Concentration Of Cell Sap Research Articles

Effect of NaCl on physiological, biochemical, and ionic parameters of naked oat (Avena nuda L.) line Bayou1

Oat (Avena nuda L.) is a globally important cereal crop grown for its nutritious grains and is considered as moderately salt-tolerant. Studying salinity tolerant mechanisms of oats could assist breeders in increasing oat production and their economic income in salt-affected areas, as the total amount of saline land in the world is still increasing. The present study was carried out to better understand the salt tolerance mechanism of the naked oat line Bayou1. A soil experiment was conducted on 17 days-old Bayou1 seedlings treated with varying concentrations of NaCl for a period of 12 days. Bayou1 plants grew optimally when treated with 50 mM NaCl, demonstrating their salinity tolerance. Reduced water uptake, decreased Ca2+, Mg2+, K+, and guaiacol peroxidase activity, as well as increased Na+ concentration in leaves, all contributed to a reduction in shoot growth. However, the damage to ionic homeostasis caused by increased Na+ concentrations and decreased K+ concentrations in the roots of Bayou1 did not inhibit its root growth, indicating that the main salt-tolerant mechanism in Bayou1 existed in its roots. Further, a hydroponic experiment found that increasing Na+ concentration in root cell sap enhanced root growth, while maintaining the integrity of root cell membranes. The accumulated Na+ may have facilitated the root growth of Bayou1 exposed to NaCl by effectively adjusting cellular osmotic potential, thereby ensuring root cell turgor and expansion.

Разработка элементов технологии возделывания малораспространненных видов многолетних луков на Среднем Урале

Abstract. In experiments conducted in 2021–2022. on the basis of the educational and experimental farm of the Ural State Agrarian University, studies were carried out on the influence of the feeding area and planting dates on the productivity and biochemical composition of perennial onions. The territory of the Middle Urals is located in a difficult climatic zone, with severe winters and warm summers. The weather in this area can change very quickly, and therefore, for cultivation in the Middle Urals, plants should be selected that will easily endure the vagaries of the weather, including green crops. These characteristics correspond to perennial onions, which are able to produce high yields of green leaves even in risky farming. Good resistance to pathogens, less susceptibility to pests compared to onions, as well as a wide variety of species that differ in external characteristics and taste make perennial onions excellent plants for obtaining valuable vitamin greens. The purpose of the study: to study the biological characteristics of perennial onions, as well as to find out the effect of the feeding area on their yield and biochemical composition. Methods. In the experiments, the following factors affecting the yield of perennial onions were investigated: leaf length, number of leaves per plant, the appearance of flower stalks, individual plant productivity. Results. In the course of the study, it was found that the highest yield is observed in all types of onions when grown with a distance in a row of 5 cm, the highest individual productivity was shown by batun onion plants when grown in a row with a distance between plants of 15 cm and slime onion with a distance between plants in a row of 25. In addition, there was a deterioration in the biochemical composition of the leaves of all the studied types of onions when planting in 2022 compared to 2021 and an increase in the concentration, electrical conductivity and acidity of cell sap in 2022 compared to 2021. Scientific novelty. Ledebur onion is the least studied of the onion species presented in the study, but it has good commercial and nutritional properties. Previously, this type of onion was not studied in the Middle Urals as a vegetable plant.

Natural Physiological Changes on Overwintering and Spring Recovery of Needles of Pinus densiflora Siebold & Zucc.

