Growth promotion by sodium in amaranthaceous plants

The amaranthaceous dwarf glasswort, Swiss chard, table beet, spinach and Mexican tea were grown in solutions containing 0, 20, 40, 80, 120, 160, 180 and 200 mol m^?3 sodium chloride (NaCl). Maximum growth and increase of biomass production compared to that at 0 mol m^?3 of dwarf glasswort was observed at 200 mol m^?3 (245%), and Swiss chard (146%), table beet (128%) and spinach (138%) at 80 mol m^?3. The growth of these species increased with increasing sodium (Na) concentration of shoot until it reached 4.18, 2.42, 1.60 and 1.58 mol kg^?1, respectively. These indicate that the order of Na-loving character is dwarf glasswort >> Swiss chard > table beet = spinach. The water contents increased with increasing Na concentration until growth reached maximum in dwarf glasswort and Swiss chard. In these highly Na-loving species, Na is activity transported to shoots and utilized for producing osmotic pressure to absorb water.     

Function of sodium and potassium in growth of sodium-loving Amaranthaceae species

We observed that the growth of three Amaranthaceae species was promoted by sodium (Na), in the order dwarf glasswort (Salicornia bigelovii Torr.) >> Swiss chard (Beta Burgaris L. spp. cicla cv. Seiyou Shirokuki) > table beet (Beta vulgaris L. spp. vulgaris cv. Detroit Dark Red). In the present study, these Na-loving plants were grown in solutions containing 4 mol m^?3 nitrate nitrogen (NO₃-N) and 100 mol m^?3 sodium chloride (NaCl) and potassium chloride (KCl) under six Na to potassium (K) ratios, 0:100, 20:80, 40:60, 60:40, 80:20 and 100:0, to elucidate the function of Na and K on specific characteristics of Na-loving plants. The growth of dwarf glasswort increased with increasing Na concentration of the shoot, and the shoot dry weight of plants grown in 100:0 Na:K was 214% that of plants grown at 0:100. In Swiss chard and table beet, growth was unchanged by the external ratio of Na to K. The water content was not changed in Swiss chard or table beet by the external Na to K ratio. These observations indicate that both Na and K have a function in osmotic regulation. However, dwarf glasswort could not maintain succulence at 0:100; therefore, Na has a specific function in dwarf glasswort for osmotic regulation to maintain a favorable water status, and the contribution of K to osmotic regulation is low. NO₃-N uptake was promoted by Na uptake in dwarf glasswort and Swiss chard. NO₃-N uptake and transport to shoots was optimal at 100:0 in dwarf glasswort and at 80:20 in Swiss chard. These functions are very important for the Na-loving mechanism, and the contribution of K was lower in dwarf glasswort than in Swiss chard.     

Mild salinity improves sugar beet (Beta vulgaris L.) quality

Abstract

Sugar beet (Beta vulgaris L.) is cultivated mainly on saline soils. Low levels of salinity stimulate growth of this crop plant possibly due to production of broader leaves as sources of assimilates. In this work, six cultivars were studied under mild salinity (EC = 5.5 dS m^?1) in a field experiment to analyse its effect on growth parameters and yield of storage root and sugar accumulation. An attempt was also made to determine the contributing role of photosynthetic gas exchange in response of sugar beet plants to salinity. Production of greater leaf area in salinized plants occurred only transitionally in the early growth period; in progression of the growing season it was decreased, and at 3rd harvest (100 days after treatment) it was significantly lower compared with control plants without cultivar differences. Leaf chlorophyll fluorescence, net photosynthesis rate, and stomatal conductance did not change by salinity significantly. Although, at the end of growth season, leaf area and potential photosynthesizing component of salinized plants on the basis of leaf area (LAR) or weight (LWR) were significantly lower than for control plants, weight of storage root and sugar content were up to 90 and 37% higher than in control plants, respectively. Consequently, a considerable higher yield under mild salinity conditions in sugar beet is not attributable to higher leaf area or, therefore, higher photosynthetic capacity of whole plants. Indeed, the storage roots benefit from lower dry matter and surface production of shoot during the late growing season (because of lower nitrogen assimilation and a slight drought stress of salinized plants) and a change in dry-matter partitioning in favor of roots takes place. However, a possible special effect of Na on carbon allocation for storage and structure and involvement of growth regulators in the change of root-shoot allometry could not be excluded.     

