Seedlings of eleven varieties of barley (Hordeum vulgare L.) showed differences in utilization of K+ from a full nutrient solution containing 3.0 mM K+. The K+ content of both roots and shoots was proportional to the fresh weights and dry weights after a week in the nutrient solution. The K+ use-efficiency ratio, which indicates the efficiency of nutrient utilization (mg dry weight produced per mg K+ absorbed), differed significantly among the varieties. There was no correlation between influx of Rb+ and the content of K+. It is suggested that there are wide varietal differences in such genetically-determined properties as ion influx and efflux and net ion transport to the shoot. Furthermore, the influx of Rb+ was closely linked to transpiration, probably due to a variety-specific non-metabolic part of Rb+ influx. Varietal differences in influx of Rb+ were more pronounced in high-K+ roots than in low-K+ roots with maximum rate of Rb+ uptake, but the rank of varieties was the same in each case. Criteria for the selection of K+ use-efficient varieties of barley are discussed

The potential of new corn hybrids in India is not obtained because of waterlogging. A field experiment on a Mollisol-udoll soil was conducted 1) to study the response of five corn varieties (cultivars) to waterlogged conditions and 2) to determine the critical growth stages and duration of waterlogging at which yield is significantly reduced. Waterlogging affected growth rate, nutrient uptake, a number of other physiological processes, and yield. Waterlogging (48 hours and 72 hours) at knee-high stage and tasselling stage retarded the growth of all the varieties except ‘Ganga-2’ and submergence for 72 hours significantly reduced the uptake of N and K and increased P uptake in all the varieties. Calcium and Mg uptake were unaffected. The grain yield of varieties was found in the decreasing order of ‘Jaunpur’ < ‘Kisan’ < ‘Vijay’ < ‘Ganga-7’ < Ganga-2. Soil flooding at knee-high stage was found to be more harmful than at tasseling stage. The critical limits of aterlogging at knee-high stage were 72 hours for Ganga-2 and 48 hours for other varieties. Flooding for 72 hours did not reduce the yield of Ganga-2 at tasselling stage but yield of other varieties was significantly decreased. Ganga-2 was more tolerant to waterlogging because it developed maximum gas spaces and an extensive adventitious root system at the surface of the water under waterlogged conditions.

The influx of Rb('+) into the roots of two barley varieties (Hordeum vulgare L. cv. Salve and cv. Ingrid) from a K('+)-free ('86)Rb-labelled nutrient solution with 2.0 mM Rb('+), was checked at intervals from day 6 to day 18. The control plants were continuously grown in complete nutrient solution containing 5.0 mM K('+), while two other groups of plants were grown in K('+)-free nutrient solution starting on day 6 and between day 6 and day 9, respectively. The pattern of Rb('+) influx was similar for both varieties, although their efficiencies in absorbing Rb('+) were different. The relationship between Rb('+) influx and K('+) concentration of the root could be interpreted in terms of negative feedback through allosteric control of uptake across the plasmalemma of the root cells. Hill plots were bimodal, but in the opposite direction. The Hill coefficients, reflecting the minimum number of interacting allosteric binding sites for K('+) (Rb('+)), were low ( 3.0). It is discussed whether the threshold value, that is the breaking point in the Hill plot, is indicative of a changed efficiency of transporting units for K('+) (Rb('+)) transport to the xylem. Moreover, feedback regulation might be involved in transport of K('+) between root and shoot. The variation of K('+) concentrations in the roots and shoots of control plants were cyclic but in phase opposition despite an exponential growth. The average K('+) concentration varied only slightly with age.

Duas variedades de soja, Santa Rosa e UFV-1 foram cultivadas em solução nutritiva deficiente em macronutrientes. Foi possível obter sintomas de carência, verificar o efeito das deficiências no crescimento, composição mineral e produção de vagens. Fez-se a diagnose foliar no caso de N, P e K e verificou-se o efeito do nivel de N na solução sobre a atividade da redutase de nitrato. | Two soybean varieties were grown in nutrient solution in the presence and in conditions of deficiency of macronutrients (supplied at 1 tenth of full strength level). During the life cycle samples were taken for leaf analyses, as well as for the determination of the activity of nitrate reductase (NO3R). At the end of the pod filling, periodical mineral analyses were carried out in all the organs of the plants under the "complete" tratment; only leaves were analysed in teh remaining plants. The main conclusion were the following (1) symptoms of deficiency which showed up (N, P, K and Ca) are in agreement with those described in the literature; (2) plants deficient in N,P, K or Ca did not produce any pods; (3) there was a differential response in quantitative terms, of the two varieties to the deficiency of elements in the substrate; (4) the adequate levels of N, P, K, Ca, Mg and S are not the same for the two varieties; (5) quick tests provided and indication of the nutritional status; (6) NO3R activity reflected the level of N in the nutrient solution.

Rice plants cultivars IAC 47 (upland) an IAC 435 (lowland) were grown in nutrient solution either under low levels of N, P, K or S, or in the absence of B, Cu or Zn. At the tillering stage the deficient element was supplied via nutrient solution or through leaf feeding. Yield data and leaf analyses allowed for the following general conclusions to be drawn: (1) the deficiency of a given element affected differently grain production in the two varieties; (2) for a given nutrient the same nutritional status, i.e., "normal" or "deficient" could be defined by different leaf levels; (3) additional yield (due to corrective measures) divided by quantity of element applied was higher in the case of foliar feeding of macronutrients; the opposite took place in the case of micronutrients. | Deficiências de N, P, K, S, B, Cu ou Zn foram induzidas em dois cultivares de arroz, I.A.C. 47 e I.A.C. 435 até o perfilhamento. O elemento deficiente foi depois aplicado na solução nutritiva ou por via foliar. A eficiência dos tratamentos foi avaliada dividindo-se o peso adicional de grãos pela quantidade de elemento fornecida pelos dois métodos. Verificaram-se, de modo geral, relações maiores no caso da adubação foliar que da radicular, em se tratando de macronutrientes; o oposto foi observado quando se tratava de micronutrientes.