Ameliorative effect of potassium on mice and tomato subjected to sodium salinization

Rice (Oryza sativa L. cv. Yamabiko) and tomato (Lycopersicon esculentum Mill cv. Saturn) plants subjected to Na-salinization (NA: 80 mmol( + ) kg^-1 Na) in hydroponics were grown after the addition of K at five concentrations (K1: 10, K2: 20, K3: 30, K4: 40, K5: 50 mmol( + ) kg^-1). The effect of K on their growth was analyzed in terms of transpiration, cation uptake, and transport. A similar tendency for the above parameters was obtained in both species. The addition of 10 mmol( + ) kg^-1 K improved the growth by decreasing the content of Na and increasing the K content of the plants. The growth of the plants, however, was reduced along with the increase of the K concentration and became comparable to that of NA at K5. The total cation content increased with the increase of the K concentration, which was due to the increase of the K content.

A close relationship was observed among the osmotic potential of the solution, cumulative transpiration, and dry weight for both species among the K treatments.

Addition of K suppressed the uptake of other cations by rice and tomato in the order of Na>Mg>Ca, with a very small suppression for Ca and Mg. The depression of Na uptake by K could be due to the antagonism between the two cations.

In rice, the addition of K resulted in a decrease of the uptake concentration (UC) of Na and an increase of that of K, but did not bring about any changes in the UC of Ca and Mg. It was worth noting that K1 and K2 led to a higher UC of Na than NA in tomato, while the trend of the UC of K, Ca, and Mg was similar to that in rice. The transport of Na and Ca to the tops of rice was not affected by the addition of K, while that of Mg increased by K addition. In tomato, the transport of all the cations was promoted by the increase of the K concentration.     

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.     

Salt tolerance of grain crops in relation to ionic balance ability to absorb microelements

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.     

盐生植物海蓬子对不同形式的氮源的响应

Salt-affected soils are agricultural and environmental problems on a global scale. Plants suffer from saline stresses in these soils and show nitrogen (N) deficiency symptoms. However, halophytes grow soundly under saline conditions. In order to clarify the N nutrition of the halophyte Salicornia bigelovii, it was grown at several N levels (1, 2, 3, and 4 mmol L^-1), supplied in the form of NO₃^- or ammonium (NH₄⁺), under high NaCl conditions (200 mmol L^-1). NH₄⁺-fed plants showed better growth than NO₃^--fed plants at 1-3 mmol L^-1 N, and plants in both treatments showed the same growth at 4 mmol L^-1 N. Nitrogen contents in NO₃^--fed plants increased with the N concentrations in solution; competitive inhibition of NO₃^- absorption by Cl^- was observed under lower N conditions. In addition, shoot dry weight was significantly correlated only with shoot N content. Therefore, growth of NO₃^--fed plants was regulated by N absorption. Inc ontrast, N contents of shoots in NH₄⁺-fed plants did not change with N concentration. Shoot Na content decreased with increasing N concentration, while K content increased. Dry weight was highly correlated only with K content in NH₄⁺-fed plants. These observations indicated that growth of NH₄⁺-fed plants was mainly regulated by K absorption.     

近滨海区鲁梅克斯K-1杂交酸模的引种及耐盐性研究

通过引种试验,对鲁梅克斯Ｋ－１杂交酸模和生长发育规律、营养成分、耐盐力等进行了研究。结果表明,该杂交酸模在肥水充足的条件下,营养价值高,蛋白质含量高达２０％～３８％;繁殖力强,一年或刈割４茬～５茬,每公顷收获鲜草１５０ｔ左右。按照抗逆半衰减定义,该牧草耐盐力０．３２５％,只有抗中等盐碱。但收获携盐能力较强,从平均盐离子含量来看,每种植１ｈｍ＾２鲁梅克斯,通过牧草收割,一年可携走土壤中的盐分１５０ｋｇ～２００ｋｇ。     

A new source of basaltic meteorites inferred from Northwest Africa 011

Eucrites are a class of basaltic meteorites that share common mineralogical, isotopic, and chemical properties and are thought to have been derived from the same parent body, possibly asteroid 4 Vesta. The texture, mineralogy, and noble gas data of the recently recovered meteorite, Northwest Africa (NWA) 011, are similar to those of basaltic eucrites. However, the oxygen isotopic composition of NWA011 is different from that of other eucrites, indicating that NWA011 may be derived from a different parent body. The presence of basaltic meteorites with variable oxygen isotopic composition suggests the occurrence of multiple basaltic meteorite parent bodies, perhaps similar to 4 Vesta, in the early solar system.     

Assessment of emitter discharge in microirrigation system as affected by polluted water

A drip irrigation system has the advantage of maintaining high water content near the plant root. However, its performance depends on water quality as it may induce the emitter clogging. In the Tohaku National Irrigation Project, in western Japan, mist spray emitters are widely used for irrigation in the field and greenhouses for vegetable and orchard crops. Seven emitters of different types were evaluated for the variation in their discharge rate without filter. The statistical analysis of mean discharge ratio and the coefficient of variation of the performance of emitters along a lateral line in the field indicated that the mist spray emitters had the best performance for irrigation in Tohaku area, particularly the new emitters or 1-year old emitters. The results suggest that after using the emitter line for two irrigation seasons it should either be replaced in the third season or washed carefully if further used.     

Difference in -response of rice and tomato subjected to sodium salinization to the addition of calcium

Rice (Oryza sativa L. cv. Yamabiko) and tomato (Lycopersicon esculentum Mill cv. Saturn) plants were subjected to Na-salinization (80 mmol( + ) kg^-1) in hydroponics. The effect of the addition of Ca on their growth was analyzed in terms of transpiration, ion uptake, and ion transporto.

The addition of 10 mmol( + ) kg^-1 Ca improved rice growth by decreasing the Na uptake and increasing the K and Ca uptake. It was worth noting that the Na uptake accompanied with water uptake (transpiration) was not affected by the addition of Ca. A close relationship was found in rice among the osmotic potential, cumulative transpiration, and top dry weight; The growth of rice, therefore, seemed to depend on the osmotic potential of the solution.

The growth suppression of the tops and roots brought about by Na and recovery by the addition of Ca were greater for tomato. Ca improved tomato growth by reducing the Na uptake and increasing the uptake of K and Ca, as was observed in rice. The selectivity of plants for potassium versus sodium (S_K,Na) increased sharply with the increase of the Ca concentration. Moreover, the transport of Na to the tops was suppressed by the addition of Ca. It was found that the osmotic potential, transpiration, and dry matter yield were not correlated with each other. It was concluded from the results that the growth recovery of tomato plants subjected to Na-salinization by the addition of Ca may be associated with the suppression of Na transport to the tops rather than with the antagonism between Ca and Na at the root surface.