Growth responses of Stylosanthes humilis (Fabaceae) populations to saline stress

The growth responses to salinity of seedlings of six populations of Stylosanthes humilis from three ecogeographic regions of Northeast Brazil, characterized by wet or semi-arid climate, were analyzed following 28 days in solution cultures at concentrations of 0, 40, 80 and 120 mM NaCl. Root and shoot mass, shoot length and characters of foliar damage (number of leaves with chlorosis and necrosis) of the populations were more affected by increasing NaCl than numbers of leaves and branches and root length. Although S. humilis has been considered a salt sensitive legume, significant differences in salt tolerance between populations were found. The estimated concentrations which reduced shoot dry mass by 50 and 25% varied between populations from 84 to 108 and from 49 to 83 mM NaCl, respectively. Salt tolerance in S. humilis during the initial growth stage was lower than the reported one for germination. With one exception, populations from semi-arid climate with saline soils showed higher salt tolerance than those from non saline soils. The results suggest that salt tolerance in these populations is mainly associated with the occurrence of salinity in the soil of their provenance.     

不同供硼水平对绿豆植株形态及其叶片生长特征的影响

利用水培以绿豆为材料,研究不同供硼水平对绿豆植株形态和叶片生长特征的影响。结果表明缺硼抑制绿豆生长,但对根的影响较对冠的影响更大,表现在缺硼导致冠根比增大;缺硼明显抑制叶面积;降低特定叶面积（SLA）,这可能是由于缺硼影响细胞伸展的缘故,造成叶片密度增加,缺硼也提高叶片重量比（LWR)并导致叶脉间失绿,说明缺硼叶片可能过量碳水化合物积累,引起叶绿素降解,与适量供硼比较,过量供硼也影响绿豆的生长,但对冠根比没有影响,表明过量供硼对根和冠具有相同的抑制作用,硼中毒导致成熟叶片脱落,从而影响叶面积,但对特定叶面积（SLA）和叶片重量比（LWR）没有影响。     

Comparison of EDTA- and Citric Acid-Enhanced Phytoextraction of Heavy Metals in Artificially Metal Contaminated Soil by Typha Angustifolia

A pot experiment was conducted to study the performance of EDTA and citric acid (CA) addition in improving phytoextraction of Cd, Cu, Pb, and Cr from artificially contaminated soil by T. angustifolia. T. angustifolia showed the remarkable resistance to heavy metal toxicity with no visual toxic symptom including chlorosis and necrosis when exposed to metal stress. EDTA-addition significantly reduced plant height and biomass, compared with the control, and stunted plant growth, while 2.5 and 5 mM CA addition induced significant increases in root dry weight. EDTA, and 5 and 10 mM CA significantly increased shoot Cd, Pb, and Cr concentrations compared with the control, with EDTA being more effective. At final harvest, the highest shoot Cd, Cr, and Pb concentrations were recorded in the treatment of 5 mM EDTA addition, while maximal root Pb concentration was found at the 2.5 mM CA treatment. However, shoot Cd accumulation in the 10 mM CA treatment was 36.9% higher than that in 2.5 mM EDTA, and similar with that in 10 mM EDTA. Shoot Pb accumulation was lower in 10 mM CA than that in EDTA treatments. Further, root Cd, Cu, and Pb accumulation of CA treatments and shoot Cr accumulation in 5 or 10 mM CA treatments were markedly higher than that of control and EDTA treatments. The results also showed that EDTA dramatically increased the dissolution of Cu, Cr, Pb, and Cd in soil, while CA addition had less effect on water-soluble Cu, Cr, and Cd, and no effect on Pb levels. It is suggested that CA can be a good chelator candidate for T. angustifolia used for environmentally safe phytoextraction of Cd and Cr in soils.     

