根系分区交替滴灌对苹果幼苗生理特性和水分利用效率的影响

以矮化红富士苹果幼苗为试验材料,采用交替滴灌(ADI)、固定滴灌(FDI)和常规滴灌(CDI)3种滴灌方式和3种灌水量对苹果幼苗的生理特性和水分利用效率进行了研究,以阐明根系分区交替灌溉下苹果幼苗生理特性和节水机理.结果表明:与CDI方式相比,当灌水定额由20 mm增大到30 mm时,ADI方式提高了苹果幼苗根干重、根系导水率、叶水势和净光合速率,降低了其蒸腾速率、棵间蒸发量和蒸散量,从而使得ADI方式下的叶片水分利用效率、总水分利用效率和灌溉水分利用效率较CDI方式大大提高;3种滴灌方式的根系导水率均存在显著的季节变化,并以8月份最大,12月份最小;与CDI方式相比, ADI和FDI方式在节水达33.3%时的平均根系导水率仅分别降低了5.81%和14.7%,但水分利用效率、灌溉水利用效率分别较CDI方式高出16.31%和14.48%、40.52%和27.65%.可见,局部根区灌溉方式能促进苹果幼苗生长和光合作用,并主要通过提高根系导水率的途径来提高水分利用效率.     

吉林省47年育成的水稻品种根系伤流液重量变化及其与剑叶光合速率的关系

为了解不同年代水稻品种根系活力的变化及其与叶片光合的关系,以根系伤流液重量作为根系活力指标,研究了吉林省1958-2005年间育成的33个水稻品种抽穗后根系伤流液重量变化及其与剑叶净光合速率的关系。2--~-的研究结果表明,47年的遗传改良导致了水稻品种根系伤流液重量增加,根系伤流液重量与品种的育成年份呈显著正相关,与剑叶光合速率也呈显著正相关。抽穗后根系伤流液重量可以作为剑叶光合能力和高产的参考指标。     

谷子叶片光合速率日变化及水分利用效率

通过降低空气湿度（ 从约３０ ％ 减少到５ ％ ） 、增加ＣＯ２ 浓度（ 从４００ μｌ ＣＯ２／Ｌ增加到７３０ μｌ ＣＯ２／Ｌ） 、烫叶鞘破坏韧皮部等处理对谷子叶片光合速率日变化和水分利用效率（ＷＵＥ） 进行了研究, 发现中午光合速率降低与光合产物积累有关; 虽然低大气相对湿度（５ ％ ） 使光合速率有所降低,但提高了ＷＵＥ。而烫叶鞘使光合物质积累既抑制了光合速率,又降低了ＷＵＥ。     

Effects of a Severe Drought on Water and Nitrogen Use by Quercus ilex and Phyllyrea latifolia

A severe drought that took place in Spain and other Mediterranean countries in 1994 produced a dieback of Quercus ilex trees on south-facing conglomerates but only minor defoliations in trees on north-facing schists. The foliar ¹³C of damaged trees continued to decrease in the next two wet years probably indicating increasing water use efficiency, and their ¹⁵N continued to increase indicating progressive ecosystem N saturation and/or N losses whereas there were no significant changes in undamaged trees. Pre-drought ¹³C values were reached in the third year after the drought, but ¹⁵N values did not yet recover. Another co-occurring small tree, Phyllyrea latifolia, did not show any damage and gained dominance in the most affected stands.     

Photosynthetic, Physiological and Biochemical Responses of Tomato Plants to Polyethylene Glycol-Induced Water Deficit

