Mina Yamada

EFFECT OF POTASSIUM NUTRITION ON CURRENT PHOTOSYNTHESIZED CARBON DISTRIBUTION TO CARBON AND NITROGEN COMPOUNDS AMONG RICE, SOYBEAN, AND SUNFLOWER

ABSTRACT Type I crops (wheat and soybean), in which the potassium concentration (Kc) decreases when the nitrogen concentration (Nc) decreases, and type II crop (sunflower), in which Kc remains constant when Nc decreases, were grown in K-sufficient and K-deficient soils in pots. The CO2 exchange rate (Pnet; photosynthetic rate, PR; photorespiratory rate, and DR; dark respiratory rate), the distribution of photosynthesized 14C to organs, and the chemical compounds and free amino acids in fully expanded leaves were investigated. The results obtained can be summarized as follows. 1) Potassium (K) deficiency affected type II crop by causing a decrease in Pnet and an increase in PR and DR, while in type I crops, K deficiency affected the CO2 exchange rate less markedly. 2) Potassium (K) deficiency affected type II crop by causing the 14C distribution ratio to TCA/amino acids to decrease at 0 hours after 14C assimilation, and the 14C distribution ratio to serine to increase at 0.5 hours after 14C assimilation. In type I crops, the 14C distribution ratio among chemical compounds and free amino acids were less affected by K deficiency. 3) When 14CO2 was assimilated for 10 min, the 14C distribution ratio to organs was less affected by K deficiency in type I crops than in type II crop. In type II crop, the 14C distribution ratio to the stem was reduced by K deficiency, an effect that was caused by a low 14C translocation from the assimilated leaf blade. When 14C-sucrose and 14C-serine were introduced directly into the phloem, the translocation rate was not reduced by K deficiency in type II crop. When 14CO2 was assimilated into the leaf at a different leaf position, 14C distribution was not affected in type I crops. In type II crop, however, when 14CO2 was assimilated into the lower leaf, 14C distribution to the roots increased under K deficiency as compared to the control. 4) In type II crop when 14C-sucrose was introduced directly to the phloem, 14C compounds were translocated quickly to the lower organs, especially the roots. When 14C-serine was introduced, a major part of the 14C compounds remained in the assimilated leaf blade. Consequently, in type II crop, it can be assumed that current photosynthate distribution to TCA/amino acids and the distribution of carbon in serine to other amino acids are restricted by K deficiency at first, then, the photosynthetic rate and the translocation of photosynthates from the leaf blade are restricted by K deficiency.

Salt Tolerance of Grain Crops in Relation to Ionic Balance and Ability to Absorb Microelements

Abstract A greenhouse experiment was conducted to investigate the effect of exchangeable Na on the growth and absorption of metal elements in barley, rye, and maize. The plants were cultivated in soils whose exchangeable sodium percentages (ESP) were 6.6 (saline soil: Saline), 17.4 (saline-sodic soil: Sodic 1), and 39.6 (sodic soil: Sodic 2), which were prepared from Tottori sand dune soil (Control). The dry weight (DW) and concentrations of metal elements Ca, Mg, Mn, Zn, and Cu) in shoots were analyzed. The shoot DW was smaller with higher ESP, but in barley the difference between all the treatments was no longer observed with time. In Sodic soils, the growth of barley was vigorous, whereas rye growth was poor, and maize plants died by 5 weeks after planting. The Na concentration in shoots of all the species was higher with higher ESP. The K concentration in shoots was low at the early growth stage, but in barley it was higher in the Saline and both Sodic soils than in the Control at the subsequent stages. The concentrations of Ca and Mg in shoots of barley and maize in the Saline and both Sodic soils were higher than those in the Control, but in rye the concentrations were lowest in Sodic 2. The concentrations of Mn, Zn, and Cu in barley shoots in the Saline and bothSodic soils tended to be higher than those in the Control, whereas in rye they were lower than in the Control in both Sodic soils. Barley showed a higher ability to absorb low available microelements than rye and maize. These results indicate that barley is tolerant to sodicity as well as salinity, maize is tolerant to salinity, but is very sensitive to sodicity, and rye is moderately sensitive to both stresses. We suggest that the tolerance of grain crops to ESP involves a tolerance to a high Na concentration in shoots, the ability to keep suitable concentrations of essential cations in the presence of a high concentration of Na in shoots and the ability to absorb low available microelements.

Ameliorative Effect of K-type and Ca-Type Artificial Zeolites on the Growth of Beets in Saline and Sodic Soils

Abstract Beets were grown on soils with various exchangeable sodium percentages (ESP). A saline non-sodic soil (SA, ESP = 3.2), a saline sodic soil (SO, ESP = 23), and a saline high sodic soil (HSO, ESP = 78) were prepared from Tottori sand dune soil (CO). K-type and Ca-type artificial zeolites (50 g kg−1) were applied to these soils in order to evaluate their effects on the chemical properties of saturation extracts of the soils, water deficit, cation uptake and transport, and cation balance of beet plants. In the zeolite-free treatments, beet growth was accelerated in SA and SO, but was suppressed in HSO compared with CO. The addition of both types of zeolites ameliorated plant growth in all the soils studied, especially HSO. The relative dry weight of the soils treated by the K-type zeolite to the zeolitefree soil was 189% for CO, 125% for SA, 130% for SO, and 222% for HSO. For the soils treated with the Ca-type zeolite, the values were 169, 116, 132, and 341%, respectively. In SA, SO, and HSO, the addition of the K-type zeolite increased the K uptake due to the increase of the K concentration of saturation extracts of soils. The addition of the Ca-type zeolite increased the Ca uptake due to the increase in the Ca concentration of the saturation extracts of soils which was accompanied by an increase in the K uptake. The increase in the uptake of K or Ca and decreased in the transport of Na by the addition of both types of zeolites improved the cation balance of the plants. The Ca-type zeolite did not increase the water deficit even though it increased the electric conductivity in all the soils. The results indicated that both types of artificial zeolites were able to improve the growth performance of beets in saline and sodic soils and that the K-type zeolite could be used as a K-fertilizer as well.