Overwintering and spring recovery of pine needles have important ecological significance. The natural changes in physiological state, photosynthetic function, and material metabolism in needles of Pinus densiflora Siebold & Zucc. from the autumn of 2020 to the spring of 2021 were assessed. The photosynthetic rate (Pn) of P. densiflora needles decreased first and then increased, with the maximum Pn observed in the autumn. After experiencing sub-zero temperatures in the winter, needles of P. densiflora still performed weak photosynthesis at a temperature above zero. In the spring, the Pn gradually recovered but could not recover to the maximum. Under sub-zero temperatures in the winter of 2020, the plasma membrane permeability and MDA content of needles increased, whereas the chlorophyll content and Fv/Fm decreased significantly. The needles showed obvious characteristics of freezing injury. During the whole process, the water content of needles remained at a low level (about 60%), which gradually decreased with the increase of leaf age. The cell sap concentration and soluble sugar content of needles decreased with the decrease in air temperature and recovered in spring. Therefore, P. densiflora needles do not improve frost resistance through osmotic adjustment. However, the increasing carotenoid content is helpful for needles to tide over the winter. The soluble sugar and protein contents increased, implying they are important for the recovery of needles in spring. This study expands our understanding of the mechanism and ecological contribution of overwintering and spring recovery of pine needles.

Exogenous silicon alleviates the adverse effects of cinnamic acid-induced autotoxicity stress on cucumber seedling growth.

Autotoxicity is a key factor that leads to obstacles in continuous cropping systems. Although Si is known to improve plant resistance to biotic and abiotic stresses, little is known about its role in regulating leaf water status, mineral nutrients, nitrogen metabolism, and root morphology of cucumber under autotoxicity stress. Here, we used cucumber seeds (Cucumis sativus L. cv. “Xinchun No. 4”) to evaluate how exogenous Si (1 mmol L−1) affected the leaf water status, mineral nutrient uptake, N metabolism-related enzyme activities, root morphology, and shoot growth of cucumber seedlings under 0.8 mmol L−1 CA-induced autotoxicity stress. We found that CA-induced autotoxicity significantly reduced the relative water content and water potential of leaves and increase their cell sap concentration. CA-induced stress also inhibited the absorption of major (N, P, K, Ca, Mg) and trace elements (Fe, Mn, Zn). However, exogenous Si significantly improved the leaf water status (relative water content and water potential) of cucumber leaves under CA-induced stress. Exogenous Si also promoted the absorption of mineral elements by seedlings under CA-induced stress and alleviated the CA-induced inhibition of N metabolism-related enzyme activities (including nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase, glutamate dehydrogenase). Moreover, exogenous Si improved N uptake and utilization, promoted root morphogenesis, and increased the growth indexes of cucumber seedlings under CA-induced stress. Our findings have far-reaching implications for overcoming the obstacles to continuous cropping in cucumber cultivation.

Garlic Pink Rot Disease and Crop Yield as Affected by Salinity and Irrigation Water Deficit

Greenhouse experiments were conducted in Ismailia governorate (El-Kassassine county), Egypt, during 2017/2018 growing seasons to determine the effect of both water salinity or water deficit at different treatments consisted of four levels of salinity (10, 15, 20 and 25 mM NaCl/L) and 3 rates of water stress (80, 60 and 40% W.H.C.) on pink root incidence and yield of garlic (Allium sativum L.) cv. (Sids-40), as well as the garlic plant responses. Irrigation with saline water increased pink root incidence in garlic inoculated with Pyrenochaeta terrestris, and yield was decreased. Irrigation of garlic until 20 mM NaCl/L did not affect cloves germination, plant height, leaves dry weight, cell sap concentration and proline concentration, but partial effect was observed at 25 mM NaCl/L of garlic grown in soil uninfested with the tested pathogen. Garlic plants exposed to 80% rate of W.H.C. weren’t significantly affected, disease incidence, cloves germination, plant height, leaves dry weight, cell sap concentration and proline concentration and yield produced from infested or uninfested soils showed insignificant variation in comparison with 100 % W.H.C. At 60 and 40 % rates of W.H.C., noticeable increases in pink root incidence were found on plants inoculated with P. terrestris, and their yield was decreased. Cloves germination, plant height and leaves dry weight values were significantly reduced, whereas cell sap concentration and proline concentration values were significantly increased under water deficit of plants grown in uninfested soil comparing to the check. In this respect, 40% of W.H.C. highly affected the disease incidence and crop yield compared to the other tested rates.

