWMD. During grain filling, the enzymatic activities of sucrose synthase in the cleavage direction(SSc), AGPase, StSase and SBE in the inferior spikelets were increased, which promoted grain filling, especially for the inferior spikelets under AWMD.However, there were no significant differences in vascular microstructures. The grain yield and grain weight could be improved by 13.1 and 7.5%, respectively, by optimizing of the irrigation regime. We concluded that the low activities of key enzymes in carbon metabolism is the key limitation for the poor grain filling, as opposed to the vascular microstructures, and AWMD can increase the amount of NSC accumulation in the stems before heading, improve the utilization rate of NSCs after heading, and increase the grain filling, especially in the inferior spikelets, by altering the activities of key enzymes in carbon metabolism.

Impacts of Defoliation on Morphological Characteristics and Non-Structural Carbohydrates of Populus talassica × Populus euphratica Seedlings

Leaves are important‘source’organs that synthesize organic matter,providing carbon sources for plant growth.Here,we used Populus talassica×Populus euphratica,the dominant species in ecological and timber forests,to simulate carbon limitation through artificial 25%,50%,and 75%defoliation treatments and explore the effects on root,stem,and leaf morphology,biomass accumulation,and carbon allocation strategies.At the 60th d after treat-ment,under 25%defoliation treatment,the plant height,specific leaf weight,root surface area and volume,and concentrations of non-structural carbohydrates in stem and root were significantly increased by 9.13%,20.00%,16.60%,31.95%,5.12%,and 9.34%,respectively,relative to the control.There was no significant change in the growth indicators under 50%defoliation treatment,but the concentrations of non-structural carbohydrates in the leaf and stem significantly decreased,showing mostly a negative correlation between them.The opposite was observed in the root.Under 75%defoliation treatment,the plant height,ground diameter,leaf number,single leaf area,root,stem,and total biomass were significantly reduced by 14.15%,10.24%,14.86%,11.31%,11.56%,21.87%,and 16.82%,respectively,relative to the control.The concentrations of non-structural carbohydrates in various organs were significantly reduced,particularly in the consumption of the starch concentrations in the stem and root.These results indicated that carbon allocation strategies can be adjusted to increase the con-centration of non-structural carbohydrates in root and meet plant growth needs under 25%and 50%defoliation.However,75%defoliation significantly limited the distribution of non-structural carbohydrates to roots and stems,reduced carbon storage,and thus inhibited plant growth.Defoliation-induced carbon limitation altered the carbon allocation pattern of P.talassica×P.euphratica,and the relationship between carbon reserves in roots and tree growth recovery after defoliation was greater.This study provides a theoretical basis for the comprehen-sive management of P.talassica×P.euphratica plantations,as well as a reference for the study of plantation car-bon allocation strategies in the desert and semi-desert regions of Xinjiang under carbon-limitation conditions.

Increasing grain weight and yield stability by increasing pre-heading non-structural carbohydrate reserves per spikelet in short-growth duration rice

Rice yield stability is a breeding goal,particularly for short-growth duration rice,but its underlying mechanisms remain unclear.In an attempt to identify the relationship between yield stability and source–sink characteristics in short-growth duration rice,a field experiment was conducted at three sites(Yueyang,Liuyang,and Hengyang)in 2021 and 2022.This study compared yield,yield components,source–sink characteristics,and their stability between two stable-yielding short-growth duration rice cultivars,Zhongzao 39(Z-39)and Lingliangyou 268(L-268),and two unstable-yielding short-growth duration rice cultivars,Zhongjiazao 17(Z-17)and Zhuliangyou 819(Z-819).The stability of agronomic parameters was represented by the coefficient of variation(CV).The respective CVs of yield in Z-17,Z-819,Z-39,and L-268 were 10.2%,10.1%,4.5%,and 5.7%in 2021 and 19.7%,15.0%,5.4%,and 6.5%in 2022.The respective CVs of grain weight were 6.3%,5.7%,3.4%,and 4.5%in Z-17,Z-819,Z-39,and L-268 in 2021,and 8.1%,6.3%,1.5%,and 0.8%in 2022.The mean source capacity per spikelet and pre-heading non-structural carbohydrate reserves per spikelet(NSC_(pre))were 7%–43%and7%–72%lower in Z-819 and Z-17than in L-268 and Z-39 in 2021 and 2022.The mean quantum yield of photosystem II photochemistry of leaf,leaf area index,and specific leaf weight of L-268 and Z-39 were higher than those of Z-819 and Z-17 at the heading stage.This study suggests that high NSC_(pre),caused by great leaf traits before heading,increases source capacity per spikelet and its stability,thereby increasing the stability of grain weight and yield.Increasing NSC_(pre)is critical for achieving grain weight and yield stability in short-growth duration rice.