Polyethylene glycol （PEG 6000）-induced water deficit causes physiological as well as biochemical changes in plants. The present study reports on the results of such changes in hydroponically grown tomato plants （Lycopersicon esculentum Mill. cv. Nikita）. Plants were subjected to moderate and severe levels of water stress （i.e. water potentials in the nutrient solution of- 0.51 and -1.22 MPa, respectively）. Water stress markedly affected the parameters of gas exchange. Net photosynthetic rate （Pn） decreased with the induction of water stress. Accordingly, a decrease in the transpiration rate （E） was observed. The ratio of both （Pn/E） resulted in a decrease in water use efficiency. One of the possible reasons for the reduction in Pn is structural damage to the thylakoids, which affects the photosynthetic transport of electrons. This was indicated by an increase in non-photochemical quenching and a reduction in the quantum yield of photosystem Ⅱ. Furthermore, a decrease in both leaf water potential and leaf osmotic potential was observed, which resulted in a significant osmotic adjustment during stress conditions. Analysis of the physiological responses was complemented with a study on changes in proline content. In stressed plants, a 10-fold increase in proline content was detected compared with control plants. It is clear that water stress tolerance is the result of a cumulative action of various physiological and biochemical processes, all of which were affected by PEG 6000-induced water stress.     

不同氮效率水稻品种根系生理生态指标的差异

以氮素利用效率差异大的两个水稻品种(氮高效品种南光和氮低效品种Elio)作为试验材料,设计高低两个供氮水平,在温室砂培条件下研究了不同氮效率水稻高效吸收利用氮素的根系生物学特性及生理机制.结果表明,在两个供氮水平下,氮高效水稻南光的产量均显著大于氮低效水稻,增幅在50%以上.随着供氮水平的提高,两个水稻品种植株的总吸氮量和干物质量随之增加,氮高效水稻南光的生育后期吸氮量和地上部及根系的生物量显著高于氮低效水稻Elio;氮高效水稻品种南光根系形态参数对氮素营养的响应度高于氮低效品种Elio,高氮处理下,南光较低氮处理分别增加127%(总根长)和114%(根系表面积),而Elio仅增加92%(总根长)和82%(根系表面积),而且Elio在齐穗期后根系形态参数水平下降显著;南光的根系伤流强度在拔节期较氮低效水稻Elio高出11%(1mmol L-1)和32%(5mmol L-1),灌浆期南光较Elio高出12%(1mmol L-1)和12%(5mmol L-1),差异均显著.由本试验结果可推断根系形态及根系活力的差异是造成水稻氮效率差异的重要原因之一.     

小麦叶片水分利用效率及相关生理性状基因的染色体定位

利用中国春-埃及红代换系对控制小麦水分利用效率、光合速率、蒸腾速率、POD活性以及SOD活性等的基因进行了染色体定位。结果表明,控制高水分利用效率的基因可能位于5A和5D染色体上;控制高光效的基因可能位于3A和3D染色体上;控制高蒸腾速率的基因可能位于7B染色体上;诱导POD和SOD活性增强的有利培因可能分别位于7D和6D、2B染色体上。这些研究结果可以为小麦机抗旱节水的遗传育种研究提供一定参号信息。     

Growth and Photosynthetic Characteristics in Pearl Millet under Water Stress and Different Potassium Supply

Influence of supra-optimal concentrations of K on growth, water relations, and photosynthetic capacity in pearl millet under severe water deficit conditions was assessed in a glasshouse. Nineteen-days-old plants of two lines, ICMV-94133 and WCA-78, of Pennisetum glaucum (L.) R.Br. were subjected for 30 d to 235.0, 352.5, and 470.0 mg(K) kg^–1(soil) and two water regimes (100 and 30 % field capacity). Increasing K supply did not alleviate the effect of water deficit on the growth of two lines of pearl millet since additional amount of K in the growth medium had no effect on shoot dry mass, relative growth rate, plant leaf area, net assimilation rate, or leaf area ratio, although there was significant effect of drought stress on these variables. Soil moisture had a significant effect on net photosynthetic rate (P _N), transpiration rate, stomatal conductance, and water use efficiency of both pearl millet lines, but there was no significant effect of varying K supply on these variables. In WCA-78 an ameliorative effect of increasing supply of K on P _N was observed under water deficit. Chlorophyll (Chl) a and b contents increased significantly in both lines with increase in K supply under well watered conditions, but under water deficit they increased only in ICMV-94133. Chl a/b ratios were reduced significantly in WCA-78 with increasing K supply under both watering regimes, but by contrast, in ICMV-94133 this variable was decreased only under water stress. Leaf water potential and osmotic potential of both lines decreased significantly with the imposition of drought. Leaf pressure potential in both lines increased with increase in K supply under water stress. Contents of total free amino acids in the leaves of both pearl millet lines increased significantly with increase in K supply under water stress. Potassium supply had no effect on leaf soluble sugars or soluble proteins. Considerable osmotic adjustment occurred in pearl millet plants experiencing water deficit under high K supply.     