Determination of the Early Ripeness of Potato Variety Samples by the Concentration of Cell Sap of Etiolated Tubers Sprout

The article presents the results of a comparative study of the concentration of cell sap in potato seedlings when evaluating for early ripeness with the methods of phenological observations and test digging of bushes.

Jasmonic acid alleviates cadmium toxicity in Arabidopsis via suppression of cadmium uptake and translocation.

Jasmonic acid (JA) is thought to be involved in plant responses to cadmium (Cd) stress, but the underlying molecular mechanisms are poorly understood. Here, we show that Cd treatment rapidly induces the expression of genes promoting endogenous JA synthesis, and subsequently increases the JA concentration in Arabidopsis roots. Furthermore, exogenous methyl jasmonate (MeJA) alleviates Cd-generated chlorosis of new leaves by decreasing the Cd concentration in root cell sap and shoot, and decreasing the expression of the AtIRT1, AtHMA2 and AtHMA4 genes promoting Cd uptake and long-distance translocation, respectively. In contrast, mutation of a key JA synthesis gene, AtAOS, greatly enhances the expression of AtIRT1, AtHMA2 and AtHMA4, increases Cd concentration in both roots and shoots, and confers increased sensitivity to Cd. Exogenous MeJA recovers the enhanced Cd-sensitivity of the ataos mutant, but not of atcoi1, a JA receptor mutant. In addition, exogenous MeJA reduces NO levels in Cd-stressed Arabidopsis root tips. Taken together, our results suggest that Cd-induced JA acts via the JA signaling pathway and its effects on NO levels to positively restrict Cd accumulation and alleviates Cd toxicity in Arabidopsis via suppression of the expression of genes promoting Cd uptake and long-distance translocation.

Measurement of the cell sap concentration of plant's leaves for irrigation's scheduling

The results of the investigations of the relationship between the Cell Sap Concentration (CSC) of leaves of tilled crops and their moisture availability are presented. The relationships between the CSC of leaves and the time of day, as well as patterns of changes in the CSC’s index in different parts of the leaf: in the handle, middle and tip, were investigated. Field experiments during 2010-2012 were carried out on the sugar beet, tomato and potato crops, which were grown under drip irrigation. The CSCs of leaves were determined by the digital refractometer Atago PAL-Alpha in 10 replications. It is established that between leaf’s CSC and soil moisture, there are reliable inverse correlation dependencies in all phases of plants growth, in particular, CSC of leaf tends to increase with decreasing of soil moisture. The correlation coefficients (r) and the error of the correlation coefficient (mr) are calculated. The dynamics of CSC’s changes during the day depended on the temperature and humidity of the surface air layers and did not depend on the type of culture and the phase of its development. The highest correlation between CSC and soil moisture was recorded in the morning hours: from 07:00 to 09:00, and then, during the day, it tended to decrease. The definition of CSC in different parts of the leaf showed that the minimum indices are typical for the petiole, and the highest was in samples taken from the leaf apex. This dependence was typical for all cultures regardless of the phase of their development. The change in the size of the CSC of the leaf, depending on the canopy level, had no regularities. For a more reliable determination of the CSC, samples must be taken from the middle of a leaf of one layer in the morning at one time; the replication of the determination is at least 5 samples.

The Water Regime of Black Saxaul in Various Environmental Conditions of the Central Asian Desert

A water regime, estimated based on transpiration rate, water content of shoots, concentration of cell sap, and water consumption per unit area, was studied for black saxaul. The seasonal course of black saxaul transpiration during the growing season increased by the middle of summer (July) and decreased towards autumn. The highest transpiration rate of black saxaul was found in Karnabchul, where ground waters poorly mineralized, located at a depth of 14–20 m in nonsaline soils. The lowest transpiration rate was detected in the Nishan “steppe,” where ground waters were also located at 14–20 m, however they were highly mineralized, and the soil profile was highly salinated. The Southwestern Kyzylkum, characterized by ground waters at a very deep location (more than 100 m) and low soil salinity, occupied an intermediate position in terms of transpiration rate. The maximal water consumption for transpiration during the vegetation period was observed in Karnabchulat 642.5 mm/ha, then in the Nishan “steppe” at 352.5. The minimal value was detected in the Southwestern Kyzylkum at 171.0.

