Na2CO3对黄秋葵种子萌发及生理特性的影响

为研究碱环境下黄秋葵种子萌发及生理特性,采用不同浓度(0、10、20、30、40 mmol·L^-1)Na2CO3溶液处理黄秋葵种子,测定其种子的萌发特性、胚根生长速度及第3天时胚根的生理特性。结果表明,随着碱浓度的增加,种子的发芽率、发芽势、发芽指数呈下降趋势,相对碱害率升高;发芽期间胚根长度与碱浓度呈负相关关系,且生长速度降低;碱胁迫下种子的抗氧化物酶(POD、CAT、SOD)活性较对照组无显著变化,MDA随碱浓度增加呈升高趋势,脯氨酸积累量变化不明显。发芽7 d后对照和10 mmol·L^-1碱液处理可萌发为幼苗,对其复水5 d后,发现10 mmol·L^-1处理侧根生长量远少于对照组。说明碱胁迫能抑制黄秋葵种子萌发及其幼苗生长,但黄秋葵种子对10 mmol·L^-1碱胁迫具有耐受性。     

5个秋葵品种果实性状、质地、营养品质及抗氧化性比较

秋葵果实具有食用和药用价值,用于生产保健食品和治疗多种疾病。比较了5个不同品种秋葵（咔里巴、红秋葵、杨贵妃、绿白一号、纤指）果实的性状、质地参数（硬度、黏着性、弹性、凝聚性、咀嚼性和回复性）、营养品质（总糖、还原糖、游离氨基酸、蛋白质、维生素C和粗纤维含量）以及抗氧化能力的差异。结果表明,绿白一号果实的各指标综合表现最优,可作为秋葵品质育种的重要材料。     

Salt‐Induced Regulation of Some Key Antioxidant Enzymes and Physio‐Biochemical Phenomena in Five Diverse Cultivars of Turnip (Brassica rapa L.)

A greenhouse experiment was carried out to examine the differential morpho‐physiological responses of five cultivars of turnip (Brassica rapa L.) to salt stress. Five diverse cultivars of turnip (shaljum desi surakh, shaljum purple top, shaljum golden bal, neela shaljum, and peela shaljum) were subjected for 6 weeks to varying levels of NaCl, i.e. 0, 80 and 160 mm in Hoagland’s nutrient solution in sand culture. Imposition of varying levels of salt substantially decreased shoot and root fresh and dry weights, chlorophyll contents, leaf osmotic potential, relative water contents, different gas exchange attributes, total phenolics, malondialdehyde, activities of superoxide dismutase, peroxidase catalase, and leaf and root K⁺ levels while enhanced the proline contents, membrane permeability, level of H₂O₂, leaf and root Na⁺ and Cl^? and leaf Ca²⁺ in all turnip cultivars under study. Of all cultivars, peela shaljum and neela shaljum were consistently higher in their growth than the other turnip cultivars at all salt concentrations of the growth medium. Photosynthetic capacity (A) and stomatal conductance (g_s) were higher in high biomass‐producing cultivars, i.e. peela shaljum and neela shaljum, which provide to be potential selection criteria of salt tolerance in turnip. However, the regulation of antioxidant system was cultivar‐specific under saline conditions.     

1‐Methylcyclopropene (1‐MCP)‐Induced Alteration in Leaf Photosynthetic Rate,Chlorophyll Fluorescence,Respiration and Membrane Damage in Rice (Oryza sativa L.) Under High Night Temperature

High night temperature (HNT) can induce ethylene‐triggered reactive oxygen species production, which can cause premature leaf senescence and membrane damage, thereby affecting production, consumption and transfer of photosyn‐thates, and yield. The 1‐methylcyclopropene (1‐MCP) can competitively bind with ethylene receptors and decrease ethylene effects. The objective was to determine the effects of HNT and 1‐MCP on leaf photosynthetic rate (P_N), chlorophyll fluorescence, total chlorophyll (TC), respiration, membrane damage, pollen germination, spikelet fertility (SF) and yield of rice hybrid ‘XL723’. Plants were grown under ambient night temperature (ANT) (25 °C) or HNT (30 °C) with or without 1‐MCP treatment. Application of 1‐MCP was at the boot stage. The decrease in yield (11 %) under HNT was associated with decreased P_N (4 %), stomatal conductance (8 %), quantum yield (11 %) TC (23 %) and SF (5 %) and increased respiration (74 %), F_o/F_m (increase in thylakoid membrane damage; 11 %) and membrane damage (leaf electrolytic leakage; 57 %). The 1‐MCP‐treated plants grown under HNT showed increased yield (17 %), which was associated with increased P_N (10 %), stomatal conductance (30 %), quantum yield (9 %), TC (37 %) and SF (11 %) and decreased respiration (39 %), F_o/F_m (5 %) and membrane damage (18 %). Plants grown under HNT showed increased grain chalkiness (154 %) compared with plants grown under ANT.     

