Differences in dry matter production,grain production,and photosynthetic rate in barley cultivars under long-term salinity

Soil salinity is a major environmental stress causing significant loss of crop productivity. Barley (Hordeum vulgare L.) is one of the few field crops that can grow in salt-affected fields and varietal differences in productivity under salinity conditions were known. To clarify the trait most responsible for grain production under salt stress, barley cultivars that were salt tolerant (OUE812) or salt sensitive (OUC613) were grown from seedling to harvest stage in vermiculite containing various concentrations of NaCl. Dry weight of aboveground parts and grain weight decreased significantly with increasing NaCl concentration. The dry weight of the aboveground parts and grain weight decreased more significantly in OUC613 than in OUE812 for plants treated with 150 mM and 200 mM NaCl. A marked reduction in ripening percentage caused significantly decreased grain production in OUC613 as compared with OUE812. In plants treated with 200 mM NaCl, the photosynthetic rate decreased three weeks after starting the NaCl treatment, but a significant difference between cultivars in photosynthetic rate did not appear until seven weeks of NaCl treatment. OUE812 kept a higher photosynthetic rate during ripening than did OUC613 and dry matter production during the period from ripening to harvest was significantly larger in OUE812 than in OUC613. Keeping a higher photosynthetic rate might have contributed to higher grain production in OUE812. Higher ripening percentage and higher rate of photosynthesis during ripening might be target traits in breeding to improve the tolerance of barley to long-term salt stress.     

Effect of Azotobacter vinelandii and compatible solutes on germination wheat seeds and root concentrations of sodium and potassium under salt stress

The effect of plant growth-promoting Rhizobacteria (PGPR) and exogenous application of compatible solutes on seed germination and root concentrations of sodium and potassium of two wheat varieties (Triticum durum L.) were evaluated under saline stress. In this experiment, Azotobacter vinelandii strain DSM85, glycine betaine and proline were used. Inoculated seeds for each variety were placed on Whatman paper in 9 cm Petri dishes containing 15 mL of distilled water or NaCl solutions at various concentrations (control, 100, 200, 300 mM) supplemented with or without glycine betaine (GB) or proline at 5 mM. The results indicated that addition of proline (5 mM) stimulated the production of indol acetic acid and the growth of A. vinelandii at 200 and 300 mM NaCl, respectively. The germination rate index and the germination final percentage decreased significantly (p < 0.05) with increasing salinity level. The germination was significantly diminished at 300 mM with significant variation among varieties and Waha variety had higher germination percentage than Bousselam variety. Inoculation of seeds by A. vinelandii and exogenous application of proline had significantly positive effect on the germination at this concentration of NaCl. The rate of accumulation of Na+ in roots was important at 100 mM and increased at 200 mM. The concentration of K+ decreased when salinity increased. The effect of inoculation or inoculation with proline decreased the accumulation of Na' and reduced the loss of K+ under salt stress. From the present study we can conclude that the use of A. vinelandii strain DSM85 and external application of low concentrations of proline on seeds might be considered as a strategy for the protection of plants under saline stress.     

Natural silicates mixed with organic fertilizers enhance corn adaptation to salt stress and improve physical characteristics of sandy soil

Soil salinity is one of the major environmental constraints to crop productivity worldwide. Therefore, the development of cost-effective and environment-friendly techniques allowing increased crop productivity and soil fertility under saline conditions is rather urgent today. The objective of this investigation was to study the effects of mixtures containing natural silicates (analcite, bergmeal, and potassium silicate) and organic fertilizers (sapropel, peat) in corn (Zea mays L.). We specifically evaluated tolerance of corn to salinity stress and certain characteristics of saline soil (viz., redox potential, conductivity, and phytotoxicity) using a factorial pot experiment, modeling NaCl salinity levels of 0, 50, 100, 150, and 200 mM under greenhouse conditions. Growth, water balance, photosynthesis, catalase activity, and accumulation of nonenzymatic antioxidants (flavonoids and anthocyanins) were measured and evaluated. Salinity stress reduced shoot and root biomass by 8–49%, photosynthetic pigment content in leaves by 15–30%, deteriorated water balance, and activated nonspecific adaptive reactions (i.e., accumulation of enzymatic and nonenzymatic antioxidants) in the corn seedlings. All the tested silicon-containing mixtures stimulated corn seedling resistance to salt stress and reduced soil phytotoxicity. This was reflected in the stimulation of growth of the corn seedlings (accumulation of shoot biomass, and formation and growth of lateral roots). The content of photosynthetic pigments, flavonoids, anthocyanins, catalase activity increased 1.3–2 times compared with plants that received NaCl only. The difference between treatments and control was most pronounced at moderate levels of salinity (100–150 mM). The mixture containing silicon minerals and sapropel (9:1 proportion) showed the highest protective effect against salinity stress.     