Sodium enhances nitrate uptake in Swiss chard (Beta vulgaris var. cicla L.)

Abstract Swiss chard (Beta vulgaris var. cicla L.) is a halophilic plant, which has increased growth under moderate salinity. The stimulation of total nitrogen (N) concentration was also observed with the increase of sodium chloride (NaCl) levels in previous studies. The purpose of this study was to investigate whether the stimulation of N uptake is the result of growth stimulation or the direct effect of NaCl. We compared the effects of NaCl on nitrate (NO3–) uptake and nitrate reductase (NR) activity in halophilic Swiss chard with those in salinity-tolerant barley (Hordeum vulgare L.). Both species were grown hydroponically at NaCl concentrations ranging from 0 to 100 mmol L−1. Leaf dry weight of both species was not significantly affected by the treatments. In barley extracted leaf sap, the NO3– concentration was positively correlated with the potassium ion (K+) concentration, but negatively correlated with the sodium ion (Na+) concentration. In contrast, in Swiss chard extracted leaf sap, the Na+ and NO3– concentrations were strongly and positively correlated. High salinity enhanced NR activity in leaves of Swiss chard, but decreased that in barley. Since NO3– is a substrate of NR, increased NO3– uptake may explain the increased NR activity. We found that the effect of NaCl on NO3– uptake in halophilic Swiss chard and salinity-tolerant barley was completely different. We concluded that the NO3– uptake was enhanced directly by Na+ in Swiss chard.

Growth promotion by sodium in amaranthaceous plants

ABSTRACT 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

Abstract 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.

Effect of K-type and Ca-type artificial zeolites applied to high sodic soil on the growth of plants different in salt tolerance

Abstract The present study aimed to investigate the effects of K-type and Ca-type artificial zeolites on the growth and water and element absorptions of kidney bean (Phaseolus vulgaris L.), tomato (Lycopersicon esculentum Mill), maize (Zea mays L.) and beet (Beta vulgaris L.) in high sodic soil. Tottori sand dune soil, which was used as a control, was converted to high sodic soil mixed with salts. Each type of zeolite was mixed into the high sodic soil at rates of 0, 1, 2 and 5%. The results showed that kidney bean, tomato and maize died in high sodic soil 25–27 days after transplanting (DAT), whereas beet survived, although its growth was extremely suppressed at 26 DAT. The addition of Ca-type zeolite improved growth in all of the tested plants. Even 4 DAT the growth of beet was improved by recovery of water absorption, and growth of tomato was improved by recovery of Ca and K absorptions and cation balance, and restriction of Na absorption. Growth of kidney bean and maize improved at 11 or 13 DAT by recovery of water absorption and Ca and K absorptions. After 4 DAT, water absorption and P and K absorptions of beet were highly recovered compared with those of the other plants; beet growth improved to a large degree. The ameliorative effect of 5% Ca-type zeolite was lower than that of 2% in tomato, maize and beet because the excessive uptake of Ca restricted P transport from root to shoot, and high electrical conductivity of the soil solution restricted water uptake. Even 1% K-type zeolite addition suppressed growth of beet at 4 DAT, and the addition of 2% or 5% of K-type zeolite suppressed the growth of tomato and maize 11 or 13 DAT. Higher concentrations of HCO− 3 and CO2− 3, and pH of the soil solution of K-type zeolite treatments might inhibit water absorption by roots.

Feasibility Study on Phytoremediation Techniques for Soil Contaminated by the Fukushima Dai-Ichi Nuclear Power Plant Accident

Tottori University and the Japan Atomic Energy Agency carried out jointly the feasibility study on phytoremediation techniques, which apply to soil contaminated by the TEPCO’s Fukushima Dai-ichi NPP accident. This paper illustrates the results from experimental investigations. Experimental investigations include both water-culture tests and field tests.Several plants, mainly halophytes that can specifically absorb more Na than K, and others like sunflower demonstrated for other domestic large-scale tests, were water-cultured and examined for screening. Easily cultivated and harvested plants without harmful effects on subsequent cultivation were also considered. New Zealand spinach was selected as a candidate for demonstrations in fields.The field tests were carried out at two sites of different agricultural types in Minami-soma, Fukushima prefecture. Concentration of 137Cs in soil is about 4.5 Bq/g-dry as the average of 10 cm depth. The aims of the field tests are to confirm absorption ability and environmental adaptation of the test plants and to document the cost and performance of projects. In conclusion, the absorption of 137Cs activity per unit area (Bq/m2) by New Zealand spinach could be approximately 0.5%.To achieve an effective result in removal of 137Cs from soil in around a decade, it is required to find the plant which has ten or more times higher absorption capacity than New Zealand spinach. From the consistency of both results in water-culture and field tests, the water-culture test can be valid for screening. In addition, applicable sites will be limited to fields which are too steep or too narrow to use mechanical diggers, and which are free from any restrictions to enter.Copyright