Effects of Multi-Stage Continuous Drought on Photosynthetic Characteristics,Yield and Water Use Efficiency of Winter Wheat

A drought event can cause entire crops to fail or yield loss. In order to study the effects of continuous drought on photosynthetic characteristics, yield, and water use efficiency (WUE) of winter wheat (Triticum aestivum L.), the winter wheat variety “Aikang 58” was selected as test material with controlling the water of the pot-planted winter wheat under a mobile rainout shelter. Based on foot planting and safe wintering, winter wheat was evaluated under different drought conditions, including light, moderate and severe drought at the jointing (B), heading (C), and filling (G) stages. The soil water content was controlled in a range of 60% to 70%, 50% to 60%, and 40% to 50% of the field capacity, respectively. In the experiment, there were 9 single-stage droughts, 3 three-stage droughts, and 1 test control (totaling 13 trials). The results are as follows: Under a single-stage drought, the change of net photosynthetic rate (Pn) and stomatal conductance (Gs) have similar trends, and they both decrease significantly with the severity of the drought. Under three-stage continuous droughts, the change curve of Gs shows a constant downward trend; the change curve of Pn showed a “valley shape,” and the minimum value of Pn appeared at the heading stage. All droughts will reduce the yield of winter wheat. Under the three-stage continuous drought conditions, except for light drought, moderate drought and severe drought will cause significant yield reduction, mainly due to lack of water at the jointing and heading stages. Continuous drought will reduce the WUE, and the difference will reach a significant level under moderate and severe drought. The present results suggested that when water resources are scarce, it is a better irrigation model to save water and achieve high grain yield by applying appropriate water stress (60%–70% FC) during the critical growth period of winter wheat.     

Photosynthetic characteristics and growth of Mosla hangchowensis and M. dianthera under different irradiances

The photosynthetic and growth characteristics of Mosla hangchowensis, an endangered species and M. dianthera, a weed, were compared under three irradiances (PPFD) similar to shaded forest understory, forest edge and open land. Both species grown at lower PPFD had lower PPFD-saturated photosynthetic rate (P_max), saturation PPFD, compensation PPFD, apparent quantum yield, total mass and root/shoot ratio and higher specific leaf area, leaf area ratio and height ratio. At the same PPFD treatment, however, specific leaf area and leaf area ratio of M. hangchowensis were higher than those of M. dianthera, other above parameters were lower than those of M. dianthera. Water use efficiency did not differ between M. hangchowensis and M. dianthera, but it reached its maximum at 70 % of full PPFD. These results suggested the optimum habitat of M. hangchowensis is the forest edge.     

低磷条件下不同基因型小麦幼苗对磷的吸收和利用效率及水分的影响

 选用在土壤磷水平为5～7mgP·kg-1土的条件下筛选出来的不同磷效率的4个冬小麦品种,采用盆栽试验研究了有效磷为3．2mgP·kg-1土时的磷效率、磷吸收效率、磷利用效率及土壤水分对这些指标的影响。结果表明：在有效磷很低的土壤上,“磷高效”品种小偃54和81(85)5—3—3—3在幼苗期并未表现出较高的磷效率。尽管这两个品种的磷吸收效率显著地高于NC37和京411,但由于它们的磷利用效率相对低于京411,从而使磷效率并未显著地提高。土壤水分对4个品种的磷吸收效率和利用效率均有显著影响。     

Effects of Elevated Temperature on Growth and Gas Exchange in Dominant Plant Species from Maowusu Sandland,China