Enlargement Quotient to Estimate Leaf Area in Two Cultivars of Okra (Abelmoschus esculentus [L.] Moench)

Two cultivars of Okra ( Abelmoschus esculentus [L.] Moench) were used to compare the relationship between linear dimensions of leaf and leaf area. Formula A = eL² (where A = leaf area, e = enlargement quotient and L = midrib length of leaf) determined leaf area more accurately.     

Effectiveness and relative discriminatory abilities of techniques measuring genotype × environment interaction and stability in okra (Abelmoschus esculentus (L) Moench)

Summary Twenty selected okra genotypes were evaluated in four different environments for stability of performance, measured by days to flowering, number of branches per plant, plant height, number of pods per plant, pod weight, and pod yield per plant. An analysis of the components of G × E interaction showed that it might not always be adequately explained by a linear function of the environment. The heritability estimates for the response of the characters showed that the number of branches per plant was under strong genotypic influence. The stability variance parameters, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqbeo8aZzaaja% WaaWbaaSqabeaacaaIYaaaaaaa!3A18!\[\hat \sigma ^2\]and W-mean square and the deviation MS employed in the analyses of stability indicated that most of the genotypes were unstable in respect of the characters. The % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqbeo8aZzaaja% WaaWbaaSqabeaacaaIYaaaaaaa!3A18!\[\hat \sigma ^2\]and W-mean square produced similar results which were different from those of deviation MS; the two stability-variance techniques were more discriminatory than the regression technique.     

水分胁迫对棉花幼苗水分利用和光合特性的影响

以转基因棉花品种农大棉8号和鲁棉研28号为材料进行盆栽试验,设置正常处理(CK)、轻度胁迫(LS)、中度胁迫(MS)、重度胁迫(SS)和极度胁迫(ES)5个水分处理。结果表明:随着水分胁迫程度的加重,棉花幼苗的生长受到明显的抑制,2个品种的叶片相对含水率、叶水势、净光合速率(Pn)、光能利用率(LUE)、PSⅡ最大光化学效率(Fv/Fm)、PSⅡ光化学量子效率(φPSⅡ)、光化学猝灭系数(qP)呈下降趋势;气孔限制值(Ls)、水分利用率(WUE)和非光化学猝灭系数(NPQ)呈上升趋势。两品种的Pn和NPQ的MS、SS和ES与CK相比差异显著,不同测定时期各胁迫处理的平均Pn比CK分别下降了11.5%、18.1%、32.1%和38.1%;平均NPQ比CK上升了24.1%、50.9%、79.4%和145.1%。表明棉花幼苗期持续轻度水分胁迫对叶片光合能力无显著影响,但高于中度的持续水分胁迫会造成叶片光合能力下降和光抑制加重。     

Differential Physio‐Biochemical Responses to Cold Stress of Cold‐Tolerant and Non‐Tolerant Grapes (Vitis L.) from China