Effect of Supplementing Inorganic Fertilizer with OrganicFertilizer on Growth and Yield of Rice-Cowpea Mixed Crop

Abstract

With the renewed interest in mixed cropping and the increasing awareness of environmental degradation arising from high chemical inputs, this experiment was conducted to assess the effect of supplementing inorganic with an organic fertilizer on the growth and yield of rice and cowpea under the mixed cropping system. Treatments comprised six sole crops and three mixed crops, each under 100% NPK (C), 50%NPK+ 50% cow dung (CCD) and cow dung alone (CD). The fertilizer treatments did not significantly affect cowpea performance. However, the number of panicles per hill and the number of spikelets per panicle of rice were higher under mixed cropping than under sole cropping. On the average, rice grain yield was significantly lower under the mixed cropping than under the sole cropping. The land equivalent ratios increased under all the fertilizer treatments indicating the efficiency of the mixed-cropping system. The results of the experiment suggest that rice– cowpea mixed cropping under CCD and CD is a viable production option.     

Salinity effects on compatible solutes, antioxidants enzymes and ion content in three wheat cultivars

In order to study effects of different salinity levels on antioxidant enzyme activities, catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) associated with compatible solutes, proline and carbohydrate and mineral nutrient content in shoots, sodium and potassium, in three wheat cultivars an experiment was conducted as completely randomized 3 x 4 factorial design with three replicates in a greenhouse. Three wheat cultivars (Pishtaz, Kavir and Hamon), that differ in their salt tolerances, were grown in four different salinity levels (S0 = control, S1 = 100, S2 = 200 and S3 = 300 mM NaCl). Twenty days after wheat cultivars subjected to salt stress, data showed salinity stress induced increase in the antioxidant enzyme activities. Among the cultivars, salinity stress decreased leaf-APX but increased the activities of leaf-GPX in Pishtaz cultivar. Our results showed a positive correlation between praline accumulation and Leaf-APX (r2 = 0.56), Leaf-GPX (r2 = 0.63) and Leaf-CAT (r2 = 0.73). In these cultivars, in their shoots Na+ showed an increase in concentration with salinity that approximately matches a decrease in K+ concentration. It seems that Na+ concentrations in the shoot may have had a more significant effect on plant antioxidant enzyme activities and compatible solutes such as proline and carbohydrates. These results indicated which in wheat under salinity stress antioxidant enzymes and compatible solutes help to plant adaptation. In this study we found a positive correlation between Na+ concentration in the shoots and the antioxidant enzyme activities and compatible solutes in the leaves.     

Alleviation of salinity stress on germination of Leymus chinensis seeds by plant growth regulators and nitrogenous compounds under contrasting light/dark conditions