We compared the effect of elevated temperature on morphological development, biomass accumulation and allocation, and gas exchange of three dominant plants (Caragana intermedia Kuanget H.C. Fu, Hedysarum mongolicum Turcz., and Artemisia ordosica Krasch.) growing in Chinese Maowusu sandland. Plants were grown in two temperature chambers (25/20, 28/23 °C, day/night) during 60 d. Tree height, number of leaves, and leaf area were increased in C. intermedia and H. mongolicum seedlings, while in A. ordosica temperature only affected tree height. Elevated temperature increased biomass and reduced the root : shoot ratio in C. intermedia and H. mongolicum seedlings, but not in A. ordosica seedlings. The net photosynthetic rate (P _N) and transpiration rate (E) were increased at days 40 and 60 in C. intermedia and H. mongolicum seedlings, while in A. ordosica seedlings no significant effects on E were observed, and P _N was increased only at day 60. Water use efficiency (WUE) was reduced at days 40 and 60 in H. mongolicum seedlings, and at day 60 in C. intermedia seedlings. No temperature effect on WUE was observed in A. ordosica seedlings. These different responses indicate that climate change could alter plant communities in Maowusu sandland.     

根域限制下水氮供应对膜下滴灌棉花叶片光合生理特性的影响

在新疆气候生态条件下,采用管栽方法,选用棉花新陆早13号和新陆早33号2个品种为供试材料,通过人工限制根系垂直生长深度和水氮供应,测定棉花叶片气体交换和叶绿素荧光参数、光合物质积累等,探讨根域限制及水氮供应对棉花光合生理特性及产量形成的影响。结果表明:与对照相比,相同水氮供应条件下,根域限制处理棉花从开花期至盛絮期叶片净光合速率(Pn)、气孔导度(Gs)和光化学猝灭系数(qp)显著降低,尤其在盛铃后期至盛絮期表现明显,但潜在最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)未受到影响;盛花期和盛絮期根重均显著降低,但地上部总干物质、蕾铃干物质累积量及籽棉产量均显著高于对照。同一根域容积不同水氮处理棉花开花期至盛絮期的Pn、Gs和Fv/Fm、ΦPSⅡ、qp均表现为W1N1>W0N1>W1N0>W0N0;根域限制条件下适量水氮供应处理盛花期和盛絮期地上部总干物质和蕾铃干物质累积量均显著增加,最终单株铃数、单铃重和籽棉产量均显著高于其它处理。因此,在膜下滴灌棉花根域容积受限制条件下,通过优化生育期水氮供应,能改善叶片光合性能、增加地上部干物质积累量及其向生殖器官分配比例,是挖掘膜下滴灌棉花产量潜力和提高效益的有效途径。     

Photosynthetic Parameters of Mosla hangchowensis and M. dianthera as Affected by Soil Moisture

We compared the photosynthetic traits in response to soil water availability in an endangered plant species Mosla hangchowensis Matsuda and in a weed Mosla dianthera (Buch.-Ham.) Maxim. The highest diurnal mean net photosynthetic rate (P _Nmean), stomatal conductance (g _s), and water use efficiency (WUE) of both species occurred at 60 % soil water holding capacity (WHC), while the lowest values occurred at 20 % WHC. The P _Nmean, g _s, and chlorophyll (Chl) a and b contents of M. hangchowensis were lower than those of M. dianthera, while the physiological plasticity indices were higher than those of M. dianthera. M. hangchowensis had strong adaptability to the changing soil water status but weak extending population ability in its habitats because of the low P _Nmean, which may be one of the causes of its endangerment.     