Potassium substitution by sodium in sugar beet (Beta vulgaris) nutrition on K‐fixing soils

Alluvial soils with illite and vermiculite clay minerals are highly potassium (K)‐fixing. Such soils have been reported to require a huge amount of K fertilization for optimum plant growth. For halophytic plants such as sugar beet, sodium (Na) can be an alternative to K under such conditions. This study was conducted to investigate the possible substitution of K by Na fertilization with reference to K‐fixing soils. Three soils, i.e., Kleinlinden (subsoil), Giessen (alluvial), and Trebur (alluvial), differing in K‐fixing capacities, were selected, and sugar beet plants were grown in Ahr pots with 15 kg soil pot^–1. Three treatments (no K and Na, K equal to K‐fixing capacity of soil, and Na equivalent to regular K fertilization) were applied. In a second experiment, containers (90 cm × 40 cm × 40 cm) were used with 170 kg Kleinlinden soil each, and one sugar beet plant per container was grown. In both experiments, plants were grown till beet maturity, and beets were analyzed for sucrose concentration and other quality parameters such as α‐amino nitrogen to calculate white‐sugar yield with the New Brunswick formula. The results showed that growth and quality of sugar beet were not affected by Na application, and ultimately there was no decrease in white‐sugar yield. Moreover, the soils with more K‐fixing capacity were more suitable for K substitution by Na. It is concluded that Na can substitute K in sugar beet nutrition to a high degree and soils with high K‐fixing capacity have more potential for this substitution.     

Soil Factors Affecting Yield,Quality, and Response to Nitrogen of Sugar Beets Grown on Light-Textured Soils in Northern Greece

For 7 years (1997–2003), five nitrogen (N) rates (0, 60, 120, 180, and 240 kg N ha^?1) were applied to sugar beets arranged in randomized complete block (RCB) design experiments with six replications and grown on light soils (sand content >50 g kg^?1) in northern Greece. The aim of this work was to identify soil characteristics that affect yield, quality, and sugar beet response to N fertilization. Before sowing, soil analyses were conducted in control plots (0 kg N ha^?1) at two depths (0–30 and 30–60 cm). Soils differed in their physical and chemical properties and especially in sand content, which ranged from 500 to 732 g kg^?1. Quantitative (root number, RN; root yield, RY; and sugar yield, SY) and qualitative (percentage sucrose content in fresh root weight, SC; potassium, K; sodium, Na; and α-amino N) traits of control plots were used as soil fertility index. The RN was positively affected by clay content, and RY and SY were positively related with sand and negatively with silt content. The SC was negatively affected by soil (NO₃)-N and sodium (Na) concentrations. Also, soil (NO₃)-N concentration was positively related with root impurities (K, Na, α-amino N). In combined data over years, N rates had a negative effect on the RN. The RY was the only trait affected by years, N rates, and their interaction. The SC and SY differed significantly between years, and N rates affected significantly the former but not the latter. In combined data over years, N rates were curvilinearly related with Na concentration in roots, whereas a strong, linear relationship was found between α-amino N concentration and N rates. To study the significant years × N rates interaction evidenced for the RY, the relative response (RR) of the RY to N was introduced. Actually, the RR expresses the increase or decrease of the RY for a 150 kg N ha^?1 rate compared to the control (0 kg N ha^?1). The RR was strongly related with soil K concentration at the 0- to 30-cm depth (y = –0.00002x² + 0.0082x + 0.5085, r² = 0.92, P < 0.01, n = 7) and with total N concentration at the deeper layer (y = 1.8335x² – 3.5312x + 2.6614, r² = 0.88, P < 0.05, n = 6). Thus, the RY response to a rate of 150 kg N ha^?1, which is the commonly applied to the sugar beet crop in Greece, can be predicted reliably by soil characteristics (K and total N concentration) determined before sowing. The strong relationship between soil K concentration and sugar beet response to N merits further research.     