The effects of plant growth regulators (PGRs) and nitrogenous compounds on alleviating salinity stress on seed germination of Leymus chinensis in light (12 h light/12 h dark) and dark (24 h dark) conditions were determined in a laboratory experiment. Seed germination was compared at various combinations of salinity and germination‐promoting compounds. Seed germination percentages were 57 and 74% under non‐saline conditions in light and dark, respectively, suggesting that germination was light‐inhibited. Germination decreased significantly with increasing salinity level in both light and dark conditions, and the reduction was greater in light than in dark at each salinity level. Seed germination percentage decreased to 22 and 7% in light but only to 51 and 27% in dark, in 100 and 200 mm NaCl solutions respectively. The influence of PGRs and nitrogenous compounds in alleviating salinity stress varied with light and salinity condition; e.g., gibberellins (GA_4 + 7) significantly increased germination percentages from 22%, 7% and 0·3% to 47%, 23% and 15% in light at 100, 200 and 300 mm NaCl, respectively, while they showed no effect on germination in darkness. In contrast, sodium nitroprusside and cytokinin significantly increased germination percentage in darkness at all salinity levels, but showed no effect on germination in light at 200 and 300 mm NaCl. Fluridone was very effective in alleviating salinity stress on germination in both light and dark; however, it was lethal to seedlings. Thiourea had no effect in alleviating salinity stress in either light or dark. Thus, alleviation of salinity stress on seed germination of L. chinensis by germination‐promoting compounds is strongly dependent on chemicals and light conditions.     

Salinity stress and sodium-potassium interactions in micropropagated potatoes

Summary Increased potassium (K) fertilization of saline soils has been implicated in alleviating salt stress in plants. We examined whether varying K concentrations in Murashige & Skoog (MS: 1962) basal medium could affect salt (NaCl) stress in micropropagated potatoes. Plantlets of cvs Sierra and Russet Burbank were evaluated after 1 month of growth in a medium containing 0. 40, or 80 mM NaCl and 6,20, or 30 mMK. The medium K was adjusted using KNO₃ while total nitrogen was kept constant using NH₄NO₃. Growth parameters were less affected in Sierra than Russet Burbank, and roots were less affected than shoots, as the medium salinity increased. Tissue Na levels were greater when the medium K was 6 mM compared with 20 mM MS control. The medium K concentration 50% greater than MS control did not promote growth and did not limit tissue Na levels. While this should be confirmed by field assessment, our results suggest that while K deficiency promotes salt damage, its addition beyond the usual fertilizer recommendations is not beneficial in alleviating salinity stress.     

Correlation between Chloroplast Ultrastructure and Chlorophyll Fluorescence Characteristics in the Leaves of Rice (Oryza sativa L.) Grown under Salinity

Abstract

The seedlings of Oryza sativa L. cv. Nipponbare grown by hydroponic culture for 3 wks were treated with 75, 100, 150 and 200 mM NaCl for 14, 14, 6 and 3 days, respectively, and examined for chloroplast ultrastructure in the region where chlorophyll fluorescence had been recorded. NaCl treatment decreased the ratio of variable to maximum chlorophyll fluorescence yield (F_v/F_m) and caused swelling of thylakoids. The swelling of thylakoids was quantified by the percentage of the length of swollen thylakoids to the total length of thylakoids. This value was increased with increasing NaCl concentration. Although F_v/F_m decreased at all concentrations of NaCl, the minimal fluorescence yield F₀ was not increased by the treatment with 75 or 100 mM NaCl. The percentage of the length of swelling was low at 75 and 100 mM NaCl. On the other hand, F₀ increased and the swelling of thylakoids was prominent with 150 and 200 mM NaCl treatment. These results suggest that the decrease in F_v/F_m due to the increase in F₀ under salt stress correlates with the ultrastructural damage. The decrease in F_v/F_m due to the increase in F₀ is expected to be useful as an indicator to evaluate the damage in chloroplasts, especially in thylakoid membranes, under salinity.     

Interactive Effects of Sodium and Potassium on the Growth and Photosynthesis of Spinach and Komatsuna

Abstract

Two cultivars of spinach and one cultivar of komatsuna were sand cultured using a nutrient solution with Na and K in various combinations. The growth (fresh weight of shoot) of spinach cv. Atlas was significantly increased when 1.4 mM KC1 of the 7 m M KO was replaced with 1.4 mM NaCl, although the growth was reduced when more KC1 was replaced with NaCl. In another spinach cv. All Right, however, NaCl substituting for 20% of KC1 showed no significant effects. In komatsuna, Na used in place of K at any ratio reduced the growth. The growth of spinach cv. Atlas was increased by applying 20 mM NaCl, irrespective of K dose (480 - 2400 mg K₂O per 1/2000 a Wagner pot). The growth of spinach cv. All Right was also increased by 20 mM NaCl when K was at a deficient level (480 - 960 mg K20 per pot), but was not when K was at: an excessive level (1920 - 2400 mg K₂O per pot). In komatsuna, 20 mM NaCl reduced the growth. In spinach, Na prevented the decrease of the photosynthetic rate and stomatal conductance caused by K deficiency.     