There are many grape species exhibiting differences in cold tolerance in China. ‘Zuoshan1’ (Vitis amurensis Rupr. cv. Zuoshan1), one kind of the most cold tolerant grapes, can endure ?40 to ?50 °C, whereas, ‘Maoputao’ (Vitis quinqanguoari Rehd. cv. Maoputao) is sensitive to the cold stress. To understand the physiological mechanism, we investigated responses of both species to a range of decreasing temperatures under the controlled condition. The cold‐tolerant ‘Zuoshan1’ showed higher accumulation of abscisic acid than non‐tolerant ‘Maoputao’, which was correlated with a more dramatic increase in solutes including sugars, proteins at early stage of our detection. At latter stages, these solutes showed more decline in ‘Zuoshan1’. Meanwhile, earlier leaf yellowing and necrosis of ‘Zuoshan1’ were detected with concomitant decrease in the chlorophyll (Chl) content along with remarkable increase in electrolyte leakage and malondialdehyde, which indicated that the earlier leaf senescence occurred to ‘Zuoshan1’. Based on the leaf morphology and parameter investigation, it was concluded that cold‐tolerant grape ‘Zuoshan1’ made quicker responses to the low temperature (LT), indicating it sensed the cold‐signal more strongly than the non‐tolerant grape ‘Maoputao’. Therefore the ability to take more active response to cold stress contributes to the higher tolerance in ‘Zuoshan1’.     

Accession Variation for Salt Tolerance in Proso Millet (Panicum miliaceum L.) Using Leaf Proline Content and Activities of Some Key Antioxidant Enzymes

Inter‐accession variation for salt tolerance of Panicum miliaceum (proso millet) was appraised using leaf proline content and activities of antioxidant enzymes as selection criteria. Eighteen accessions of proso millet were grown under control conditions and after 14 days subjected to saline (120 mm NaCl) stress for 4 weeks. Salt stress substantially decreased relative water content (RWC), while increased leaf free proline and malondialdehyde (MDA) and activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) of all accessions of proso millet. The difference among the accessions of P. miliaceum was significant in yield as well as in the activities of antioxidant enzymes analyses. On the basis of seed yield (expressed as per cent of control), of 18 accessions, three were categorised as salt‐tolerant (008211, 008214 and 008226), seven as moderately tolerant (008210, 008213, 008216, 008220, 008222, 008223 and 008242) and eight as salt‐sensitive (008208, 008215, 008217, 008218, 008221, 008225, 008230 and 008236). Of all P. miliaceum accessions, 008211, 008226, 008215 and 008218 were relatively higher in proline, 008214 and 008221 in MDA contents, 00812, 008225, 008236, 008222 and 008242 in SOD activity and 008218, 008220, 008211 and 008226 in POD and CAT enzyme activities. Thus, because of differential response of high or low seed yielded accessions in accumulation of proline and antioxidant enzyme activities, these variables were not found effective criteria for discriminating the P. miliaceum accessions for salt tolerance.     

Potassium and Silicon Improve Yield and Juice Quality in Sugarcane (Saccharum officinarum L.) under Salt Stress

Soil salinity is a major abiotic stress which adversely affects the yield and juice quality in sugarcane. However, the mineral nutrient status of plant plays a crucial role in increasing plant tolerance to salinity. We investigated the effects of K and/or Si on plant growth, yield and juice quality in two sugarcane genotypes differing in salinity tolerance. Addition of K and Si significantly (P ≤ 0.05) increased K and Si concentrations and decreased the accumulation of Na⁺ in plants under salt stress. Cane yield and yield attributes were significantly (P ≤ 0.05) higher where K and Si were added. Juice quality characteristics like Brix (% soluble solids in juice), Pol (% sucrose in juice), commercial cane sugar (CCS) and sugar recovery in both sugarcane genotypes were also significantly (P ≤ 0.05) improved with the supplementation of K and Si. For most of the growth parameters, it was found that K either alone or in combination with Si was more effective to alleviate salt stress in both sugarcane genotypes than Si alone. Moreover, the beneficial effects of K and Si were more pronounced in salt sensitive genotype than in salt tolerant genotype. The results suggested that K and Si counteracted the deleterious effects of high salinity/sodicity in sugarcane by lowering the accumulation of Na⁺ and increase in K⁺ concentration with a resultant improvement in K⁺/Na⁺ ratio which is a good indicator to assess plant tolerance to salinity.     

