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1.
为探究半干旱地区雨养春小麦旗叶的光合作用限制因素、不同生育期差异及其适应策略,分析了大田条件下春小麦旗叶在抽穗期和灌浆期光合生理特征的动态变化规律,探讨了自然条件下光合作用的气孔与非气孔限制特征。结果表明:净光合速率日变化趋势在抽穗期和灌浆期分别为单峰型和双峰型,峰值相当,为18.5μmol(CO2)·m-2·s-1左右。气孔导度具有与净光合作用几乎相似的日变化规律,胞间CO2浓度大致为上午下降、下午回升。胞间CO2浓度变化除受光合作用消耗和气孔限制共同作用外,下午时段叶肉导度增大,也影响胞间CO2浓度变化。在抽穗期和灌浆期,春小麦旗叶光合作用速率与气孔导度相关性十分显著,相关系数分别达0.916(P=0.000)和0.945(P=0.000)。并且2个生育期均出现明显的光合气孔限制,抽穗期达0.64,灌浆期为0.53。其中,抽穗期气孔导度对饱和水汽压差响应十分敏感,下午出现较为明显的气孔限制;灌浆期中午出现较为明显的光合"午休"现象,其主要原因是半干旱区较大饱和水汽压差和强烈辐射致使气孔关闭,气孔限制达到极大值,并且非气孔限制因素也较为突出。抽穗期至灌浆期,由于气孔对饱和水汽压差敏感性的下降以及"午休"策略,光合气孔限制逐渐减小,是春小麦在半干旱地区维持较高光合速率和保证产量的重要自适应机制。  相似文献   

2.

Purpose

This study investigated how nitrogen (N) nutrition and key physiological processes varied under changed water and nitrogen competition resulting from different weed control and fertilisation treatments in a 2-year-old F1 hybrid (Pinus elliottii Engelm var. elliottii?×?P. caribaea var. hondurensis Barr. ex Golf.) plantation on a grey podzolic soil type, in Southeast Queensland.

Materials and methods

The study integrated a range of measures including growth variables (diameter at ground level (DGL), diameter at breast height (DBH) and height (H)), foliar variables (including foliar N concentration, foliar δ13C and δ15N) and physiological variables (including photosynthesis (An), stomatal conductance (gs), transpiration (E), intrinsic water use efficiency (WUEi) (A/gs) and xylem pressure potential (ΨXPP)) to better understand the mechanisms influencing growth under different weed control and fertilisation treatments. Five levels of weed control were applied: standard (routine), luxury, intermediate, mechanical and nil weed control, all with routine fertilisation plus an additional treatment, routine weed control and luxury fertilisation. Relative weed cover was assessed at 0.8, 1.1 and 1.6 years after plantation establishment to monitor the effectiveness of weed control treatments. Soil investigation included soil ammonium (NH4 +-N), nitrate (NO3 ?-N), potentially mineralizable N (PMN), gravimetric soil moisture content (MC), hot water extractable organic carbon (HWETC), hot water extractable total N (HWETN), total C, total N, stable C isotope composition (δ13C), stable N isotope composition (δ15N), total P and extractable K.

Results and discussion

There were significant relationships between foliar N concentrations and relative weed cover and between tree growth and foliar N concentration or foliar δ15N, but initial site preparation practices also increased soil N transformations in the planting rows reducing the observable effects of weed control on foliar δ15N. A positive relationship between foliar N concentration and foliar δ13C or photosynthesis indicated that increased N availability to trees positively influenced non-stomatal limitations to photosynthesis. However, trees with increased foliar N concentrations and photosynthesis were negatively related to xylem pressure potential in the afternoons which enhanced stomatal limitations to photosynthesis and WUEi.