Growth Irradiance Effects on Productivity,Photosynthesis, Nitrate Accumulation and Assimilation of Aeroponically Grown Brassica alboglabra

Brassica alboglabra plants were first grown aeroponically with full nutrients under full sunlight with average midday photosynthetic photon flux density (PPFD) of 1200 μmol m^?2 s^?1. Thirty days after transplanting, plants were respectively, subjected to 10 days of average midday PPFD of 1200 (control, L1), 600 (L2) and 300 μmol m^?2 s^?1 (L3). Productivity, photosynthetic CO₂ assimilation and stomatal conductance were significantly lower in low-light (L2 and L3) plants than in high-light (L1) plants. Low light plants had the highest nitrate (NO₃^?) accumulation in the petioles. Low light also had an inverse effect total reduced N content. After different light treatments, all plants were re-exposed to another 10 days of full sunlight. Low-light plants demonstrated their ability to recover their photosynthetic rate, enhance productivity and reduce the NO₃^? concentration. These results have led to the recommendation of not harvesting this popular vegetable during or immediately after cloudy weather conditions.     

CONTRIBUTION OF PROLINE AND INORGANIC SOLUTES TO OSMOTIC ADJUSTMENT IN COTTON UNDER SALT STRESS

Physiological responses to salt stress were investigated in two cotton (Gossypium hirsutum L.) cultivars (Pora and Guazuncho) grown hydroponically under various concentrations of NaCl. Dry matter partitioning, plant water relations, mineral composition and proline content were studied. Proline and inorganic solutes were measured to determine their relative contribution to osmotic adjustment. Both leaf water potential (Ψ_w) and osmotic potential (Ψ_s)decreased in response to NaCl levels. Although Ψ_wand Ψ_s decreased during salt stress, pressure potential Ψ_p remained between 0.5 to 0.7 MPa in control and all NaCl treatments, even under 200 mol m^?3 NaCl. Increased NaCl levels resulted in a significant decrease in root, shoot and leaf growth biomass. Root / shoot ratio increased in response to salt stress. The responses of both cultivars to NaCl stress were similar. Increasing salinity levels increased plant Na⁺ and Cl^?. Potassium level remained stable in the leaves and decreased in the roots with increasing salinity. Salinity decreased Ca²⁺ and Mg²⁺ concentrations in leaves but did not affect the root levels of these nutrients. The K/Na selectivity ratio was much greater in the saline treated plants than in the control plants. Osmotic adjustment of roots and leaves was predominantly due to Na⁺ and Cl^? accumulation; the contribution of proline to the osmotic adjustment seemed to be less important in these cotton cultivars.     

不同浓度钠对甜菜生长及生理特性的影响

采用1/2 Hoagland 营养液室内培养试验,研究不同浓度Na+ 对甜菜幼苗生理生化指标和营养元素吸收的影响。结果表明,0.759 mmol/L Na+可提高甜菜幼苗体内Na+ 含量和幼苗高度,增加叶面积（除了9 mmol/L Na+）和干物质量,降低叶片水势,提高叶片的相对含水量、 GPX和CAT的活性,促进甜菜幼苗叶片的吸水及保水能力。3 mmol/L Na+对甜菜幼苗的生长促进作用最明显,可提高CAT、 GPX活性并维持较高的SOD活性,降低MDA含量和相对电导率,未明显降低甜菜体内N、 P和K含量,是甜菜幼苗生长的最佳Na+浓度。     

Sugar beet yield response to different levels of saline irrigation water and leaching in an arid region

The main objective of this work was to evaluate the effects of saline irrigation water and leaching on the sugar beet yield components. In a field experiment in Rudasht region (Isfahan, Iran), three irrigation water salinity levels (1.6, 8.1, and 12.3 dS m^?1) and with/without leaching were applied. The experimental units comprised of a completely randomized block design, with split plot in four replications. The results indicated that the white sugar yield and alkalinity decreased by increasing the water salinity. Salts leaching significantly increased the root yield, white sugar yield, and white sugar concentration. With higher levels of water salinity molasses sugar, leaf weight, and the concentrations of Na, K, and α- amino-N in sugar beet significantly increased. Consequently, it appears that the use of drainage water in combination with fresh water could be recommended as a strategic management way to grow sugar beet in the investigated arid region.     