Ozone affects gas exchange, growth and reproductive development in Brassica campestris (Wisconsin fast plants)

Exposure to ozone (O(3)) may affect vegetative and reproductive development, although the consequences for yield depend on the effectiveness of the compensatory processes induced. This study examined the impact on reproductive development of exposing Brassica campestris (Wisconsin Fast Plants) to ozone during vegetative growth. Plants were exposed to 70 ppb ozone for 2 d during late vegetative growth or 10 d spanning most of the vegetative phase. Effects on gas exchange, vegetative growth, reproductive development and seed yield were determined. Impacts on gas exchange and foliar injury were related to pre-exposure stomatal conductance. Exposure for 2 d had no effect on growth or reproductive characteristics, whereas 10-d exposure reduced vegetative growth and reproductive site number on the terminal raceme. Mature seed number and weight per pod and per plant were unaffected because seed abortion was reduced. The observation that mature seed yield per plant was unaffected by exposure during the vegetative phase, despite adverse effects on physiological, vegetative and reproductive processes, shows that indeterminate species such as B. campestris possess sufficient compensatory flexibility to avoid reductions in seed production.     

Impact of chelator-induced phytoextraction of cadmium on yield and ionic uptake of maize

Enhanced phytoextraction uses soil chelators to increase the bioavailability of heavy metals. This study tested the effectiveness of ethylenediaminetetraacetic acid (EDTA) and citric acid in enhancing cadmium (Cd) phytoextraction and their effects on the growth, yield, and ionic uptake of maize (Zea mays). Maize seeds of two cultivars were sown in pots treated with 15 (Cd₁₅) or 30 mg Cd kg^?1 soil (Cd₃₀). EDTA and citric acid at 0.5 g kg^?1 each were applied 2 weeks after germination. Results demonstrated that the growth, yield per plant, and total grain weight were reduced by exposure to Cd. EDTA increased the uptake of Cd in shoots, roots, and grains of both maize varieties. Citric acid did not enhance the uptake of Cd, rather it ameliorated the toxicity of Cd, as shown by increased shoot and root length and biomass. Cadmium toxicity reduced the number of grains, rather than the grain size. The maize cultivar Sahiwal-2002 extracted 1.6% and 3.6% of Cd from soil in both Cd+ EDTA treatments. Hence, our study implies that maize can be used to successfully phytoremediate Cd from soil using EDTA, without reducing plant biomass or yield.     

Impact of yellow mite (Polyphagotarsonemus latus [Banks]) density on host's (Corchorus capsularis L.) phenology and assessment of yield loss under field conditions

Yellow mite, Polyphagotarsonemus latus [Banks] (Acari: Tarsonemidae) is one of the major pests of jute crops (Corchorus capsularis L.) in Bangladesh. In this study, indigenous varieties of jute were used for treatments, namely, CVL‐1, CVE‐3, BJC‐7370 and BJC‐83. The paired plot treatments (treated and untreated controls) were laid out under field conditions. The effects of yellow mite were studied at three stages of the jute plants: 60 days after sowing (DAS), 90 DAS and 120 DAS. A higher number of mite stages was observed up to 90 DAS and then declined up to 120 DAS in var. BJC‐7370 among two other varieties, Deshi and Tossa. The percentage of infestation and damage indexes (scale 0–5) were measured to relate yellow mite injuries to the number of leaves, leaf area, fresh leaf weight, dry leaf weight, soluble solids, plant height, base diameter, fiber weight, stick weight, number of flowers per plant, number of pods, pod weight per plant, seeds per pod, seed weight and 1000 seeds' weight of plants infested at three different phenological stages. The highest fiber yield loss was found in the variety BJC‐7370 (59.75%), followed by BJC‐83 (55.56%), CVE‐3 (54.30%) and CVL‐1 (50.05). The highest stick yield losses were found in the following order: BJC‐7370 (54.54%) > BJC‐83 (51.17%) > CVL‐1 (43.68%) > CVE‐3 (37.80%) and BJC‐7370 (30.33%) > CVL‐1 (27.83%) > BJC‐83 (24.16%) > CVE‐3 (22.11%) for the highest seed yield under field conditions for Corchorus capsularis. High yellow mite population in untreated checks decreased plant growth and showed significant losses in yield production for the variety BJC‐7370.     