Conclusions

Luxury and intermediate weed control and luxury fertilisation positively influenced growth at early establishment by reducing the competition for water and N resources. This influenced fundamental key physiological processes such as the relationships between foliar N concentration, A n, E, gs and ΨXPP. Results also confirmed that time from cultivation is an important factor influencing the effectiveness of using foliar δ15N as an indicator of soil N transformations.
  相似文献   

3.
大豆幼苗光合特性对锰营养的响应   总被引：2，自引：0，他引：2  
采用溶液培养方法,设Mn2+浓度为0、0.05、0.50、5、30、50.mg/L,探讨了2种大豆品种(浙春2号、东北大豆854-11)的幼苗光合特性对不同锰浓度的响应。结果表明,低锰浓度提高了大豆叶片的初始荧光(Fo)、最大荧光(Fm)、PSⅡ原初光能转化效率(Fv/Fm)、潜在光化学活性(Fv/Fo)和光化学猝灭系数(qP),高锰降低了Fo、Fm、Fv/Fm、Fv/Fo、qP。随着锰营养的增加,非光化学猝灭系数(qN)增大。适量的锰浓度显著提高了大豆的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs),降低了气孔阻力(Rs)和细胞间CO2浓度(Ci),随着锰浓度的逐渐增大,降低了Pn、Tr、Gs,提高了Rs、Ci。0.50.mg/L下的锰浓度有最大的Fo,5.mg/L下的锰浓度有最大的Fm、qP、Fv/Fm、Fv/Fo,表明0.505～mg/L的锰浓度有利于大豆的光合作用。在50.mg/L的锰浓度下,两个大豆品种有最大的qN、Rs、Ci和最小的Tr、Pn,此时两个品种大豆耗散了过剩的激发能,降低了大豆叶片的光合速率,对大豆已产生了一定的伤害。两个品种大豆光合特性对锰的响应存在着基因型差异,浙春2号较东北大豆耐锰胁迫。  相似文献   

4.
Terminal drought stress (drought at reproductive growth stage) has been considered a severe environmental threat under changing climatic scenarios and undoubtedly inhibits sunflower production. A field study was conducted to explore the potential role of foliar applied boron (B) (0, 15, 30, 45 mg L?1) at late growth periods of sunflower in alleviating the adversities of terminal drought stress (75, 64, 53 mm DI) grown from inflorescence emergence to maturity stages. The plant water relations such as leaf relative water content (RWC), water potential (Ψw), osmotic potential (Ψs), and turgor pressure (Ψp) were increased significantly with B foliar sprays while exposed to terminal drought stress. Foliar B application considerably improved the nitrogen and B concentrations in leaf and seed tissues, and also chlorophyll a and b pigments under terminal drought stress conditions. Drought-induced proline accumulation prevented the damages caused by drought stress, nevertheless, B foliar spray increased its contents. Compared to well-watered conditions, terminal drought stress substantially declined the growth performance in terms of reduced leaf area index (LAI), crop growth rate (CGR), net assimilation rate (NAR), and total dry matter (TDM) production; however, foliar B supply (30 mg L?1) might be helpful for improving drought tolerance in sunflower with reduced growth losses.  相似文献   

5.
To improve the performance of a coupled model based on a Leuning–Ball stomatal conductance (gs) model for rice under water deficit conditions, leaf temperature rising (ΔT) was incorporated into the Leuning–Ball model and a revised coupled model for simulation of stomatal conductance gs–net photosynthesis rate (Pn)–transpiration rate (Tr) was developed based on data collected from a rice paddy with nonflooded controlled irrigation in 2003 and 2004. Both a Leuning–Ball and revised Leuning–Ball and coupled model based on both were evaluated with internal conductance (gic) determined by different equations. The performance of the Leuning–Ball model was improved under water deficit condition by incorporating ΔT, and the revised Leuning–Ball model performed better than the Leuning–Ball model in the coupled model of stomatal conductance–photosynthesis–transpiration for rice under water deficit conditions. Meanwhile, accuracy in gic calculation is essential for simulation of Pn, but not for simulation of Tr. Thus, leaf temperature rising ΔT is suitable as a leaf water status indicator in a simulation of rice leaf gas exchange response to water deficit conditions.  相似文献   