Study on the Changes of Non-structural Carbohydrates and Nitrogen Contents of Quercus aquifolioides Scrub along Different Elevation Gradient

[Objective] The aim was to compare the content changes between the non-structural carbohydrates（NSC）and the total nitrogen in various growing seasons,and to explore the response relationship between altitude and the contents.[Method] Taking Quercus aquifolioides scrub which widely distributed in Zheduoshan in the west of Sichuan as the experimental objects,the changes between NSC and the toal nitrogen in various growing seasons at different altitude were studied.[Result] The results showed that the content of NSC in Quercus aquifolioides underground increased with the lift of elevation in the dormancy,but decreased in the early germination,growing period and growth stage.The content of NSC in the ground tissue changed non-linearly with increasing elevation.In addition,the total nitrogen of Quercus aquifolioides organizations was decreasing with increasing elevation in the dormant period,which did not change significantly in the other periods.This result implied that the content of NSC in Quercus aquifolioides underground was more sensitive to temperature.[Conclusion] The experiment laid basis for the exploration of the physical and ecological mechanism of underground plants adaptability to highland environment,their response to global climate changes and adjustment to high altitude ecological system.

Accumulation of Carbohydrate and Regulation of 14-3-3 Protein on Sucrose Phosphate Synthase(SPS) Activity in Two Tomato Species

To explore the differences of carbohydrate metabolism in two tomato species and discuss the possible regulation of 14-3-3 proteins on the sucrose phosphate synthase （SPS） activity, we determined the contents of soluble sugar and starch through high performance liquid chromatography （HPLC）. The activities of sugar-metabolizing enzymes were assayed in desalted extract, and the relative expression levels of related genes in sugar metabolism were determined though real-time RT-PCR. The results indicated that glucose and fructose were mainly accumulated during the maturation of the fruit because of the high acid invertase （AI） and neutral invertase （NI） in Micro-Tom （Solanum lycopersicum） fruit, while in Solanum chmielewskii fruit, SPS which went along with the change of sucrose content led to the rapid sucrose increase during the fruit ripening. TFT1 and TFT10, belonging to 14-3-3 protein in tomato, were likely to down-regulated SPS activity during young and intumescence period.

Effects of Panicle Nitrogen Fertilization on Non-Structural Carbohydrate and Grain Filling in Indica Rice

Grain filling, a crucial stage of grain yield formation in rice, is usually affected by the panicle nitrogen （N） fertilization. Field and pot culture experiments were conducted to explore the underlying mechanisms of N effect. Two rice cultivars with high lodging resistance were grown in the field and pot. Four panicle N fertilization treatments were conducted in 2006 and repeated in 2007. The result showed that medium level of panicle N fertilization treatment （NM） enhanced the accumulation and translocation of non-structural carbohydrate （NSC） in the stem and sheath. Compared with non-nitrogen treatment （NO）, NM promoted the translocation of labeled ^13C from stem and sheath to grain. But, low level of panicle N fertilization treatment （NL） and high level of panicle N fertilization treatment （NH） showed the negative effect. The endosperm cell, grain length, and grain width of NM increased more quickly than that of NO from 4 to 10 d after anthesis. During the early period of grain filling, sucrose-phosphate synthase （EC 2.4.1.14, SPS） activity were significantly higher for the NM treatment than those of the NL and NH treatments. Sucrose synthase （EC 2.4.1.13, SuSase） activity in the grains was substantially enhanced by NM, with the duration of higher activity being longer than those of the other treatments. At maturing stage, NM significantly increased the filled grain number, the seed-setting rate, and the grain weight compared with NL and NH. The results suggest that NM have a positive effect on the activities of enzymes of physiological importance, thereby increasing the grain size and promoting grain filling.