The effect of water salinity on potatoes (Solanum tuberosum L.): Physiological indices and yielding capacity

Summary The response of several potato cultivars to salinity levels of 20.5, 34.2 and 51.3 mM NaCl was investigated. Salinity tended to lower the water and the osmotic potentials of leaves and tubers while increasing the content of total soluble solids and of proline; it also increased the content of dry matter in the tubers and reduced tuber yields. Susceptibility to salinity was described by the relative loss of tuber dry weight. ‘Blanka’ tolerated the lowest NaCl level (20.5 mM) and exhibited moderate tolerance to higher levels when exposed to salinity stress for 37 days.before harvest, but was susceptible when exposed to the higher levels for 63 days. Cv. Alpha showed moderate tolerance, loosing up to 15% of tuber dry weight when exposed to salinity levels of 20.5 and 34.2 mM NaCl. Mechnisms involved in the adaptation of potatoes to salinity stress are discussed. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 2206-E, 1987 series.     

盐胁迫对垂盆草生长和生理特性的影响

以垂盆草为材料,研究不同浓度NaCl[0(对照)、25、50、100、150、200 mmol/L]对垂盆草生长和生理特性的影响.结果表明:与对照相比,随着NaC1浓度的增加,垂盆草鲜重、干重、含水量、K+含量、根Na+/叶Na+、叶的K+/Na+和SOD活性均呈下降趋势;而Na+、游离氨基酸、可溶性糖、有机酸、脯氨酸、丙二醛含量和质膜透性均呈上升趋势;叶绿素含量、硝酸还原酶活性呈先上升后下降趋势,而NO3-含量则呈相反的变化趋势.综合分析显示,盐胁迫对垂盆草生长有抑制作用,其耐盐阈值为100 mmol/L NaCl;盐胁迫下垂盆草通过积累Na+、有机酸、游离氨基酸、可溶性糖、脯氨酸进行渗透调节.     

人心果在NaCl胁迫下的离子效应及耐盐方式

为了研究人心果在NaCl胁迫下的离子效应及耐盐方式,本试验测定了人心果根、枝条、叶在NaCl胁迫下Cl-、Na+、K+、Ca2+的含量及分布特点.结果表明,人心果根、枝条、叶的Cl-、Na+、Ca2+含量随处理浓度升高而升高,K+、K+/Na+随处理浓度升高而降低.在8‰处理浓度时,根、枝条、叶的Cl-含量分别为对照的8.94、6.77、4.49倍,Na+含量分别为对照的2.16、2.88、2.45倍,K+/Na+分别为0.13、0.43、0.35.相同处理浓度下,根的Cl-、Na+含量均最高,含量高低顺序如下:Cl-:枝条＜叶＜根;Na+:叶＜枝条＜根;K+:根＜叶＜枝条;Ca2+:根＜枝条＜叶.研究结果表明:Cl-、Na+进入植物体后,较大部分滞留在根部,人心果具有根系截留效应,推测其抗性方式为避盐性,研究结果还推测人心果的盐害和细胞Ca2+的自动动态平衡遭到破坏有关.     