Effect of Salt Stress on the Salicylic Acid Synthesis in Young Maize (Zea mays L.) Plants

The effect of salt stress on salicylic acid (SA) synthesis was investigated parallel with the induction of antioxidant enzymes in young maize plants. Two-week-old maize plants grown in hydroponic solution were treated with 50 or 100 m m NaCl for 7 days. Antioxidant enzyme activities, and the SA and o -hydroxy-cinnamic acid (oHCA) levels were measured on the 3rd and 7th day of treatment and after 4 days of recovery. Ascorbate peroxidase activity increased in the leaves, but changes in guaiacol peroxidase activity only could be detected in the roots after 7 days. Glutathione reductase activity increased both in the leaves and in the roots after the 3rd day of 100 m m NaCl treatment. Free SA only increased during recovery in the leaves and roots. In the leaves of plants treated with 100 m m NaCl, a slight increase was observed in the free oHCA level, which rose dramatically after recovery, while in the roots an increase could only be seen after recovery. These results suggest that oHCA may serve not only as a precursor of SA but may also have an antioxidant role during salt stress and recovery.     

Sexual hybridization between Capsella bursa‐pastoris (L.) Medik (♀) and Camelina sativa (L.) Crantz (♂) (Brassicaceae)

The development of transgenic oilseed Camelina sativa (2n = 40) and the potential for hybridization with its weedy relative Capsella bursa‐pastoris (2n = 36) necessitates a careful evaluation of the reproductive compatibility between the species. Here, we conducted over 1800 crosses (emasculation and manual pollination) to examine the ability of 10 Canadian C. bursa‐pastoris (♀) accessions to hybridize with five accessions of C. sativa (♂). Seven hybrids were confirmed among 586 putative hybrids screened with species‐specific markers, indicating a hybridization rate of 1.5 hybrids per 10 000 ovules pollinated. All seven hybrids had intermediate DNA content compared to their parents, were morphologically distinct, had low (1.9%) pollen fertility and failed to produce selfed or backcrossed seed. Given the abundance of C. bursa‐pastoris along field margins, hybrids will likely be generated in the wild, but they will be unable to establish lineages unless fertility is restored. The large number of crosses and the diversity captured by the use of multiple accessions resulted in strong statistical power and a high degree of confidence in the estimated hybridization rate.     

盐胁迫下棉花K~+和Na~+离子转运的耐盐性生理机制

为了探究棉花的耐盐机制,以中棉所49、中棉所35和中51504为材料,研究了盐胁迫对棉花幼苗的生长及K+/Na+平衡生理的影响。结果表明,150 mmol·L-1 Na Cl处理对幼苗的生长具有明显抑制作用,降低了叶片的光合速率(Pn)、PSⅡ实际光量子产额(ΦPSII)和电子传递速率(ETR),增加了非光化学荧光猝灭系数(q N)。与中棉所49和中棉所35相比,中51504的干物质累积受盐胁迫影响最小,且保持较高的Pn、ΦPSII、ETR和q N值及较低的ETR/Pn值。盐胁迫提高了棉花组织中Na+的浓度,降低了K+的浓度;但中51504组织中保持了相对较低的Na+浓度和较高的K+浓度,维持了较高的K+/Na+比;通过非损伤微测技术(NMT)测定的离子流结果也表明,中51504的根系对Na+有较强的外排能力,而对K+有较强的保留和向地上部转运能力。能够有效地调节Na+和K+的跨膜转运进而维持K+/Na+平衡是棉花耐盐的重要生理机制之一。     

Growth Properties and Ion Distribution in Different Tissues of Bread Wheat Genotypes (Triticum aestivum L.) Differing in Salt Tolerance

Four bread wheat genotypes differing in salt tolerance were selected to evaluate ion distribution and growth responses with increasing salinity. Salinity was applied when the leaf 4 was fully expanded. Sodium (Na⁺), potassium (K⁺) concentrations and K⁺/Na⁺ ratio in different tissues including root, leaf‐3 blade, flag leaf sheath and flag leaf blade at three salinity levels (0, 100 and 200 mm NaCl), and also the effects of salinity on growth rate, shoot biomass and grain yield were evaluated. Salt‐tolerant genotypes (Karchia‐65 and Roshan) showed higher growth rate, grain yield and shoot biomass than salt‐sensitive ones (Qods and Shiraz). Growth rate was reduced severely in the first period (1–10 days) after salt commencements. It seems after 20 days, the major effect of salinity on shoot biomass and grain yield was due to the osmotic effect of salt, not due to Na⁺‐specific effects within the plant. Grain yield loss in salt‐tolerant genotypes was due to the decline in grain size, but the grain yield loss in salt‐sensitive ones was due to decline in grain number. Salt‐tolerant genotypes sequestered higher amounts of Na⁺ concentration in root and flag leaf sheath and maintained lower Na⁺ concentration with higher K⁺/Na⁺ ratios in flag leaf blade. This ion partitioning may be contributing to the improved salt tolerance of genotypes.     