Accumulation and Distribution Dynamics of Soluble Carbohydrate in Helianthus tuberosus under Drought Stress

With Qingyu 1 and Qingyu 2 as test materials, variation of soluble carbohydrate content in different parts were studied under two types of artificially simulated drought stress （polyethylene glycd PEG-6000 stress and water-controlling stress）. The results showed that under the stress of PEG, soluble carbohydrate content in leaves of Qingyu 1 and Qingyu 2 increased with the prolonging time of stress; soluble carbohydrate content in stems of Qingyu 1 did not show regular changes with the prolonging time of stress, while 30% PEG stress received the best effect on Qingyu 2 after 24 h; soluble carbohydrate content in roots of Qingyu 1 and Qingyu 2 increased with the prolonging time of stress. Under different intensities of water-controUing stress, soluble carbohydrate content in leaves of Qingyu 1 first increased then decreased, while that in leaves of Qingyu 2 increased; soluble carbohydrate content in stems of Qingyu 1 and Qingyu 2 increased with the pro- longing time of water-controlling stress; soluble carbohydrate content in roots of Qingyu 1 decreased with the prolonging time of water-contmlling stress, while that in roots of Qingyu 2 differed slightly.

Non-structural carbohydrate levels of three co-occurring understory plants and their responses to forest thinning by gap creation in a dense pine plantation

We investigated non-structural carbohydrates（NSC） levels and components（starch,glucose,fructose and sucrose） in the leaves of three typical co-occurring forestfloor plants,moss Eurhynchium savatieri（ES）,fern Parathelypteris nipponica（PN） and forb Aruncus sylvester（AS） in a 30-year-old Chinese pine（Pinus tabulaeformis）plantation forest on the eastern Tibetan Plateau.We also explored their responses to three gap creation treatments（control and two gap creations of 80 and 110 m2） based on NSC levels.PN had the highest leaf NSC level of the three plants,with AS second and ES lowest.Starch was the predominant component of NSC and the contents of glucose were higher than those of fructose or sucrose for all three species.The NSC level of ES in intermediate gaps was significantly higher than at control sites.PN also had higher NSC levels in both small and intermediate gaps than in control sites.But the differences between treatments were not obvious for AS.Our results suggest that ES and PN benefit from gap formation while the two species have different NSC response sensitivities to gap size,but the leaf NSC level of AS is less sensitive to the disturbance.

Radial growth and non-structural carbohydrate partitioning response to resin tapping of slash pine(Pinus elliottii Engelm.var.elliottii)

Slash pine(Pinus elliottii Engelm.var.elliottii)is a resin-producing species grown worldwide for significant economic benefits for wood production.Resin tapping cre-ates a carbon sink at the expense of carbon allocation for growth and consequently,wood production may be reduced.Non-structural carbohydrates comprising starch and sugars stored in plant organs,may serve as intermediate pools between assimilation and utilisation.However,the effect of resin tapping between tree growth and non-structural carbo-hydrates is not well understood.This study investigated(1)the effects of resin tapping on radial growth,(2)the effects of resin tapping on non-structural carbohydrate pools in different compartments,and(3)the feasibility of resin pro-duction without disruption of tree growth.Twenty one-year-old slash pines were subjected to resin tapping over two suc-cessive years.Non-structural carbohydrate concentrations in needles,branches,stem phloem,and roots of tapped and untapped trees in summer and winter were determined after the second year of resin harvest.The results showed that tapping had no significant effects on annual increments.Starch was the dominant non-structural carbohydrate frac-tion,regardless of tissues and season,and constituted up to 99%of the total non-structural carbohydrates in the phloem and roots.Glucose and fructose were the dominant sugars;sucrose was negligible.Compared with the controls,tapped trees showed 26%lower non-structural carbohydrate concen-tration in the phloem above the tapping wound in summer,which was attributable to the decreased abundance of starch,glucose,fructose,and sucrose.In winter,the altered non-structural carbohydrate profiles in the phloem above the tap-ping wounding were minimised as a result of recovery of the sugar concentrations.In contrast to free sugars,which accu-mulated substantially in needles and branches during winter,starch was enriched in the phloem,roots,and current-year needles.The results provide evidence for a localised effect of resin tapping,and highlight the observation that resin extrac-tion does not always cause a sacrifice in wood growth under a moderate resin-tapping intensity in slash pine plantations.