Диагностика сроков полива Actinidia deliciosa во влажных субтропиках России

The study of the water regime of A. deliciosa under various drip irrigation regimes in humid subtrops allows to determine the petiole of leaf as indicator organ, in which the concentration of the cell sap is closely related to the moisture content of the root layer. The optimal watering regime was established to be 80% of the least moisture capacity and moisture content was established according the concentration of cell sap. An express method for diagnosing the irrigation period by concentration of the cell sap, which ensures the effi ciency and reliability of the optimization of the water regime of A. deliciosa has been elaborated.

Diagnostics of subtropical plants functional state by cluster analysis

The article presents an application example of statistical methods for data analysis on diagnosis of the adaptive capacity of subtropical plants varieties. We depicted selection indicators and basic physiological parameters that were defined as diagnostic. We used evaluation on a set of parameters of water regime, there are: determination of water deficit of the leaves, determining the fractional composition of water and detection parameters of the concentration of cell sap (CCS) (for tea culture flushes). These settings are characterized by high liability and high responsiveness to the effects of many abiotic factors that determined the particular care in the selection of plant material for analysis and consideration of the impact on sustainability. On the basis of the experimental data calculated the coefficients of pair correlation between climatic factors and used physiological indicators. The result was a selection of physiological and biochemical indicators proposed to assess the adaptability and included in the basis of methodical recommendations on diagnostics of the functional state of the studied cultures. Analysis of complex studies involving a large number of indicators is quite difficult, especially does not allow to quickly identify the similarity of new varieties for their adaptive responses to adverse factors, and, therefore, to set general requirements to conditions of cultivation. Use of cluster analysis suggests that in the analysis of only quantitative data; define a set of variables used to assess varieties (and the more sampling, the more accurate the clustering will happen), be sure to ascertain the measure of similarity (or difference) between objects. It is shown that the identification of diagnostic features, which are subjected to statistical processing, impact the accuracy of the varieties classification. Selection in result of the mono-clusters analysis (variety tea Kolhida; hazelnut Lombardsky red; variety kiwi Monty and Hydrangea forma rosea) shown as a helpful tool to detect drastically different varieties.

Overexpressing OsPIN2 enhances aluminium internalization by elevating vesicular trafficking in rice root apex.

Aluminium (Al) sequestration is required for internal detoxification of Al in plant cells. In this study, it was found that the rice OsPIN2 overexpression line (OX1) had significantly reduced Al content in its cell wall and increased Al concentration in cell sap only in rice root tips relative to the wild-type (WT). In comparison with WT, OX1 reduced morin staining of cytosolic Al, enhanced FM 4-64 staining of membrane vesicular trafficking in root tip sections (0-1mm), and showed morin-FM 4-64 fluorescence overlap. Recovery treatment showed that cell-wall-bound Al was internalized into vacuoles via endocytic vesicular trafficking after removal of external Al. In this process, OX1 showed a higher rate of Al internalization than WT. Brefeldin A (BFA) interfered with vesicular trafficking and resulted in inhibition of Al internalization. This inhibitory effect could be alleviated when BFA was washed out, and the process of alleviation was slower in the cells of WT than in those of OX1. Microscopic observations revealed that, upon Al exposure, numerous multilamellar endosomes were detected between the cell wall and plasma membrane in the cells of OX1. Moreover, more vesicles enriched with Al complexes accumulated in the cells of OX1 than in those of WT, and these vesicles transformed into larger structures in the cells of OX1. Taken together, the data indicate that endocytic vesicular trafficking might contribute to Al internalization, and that overexpressing OsPIN2 enhances rice Al tolerance via elevated endocytic vesicular trafficking and Al internalization.