Differential Sensitivity of Chloroplasts in Mesophyll and Bundle Sheath Cells in Maize,an NADP-Malic Enzyme-Type C4 Plant,to Salinity Stress

Abstract

The changes in chloroplast ultrastructure and the contents of chlorophyll, Na and K in response to salinity stress were investigated in leaves of maize, an NADP-malic enzyme-type C₄ plant species possessing dimorphic chloroplasts. The seedlings were treated with 0, 1, 2 or 3% NaCl for three or five days under a light or dark condition. In both light and dark conditions, the dry weight of salt-treated plants decreased as NaCl concentration increased. Chlorophyll and K contents of the second leaf blade decreased as NaCl concentration increased under the light condition but not under the dark condition. Na content of the second leaf blade was significantly higher at high NaCl concentrations under both light and dark conditions. However, Na content was much lower under the dark condition than light condition. Higher concentrations (2 and 3%) of NaCl significantly increased the size of plastoglobules, decreased the number and size of starch granules and altered the chloroplast ultrastructure. Under the light condition, mesophyll cell (MC) chloroplasts appeared more sensitive to the damaging effect of salinity than the bundle sheath cell (BSC) chloroplasts. MC chloroplasts became more globular in shape and showed swollen and disorganized thylakoids and reduced thickness of grana by salinity. BSC chloroplasts were less affected by salinity than MC chloroplasts. Although chloroplast size and number and size of starch granules were reduced, there was no structural distortion in the thylakoids of BSC chloroplasts. However, the thickness of grana was increased by salinity. Under the dark condition, the chloroplast structure was less affected by salinity. Though the envelope of BSC chloroplasts was occasionally damaged, the thylakoids in both MC and BSC chloroplasts were preserved under salinity stress. The present study suggests that the chloroplast damage caused by salinity is light-dependent and MC chloroplasts are more sensitive to salinity than BSC chloroplasts.     

Short-term evaluation of oxygen transfer from rice (Oryza sativa) to mixed planted drought-adapted upland crops under hydroponic culture

Mixed cropping is a cultivation method widely practiced in tropical regions. The newly developed close mixed planting technique mitigates the flood stress of drought-adapted upland cereal species by co-growing rice (Oryza sativa) plants under field flood conditions. We tested the hypothesis that O₂ was transferred from rice to upland crops using the model system of hydroponic culture. To confirm the hypothesis, the phenomena of O₂ absorption and release by plants were evaluated in a water culture condition without soil. Experiments were conducted in a climate chamber to estimate the amount of O₂ released from the roots of rice and pearl millet (Pennisetum glaucum) under both O₂-rich (20.0 ± .0% conc. in phase I) and O₂-free dark (.8 ± .0% conc. in phase II) conditions. The total O₂ change (between the two phases) in a single planting of rice and pearl millet was significantly higher than that of the mixed planting of rice and pearl millet, which indicated that O₂ was transferred from rice to pearl millet under a water culture condition. The result indicated that approximately 7 μM O₂ g fresh root weight^?1 h^?1 was transferred between the two plant species. O₂ transfer was confirmed between the two plant species in a mix cultured in water, implying its contribution to the phenomenon that improved the physiological status of drought-adapted upland crops under field flood conditions.     

Antioxidant Capacity and Damages Caused by Salinity Stress in Apical and Basal Regions of Rice Leaf

Abstract

We investigated the mechanisms of increased sensitivity to Na⁺ in the apical and basal regions of the rice leaf under salinity. Three-week-old plants were treated with 200 mM NaCl in hydroponic culture for 3 d. Segments 6 cm in length were obtained from the apical and basal regions of the fully expanded uppermost leaves (6th leaf blades) as old and young tissues, respectively. In the plants exposed to 200 mM NaCl, Nitro blue tetrazolium (NBT) reducing activity, and H₂O₂ and Malondialdehyde (MDA) contents significantly increased, accompanied by the swelling of thylakoids and destruction of thylakoid membranes in the apical regions. However, no indication of oxidative damages was observed in the basal region, even though the Na⁺ content in the basal region was comparable to that in the apical region. In the apical region, the capacity to scavenge H₂O₂ was lower than that in the basal region due to decrease in the constitutive levels of ascorbate peroxidase and guaiacol peroxidase. In addition, the activities of antioxidant enzymes except superoxide dismutase and guaiacol peroxidase decreased drastically after 48 hr of exposure to NaCl. By contrast, the activities of catalase and glutathione reductase in the basal region increased compared with those in the control, and other antioxidant enzymes did not decrease under salinity during the experimental period. These results suggest that the capacity to scavenge reactive oxygen species decreased with age, and thus the apical region of the leaf blade suffered severer damage by Na⁺ than the basal region.     