Importance of seed Zn content for wheat growth on Zn-deficient soil

Seed nutrient reserves may be important for an early establishment of crops on low-fertility soils. This glasshouse pot study evaluated effects of seed Zn content on vegetative growth of two wheat (Triticum aestivum L.) genotypes differing in Zn efficiency. Low-Zn (around 250 ng Zn per seed) and high-Zn seed (around 700 ng Zn per seed on average) of Excalibur (Zn efficient) and Gatcher (Zn inefficient) wheats were sown in a Zn-deficient siliceous sand fertilised with 0, 0.05, 0.2, 0.8 or 3.2 mg Zn kg^-1 soil. After 3 weeks, plants derived from the high-Zn seed had better root and shoot growth; the cv. Excalibur accumulated more shoot dry matter than the cv. Gatcher. After 6 weeks, greater root and shoot growth of plants grown from the high-Zn seed compared to those from the low-Zn seed was obvious only at nil Zn fertilisation. A fertilisation rate of 0.2 mg Zn kg^-1 soil was required for achieving 90% of the maximum yield for plants grown from the high-Zn seed compared to 0.8 mg Zn kg^-1 soil for plants derived from the low Zn seed. The critical Zn level in youngest expanded leaves for 90% maximum yield was 16 mg Zn kg^-1 dry matter for both genotypes. Zn-efficient Excalibur had greater net Zn uptake rates compared to Zn-inefficient Gatcher after 3 weeks but they were not different at the 6-week harvest. Zinc-deficient plants had greater net uptake rates of Cu, Mn, B, P, and K but a reduced uptake rate of Fe. It is concluded that higher seed Zn content acted similar to a starter-fertiliser effect by improving vegetative growth and dissipating differences in Zn efficiency of wheat genotypes.     

Effects of seed treatment with a plant growth regulator on growth and tillering in spring barley (Hordeum distichum) cv. Triumph

Doses of the growth retardant, Terpal, were applied to seeds of spring barley. Germination was delayed as the concentration and duration of exposure to Terpal increased. Tiller bud outgrowth was promoted in treated seedlings and at maturity the total tiller production and number of ear-bearing tillers per plant was increased by the Terpal treatment. The yield of the main shoot was similar in both control and treated plants but the mean ear weight of the tillers was reduced in the latter, and thus there was no overall effect of the treatment on yield. Observations on vegetative plants showed that Terpal also reduced the growth of successive main shoot leaves and the elongation and dry weight of the seminal root system. The results are discussed in terms of an early modification in the distribution of resources during establishment that favour the outgrowth of tiller buds at the expense of the initial development of the main shoot and root system. It is proposed that seed treatment is a viable alternative to foliar spraying particularly in arid regions.     

Natural variation in cadmium tolerance and its relationship to metal hyperaccumulation for seven populations of Thlaspi caerulescens from western Europe

Thlaspi caerulescens J. & C. Presl is a distinctive metallophyte of central and western Europe that almost invariably hyperaccumulates Zn to> 1.0% of shoot dry biomass in its natural habitats, and can hyperaccumulate Ni to> 0.1% when growing on serpentine soils. Populations from the Ganges region of southern France also have a remarkable ability to accumulate Cd in their shoots to concentrations well in excess of 0.01% without apparent toxicity symptoms. Because hyperaccumulation of Cd appears to be highly variable in this species, the relationship between Cd tolerance and metal accumulation was investigated for seven contrasting populations of T. caerulescens grown under controlled conditions in solution culture. The populations varied considerably in average plant biomass (3.1‐fold), shoot : root ratio (2.2‐fold), Cd hyperaccumulation (3.5‐fold), shoot : root Cd‐concentration ratio (3.1‐fold), and shoot Cd : Zn ratio (2.6‐fold), but the degree of hyperaccumulation of Cd and Zn were strongly correlated. Two populations from the Ganges region were distinct in exhibiting high degrees of both Cd tolerance and hyperaccumulation (one requiring 3 µM Cd for optimal growth), whereas across the other five populations there was an inverse relationship between Cd tolerance and hyperaccumulation, as has been noted previously for Zn. Metal hyperaccumulation was negatively correlated with shoot : root ratio, which could account quantitatively for the differences between populations in shoot Zn (but not Cd) concentrations. On exposure to 30 µM Cd, the two Ganges populations showed marked reductions in shoot Zn and Fe concentrations, although Cd accumulation was not inhibited by elevated Zn; in the other five populations, 30 µM Cd had little or no effect on Zn or Fe accumulation but markedly reduced shoot Ca concentration. These results support a proposal that Cd is taken up predominantly via a high‐affinity uptake system for Fe in the Ganges populations, but via a lower‐affinity pathway for Ca in other populations. Total shoot Cd accumulated per plant was much more closely related to population Cd tolerance than Cd hyperaccumulation, indicating that metal tolerance may be the more important selection criterion in developing lines with greatest phytoremediation potential.     