ИСПОЛЬЗОВАНИЕ ФИЗИОЛОГО-БИОХИМИЧЕСКИХ МЕТОДОВ ДЛЯ ВЫЯВЛЕНИЯ МЕХАНИЗМОВ АДАПТАЦИИ СУБТРОПИЧЕСКИХ, ЮЖНЫХ ПЛОДОВЫХ И ДЕКОРАТИВНЫХ КУЛЬТУР В УСЛОВИЯХ СУБТРОПИКОВ РОССИИ

A problem of assessing the sustainability in crops, for which the humid subtropical zone of Russia is quite favorable, has a great value since there are a lot of stress factors (for example droughts, high or low temperatures, fogs etc.) due to climatic features of the region. For the first time we have carried out a 20-year comprehensive study of physiological and biochemical responses of plants, their organs, tissues and systems to the effect of abiotic stressors with the aim to identify some specific adaptation mechanisms of subtropical, southern fruit and ornamental crops as well as tea to the environment. This paper reports the peculiarities in water regime and photosynthetic apparatus (basic physiological functions), activity of catalase enzyme and carotenoid content (protective components in plants' oxidant-antioxidant system). As a result, there were selected some physiological and biochemical parameters (quantity of water scarcity, concentration of cell sap, catalase activity, carotenoids content, etc.), which allowed to estimate the crop state and resistance to abiotic stressors in Corylus pontica C. Koch, Prunus persica (L.) Batsch, Actinidia deliciosa Chevalier, Camellia sinensis (L.) Kuntze, beautifully-blossoming shrubs Hydrangea macrophylla Ser., Weigela ½ wagneri L.H. Bailey, etc. The regularities in changing physiological parameters as a response to the impact of adverse conditions are identified; the criteria, scales and methodology are proposed for assessing adaptive capacity of the studied cultures. Specific features of the dynamics of photosynthetic pigments accumulation for all the cultures are studied; the dependence of this process on the main regional factors was revealed; the parameters of water regime and drought resistance coefficients are determined; the influence of hydrothermal factors on enzyme activity is identified, as well as correlation between enzyme activity and abiotic environmental factors; the effect of microelements on increase of plants adaptive properties (for example, tea) was determined. As a result, there were developed some recommendations on micronutrients foliar feeding for young tea plantations and mature tea plants, as well as on the diagnostics of plants micronutrient requirements, on the application of sustainability indicators of tea plants to stress factors, and on evaluation of H. macrophylla Ser. drought resistance. The most adaptive cultivars of subtropical, southern fruit, ornamental crops and tea are identified and recommended for growing. They are characterized by increased resistance to stress factors in humid subtropics of Russia (for kiwi Monty cultivar, for filbert President cultivar originated by All-Russian Research Institute of Floriculture and Subtropical Crops; for peach Donetskii zheltii, Medin Red, Earley Red, Earley Blow, Larisa, Slavutich and Redhaven; for H. macrophylla Mariesii Perfecta, Draps Wonder и Madame Maurice Hamard. The data obtained relate to the fundamental physiological bases of adaptation to stress conditions, and in particular to plant adaptive features in specific conditions of Russian subtropics.

Water relations in rice seedlings in saline medium

We evaluated the seedling water content (SWC), leaf relative water content (LRWC), transpiration intensity (TI), and the cell sap concentration (CSC) in four rice varieties, differentiated by the degree of their salt tolerance. Pokkali and IR24 were tested for salt tolerance and MI 48 and Perla for susceptible behavior. Seedlings of four varieties were sown in nutrient solution under controlled laboratory conditions using Hoagland nutrient solution (control) and Hoagland nutrient solution enriched with NaCl (0.7%,). The pH was kept at 5.0. The SWC, LRWC, and TI were determined by gravimetric methods and the CSC by refractometry in five replications at 21 d after planting. The SWC, LRWC, and TI significantly diminished under salinity stress in all varieties (see table) because plants could not absorb adequate water. The TI was more pronounced than SWC or LRWC. Plants adjust their T1 as a defense mechanism to compensate for water loss.