Yield formation of five crop species under water shortage and differential potassium supply

A long‐term field experiment on a Haplic Phaeozem, established 1949 with four levels of potassium (K) supply (5, 69, 133, and 261 kg K ha^?1), was analyzed for the interaction between K supply and yield loss of five crop species by water shortage. The crop species were cultivated simultaneously side‐by‐side in the following rotation: potato (Solanum tuberosum L.), silage maize (Zea mays L.), spring wheat (Triticum aestivum L.), beet (Beta vulgaris L.), and spring barley (Hordeum vulgare L.). The treatment with 133 kg K ha^?1 supply had a nearly balanced K budget. In the treatments with lower supply, the soil delivered K from its mineral constituents. On the low‐K plots (especially on those with only 5 kg K ha^?1), crops suffered yield depressions of nearly all main harvest products (cereal grains, potato tubers, beet storage roots, silage maize) and by‐products (straw, beet leaves) by up to 40.7% of dry matter. Only wheat grains were an exception. Potassium concentrations in the harvested plant parts decreased nearly in parallel to the reduction of their dry matter yields, with the exception of cereal grains, which kept stable concentrations even in the treatment with only 5 kg K ha^?1. A comparison of four year‐pairs with differing levels of precipitation in yield‐relevant periods showed an average water shortage‐induced depression of dry matter yields by 19.7% in the main harvest products. The severity of this yield depression was not mitigated by elevated K supply, with the exception of beet leaves, where the dry matter production was stabilized by high K supply. In this crop, the reduction of storage‐root yield was associated with a decrease in harvest index and was therefore obviously caused by an inhibition of assimilate translocation from the leaves into these organs, in contrast to cereals, where water shortage primarily affected dry matter production in vegetative organs. It is concluded that the physiological causes of yield reduction by drought stress and the possibility of its amelioration by K supply differ between plant species and organs.     

THE EFFECTS OF NITROGEN SOURCE AND CONCENTRATION ON THE GROWTH AND MINERAL COMPOSITION OF PRIVET

Abstract

Sodium (Na) movement between plants and humans is one of the more critical aspects of bioregenerative systems of life support, which NASA is studying for the establishment of long‐term bases on the Lunar or Martian surface. This study was conducted to determine the extent to which Na can replace potassium (K) in red beet (Beta vulgaris L. ssp vulgaris) without adversely affecting metabolic functions such as water relations, photosynthetic rates, and thus growth. Two cultivars, Ruby Queen and Klein Bol, were grown for 42 days at 1200 μmol mol^?1 CO₂ in a growth chamber using a re‐circulating nutrient film technique with 0%, 75%, 95%, and 98% Na substitution for K in a modified half‐strength Hoagland solution. Total biomass of Ruby Queen was greatest at 95% Na substitution and equal at 0% and 98% Na substitution. For Klein Bol, there was a 75% reduction in total biomass at 98% Na substitution. Nearly 95% of the total plant K was replaced with Na at 98% Na substitution in both cultivars. Potassium concentrations in leaves decreased from 120 g kg^?1 dwt in 0% Na substitution to 3.5 g kg^?1 dwt at 98% Na substitution. Leaf chlorophyll concentration, photosynthetic rate, and osmotic potential were not affected in either cultivar by Na substitution for K. Leaf glycinebetaine levels were doubled at 75% Na substitution in Klein Bol, but decreased at higher levels of Na substitution. For Ruby Queen, glycinebetaine levels in leaf increased with the first increase of Na levels and were maintained at the higher Na levels. These results indicate that in some cultivars of red beet, 95% of the normal tissue K can be replaced by Na without a reduction in growth.     