Seedling growth strategies and seed size effects in fourteen oak species native to different soil moisture habitats

 Seedling growth and morphology are thought to reflect evolutionary responses to habitat or influences of seed size. To test these hypotheses, we selected fourteen species of North American oaks differing in soil moisture habitat preference and seed size. Seedlings were grown for 1 – 2 years with abundant soil water and moderate soil nutrition in pots placed outdoors and in a common garden. Oak species native to xeric environments produced the smallest seedlings. Oaks from hydric soils had more shoot weight per unit of root weight and more height per unit of total plant weight than did mesic or xeric oaks. Essentially no differences in leaf area per unit of total plant weight were detected. Species with thinner and larger individual leaves tended to produce larger seedlings. Within species, seed size was generally unrelated to seedling growth, although results may have been complicated by uncontrolled genotypic variability. However, when species were compared, those with larger mean seed size produced larger seedlings. Root/shoot allometry, height growth and leaf thickness in the tested species may reflect evolutionary responses to soil moisture and flooding. Although seed size influenced seedling growth, no clear relationship between seed size and soil moisture habitat was found. Received: 26 March 1995 / Accepted: 30 November 1995     

Sulphur application improves the growth, seed yield and oil quality of canola

Sulphur (S) nutrition is very important for harvesting potential seed and oil yield of rapeseed. This study evaluated response of foliage applied thiourea on the performance of two canola cultivars Shiralee and Dunkeld. Sulphur was applied to soil (40 kg ha^?1) or foliage (500 and 1,000 mg L^?1) at rosette, bud initiation and flowering stages using elemental S or thiourea as source, respectively; no S application was taken as control. Among all the treatments, soil application of S improved the crop growth, yield and oil quality in both cultivars and was followed by foliar application of thiourea at 1,000 mg L^?1 compared with no application. Soil applied S and foliar thiourea (1,000 mg L^?1) delayed the flowering and maturity. Soil and foliar applied S significantly improved leaf area index, crop growth rate, net assimilation rate and chlorophyll contents. Plant height, number of branches, siliqua per plant, seed number per siliqua, 1,000-seed weight, biological and seed yield were also increased by soil applied S and foliage applied thiourea (1,000 mg L^?1). Nonetheless, improvement in harvest index, seed oil, protein and glucosinolate contents was only observed from foliage applied thiourea (1,000 mg L^?1). Response of cv. Shiralee to sulphur application was better than cv. Dunkeld. In conclusion, foliar applied thiourea (1,000 mg L^?1) can have potential to improve growth, yield and oil quality in canola and can be economically viable and attractive alternative source.     

Effect of Defoliation on the Growth and Yield of Wheat

The effect of removal of the fifth (L₁), fifth and sixth (L₂) and fifth, sixth and seventh leaves (L₃) from the main shoot and of similar number of leaves from the primary and secondary tillers, on the growth and yield of two varieties of wheat, was investigated. The plants were grown in pots under natural conditions. Defoliation did not affect tillering, ear number, and number of spikelets per ear. The area of the last 3 leaves was reduced only in L₃. Defoliation reduced the growth of stem up to the flag leaf stage but thereafter there was a remarkable recovery in increase in height and dry weight. The grain yield of the main shoot was affected relatively more than that of the primary and secondary tillers by defoliation. The grain yield per plant was reduced by 5 per cent in L₁, and L₂ and by 11 per cent in L₃. The bearing of these observations on productivity per unit area is indicated and it is suggested that a plant with two fewer leaves per shoot may suffer less from mutual shading of leaves and hence prove more efficient in a dense community.     