Studies on the cell sap concentration determined by the refractometric method and some other physiological properties of mulberry leaves (II) On their changes according to the growth of the leaves

Studies on the cell sap concentration determined by the refractometric method and some other physiological properties of mulberry leaves (II) On their changes according to the growth of the leaves

Research note: Low-boron acclimation induces uptake of boric acid against a concentration gradient in root cells of Olea europaea.

Low concentrations of boron (B) in the external medium can induce uptake mechanisms whereby plants can develop a concentration gradient for B against the external medium. These mechanisms seem to be widespread among herbaceous species. In this study, olive (Olea europaea L.) plants were acclimated to either high (23 μm; controls) or low (0.5 μm; low-B plants) concentrations of B for 45 d, in a hydroponic culture. Afterwards, a 7-h uptake experiment was conducted by transferring plants of both groups to a series of nutrient solutions with B concentrations ranging from 0.5 to 23 μm. Analysis of B concentration in cell sap of root and xylem exudate was performed by the borate-chromotropic acid HPLC assay. Plants acclimated to high-B concentration showed root cell and xylem exudate B concentrations that were comparable to those of the external medium. In contrast, plants acclimated to low-B concentration were able to develop concentrations of B in root cells up to 2-fold higher than those of the external medium. Moreover, B concentrations in xylem exudate for both plant groups corresponded to those of the root cell sap, indicating diffusion equilibrium. These results support the existence of a mechanism that concentrates B in the root cell sap against the nutrient solution when olive plants are acclimated to low-B conditions.

Ammonium improves iron nutrition by decreasing leaf apoplastic pH of sunflower plants (Helianthus annuus L. cv. Frankasol)

The effect of nitrogen form on pH and concentration of soluble iron (Fe) in leaf apoplast was investigated in hydrophonically grown sunflower plants (Helianthus annuus L. cv. Frankasol), and the mechanism underlying the improved Fe nutrition by ammonium (NH4) supply was also elucidated. Ammonium supply ameliorated Fe nutrition of plants grown without Fe through decreasing apoplastic pH and increasing soluble Fe concentration in apoplastic fluid of young leaves. The soluble Fe concentration in apoplastic fluid and cell sap of young leaves, and xylem exudates of NH4 fed-plants was higher than that of nitrate (NO3) fed-plants, and no typical Fe-deficiency chlorosis in young leaves was observed in NH4, fed plant without Fe supply. The apoplastic pH was 6.15 and 5.94 in young leaves of Fe-deficient plants fed respectively with NO3 and NH4, while in Fe-sufficient plants, the apoplastic pH was 6.43 with NO3, and 5.50 with NH4 supply. In primary leaves, the apoplastic pH was around 6.25 irrespective of nitrogen form and Fe supply. The pH of xylem exudate was 5.72 in Fe-deficient plants fed with NO3 and 5.49 with NH4. Iron nutrition increased the pH of xylem exudate by 0.27 and 0.16 unit under NO3 and NH4 supply respectively.