Role of Arbuscular Mycorrhizae in the Alleviation of Ionic, Osmotic and Oxidative Stresses Induced by Salinity in Cajanus cajan (L.) Millsp. (pigeonpea)

Salinity stress causes ion toxicity and osmotic imbalances, leading to oxidative stress in plants. Arbuscular mycorrhizae (AM) are considered bio‐ameliorators of saline soils and could develop salinity tolerance in crop plants. Pigeonpea exhibits strong mycorrhizal development and has a high mycorrhizal dependency. The role of AM in enhancing salt tolerance of pigeonpea in terms of shoot and root dry weights, phosphorus and nitrogen contents, K⁺ : Na⁺, Ca²⁺ : Na⁺ ratios, lipid peroxidation, compatible solutes (proline and glycine betaine) and antioxidant enzyme activities was examined. Plants were grown and maintained at three levels of salt (4, 6 and 8 dSm^?1). Stress impeded the growth of plants, led to weight gain reductions in shoots as well as roots and hindered phosphorus and nitrogen uptake. However, salt‐stressed mycorrhizal plants produced greater root and shoot biomass, had higher phosphorus and nitrogen content than the corresponding uninoculated stressed plants. Salt stress resulted in higher lipid peroxidation and membrane stability was reduced in non‐AM plants. The presence of fungal endophyte significantly reduced lipid peroxidation and membrane damage caused by salt stress. AM plants maintained higher K⁺ : Na⁺ and Ca²⁺ : Na⁺ ratios than non‐AM plants under stressed and unstressed conditions. Salinity induced the accumulation of both proline and glycine betaine in AM and non‐AM plants. The quantum of increase in synthesis and accumulation of osmolytes was higher in mycorrhizal plants. Antioxidant enzyme activities increased significantly with salinity in both mycorrhizal and non‐mycorrhizal plants. In conclusion, pigeonpea plants responded to an increased ion influx in their cells by increasing the osmolyte synthesis and accumulation under salt stress, which further increased with AM inoculation and helped in maintaining the osmotic balance. Increase in the antioxidant enzyme activities in AM plants under salt stress could be involved in the beneficial effects of mycorrhizal colonization.     

Effects of Mild and Severe Drought Stress on Photosynthetic Efficiency in Tolerant and Susceptible Barley (Hordeum vulgare L.) Genotypes

Drought stress is one of the most important abiotic factors which adversely affect growth, metabolism and yield of crops worldwide. The objective of this study was to determine the effects of drought stress on photosynthesis in barley and examine the differential responses of photosynthetic apparatus in relatively tolerant (Yousof) and susceptible (Morocco) barley genotypes. Plants were subjected to different levels of soil water availability including control, mild and severe drought stress. In both genotypes, drought stress led to decrease in chlorophylls, β‐carotene and stomatal conductance accompanied by decrease in CO₂ assimilation rate. Significant increase in α‐tochoperol content was only observed in Yousof cultivar under drought stress. Initial slope and plateau phase of CO₂ response curve of drought‐stressed plants as well as polyphasic chlorophyll a fluorescence transient curve (OJIP test) and fast fluorescence induction kinetics were influenced by drought stress. These parameters were more affected in Morocco cultivar by drought stress compare with Yousof. Drought stress also resulted in reduction of D1 protein content in both genotypes and accelerated photoinhibition process. Based on our results, stomatal conductance is the main factor limiting photosynthesis in Yousof genotype under mild drought stress. However, in Morocco, in addition to stomatal limitation, damage to photosystem II (PSII), reduced electron transport and carboxylation efficiencies were important parts of limitation in photosynthesis. Severe drought stress resulted in structural and biochemical impairment of light‐dependent reactions as well as carboxylation process of photosynthesis in both genotypes. Alpha‐tocopherol showed an important protective role against drought stress in Yousof cultivar as a relatively drought‐tolerant cultivar.     