The pleiotropic effects of extract containing rhizobial Nod factors on pea growth and yield

Rhizobial lipochitooligosacharides (Nod factors) influence the development of legume roots, including growth stimulation, nodule induction and root hair curling. However, their effect on the green parts of plants is less known, therefore we evaluated seed and foliar application of an extract containing Nod factors on pea growth and yield. Pea plants were examined from emergence to full maturity, including growth dynamics and morphological (nodule number and weight, the quantity and surface area of leaves) or physiological (photosynthesis and transpiration intensity, chlorophyll and nitrogen content) parameters. The foliar application Nod factor extract, or seed dressing followed by foliar application, resulted in the best outcomes. The number and weight of root nodules, the chlorophyll content in leaves, and the intensity of net photosynthesis were all elevated. As a consequence of Nod factor treatment, the dynamics of dry mass accumulation of pea organs were improved and the pod number was increased. A significant increase in pea yield was observed after Nod factor application. Increase of nodule and pod numbers and improved growth of roots appear to be amongst the beneficial effects of Nod factor extract on the activation of secondary plant meristems.     

硒对镉胁迫下水稻幼苗生长及生理特性的影响

采用溶液培养 ,研究不同浓度的硒和镉处理对稻苗的株高、叶片干重、叶绿素、还原糖、叶片丙二醛含量以及保护酶 SOD、POD、CAT活性的影响。结果表明 ,镉胁迫下稻苗矮化 ,镉毒害使叶片失绿 ,干重降低 ,还原糖含量下降 ,叶片 MDA含量增加 ,POD活性增强 ,而 SOD、CAT活性降低 ;硒可减轻镉对水稻的毒害 ,表现为 :减轻镉胁迫对株高增加的抑制 ,提高叶绿素含量 ,增加叶片干物质积累 ,提高叶片还原糖含量 (Cd0 .5 mg/ L加 Se 0 .1 0～ 0 .5 0 mg/ L例外 ) ,降低 MDA含量与 POD活性 ,提高 SOD、CAT活性     

Effects of below- and above-ground herbivores on plant growth,flower visitation and seed set

Separate and combined effects of root and leaf herbivores on plant growth, flower visitation and seed set were tested in a factorial experiment using potted mustard, Sinapis arvensis, at an old fallow field. A 50% leaf removal by cabbageworms (Pieris rapae) when the seedlings had their first four leaves reduced plant height and shoot mass, and delayed the onset of flowering. Root herbivory by two wireworms (Agriotes sp.) over the whole experiment changed flower visitation; the number of flower visitors per plant was higher in plants with root herbivores than in plants without root herbivores. Combined leaf and root herbivory affected flowering period, number of fruits per plant and number of seeds per fruit. Plants attacked by leaf and root herbivores had a shorter flowering period and produced fewer fruits per plant than plants with root herbivores only. Although the experimental plants faced major herbivore-induced growth changes, plant reproduction (seed set and weight per plant) was similar in all treatments, documenting their ability to effectively compensate for leaf and root herbivory.     

Varietal differences in uptake and utilization of nitrogen and other macro-elements in seedlings of barley, Hordeum vulgare

Growth and uptake of N, P, S, K, Ca and Mg in barley ( Hordeum vulgare L.) were studied in water culture using young plants of 17 cultivars. Large varietal differences were obtained in dry weight production and mineral accumulation. The differences were not the same for plants grown in high- and low-salt media. For plants grown under both conditions there was a good correlation between dry weight production and total N content. Total shoot contents of K and Ca were closely correlated with shoot dry weight. Utilization of P and S in high- and low-salt plants and Mg in low-salt plants was variable in relation to dry weight production in both types of nutrient conditions. The correlation between dry weight and total content of Mg in high-salt plants was good. These differences in mineral economy between young barley plants were partly caused by varietal differences in relative growth rate, and in high-salt seedlings also by differences in seed content of N. The significance of root size, and of uptake, root-shoot partitioning and use-efficiency of specific elements differed; all four factors were important for P and S, but had varying impact on K, Mg and Ca. For N, differences in root size and ion accumulation were the most important factors causing varietal variation in mineral nutrition. – In a special experiment seedlings of barley were transferred to N-free nutrient solution after six days of adequate N supply. There was no significant varietal differences in use-efficiency ratio of N. Root/shoot partitioning of N was unaffected.     