Influence of Salt Stress on the Nutritional State of Cordyline fruticosa var. Red Edge, 2: Sodium,Potassium, Calcium,and Magnesium

The aim of this trial was to study the nutritional behavior generated by modifications in the salt concentration in the nutrient solution used for the fertigation of Cordyline fruticosa var. Red Edge plants. Four treatments were tested: T₁ [control, 1.5 dS m^?1, 14.3 mmol L^?1 sodium chloride (NaCl)]; T₂ (2.5 dS m^?1, 22.2 mmol L^?1 NaCl); T₃ (3.5 dS m^?1, 32.7 mmol L^?1 NaCl); and T₄ (4.5 dS m^?1, 38.2 mmol L^?1 NaCl). There is an accumulation of sodium (Na⁺) in roots, stem, and petiole when salinity increases, which avoid leaf damages. Potassium (K) concentration increases with the intermediate saline treatments in stems and leaves but decreases when plants are fertigated with T₄. Calcium (Ca) accumulates in roots with T₃ and T₄, in stems with T₄, and in petioles and leaves with T₃. Magnesium (Mg) concentration is greater in stems, petioles, and leaves of T₄, but is greater in roots of T₃. Plants fertigated with the three saline treatments extract 1.4 times more Na⁺ than T₁ plants. The greatest K⁺ extraction is observed in T₂, followed by T₃, and T₄. T₂, T₃, and T₄ plants extracted more Ca²⁺ than T₁ plants. Finally, Mg²⁺ extractions in T₃ are twice as much as they are in T₁, while in T₄ and T₂ are much greater.     

Efficiency of Potassium Fertilization and Salicylic Acid on Yield and Nutrient Accumulation of Sugar Beet Grown on Saline Soil

Rising soil salinity has been a major problem in the soils of Egypt in recent decades. Potassium fertilization and salicylic acid (SA) play an important role in promoting plants to tolerate salt stress and increased the yield of sugar beet crop. A field experiment on sugar beet (Beta vulgaris L.) grown on saline soil was carried out during 2014 growing season in Port Said Governorate, Egypt, to study the effect of potassium fertilization of the soil at applications of 0, 100, 150, and 200 kg potassium (K) ha^?1 and foliar spray of SA by solution of 1000 mg L^?1, twice (1200 L ha^?1 each time) on yield and nutrient uptake. Application of 200 kg K ha^?1 in combination with salicylic foliar spray gave the highest root length, root diameter, shoot and root yield, sucrose, juice purity percentage, gross sugar yield, and white possible extractable sugar, nitrogen (N), phosphorus (P), and potassium (K) content, and uptake of sugar beet. The highest increase in sucrose (20%) as well as white possible extractable sugar (184%) was obtained by 200 kg K ha^?1 in combination with salicylic foliar spray compared with untreated soil with potassium fertilization and without salicylic foliar spray.     

Sodium‐induced calcium deficiency in sugar beet during substitution of potassium by sodium

Functions of sodium (Na⁺) and potassium (K⁺) are closely associated. In some crops, Na⁺ is able to prevent or reduce considerably the occurrence of K⁺ deficiency. Sugar beet (Beta vulgaris L.) is a natrophilic crop, and positive effects of Na⁺ applications on yield were observed when K⁺ was sufficiently supplied. However, it is not known which specific function of K⁺ can limit the growth of sugar beet when K⁺ is substituted by an equivalent amount of Na⁺. Therefore, K⁺ substitution by Na⁺ was investigated for sugar beet in hydroponics. Surprisingly, no K⁺‐deficiency symptoms were observed. However, calcium (Ca²⁺) concentrations in the leaves were significantly decreased. Moreover, Ca²⁺ uptake and translocation through xylem sap were reduced in Na⁺‐treated plants. It is concluded that Ca²⁺ uptake by roots and its translocation via xylem sap primarily limit the possibility of K⁺ substitution by Na⁺ in sugar beet nutrition.     