6.
Understanding the effect of boron (B) on plant physiology will help to refine the diagnosis of B deficiency and improvement in B fertilizer recommendations for cotton (Gossypium hirsutum L.) growing areas. This study shows the testing of hypotheses “that application of B-fertilizer improves net photosynthetic rate (PN) and water use efficiency (WUE) for cotton plant on a B-deficient soil [< 0.50 mg B kg?1 hydrochloric acid (HCl)-extractable] in an arid environment”. Thus, a permanent layout [two-year field experiment (2004 and 2005)] was conducted to study the impact of B fertilizer at 0, 1.0, 1.5, 2.0, 2.5, and 3.0 kg ha?1 on gas exchange and electrolyte leakage (EL) characteristics of cotton crop (cv. ‘CIM-473’). The soil at experimental site was alkaline (pH 8.1), calcareous [calcium carbonate (CaCO3 5.6%)], and silt loam (Typic Haplocambid). Boron use decreased EL of plant membrane (P ≤ 0.05), and increased PN, transpiration rate (E) and stomatal conductance (gs), while intercellular concentration of carbon dioxide (CO2; Ci) significantly decreased (P ≤ 0.05) during both experimental years. There was a positive, but non-significant effect of B concentration on chlorophyll content in plant leaves. Application of 3.0 kg B ha?1 improved WUE up to 9.7% [4.62 μmol (CO2) mmol?1 water (H2O)] compared to control plants (4.21 [μmol (CO2) mmol?1 (H2O)]. Principal component analysis (PCA) of data indicates positive correlations between leaf B concentration and PN, E, gs, and WUE, while a negative relationship existed between leaf B concentration and intercellular CO2 (Ci). This study showed that addition of B fertilizer in the B-deficient calcareous soil proved beneficial for growth and development for cotton crop by enhancing its WUE and gas exchange characteristics.  相似文献   

7.
Water and temperature are critical for producing vegetable crops, especially during winter, when the availability of water is meager and temperature falls. Studies of drip irrigation and mulch were undertaken to find the effect on different growth and yield parameters in pepper (Capsicum annuum L.). The experiment was laid out in a split-plot design with four main and four subplots. Irrigation levels were placed on main plots and mulches on subplots with three replicates for each. All recorded vegetative parameters were higher with drip irrigation at 1.0 pan evaporation (Epan) and black polythene mulch. Physiological parameters such as photosynthesis rate (18.01 and 17.45 μmol m?2 s?1), transpiration rate (6.19 and 5.86 mmol H2O m?2 s?1) and chlorophyll content (27.34 and 28.39; 39.22 and 41.27 SPAD, respectively at 50 and 100 days after planting) were maximal in crops with drip irrigation at 1.0 Epan and mulched with black polythene. Soil and canopy temperature were significantly higher on flood irrigation at 1.0 Epan. Soil temperature was higher with the black polythene mulch, but canopy temperature was higher with no mulch. A higher level of drip irrigation and black polythene mulch result in early picking with higher yields compared with flood irrigation and no mulch.  相似文献   

8.
研究旨在通过大田试验了解水分调亏对膜下滴灌板蓝根生长、耗水规律、产量、水分利用效率及品质的影响。于2018年在甘肃河西中部的民乐县益民灌溉试验站开展板蓝根水分控制试验,在板蓝根苗期和肉质根生长期保持充分灌水,营养生长期和肉质根生长期分别进行不同梯度(轻度、中度和重度)的水分调亏处理,并测定各项生长指标、产量、水分利用效率和品质。结果表明:(1)营养生长期和肉质根生长期中度和重度水分调亏显著降低了板蓝根株高、叶片数、主根长和主根直径,且降幅随调亏程度的加剧而增大,而轻度水分调亏与对照组无显著差异。(2)板蓝根在营养生长期和肉质根生长期各处理的耗水量呈现出随着水分调亏程度的加重而逐渐降低趋势,与对照相比降低显著(P<0.05);耗水强度变化次序为营养生长期和肉质根生长期(约3.0 mm/d)>肉质根成熟(约1.5 mm/d)>苗期(约1.0 mm/d)。(3)营养生长期轻度水分调亏处理的板蓝根产量与水分利用效率最高,分别达到8475.38 kg/hm^2和23.33 kg/(hm^2·mm),营养生长期和肉质根生长期连续轻度水分调亏处理次之,其余水分调亏处理产量和水分利用效率均有所下降,且与对照组之间差异显著(P<0.05)。(4)在营养生长期和肉质根生长期轻中度连续水分调亏有利于靛蓝、靛玉红、(R,S)-告依春、多糖含量的提高,且与对照组差异显著(P<0.05),重度水分调亏处理各项指标均最低。因此,综合分析板蓝根产量、水分利用效率和品质可知,最优控水处理为营养生长期和肉质根生长期连续轻度水分调亏,即该阶段土壤相对含水率为65%~75%,可作为河西冷凉灌区板蓝根种植的最佳灌水策略。  相似文献   