Induction of Freezing Tolerance by the Application of Hydrogen Peroxide and Salicylic Acid as Tuber-Dip or Canopy Spraying in <Emphasis Type="Italic">Solanum tuberosum</Emphasis> L. Plants

Low temperature stress is a current challenge to plants that is associated with climate change. In plants, exposure to extreme temperatures is followed by the accumulation of reactive oxygen species, such as hydrogen peroxide (H₂O₂), leading to oxidative stress. Salicylic acid (SA) and H₂O₂ mediate the tolerance responses to stress and have been reported to induce freezing tolerance in potato microplants. The objectives of the present investigation were (1) to evaluate the short- and long-term effects of H₂O₂ and SA treatments on freezing tolerance in potato (Solanum tuberosum L.) plants grown from tubers and (2) to analyse the relationship between catalase (CAT) activity and H₂O₂ concentration associated with freezing tolerance responses. We observed the lowest freezing survival rates in 45-day-old potato plants (cv. Granate) compared to younger plants. The two treatments consisted of (1) the tuber-dip (long-term) treatment in which sprouted minitubers were saturated for 1 h in SA 10^?5 M or H₂O₂ 1 mM and planted in soil under greenhouse conditions and (2) the crop-spray (short-term) treatment in which plants 5–8 cm high were sprayed twice a week with SA 10^?5 M or H₂O₂ 1 mM until 45 days of age. In all treatments, 45-day-old plants were then exposed to ? 6?±?1 °C for 4 h. The survival rate was measured 15 days after freezing. CAT and H₂O₂ measurements were performed 1 h before and after the freezing treatment. The results showed that SA and H₂O₂ induced freezing tolerance in both the short- and long-term treatments. Survival was significantly higher in SA- and H₂O₂-treated plants than in control plants. In both the long- and short-term treatments this higher survival was associated with lower internal H₂O₂ concentrations after freezing compared with control plants and decreasing oxidative stress. SA and H₂O₂ induced different levels of CAT activity after freezing compared to that found in the control plants in the long- and the short-term treatments. These results suggest the SA and H₂O₂ function in independent pathways in terms of their induction of freezing tolerance that depends on the method the treatment was applied, by spraying the canopy or by immersion of the sprouted seed tuber.     

Growth photosynthetic activity and antioxidant responses of mycorrhizal and non-mycorrhizal bajra (Pennisetum glaucum) crop under salinity stress condition

Arbuscular mycorrhizal (AM) fungi alleviating the adverse salt effects on growth was tested in bajra (Pennisetum glaucum). Towards this objective we analyzed the photosynthetic activity, proline, phosphatase activity and various antioxidant enzymes such as peroxidase, catalase and superoxide dismutase at 0, 100, 200 and 300 mM salinity levels in AM inoculated and non inoculated bajra plants. Total chlorophyll content was significantly higher in moderate salinity condition in AM fungus (Glomus fasciculatum) inoculated plants, which lead to increase in growth and nutrient uptake capacity of mycorrhizal plants. Antioxidant activity was either increased or decreased due to responses to different salinity stress conditions. Proline accumulation was induced by salt and it was more in shoot of non-AM inoculated plants, but in roots proline accumulation was higher in AM plants at all levels of salinity. This work suggests that the AM fungus helps bajra plants to perform better under moderate salinity levels by enhancing the antioxidant activity and proline accumulation as compared to non-mycorrhizal plants.     