Reaktion der Zuckerrübe (Beta vulgaris var. altissima) auf die Kaliumdüngung – ein 20‐jähriger Feldversuch

Response of sugar beet ( Beta vulgaris var. altissima ) to potassium fertilization—a 20‐year field experiment A long‐term fertilizer experiment was performed to develop a K fertilization strategy to achieve highest extractable sugar yields (BZE). Sugar beet was grown in a crop rotation with wheat and barley on an alluvial soil (clayic silt) in Lower Saxony with annual recycling of straw and beet tops, respectively. Since 1983, the treatments were as follows: 1) K fertilization with 0, 29, 58, 87,174, and 524 kg K ha^–1 a^–1 corresponding to 0, 0.5, 1, 1.5, 3, and 9 times the average annual K removal by the marketable products of the crop rotation—since 1995, the two highest treatments (3 and 9 times the removal) received only 174 kg ha^–1 every third year; 2) K fertilization according to the average K removal, given each year (58 kg K ha^–1) or every third year (174 kg ha^–1) to sugar beet; 3) annual K fertilization of 87 kg K ha^–1 (1.5 times the removal) applied in autumn or spring, respectively; 4) annual K fertilization, applied as mineral fertilizer or as organic material (recycling of grain and straw or root and leaves); 5) application of 29 kg NaCl ha^–1 to sugar beet supplemental to a yearly application of 58 kg K ha^–1. Both root yield and soil concentration of lactate‐soluble K increased with K fertilization up to the highest K treatment. The extractable sugar content reached a maximum at a yearly application of 174 kg K ha^–1. Averaged over years, the extractable sugar yield (BZE) increased up to the highest K application. The time of K application (autumn or spring) and the source of K (mineral fertilizer or organic material) had no effect on BZE. An additional fertilization with NaCl increased BZE only slightly in single years. Low‐grade muriate of potash containing 33% K and 3% Na can thus be used. The economically optimal K‐fertilization rate was 174 kg K ha^–1 given once in the crop rotation to sugar beet. A soil K concentration of about 110 mg (kg soil)^–1 (lactate‐extractable K) is sufficient in this soil to achieve a high BZE.     

Comparative studies on the distribution of foliar or root applied 15N-nitrogen in Beta vulgaris species

Recent anatomical studies on sugar beet suggest direct vascular connections between ontogenetically corresponding leaves and segments in the storage root (Stieber and Beringer, 1984). The objectives of two experiments were to test the use of these transport routes in the distribution of ¹⁵N. In adult Beta vulgaris L., spp. vulgaris plants (fodder beet cv Kyros and sugar beet cv Kawetina) ¹⁵NH₄ ¹⁵NO₃ was applied to leaf 10 (young) and 21 (old) respectively. Distribution of ¹⁵N within the plant was determined 2, 7 and 21 days later. In fodder beet ¹⁵N applied to leaf 21 was exported to 63% into the storage root, to 11% into younger leaves; the corresponding percentages in sugar beet were 51% and 31% respectively. ¹⁵N applied to leaf 10 was exported to only 37% into the storage root, 7% and 15% were translocated into the older leaves of fodder and sugar beet respectively. This pattern of ¹⁵N distribution does not fully contradict with the expected use of assumed vascular routes. It is suggested that N exported from an older leaf does not exclusively migrate into the ontogenetically corresponding tissues of the storage root, but part of the N is imported by the younger leaves and from there exported into the peripheral regions of the storage root. This view is supported by a short-term experiment on ¹⁵NO₃^- root-uptake by six week old fodder and sugar beet plants which gave the following sequence of specific ¹⁵N labeling: lateral roots ≧ young leaves > root crown > old leaves > storage root.     

Compositional nutrient diagnosis in sugar beet with sodium supplementation

A plant stress is related both to deficiency of a particular nutrient and to inadequate relationships between nutrients. The objective of the study was to assess the sugar beet nutritional status in response to sodium chloride (NaCl) application. Plant sampling was conducted at two early stages of beet growth (7-leaf – BBCH 17, and well-developed rosette – BBCH 43). The white sugar yield (WSY) was used as an evaluation criterion. The data used in this study originate from a set of 20 field experiments, conducted in years with a significant shortage of precipitation. Each trial was consisted of control (NPK) and a plot with 50 kg Na ha^?1 (NPK+Na). The nutrient concentration approach and the Compositional Nutrient Diagnosis, based on centered log ratios (CND-clr), were used to evaluate sugar beet nutritional status. The effect of sodium (Na) was evaluated within two subsets of fields: NR – without, and R – with a significant increase in WSYs. The CND-clr indices for Na increased, but for K, Ca and Mg decreased along with Na application, irrespective of the growth stage and subset of fields. However, Na application improved relation between nutrients in fields responding to sodium application, especially at BBCH 43.     