9.
The deficiency of potassium (K) has resulted in decreasing the yield and quality of food grains. Moreover, with decreasing water resources the use of wastewater in agriculture as an alternative source of water and nutrients is being debated. This study was therefore undertaken to test wastewater for its suitability as irrigation water together with uniform basal doses of nitrogen (N) and phosphorus (P) and varying doses of potassium (K0, K20, K40 and K60). It was observed that the plants receiving wastewater as a source of irrigation water performed better with a lower K dose. Potassium at 20?kg?ha?1 along with wastewater resulted in better growth, photosynthetic rate (P N), stomatal conductance (g s) and yield of the chickpea (Cicer arietinum L.). Thus fertilizer rates could be lowered with the use of wastewater which can serve not only as the source of water but of nutrients also. However, regular monitoring of wastewater and soil for any buildup of heavy metal is necessary. The physical and chemical parameters of wastewater were also tested and most of them were found to be well within the permissible limits as set by the Food and Agriculture Organization (FAO).  相似文献   

10.
Sorghum [Sorghum bicolor (L.) Moench] was grown hydroponically with or without 50 ppm silicon (Si), and exposed to water stress from 10 days after sowing (DAS). At 15 and 23 DAS, we measured dry weight and diurnal variations in photosynthetic rate (P N), stomatal conductance (g s), transpiration rate (T), leaf water potential (ψ L), and water uptake rate (23 DAS only). The reduction in dry weight at 23 DAS caused by water stress was ameliorated by silicon. Under water stress, silicon-treated seedlings showed higher g s, P N, and T than untreated ones. ψ L remained almost constant within treatments throughout the daytime. Water uptake rate was reduced by water stress, but the reduction was ameliorated by silicon. We conclude that silicon enhanced water uptake and g s, improving water supply to the leaves. These effects of silicon occurred soon after exposure to water stress.  相似文献   