Carbon allocation in Picea jezoensis:Adaptation strategies of a non-treeline species at its upper elevation limit

Understanding the physiological adaptations of non-treeline trees to environmental stress is important to understand future shifts in species composition and distribution of current treeline ecotone.The aim of the present study was to elucidate the mechanisms of the formation of the upper elevation limit of non-treeline tree species,Picea jezoensis,and the carbon allocation strategies of the species on Changbai Mountain.We employed the^(13)C in situ pulse labeling technique to trace the distribution of photosynthetically assimilated carbon in Picea jezoensis at different elevational positions(tree species at its upper elevation limit(TSAUE,1,700 m a.s.l.)under treeline ecotone;tree species at a lower elevation position(TSALE,1,400 m a.s.l.).We analyzed^(13)C and the non-structural carbohydrate(NSC)concentrations in various tissues following labeling.Our findings revealed a significant shift in carbon allocation in TSAUE compared to TSALE.There was a pronounced increase inδ^(13)C allocation to belowground components(roots,soil,soil respiration)in TSAUE compared to TSALE.Furthermore,the C flow rate within the plant-soil-atmosphere system was faster,and the C residence time in the plant was shorter in TSAUE.The trends indicate enhanced C sink activity in belowground tissues in TSAUE,with newly assimilated C being preferentially directed there,suggesting a more conservative C allocation strategy by P.jezoensis at higher elevations under harsher environments.Such a strategy,prioritizing C storage in roots,likely aids in withstanding winter cold stress at the expense of aboveground growth during the growing season,leading to reduced growth of TSAUE compared to TSALE.The results of the present study shed light on the adaptive mechanisms governing the upper elevation limits of non-treeline trees,and enhances our understanding of how non-treeline species might respond to ongoing climate change.

The effects of stump size and within-gap position on sprout non-structural carbohydrates concentrations and regeneration in forest gaps vary among species with different shade tolerances

Background:To restore secondary forests(major forest resources worldwide),it is essential to accelerate the natural regeneration of dominant trees by altering micro-environments.Forest gaps are products of various disturbances,ranging from natural storms or wildfires to anthropogenic events like logging and slashing-andburning,and sprouts of most tree species with non-structural carbohydrates(NSCs)storage can regenerate from stumps after gap formation.However,how the stump sprouts with diverse NSCs storages and stump sizes(i.e.,diameters)adapt to various micro-environments of within-gap positions remains unclear.Therefore in this study,we monitored the stump sprout regeneration(density,survival,and growth)and NSCs concentrations of three dominant tree species with different shade tolerances and varying stump diameters at five within-gap positions for the first two consecutive years after gap formation.Results:Stump diameter was positively correlated with sprout density,growth,and survival of all three tree species,but insignificantly related with sprout NSCs concentrations at the early stage after gap formation.The effect of within-gap position on sprout NSCs concentrations was different among species.After an environmental adaptation of two growing seasons,the north of gap(higher light availability and lower soil moisture habitat)was the least conducive for shade-intolerant Quercus mongolica to accumulate leaf NSCs,and the east of gap(shadier and drier habitat)was conducive to increasing the leaf NSCs concentrations of shade-tolerant Tilia mandshurica.Conclusions:Within-gap position significantly affected leaf NSCs concentrations of all three tree species,but most of the sprout growth,survival,and stem NSCs concentrations were independent of the various within-gap positions.Besides stump diameter,the NSCs stored in stump and root systems and the interspecific differences in shade tolerance also contributed more in sprout regeneration at the early stage(2 years)of gap formation.A prolonged monitoring(>10 years)is needed to further examine the long-term effects of stump diameter and within-gap position on sprout regeneration.All of these findings could be applied to gap-based silviculture by promoting sprout regeneration of dominant tree species with different shade tolerances,which would help accelerate the restoration of temperate secondary forests.