滨海沙地不同树种人工林叶片和土壤表层稳定碳氮同位素及水分利用效率研究

以福州市滨海后沿沙地人工营造的湿地松、木麻黄、尾巨桉、肯氏相思和纹荚相思防护林为研究对象,测定不同年龄(新叶、老叶)叶片、表层土壤(0~10cm)天然稳定碳、氮同位素丰度值(δ~(13) C、δ~(15)N),研究稳定碳、氮同位素丰度值与水分利用效率和土壤氮饱和程度的相互关系,以揭示不同树种水分利用效率、氮饱和程度和碳氮循环速率差异的机理。结果表明:(1)滨海沙地不同树种叶片δ~(13) C变化范围为-31.682‰~-29.323‰,其δ~(13) C大小为:湿地松肯氏相思木麻黄纹荚相思尾巨桉,除尾巨桉外各树种δ~(13) C均表现为新叶老叶;各树种叶片δ~(15)N变化范围为-5.548‰~-2.167‰,其δ~(15)N大小为:肯氏相思纹荚相思木麻黄湿地松尾巨桉,且各树种均表现为新叶老叶。(2)不同树种表层土壤δ~(15)N变化范围为-4.675‰~-2.975‰,表层土壤δ~(15)N大小为:纹荚相思肯氏相思木麻黄尾巨桉湿地松,但不同树种表层土壤C含量无显著差异。(3)滨海沙地湿地松、木麻黄、肯氏相思和纹荚相思的水分利用效率随叶龄增加均呈显著递减趋势;不同树种新叶的水分利用效率变化范围为39.09~76.57μmol·mol~(-1),其大小依次为:湿地松肯氏相思木麻黄纹荚相思尾巨桉;老叶的水分利用效率变化范围为38.56~62.59μmol·mol~(-1),其大小依次为:湿地松木麻黄肯氏相思尾巨桉纹荚相思。(4)不同树种人工林水分利用效率与其新叶水分利用效率呈显著正相关关系,说明林分水分利用效率主要体现在新叶的水分利用效率上,同时林分水分利用效率受林分类型的影响。     

Differential <Superscript>13</Superscript>C Isotopic Discrimination in Maize at Varying Water Stress and at Low to High Nitrogen Availability

The relationships between ¹³C isotopic discrimination and water stress are well documented for C₃ and C₄ plants. However, the application in the field is hampered by complex interaction patterns with other common stress factors, such as nutrient deficiency. In addition, questions arise if temporal reductions in water availability during crop growth can be traced back using δ¹³C data in the field. The objective of this study therefore is to assess the potential use of δ¹³C observations to quantify water stress and its dynamics in maize (Zea mays L.) grown under low to high nitrogen availability, and to develop tools based on δ¹³C values for its diagnosis in the field. In a pot experiment, carried out in a screen house in Ibadan, Nigeria, we grew maize for 60 days under four watering regimes, (i) optimum (at field capacity) during 60 days, (ii) optimum from 0 to 30 days and stressed (50% field capacity) from 30 to 60 days, (iii) stressed from 0 to 30 days and optimum from 30 to 60 days, and (iv) stressed throughout the 60 days. Nitrogen was applied at three rates (none, moderate (45 kg N ha⁻¹) and high (120 kg N ha⁻¹)). Plants were sampled after 30 and 60 days. At 60 days, leaves developed during the first 30 days were sampled separately from those developed between 30 and 60 days. Shoot production showed a clear water–nitrogen interaction. Nitrogen response increased with decreasing water stress, in particular from 30 to 60 days. δ¹³C values ranged from −12.42‰ to −10.80‰. Overall, a clear and significant water and nitrogen effect (P<0.0001) on the isotopic discrimination in maize was observed, opposite in direction from C₃ plants. δ¹³C values decreased with increasing water stress, but increased with decreasing nitrogen availability, particularly when combined with limited water supply. In addition, isotopic discrimination was observed to be variable within plant, and could be related to a water stress in that growth period, in which the plant parts were developed. This shows that δ¹³C values measured in different plant parts at harvest can be used as a historical account on how water availability varied during the entire cropping cycle.     

The Effect of CO2 Enrichment on the Growth of Nodulated and Non-Nodulated Isogenic Types of Soybean Raised Under Two Nitrogen Concentrations