11.
为探究不同新型肥料对贵州省酸性黄壤小白菜产量、品质、光合特性及肥料利用的影响,同时筛选出适合贵州黄壤施用的新型肥料产品,以贵州酸性黄壤为基础,通过盆栽试验设置对照(CK,不施氮肥)、西洋复合肥(常规施肥)、保水型功能性肥和稳定性缓释肥4个处理,研究了新型肥料对小白菜产量、品质、光合特性以及养分吸收利用的影响。结果表明:施用保水型功能性肥和稳定性缓释肥可显著增加小白菜播种后34 d的生物量,较常规施肥处理相比鲜重分别增加4.16%和22.28%,干重分别增加41.55%和62.35%;施用新型肥料还可以改善小白菜的营养品质,与常规施肥处理相比,保水型功能性肥可显著降低硝酸盐含量18.61%,而还原性糖、V_c和游离氨基酸含量分别增加25.74%、130.95%和16.91%;而稳定性缓释肥则使硝酸盐、还原糖和Vc含量分别提高26.68%、15.35%和50.00%,但是游离氨基酸含量则较常规施肥相比降低14.43%;而且新型肥料还增强了小白菜叶片的光合能力(净光合速率Pn、气孔导度gs、胞间CO_2浓度Ci以及蒸腾速率Tr),其中以稳定性缓释肥处理的小白菜光合能力最佳,且气孔因素是导致净光合速率增加的主要原因。施用新型肥料小白菜对氮素的吸收显著增加,氮肥利用效率显著提高,新型肥料处理的氮肥农学效率(AEN)、偏生产力(PFPN)、生理利用率(PE_N)和表观利用率(REN)平均分别为48.30 kg·kg~(-1)、59.85 kg·kg~(-1)、95.46 kg·kg~(-1)和52.79%,以稳定性缓释肥处理的氮肥利用效率最佳,尤其是氮肥表观利用率达66.66%。此外,相关性分析结果显示,小白菜产量与叶片净光合速率P_n、气孔导度g_s以及蒸腾速率T_r均呈显著正相关关系,说明提高小白菜叶片的气体交换参数P_n、g_s和T_r可以增加小白菜产量;同时小白菜叶片氮含量与氮肥生理利用率和氮肥表观利用率存在极显著相关性,r值分别为-0.937和0.978,表明增加小白菜叶片氮含量可以提高小白菜对氮肥的利用效率。综上所述,新型肥料对贵州酸性黄壤上小白菜的生物增产效应以及光合特性提高等效果显著,可为将来在贵州农业生产中推广应用提供参考和理论依据。  相似文献   

12.
The objective was to develop and adapt a versatile analytical method for the quantification of solvent extractable, saturated long‐chain fatty acids in aquatic and terrestrial environments. Fulvic (FA) and humic (HA) acids, dissolved organic matter (DOM) in water, as well as organic matter in whole soils (SOM) of different horizons were investigated. The proposed methodology comprised extraction by dichloromethane/acetone and derivatization with tetramethylammonium hydroxide (TMAH) followed by gas chromatography/mass spectrometry (GC/MS) and library searches. The C10:0 to C34:0 methyl esters of n‐alkyl fatty acids were used as external standards for calibration. The total concentrations of C14:0 to C28:0 n‐alkyl fatty acids were determined in DOM obtained by reverse‐osmosis of Suwannee river water (309.3 μg g—1), in freeze‐dried brown lake water (180.6 μg g—1), its DOM concentrate (93.0 μg g—1), humic acid (43.1 μg g—1), and fulvic acid (42.5 μg g—1). The concentrations of the methylated fatty acids (n‐C16:0 to n‐C28:0) were significantly (r2 = 0.9999) correlated with the proportions of marker signals (% total ion intensity (TII), m/z 256 to m/z 508) in the corresponding pyrolysis‐field ionization (FI) mass spectra. The concentrations of terrestrial C10:0 to C34:0 n‐alkyl fatty acids from four soil samples ranged from 0.02 μg g—1 to 11 μg g—1. The total concentrations of the extractable fatty acids were quantified from a Podzol Bh horizon (26.2 μg g—1), Phaeozem Ap unfertilized (48.1 μg g—1), Phaeozem Ap fertilized (57.7 μg g—1), and Gleysol Ap (66.7 μg g—1). Our results demonstrate that the method is well suited to investigate the role of long‐chain fatty acids in humic fractions, whole soils and their particle‐size fractions and can be serve for the differentiation of plant growth and soil management.  相似文献   

13.
Singh  R. K.  Chaudhary  R. S.  Somasundaram  J.  Sinha  N. K.  Mohanty  M.  Hati  K. M.  Rashmi  I.  Patra  A. K.  Chaudhari  S. K.  Lal  Rattan 《Journal of Soils and Sediments》2020,20(2):609-620
Purpose

Accelerated erosion removes fertile top soil along with nutrients through runoff and sediments, eventually affecting crop productivity and land degradation. However, scanty information is available on soil and nutrient losses under different crop covers in a vertisol of Central India. Thus, a field experiment was conducted for 4 years (2010–2013) to study the effect of different crop cover combinations on soil and nutrient losses through runoff in a vertisol.