再生季稻与同期抽穗主季稻干物质分配特性及机制研究

研究再生稻干物质积累与转运特性对深入理解再生稻产量形成的生理机制及进一步挖掘增产潜力有重要的理论与实际意义。本研究以华东南稻区推广的常规籼稻佳辐占和籼粳杂交稻甬优2640两个再生稻品种作为供试材料,在确保2个供试水稻品种的再生季稻和主季稻在籽粒灌浆阶段处于同一晚秋气温条件下抽穗成熟,比较再生季稻及其同期抽穗的主季晚稻的光合生理、激素含量、干物质生产、非结构性碳水化合物(NSC)、13C同化物在植株地上部和地下部的干物质积累与分配差异。结果表明,相比同期抽穗的同基因型主季晚稻,2个供试品种的再生季稻生育期缩短50%,但有效穗数和收获指数分别增加50%和10%,最终产量可达到对照产量的55%~65%;再生季稻在籽粒灌浆前期叶片光合速率和SPAD值均明显增高,但齐穗后20 d至成熟期其光合速率和SPAD值则明显降低;再生季稻株体内的ZR、IAA含量在齐穗期较高,之后相比较低,再生季稻株内的ABA含量在齐穗期至齐穗后10 d或20 d较高,达到10%~20%,而其GA3含量普遍较低;再生季稻稻桩、叶片和茎鞘的NSC转运率高达67%~78%、59%~67%和52%~61%,因此其NSC转运对产量贡献率也分别高达10%~18%;13C光合同化物分配在穗部占比大,成熟期再生季稻穗部的分配率高20.83%,同时,减少了再生季稻13C同化物向地下部的转移量达5%,因而有效穗多,收获指数高。再生季稻减少了光合同化物向根际土壤的转移与分配,既能提高其收获指数,又有利于减少水稻的CH4等温室气体排放量,是一种经济高效益和环境友好型的稻作模式。

Border effects of the main and ratoon crops in the rice ratooning system

The border effect(BE)is widely observed in crop field experiments,and it has been extensively studied in many crops.However,only limited attention has been paid to the BE of ratoon rice.We conducted field experiments on ratoon rice in Qichun County,Hubei Province,Central China in 2018 and 2019 to compare the BE in the main and ratoon crops,and to quantify the contribution of BE in the main crop to that in the ratoon crop.The BE of two hybrid varieties was measured for the outermost,second outermost,and third outermost rows in each plot of both crops.To determine the contribution of BE between the two crops,portions of hills in the outermost and second outermost rows were uprooted during the harvest of the main crop so that the second and third outermost rows then became the outermost rows in the ratoon crop.Overall,the BE on grain yield was greater in the main crop than in the ratoon crop.In the main crop,the BE on grain yield was 98.3%in the outermost row,which was explained by the BE on panicles m^(–2),spikelets/panicle,spikelets m^(–2),and total dry weight.In the ratoon crop,the BE on grain yield was reduced to 60.9 and 27.6%with and without the contribution of the BE in the main crop,respectively.Consequently,55.1%of the BE on grain yield in the ratoon crop was contributed from the main crop.High stubble dry weight and non-structural carbohydrate(NSC)accumulation at the harvest of the main crop were responsible for the contribution of BE in the main crop to that in the ratoon crop.Our results suggest that increases in stubble dry weight and NSC accumulation at the harvest of the main crop could be important strategies for developing high-yielding cropping practices in the rice ratooning system.