COLONIZATION WITH BACTERIAL FERTILIZER IMPROVES RESISTANCE TO LOW LIGHT INTENSITY IN CUCUMBER SEEDLINGS

Irradiance level is a limiting factor for plant growth, especially in a greenhouse. A bacterial fertilizer was applied to test its role on cucumber seedlings to overcome low light intensity. Five light intensity levels of 100, 200, 400, 600 and 800 μmol? m^?2s^?1 were used. The results revealed that the bacterial fertilizer can stimulate nitrogen (N) and potassium (K) uptake at 400 and 600 μmol? m^?2s^?1 and phosphorus (P) uptake except for 800 μmol? m^?2s^?1. Nitrogen, P, and K in soils were highly improved at various light intensities. The effect of promoting iron (Fe) and zinc (Zn) was stronger in roots than in shoots. The significant improvements of chlorophyll, carotinoid, soluble sugar, and photosynthesis rate were also observed. The bacterial fertilizer increased plant height, stem diameter, leaf area, fresh and dry weight except for the decline of height at 100 and 200 μmol? m^?2s^?1. The sharp decline or increase occurred mostly at the light intensity of 400 μmol? m^?2s^?1.     

Reclamation of saline calcareous soils using vegetative bioremediation as a potential approach

Vegetative bioremediation of saline calcareous soil (EC_1:1 11.01 dS m^?1) was practised through growing fodder beet (Beta Beta vulgaris var. magnum) and millet (Panicum spp.) in soil columns. Beet was grown at a planting density of 4427 plants m^?2, whereas millet was grown at two planting densities: 5202 (M1) and 8928 (M2) plants m^?2. Some plants were irrigated with 233 μ S cm^?1 water throughout the experiment (70 days), while for others non-saline water was replaced with saline water (2.52 dS m^?1) at the middle of the experiment. The control was leaching of uncropped soil. Beet had higher ash content and efficiently extracted higher amount of salts (particularly Na and Cl) along with their aboveground biomass than millet under the two irrigation regimes. Millet grown at high planting density had higher ash content and extracted higher amount of salts (particularly Cl) than those at low planting density. Bioremediation, particularly in the case of millet (M1), considerably enhanced soil hydraulic conductivity as compared with leaching treatment; thus, facilitating the removal of some soluble salts beyond the root zone. Accordingly, soil electrical conductivity was considerably decreased by 54–69% compared with the untreated soil. It is concluded that mainly fodder beet is a potential candidate for efficient bioremediation of saline calcareous soils.

     

Growth response of Suaeda salsa (L.) Pall to graded NaCl concentrations and the role of chlorine in growth stimulation

Abstract

Growth response of a halophyte species, Suaeda salsa (L.) Pall, to graded NaCl concentrations was examined under water culture conditions. Growth increased with increasing NaCl concentration from 2 to 200 mol m^?3, but decreased at NaCl concentrations above 200 mol m^?3. Maximum growth was attained at 50 to 200 mol m^?3. The role of Na and Cl in the growth stimulation by NaCl was examined by growing S. salsa in nutrient solutions with or without Na and Cl separately at 5 and 50 mol m^?3. The growth stimulation induced by Cl was greater than that induced by Na, and Na did not significantly induce growth stimulation. The effect of Na or Cl on O₂ evolution from leaves was examined under 5 and 50 mol m^?3 concentrations using an oxygen electrode. Oxygen evolution from leaves in –Cl treatments was smaller than that in +Cl treatments both at 5 and 50 mol m^?3. The O₂ evolution in Na treatments with Cl was similar to that at NaCl. These results indicated that the mechanism of growth stimulation induced by Cl was mainly an increased photosystem II of photosynthesis in leaves. The contribution of Na on the growth stimulation of S. salsa by NaCl was smaller than Cl.