Materials and methods

Very limited information is available on runoff, soil, and nutrient losses under different vegetative covers in a rainfed vertisol. Thus, the hypothesis of the study was to evaluate if different crop cover combinations would have greater impact on reducing soil and nutrient losses compared to control plots in a vertisol.

This experiment consisted of seven treatment combinations of crop covers namely soybean (Glycine max) (CC1), maize (Zea mays) (CC2), pigeon pea (Cajanus cajan) (CC3), soybean (Glycine max)?+?maize (Zea mays) ??1:1 (CC4), soybean (Glycine ma x))?+?pigeon pea (Cajanus cajan) ?2:1 (CC5), maize (Zea mays)?+?pigeon pea (Cajanus cajan) ??1:1 (CC6), and cultivated fallow (CC7). The plot size was 10?×?5 m with 1% slope, and runoff and soil loss were measured using multi-slot devisor. All treatments were arranged in a randomized block design with three replications.

Results and discussion

Results demonstrated that the runoff and soil loss were significantly (p?<?0.05) higher (289 mm and 3.92 Mg ha?1) under cultivated fallow than those in cropped plots. Among various crop covers, sole pigeon pea (CC3) recorded significantly higher runoff and soil loss (257 mm and 3.16 Mg ha?1) followed by that under sole maize (CC2) (235 mm and 2.85 Mg ha?1) and the intercrops were in the order of maize?+?pigeon pea (211 mm and 2.47 Mg ha?1) followed by soybean?+?maize (202 mm and 2.38 Mg ha?1), and soybean?+?pigeon pea (195 mm and 2.15 Mg ha?1). The lowest runoff and soil loss were recorded under soybean sole crop (194 mm and 2.27 Mg ha?1). The data on nutrient losses indicated that the highest losses of soil organic carbon (SOC) (25.83 kg ha?1), total nitrogen (N), phosphorus (P), and potassium (K) (7.76, 0.96, 32.5 kg ha?1) were recorded in cultivated fallow (CC7) as compared to those from sole and intercrop treatments. However, sole soybean and its intercrops recorded the minimum losses of SOC and total N, P, and K, whereas the maximum losses of nutrients were recorded under pigeon pea (CC3). The system productivity in terms of soybean grain equivalent yield (SGEY) was higher (p?<?0.05) from maize?+?pigeon pea (3358 kg ha?1) followed by that for soybean?+?pigeon pea (2191 kg ha?1) as compared to sole soybean. Therefore, maize?+?pigeon pea (1:1) intercropping is the promising option in reducing runoff, soil-nutrient losses, and enhancing crop productivity in the hot sub-humid eco-region.

Conclusions

Study results highlight the need for maintenance of suitable vegetative cover as of great significance to diffusing the erosive energy of heavy rains and also safe guarding the soil resource from degradation by water erosion in vertisols.

  相似文献   

14.
The objective of this study was to investigate the influence of saline groundwater depths (SGDs) (0.3, 0.55, and 0.80 m) with salinity equivalent to irrigation water salinity (WS) and irrigation WS (10, 20, 30, and 40 dS m?1) on physiological characteristics, gas exchange, and plant ion relations of quinoa in cylindrical lysimeters in greenhouse conditions. Root length density (RLD) in the soil layer close to the saline shallow groundwater decreased. Soil aeration was the key point for reduction in RLD by decreasing SGD that was intensified by the increase in WS. It is concluded that root of quinoa was sensitive to anaerobic soil conditions. Results showed that the mean value of leaf water potential (Ψ) dropped from ?1.53 to ?3.09 MPa by increasing WS from 10 to 40 dS m?1. Increasing WS from the lowest to the highest level resulted in 48% decrease in leaf photosynthesis rate (An). Results revealed that leaf stomatal conductance (gs) was more sensitive to salinity than An. Stomatal closure in quinoa started to occur when the Ψ value fell below approximately ?1.0 MPa. In general, increasing WS from 10 to 40 dS m?1 resulted in about 4.6-fold, 2.1-fold, and 2.6-fold increase in plant Na+, Ca2+, and Cl? concentration, respectively.  相似文献   