Grain yield,nitrogen use efficiency and physiological performance of indica/japonica hybrid rice in response to various nitrogen rates

Utilizing the heterosis of indica/japonica hybrid rice(IJHR)is an effective way to further increase rice grain yield.Rational application of nitrogen(N)fertilizer plays a very important role in using the heterosis of IJHR to achieve its great yield potential.However,the responses of the grain yield and N utilization of IJHR to N application rates and the underlying physiological mechanism remain elusive.The purpose of this study was to clarify these issues.Three rice cultivars currently used in rice production,an IJHR cultivar Yongyou 2640(YY2640),a japonica cultivar Lianjing 7(LJ-7)and an indica cultivar Yangdao 6(YD-6),were grown in the field with six N rates(0,100,200,300,400,and 500 kg ha^(-1))in 2018 and 2019.The results showed that with the increase in N application rates,the grain yield of each test cultivar increased at first and then decreased,and the highest grain yield was at the N rate of 400 kg ha^(-1)for YY2640,with a grain yield of 13.4 t ha^(-1),and at 300 kg ha^(-1)for LJ-7 and YD-6,with grain yields of 9.4–10.6 t ha^(-1).The grain yield and N use efficiency(NUE)of YY2640 were higher than those of LJ-7 or YD-6 at the same N rate,especially at the higher N rates.When compared with LJ-7 or YD-6,YY2640 exhibited better physiological traits,including greater root oxidation activity and leaf photosynthetic rate,higher cytokinin content in the roots and leaves,and more remobilization of assimilates from the stem to the grain during grain filling.The results suggest that IJHR could attain both higher grain yield and higher NUE than inbred rice at either low or high N application rates.Improved shoot and root traits of the IJHR contribute to its higher grain yield and NUE,and a higher content of cytokinins in the IJHR plants plays a vital role in their responses to N application rates and also benefits other physiological processes.

不同施氮处理对乌桕容器苗养分状况的影响

研究不同施N处理对乌桕容器苗营养元素和非结构性碳水化合物的影响,筛选出培育乌桕容器苗的最佳施肥方法和施氮量。以当年生乌桕容器苗为试验材料,设置传统施肥(C600)、指数施肥(Z200、Z400、Z600、Z800、Z1000)和不施肥(CK)共7个处理,分别测定不同N素施肥处理对乌桕容器苗N、P、K等营养元素浓度(质量分数,下同)、积累量和可溶性糖等非结构性碳水化合物含量的影响。结果表明,各施N处理对乌桕容器苗养分状况均有显著影响。随施N量的增加,乌桕容器苗各器官的N浓度都是先增后减,最大值出现在指数施肥Z600处,根、茎、叶的N浓度分别为101.80、91.50 mg·g^(-1)和121.33 mg·g^(-1)。乌桕容器苗各器官P浓度都较对照有所降低。指数施肥条件下,根和茎中的K浓度随施N量的增加逐渐降低,叶中的K浓度随施N量增加呈现先增后减趋势,在Z600处达到最大;乌桕容器苗地上部分、地下部分和全株的营养元素积累量都随施N量的增加出现先增后减趋势,最大值都出现在Z600处;在指数施肥的各处理中,乌桕容器苗根、茎、叶各器官中的可溶性糖含量随施N量增加均呈现先增后减趋势,在指数施肥Z600处达到最大,分别为63.73、55.55 mg·g^(-1)和134.70 mg·g^(-1),指数施肥促进乌桕容器苗可溶性糖含量积累的作用要优于传统施肥;除C600和Z200外,其他各施肥处理组根淀粉含量均较对照有下降趋势,且在指数施肥条件下根淀粉含量随施N量的增加而减少。在茎和叶中,各施肥处理组和对照组淀粉含量无明显差异。指数施肥优于传统施肥,Z600处理下的乌桕容器苗的营养元素浓度、积累量和非结构性碳水化合物含量最高,为乌桕容器苗最佳施肥处理。