鱼腥藻提取液对水稻生长发育和产量的促进作用

以田间小区试验和大区产量直接对比的方法研究了鱼腥藻提取认对水稻幼苗生长和产量以及产量构成要素的影响,并探讨了方便有效且适宜于大田使用的方法。用藻液处理后水稻幼苗增高,根数、根长增加,分蘖能力增强,秧龄提前,叶面积明显加大。水稻成熟后除株高比对照略有下降外,各项产量构成要素如粒数、粒重、有效分蘖数、植株干重、千粒重、穗长等都优于对照组,但增产幅度随水稻品种和处理方式不同而异。大田使用时以１％鱼腥藻提     

Boron induced changes in biochemical constituents,enzymatic activities,and growth performance of wheat

The present study investigates how excess boron (B) affects and alters the biochemical constituents and enzymatic activities of wheat (Triticum aestivum var. ‘Raj 4037’), consequently leading to reduced plant growth and yield. Plants were raised in soils supplemented with various concentrations of B (0, 1, 2, 4, 8, 16, and 32 µg B g^?1 soil). Biochemical constituents including soluble leaf protein contents, total phenol contents, soluble sugar contents, proline contents, enzymatic activities of peroxidase (POX), and nitrate reductase (NR) were analyzed. In addition, growth parameters namely shoot–root length, shoot–root fresh and dry weight, seed number and seed weight were analyzed to assess the impact of B toxicity. Results indicate that change in biochemical constituents were correlated with B treatments. Boron concentrations beyond 4 µg g^?1 significantly increased soluble leaf protein contents, total phenol contents, soluble sugar contents, and proline contents. The POX activity was found to be positively correlated with B treatments. B significantly affects nitrogen metabolism and nitrate accumulation which is reflected by the downregulation of NR activity at higher B concentrations. B induced changes in physiological parameters of the plant which subsequently led to the reduction in growth, biomass production, and yield attributes. Out of the various concentrations of B, 8 µg g^?1 was moderately toxic while 16 and 32 µg g^?1 generated high toxicity and induced B stress response to confer tolerance in wheat. Further, a possible mechanism of B toxicity response in wheat is suggested.     

Calcium modifies Cd effect on runner bean plants

The effect of different Ca concentrations in the growth medium on the toxicity of 25 μM CdSO₄ was studied in runner bean plants (var. Pi kny Ja ) at two different growth stages of primary leaves. In young plants growing in a medium with low level of Ca a treatment with Cd for 12 days resulted in Ca accumulation in roots, a strong reduction of the leaf area, a decreased monogalactosyl diacylglycerol/digalactosyl diacylglycerol ratio and efficiency of the photosynthetic apparatus. In leaves of older plants growing under the same conditions, and surviving Cd treatment, a high accumulation of Ca but a low one of Cd, chlorosis of leaves, a decrease of the ratio monogalactosyl diacylglycerol/digalactosyl diacylglycerol and photosynthetic activity were shown. At a high level of Ca in the nutrient medium plant roots showed a remarkably high specificity to accumulate Cd but the toxic effect of the metal on plant growth parameters and content of pigments was decreased. No changes were observed in the level of galactolipids, but changes in fluorescence quenching were recorded. Calcium deficit enhanced the effect of Cd toxicity, including primary photochemistry, whereas excess Ca reduced toxic effects, while it is increasing the nonphotochemical quenching of excitation energy.     

Effects of mixtalol and paclobutrazol on photosynthesis and yield of rape (Brassica napus)

Photosynthetic and yield effects of paclobutrazol and mixtalol sprayed, respectively, on rape at the three-leaf stage and shoot or anthesis stages were examined. They significantly increased chlorophyll content and photosynthetic rates, prolonged leaf longevity, and increased green pod area. Paclobutrazol-treated plants were shorter, more branched, and produced more seeds. Foliar sprays of mixtalol increased podding percentage, pods per plant, and seeds per pod. A high seed yield of 1809.0 kg/ha was obtained with mixtalol sprayed at anthesis, while significant yields were also achieved with treatments of mixtalol at the shoot stage and paclobutrazol at the three-leaf stage. The photosynthetic and yield effects of mixtalol or paclobutrazol were reduced when both growth regulators were applied together, and this led to yield reductions. No adverse effects from mixtalol or paclobutrazol were observed on seed oil content, erucic acid, and glucosinolate content. The total rape oil production with mixtalol sprayed at anthesis and shoot stages and paclobutrazol at the three-leaf stage increased significantly by 20.9%, 14.4%, and 13.4%, respectively, over the controls.