Osmotic Adjustment and Root Growth Associated with Drought Preconditioning‐Enhanced Heat Tolerance in Kentucky Bluegrass

Prior exposure to drought stress (drought preconditioning) affects turfgrass tolerance to subsequent heat stress. The study was designed to examine whether these effects for Kentucky bluegrass (Poa pratensis L.) are associated with osmotic adjustment and root growth. Plants were subjected to two cycles of drying and rewatering, and turf quality was then allowed to recover to the well watered control level before being exposed to 21 d of heat stress (35°C/30°C) in growth chambers. Compared with nonpreconditioned plants, drought‐preconditioned plants had 13 and 21% higher turf quality, 6 and 10% higher leaf relative water content, and 17 and 48% higher osmotic adjustment at 14 and 21 d of heat stress, respectively. Total ion (K+, Ca2+, Na+, Ma2+, Cl−, and P) concentration of cell sap increased during heat stress and was 11 to 16% higher in drought‐preconditioned plants than nonpreconditioned plants. The concentration of K+ accounted for 59 to 65% of total ion solutes in both groups of plants during heat stress. Soluble carbohydrate content (WSC) of leaves increased during heat stress and was about 21 and 44% higher in drought‐preconditioned plants than nonpreconditioned plants at 14 and 21 d, respectively. Heat stress decreased root dry weight (DW) and WSC, but significant higher DW and WSC content of roots in the 40–60 cm soil layer were observed for preconditioned plants than nonpreconditioned plants before and after heat stress. The results demonstrated that drought preconditioning enhanced heat tolerance in Kentucky bluegrass, which could be related to the maintenance of higher osmotic adjustment associated with accumulation of ion solutes and water soluble carbohydrates and development of extensive roots deeper in the soil profile.

Effects of boron starvation on boron compartmentation, and possibly hormone‐mediated elongation growth and apical dominance of pea (Pisum sativum) plants

Two experiments were carried out to study the effects of boron (B) deficiency on 7‐day‐old pea plants for 6 or 9 days under controlled growth chamber conditions. Growth and apical dominance (AD) of the plants and their B concentration and compartmentation were followed throughout the starvation period. Additionally, auxin (indoleacetic acid, IAA) concentration in the shoot apex and polar transport from it were measured along with the cytokinin (CK) concentration in the shoot apex and the roots. The results demonstrate that during a 6‐day B‐deficiency period, B concentration in the water‐insoluble residue of the roots was very stable and could not easily be reduced. In contrast, B concentration in the cell sap fraction was very sensitive to external B supply. Twelve hours after transferring the plants from B‐sufficient to B‐deficient solutions, the B concentration in root cell sap declined to half the concentration of the control plants. In addition, B concentration in the new aerial plant parts, which developed after the onset of the B‐deficiency treatment, was extremely low. A decline in elongation growth could be observed as soon as about 4 days after the imposition of B deficiency. This preceded the first measurable growth of lateral buds (release from AD). Before the onset of these morphological changes, there was a considerable decline in CK concentration, accompanied by a dramatic decrease in IAA export out of the shoot apex, a decline in IAA concentration in the shoot apex and the roots and a reduced capacity for polar IAA‐transport. These changes are discussed as possible reasons for the observed reduction in elongation growth and AD. These hormonal changes themselves are possibly the result of the decreased symplasmic B concentration, which in turn may be responsible for the reduced concentration in apical CKs. A sequence of events, which may be causally related, is suggested to explain the effects of B deficiency on the growth and AD of pea plants.

Effect of Elevated Medium Sucrose Levels on Cold Hardiness of `Festival' Red Raspberry in Vitro

Low tissue-water content and increased osmotic concentration of cell sap are associated with frost resistance. Changes in total osmotic concentration of cell sap are due mainly to changes in concentration of sugars. Generally, sugar content increases with hardening and decreases with dehardening. This study examined the effect of elevated sucrose levels (3% to 15%) in the medium on the cold hardiness of `Festival' red raspberry (Rubus idaeus L.) shoots in vitro. To determine whether expected hardening is caused by elevated sucrose levels or by osmotic stress, different levels of mannitol in the media have been tested. After growing raspberry shoots on media with different levels of sucrose and mannitol for 2 weeks, shoot moisture content (percent) was determined. Cold hardiness of the shoots was determined by using differential thermal analysis or artificially freezing the shoots and assessing the survival by regrowth test and visual rating.