To find the effects of CO₂ enrichment on plant development and photosynthetic capacity of nodulated (line A62-1) and non-nodulated (line A62-2) isogenic lines of soybean (Glycine max Merr.), we examined the interactions among two CO₂ treatments (36±3 Pa = AC and 70±5 Pa = EC), and two nitrogen concentrations [0 g(N) m⁻²(land area) = 0N; 30 g(N) m⁻²(land area) = 30N]. Nodules were found in both CO₂ treatments in 0N of A62-1 where the number and dry mass of nodules increased from AC to EC. While the allocation of dry mass to root and shoot and the amount of N in each organ did not differ between the growth CO₂ concentrations, there was larger N allocation to roots in 0N than in 30N for A62-2. The CO₂-dependence of net photosynthetic rate (P _N) for A62-1 was unaffected by both CO₂ and N treatments. In contrast, the CO₂-dependence of P _N was lower in 0N than in 30N for A62-2, but it was independent of CO₂ treatment. P _N per unit N content was unaffected by CO₂ concentrations. The leaf area of both soybean lines grown in 30N increased in EC. But in 0N, only the nodulated A62-1 showed an increase in leaf area in EC. Nitrogen use efficiency of plants, NUE [(total dry mass of the plant)/(amount of N accumulated in the plant)] in 30N was unaffected by CO₂ treatments. In 0N, NUE in EC was lower than in AC in A62-1, and was higher than that at AC in A62-2. Hence, the larger amount and/or rate of N fixation with the increase of the sink-size of symbiotic microorganisms supplied adequate N to the plant under EC. In EC, N deficiency caused the down-regulation of the soybean plant. This revised version was published online in June 2006 with corrections to the Cover Date.     

盐碱地马蔺光合生理特性的研究

研究了盐碱地生长的马蔺叶片净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）和水分利用效率（WUE）以及环境因素的日变化。结果表明,马蔺叶片Pn和Tr均呈现双峰曲线,具有光合午休现象。这种现象出现的原因是由于较高的太阳辐射引起叶片温度的升高,叶片的羧化效率(CE)和表观量子产额(AQY)的下降造成的。     

Photosynthesis and Chlorophyll Fluorescence in Two Hybrids of Sorghum under Different Nitrogen and Water Regimes

In two hybrids of sorghum (Sorghum bicolor Moench.), C51 and C42, high nitrogen concentration (HN) increased net photosynthetic rate (PN), stomatal conductance (gs), and transpiration rate (E) of well watered (HW) plants. Water stressing (LW plants) resulted in low PN, gs, and E in both hybrids, but the values were still higher in HN plants as compared to low nitrogen-grown (LN) plants. Intercellular CO2 concentration (Ci) increased in droughted plants. This increase was much higher in LN plants as compared to HN plants. Instantaneous water use efficiency was lower in LN plants as a consequence of a greater effect of water stress on photosynthesis. Leaf water potential was reduced by water stress in all treatments. Analysis of chlorophyll a fluorescence at room temperature showed that photosystem 2 (PS2) was rather tolerant to the water stress imposed. Water stress caused a slight decrease in the efficiency of excitation capture by open PS2 reaction centres (Fv/Fm). The in vivo quantum yield of PS2 photochemistry (PS2) and the photochemical quenching coefficient (qP) were slightly reduced, while the nonphotochemical quenching coefficient (qN) was increased under the water stress. However, in hybrid C42 these characters were little or not affected by the water stress.     

Alterations in Growth and Yield of Camelina Induced by Different Planting Densities under Water Deficit Stress

Camelina (Camelina sativa L.) is famous for its oil quality and unique fatty acid pattern. Growth and yield of crops reduced under water deficit conditions. Environmental threat such as drought or water deficit condition is the emerging problem which creates the negative impact on the growth of plants. Based upon the current situation a pot study was performed in rain out-shelter to explore the effect of different plant densities (15, 10 and 5 plants per pot) on growth and seed yield of two camelina genotypes under normal (100% WHC) and water deficit (60% WHC) conditions by using completely randomized design with factorial arrangement having three replicates. Results indicated that individual effects of plant densities and water deficit stress levels considerably influenced the growth and seed yield of camelina but interaction effects did not indicate any significant variation. Maximum values of leaf area index (LAI) and crop growth rate (CGR) were recorded in P3 treatment (15 plants per pot). However, maximum values of leaf area duration (LAD), net assimilation rate (NAR), yield and yield components were observed in the treatment P₁ (5 plants per pot). Water deficit condition (60% WHC) significantly minimized the growth, seed yield (0.82 g/m² ) and yield components of camelina genotypes. Both camelina genotypes (611 and 618) did not differ significantly under water deficit conditions.