Mixed Planting with Legumes Modified the Water Source and Water Use of Pearl Millet

Abstract

In semi-arid areas, pearl millet is an important staple food crop that is traditionally intercropped with cowpea. This study evaluated the water competition between pearl millet and cowpea using deuterated water. At vegetative stage, pearl millet biomass production was lower in the pearl millet-cowpea (PM-CP) combination than in the pearl millet-pigeon pea (PM-PP) and pearl millet-bambara nut (PM-BN) combinations. PM-CP used more water than PM-PP and PM-BN under well-watered conditions; however, all combinations used similar amounts of water under dry conditions. The biomass production, photosynthetic rates, transpiration rates, and midday leaf water potential of pearl millet at early flowering stage were not significantly reduced by mixed planting with cowpea sown two weeks later as compared with single planted pearl millet. When pearl millet and cowpea were sown at the same time, mix planting significantly increased the recovery rates of recently irrigated heavy water in pearl millet, but not in cowpea in both vegetative and early flowering stages. Midday leaf water potential and transpiration rates in pearl millet were lowered by mixed planting but those in cowpea were not. These indicate that the water source of pearl millet is shifted to the recently irrigated and easily accessible water. By contrast, when cowpea was sown two weeks later than pearl millet, this trend was not observed. These results provide new evidence on water competition in the PM-CP intercropping system; cowpea has higher ability to acquire existing soil water than pearl millet when both crops are sown at the same time.     

Relationship between the Amount of Root Exudate and the Infection Rate of Arbuscular Mycorrhizal Fungi in Gramineous and Leguminous Crops

Abstract

We measured the concentration of polyols (pinitol, ononitol, and myo-inositol), which are known to have health-promoting and/or disease-preventing functions, in the common ice plant (Mesembryanthemum crystallinum L.) cultured under salt- and drought-stressed treatments. In NaCl-treated plant the concentration of pinitol/ononitol increased with increasing NaCl concentration in culture solution. The maximal concentration was 3.6 mg g-¹ FW, which was foundin the shoot top, followed by small side shoots (2.1 mg g-¹ FW) of mature plants grown with 400 mM NaCl for 35 ds. The drought stress also accelerated the accumulation of pinitol/ ononitol. The maximal concentration was 1.2 mg g-¹ FW, which was found in the shoot top of plants under the stress for 25 ds. The myo-inositol increased in salt-stressed plants at 3 ds after the start of the treatment and then decreased with the lapse of time during stress. The concentration of polyols in the ice plant was comparable to that in the other species reported to accumulate polyols at high levels. Radical scavenging activity evaluated by DPPH assay was increased two-fold by 400 mM NaCl treatment, which was twice as high as that in the leaves of lettuce (Lactuca sativa L.). These results indicated the high potential of the ice plant as a polyol-rich high-functional food.     

Crop response to biochar under differing irrigation levels in the southeastern USA

Application of biochar to soils is hypothesized to increase crop yield. Crop productivity impacts of biochar application in southeastern cropping systems consisting of peanut (Arachis hypogaea L.), corn (Zea mays L.), and cotton (Gossypium hirsutum L.) produced under varying rates of irrigation have not been addressed. This research incorporated biochar at two different rates into a long-term irrigation and cropping systems study to compare yield and quality response of peanut, corn, and cotton. Biochar was incorporated into soil once at the beginning of the 4-year project at rates of 22.4 and 44.8 Mg ha^?1. Peanut, corn, and cotton were produced under three sprinkler irrigation levels (100%, 66%, and 33%), shallow surface drip irrigation (100%), and a nonirrigated control. Crop input management followed best management practices. Sprinkler irrigation was scheduled by Irrigator Pro for Peanuts, Corn, and Cotton at the 100% level and the 66% and 33% levels were applied at the same time as the 100% level. Significant year, irrigation, and year × irrigation effects for corn, cotton, and peanut yield resulted (p < 0.001). No differences resulted for biochar in corn (p = 0.930) or cotton (p = 0.678). Peanut yield showed a significant response to biochar comparing the 44.8 Mg ha^?1 rate to the untreated control in nonirrigated production at the p = 0.05 level and in the 33% irrigated treatment at the p = 0.10 level. No negative effects resulted from biochar opening opportunities for biochar application in southeastern U.S. cropping systems for purposes related to carbon sequestration without compromising productivity of producers and related agricultural sectors.