外源亚精胺对盐胁迫下黄瓜幼苗光合作用和根叶碳水化合物积累的影响

采用营养液水培,以盐敏感黄瓜品种‘津春2号’为试材,研究外源亚精胺(Spd)对盐胁迫下黄瓜幼苗光合作用及根叶碳水化合物积累的影响。结果表明:与对照相比,50 mmol·L-1 NaCl抑制了幼苗生长和光合作用;盐胁迫提高了叶片可溶性总糖、蔗糖、淀粉含量及根系可溶性总糖和蔗糖含量,降低根系淀粉含量;盐胁迫提高了根系磷酸蔗糖合酶(SPS)、蔗糖合酶(SS)和淀粉水解酶活性及叶片SPS、SS活性,降低叶片淀粉水解酶活性。与单纯盐胁迫相比,外施Spd显著提高了幼苗生长及光合作用,降低了叶片碳水化合物含量及根系可溶性总糖、蔗糖含量,提高了根系淀粉含量,降低了叶片中SPS、SS活性和根系SPS、SS和淀粉水解酶活性,提高叶片淀粉水解酶活性。推测外源Spd可能参与了盐胁迫下气孔调控,并调节相关酶活性以减少碳水化合物积累对光合作用的负反馈抑制,从而缓解了盐胁迫对光合作用的伤害,提高了植株盐胁迫耐性。

甘薯块根碳水化合物合成与积累动态特性研究

以不同干物质类型的甘薯品种绵粉1号、南薯88和商丘52-7为材料,研究了甘薯块根形成与膨大期间碳水化合物积累与淀粉合成相关酶活性的动态变化及其相互关系。结果表明,作为品种的固有特征,干物质含量或淀粉含量的差异主要决定于品种的遗传特性。对于中高干率品种而言,淀粉在生育中后期积累较快。磷酸蔗糖合成酶(SPS)活性与品种间淀粉积累量一致,中等干物质品种(南薯88)中后期的蔗糖合成酶(SS)活性较高,淀粉积累量也最多,SPS和SS对淀粉合成与积累具有促进作用,ADPG焦磷酸化酶有随气温降低而活性下降的趋势。此外不同品种均表现出甘薯块根干物质含量与可溶性糖含量、淀粉产量与可溶性糖含量呈极显著的负相关关系。

渍水对小麦节间水溶性碳水化合物积累与再分配的影响

盆栽小麦挑旗期至花后 2 0天长期渍水处理植株节间可溶性总糖含量除在花后 10～ 15天低于对照外 ,其余时期尤其是成熟期均高于对照。渍水使 WSC主要组分果聚糖的合成关键酶 SST(Sucrose:sucrose fructosyltransferase)、FFT(Fructan:fructan fructosyltransferase)活性减弱 ,果聚糖积累速率下降 ,积累持续时间缩短 ;开花后果聚糖外水解酶 FEH(Fructan exo- hydrolase)活性降低。

土壤碳水化合物的转化与累积研究进展

碳水化合物虽然仅占土壤有机质的10％～20％，却是土壤中最活跃的有机碳库，是微生物的主要能源和碳源，歼参与土壤团聚体的形成，是土壤有机质和土壤性质研究中的重要指标和对象。本文综述了土壤碳水化合物种类、来源和在团聚体中的分布特征、微生物群落结构对碳水化合物的转化和积聚的影响，同时讨论了耕作、施肥等农业措施对碳水化合物含量和分布的影响。从现有文献资料来看，碳水化合物的含量因土壤粒级不同而异；外源碳水化合物在土壤中的转化和累积与微生物群落结构特征密切相关，细菌在单糖等简单碳水化合物的转化中起主要作用，而复杂碳水化合物则首先在真菌的作用下水解成单糖；真菌和革兰氏阳性菌丰富的土壤更有利于碳水化合物来源碳的累积，但是详细的转化过程和存在形态认识有限，有待深入研究。