15.
The scarcity of good-quality water is forcing the use of brackish water for irrigation in many areas around the world. Alternate fresh- and brackish water irrigation is a feasible irrigation method (IM). A pot experiment was carried out with three brackish water IMs and at three levels (1, 3 and 5?g NaCl L?1). The various levels of brackish waters were irrigated at the seedling stage, the jointing and tasseling stage and the after tasseling stage, respectively. The responses of maize (Zea mays L.) to alternate irrigation were investigated through gas exchange and chlorophyll fluorescence. The results showed that the alternate use of fresh- and brackish water reduced the increasing soil salinity caused by brackish water irrigation. The changes in net photosynthesis rate (Pn), stomatal conduction (gs), intercellular CO2 concentration (Ci) and chlorophyll content (SPAD) values revealed that maize was more resistant to brackish water at the after tasseling stage. Moreover, significant reductions in maximum quantum yield (Φpo), effective quantum yield of photochemical energy conversion (Φ2), photochemical quenching (qp), non-photochemical quenching of variable chlorophyll fluorescence (qN) and non-photochemical chlorophyll fluorescence quenching (NPQ) of photosystem II, grain yield and biomass weight of maize subjected to high NaCl level brackish water at the jointing and tasseling stage were observed. This implied that maize plants were extremely sensitive to brackish water irrigation during the jointing and tasseling stage, and freshwater should be applied at this growth period. Our results would be helpful for sustainable maize production using alternate irrigation with fresh- and brackish water in arid and semi-arid areas.  相似文献   

16.
《Journal of plant nutrition》2013,36(12):2085-2099
Abstract

The effects of iron (Fe) deficiency on catalase and peroxidase activity, net photosynthesis (Pn), stomatal conductance (g s ), plant water relations, and specific leaf weight, were studied under greenhouse conditions in two sweet orange (C. sinensis) cultivars grafted on sour orange (Citrus aurantium) and Swingle citrumelo (C. paradisi × P. trifoliata). Iron deficiency caused by the absence of Fe in the Hoagland nutrient solution reduced significantly catalase and peroxidase activity, photosynthesis (Pn), osmotic potential (Ψ π ), turgor potential (Ψ p ), and specific leaf weight, but did not influence g s and leaf water potential (Ψ L ). Iron deficiency caused by increasing concentrations of bicarbonate supplied as NaHCO3 (10 and 40 mM) in the nutrient solution reduced significantly g s , Pn, and Ψ p and increased Ψ L and Ψ π . Furthermore, remarkable differences were recorded between the various cultivars/rootstocks combinations.  相似文献   

17.
Growing areas under transgenic crops have created a concern over their possible adverse impact on the soil ecosystem. This study evaluated the effect of Bt-cotton based cropping systems on soil microbial and biochemical activities and their functional relationships with active soil carbon pools in Vertisols of central India (Nagpur, Maharastra, during 2012–2013). Culturable groups of soil microflora, enzymatic activities and active pools of soil carbon were measured under different Bt-cotton based cropping systems (e.g. cotton-soybean, cotton-redgram, cotton-wheat, cotton-vegetables and cotton-fallow). Significantly higher counts of soil heterotrophs (5.7–7.9 log cfu g?1 soil), aerobic N-fixer (3.9–5.4 log cfu g?1 soil) and P-solubilizer (2.5?3.0 log cfu g?1 soil) were recorded in Bt-cotton soils. Similarly, soil enzymatic activities, viz. dehydrogenase (16.6–22.67 µg TPF g?1 h?1), alkaline phosphatase (240–253 µg PNP g?1 h?1) and fluorescein di-acetate hydrolysis (14.6–18.0 µg fluorescein g?1 h?1), were significantly higher under Bt-cotton-soybean system than other Bt- and non-Bt-cotton based systems in all crop growth stages. The growth stage-wise order of soil microbiological activities were: boll development > harvest > vegetative stage. Significant correlations were observed between microbiological activities and active carbon pools in the rhizosphere soil. The findings indicated no adverse effect of Bt-cotton on soil biological properties.  相似文献   