Effects of Salt Stress on Some Physiological and Photosynthetic Parameters at Three Different Temperatures in Six Soya Bean (Glycine max L. Merr.) Cultivars

The effect of NaCl (?0.1, ?0.4 and ?0.7 MPa) on some physiological parameters in six 23‐day‐old soya bean cultivars (Glycine max L. Merr. namely A 3935, CX‐415, Mitchell, Nazl?can, SA 88 and Türksoy) at 25, 30 and 35 °C was investigated. Salt stress treatments caused a decline in the K⁺/Na⁺ ratio, plant height, fresh and dry biomass of the shoot and an increase in the relative leakage ratio and the contents of proline and Na⁺ at all temperatures. Effects of salt stress and temperature on Chl content, Chl a/b ratio (antenna size) and qN (heat dissipation in the antenna) varied greatly between cultivars and treatments; however, in all cases approximately the same qP value was observed. It indicates that the plants were able to maintain the balance between excitation pressure and electron transport activity. Pigment content and the quantum efficiency of photosystem II exhibited significant differences that depended on the cultivar, the salt concentration and temperature. The cultivars were relatively insensitive to salt stress at 30 °C however they were very sensitive both at 25 and 35 °C. Of the cultivars tested CX‐415 and SA 88 were the best performers at 25 °C compared with SA 88 and Türksoy at 35 °C.     

Water Relation, Photosynthetic Ability and Growth of Thai Jasmine Rice (Oryza sativa L. ssp. indica cv. KDML 105) to Salt Stress by Application of Exogenous Glycinebetaine and Choline

Rice reportedly possesses a very low capacity to accumulate glycinebetaine (Glybet), but may be accumulated by the exogenous application of Glybet or Choline (Cho) as an alternative way to improve its salt‐tolerant ability. The aim of this research was to determine whether Glybet accumulation could be induced in Thai jasmine rice by the exogenous application of Glybet and Cho, and to determine the effects of Glybet and Cho treatment on various growth parameters of seedlings cultured under salt‐stress conditions. Thai jasmine rice seeds were aseptically germinated in vitro on solidified Murashige–Skoog media, supplied with either Glybet or Cho in the culture media for 12 days and then treated with 342 mm NaCl (salt stress) for 4 days. GlyBet content, water relation, photosynthetic capabilities and growth characteristics of salt‐stressed seedlings were measured. The addition of Glybet or Cho to plant culture media containing 342 mm NaCl resulted in increased accumulation of Glybet in rice seedlings. Increased Glybet accumulation was strongly associated with a high efficiency of water usage (r = 0.96), which in turn correlated with increased maximum quantum yield of PSII (F_v/F_m) (r = 0.86). Moreover, the pigment concentrations of seedlings cultured under salt stress were maintained by a function of Glybet, led to high efficiency of photochemical and non‐photochemical quenching of PSII as well as to exhibit on net photosynthetic rate. Thus, our results suggest that the addition of either Glybet or Cho to the plant growth media can improve growth performance under salt stress conditions by increasing the salt tolerance of Thai jasmine rice. The exogenous application of Glybet and/or Cho to culture media may be an effective method of improving resistance to salt stress via the promotion of Glybet accumulation with in rice seedlings.     

Deep Roots are Pivotal for Regulating Post‐Anthesis Leaf Senescence in Wheat (Triticum aestivum L.)

Root activity plays a dominant role in grain filling in cereal crops. However, the importance of deep roots for regulating post‐anthesis leaf senescence is not clearly understood in wheat (Triticum aestivum L.). In this study, we used ³²P tracing to estimate the difference in wheat root activity at soil depths of 30 and 70 cm and the root restriction method to investigate the effects of vertical distribution of deep roots on leaf senescence, with non‐restricted plants as controls. Recovery of radioactive ³²P indicated that deep roots had significantly higher activity than upper roots in wheat. Root restriction at a soil depth of 50 cm caused significant decreases in the activities of superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7), catalase (EC 1.11.1.6) and ascorbate peroxidase (EC 1.11.1.11) at 16 days after anthesis and thereafter resulting in an increase in malondialdehyde. As a result, chlorophyll levels and net photosynthesis decreased. Ultimately, the root‐restricted wheat produced a significantly lower grain yield than the non‐restricted controls. These data suggest that deep roots are pivotal for regulating plant senescence, duration of grain filling, and yield formation.