18.
ABSTRACT

Black walnut (Juglans nigra L.) half-sib 1+0 seedlings were exponentially fertilized with ammonium (NH4 +) as ammonium sulfate [(NH4)2SO4], nitrate (NO3 ?) as sodium nitrate (NaNO3), or a mixed nitrogen (N) source as ammonium nitrate (NH4NO3) at the rate of 0, 800, or 1600 mg N plant?1 and grown for three months. One month following the final fertilization, N concentration, growth, and photosynthetic characteristics were assessed. Compared with unfertilized seedlings, N addition increased plant component N content, chlorophyll content, and photosynthetic gas exchange. Net photosynthesis ranged from 2.45 to 4.84 μmol m?2 s?1 for lower leaves but varied from 5.95 to 9.06 μmol m?2 s?1 for upper leaves. Plants responded more favorably to NH4NO3 than sole NH4 + or NO3 ? fertilizers. These results suggest that N fertilization can be used to promote net photosynthesis as well as increase N storage in black walnut seedlings. The NH4NO3 appears to be the preferred N source to promote black walnut growth and physiology.  相似文献   

19.
调亏灌溉对膜下滴灌菘蓝生长发育和产量的影响   总被引：1，自引：0，他引：1  
2019年在河西绿洲冷凉灌区民乐县益民灌溉试验站进行了调亏灌溉对膜下滴灌菘蓝生长动态、产量和水分利用效率影响的大田试验研究。在苗期充分供水条件下,以全生育期充分供水(75%～85%的田间持水量)为对照,在营养生长期进行轻度、中度和重度水分调亏,在肉质根生长期进行轻度和中度水分调亏,在肉质根成熟期进行轻度水分调亏,分别测定了水分调亏菘蓝农艺性状的阶段性改变、干物质积累和分配、产量及水分利用效率。结果表明,在营养生长期和肉质根生长期对菘蓝进行中度和重度水分调亏、成熟期进行轻度水分调亏均会显著降低其株高、主根长、主根直径和叶面积指数(P0.05),而营养生长期和肉质根生长期对菘蓝进行轻度调亏其株高、主根长、主根直径和叶面积指数与对照处理间无显著差异(P0.05)。营养生长期以及肉质根生长期进行中度水分调亏和重度水分调亏会降低菘蓝干物质积累量,降幅为3.11%～15.67%,而轻度水分调亏则不会显著影响其干物质积累量。WT1和WT4处理的经济产量与对照无显著差异,其值分别为8 554.18,8 398.70 kg/hm~2,其他各处理均导致菘蓝经济产量降低,降幅为6.89%～18.33%,WT4处理的水分利用效率和灌溉水利用效率最高,比对照提高7.91%和7.39%。因此,在营养生长期—肉质根生长期施加连续轻度水分调亏,其他生育期充分供水是实现河西绿洲冷凉灌区菘蓝节水高产高效灌溉制度。  相似文献   

20.
Abstract

The diurnal net photosynthesis of Ficus benjamina L., cultivar Cleo, was studied at different daylengths (12, 18 and 24 h day?1), photosynthetic photon flux densities (40 and 120 μmol m?2 s?1 PPFD) and CO2 concentrations (350 and 700 μmol mol?1). Net photosynthesis increased to a maximum after 5–6 and 6–7h of light at 12 and 18h day?1photoperiods, respectively, followed by a decrease towards the end of the photoperiod. At a photoperiod of 18 h day?1 similar diurnal curves were found at 350 and 700 μmol mol?1 CO2, and at 40 and 120 μmol m?2 s?1 PPFD. Five days after the photoperiod was changed from 18 to a 24h day?1the diurnal rhythm disappeared. Transpiration followed the same diurnal rhythm as that for photosynthesis. The water-use efficiency was enhanced by raising the CO2 concentration. A decrease in the CO2 concentration from 700 to 350 μmol mol?1after six days at high CO2 first significantly decreased the photosynthesis, but three days later it reached the same level as that at high CO2.  相似文献   

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