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1.
Influence of high temperature stress on photosynthesis and allocation of carbon into different biochemical fractions in mature leaves of Indian mustard [ Brassica juncea (L) Czern] was investigated. Heat stress reduced 14CO2 fixation and inhibited the translocation of carbon from the leaves. Allocation of 14C into starch and residue fractions was significantly lower in heat stressed plant leaves. Starch content was significantly reduced in heat stressed plants.  相似文献   

2.
Spatio-temporal differences under short-term NaCl-salinity (0, 50, 100, 150 m m l−1) stress for 24 h and post-NaCl recovery after 24 h on the growth, water relations, ionic composition, proline and antioxidants of 12-day-old roots, stem and leaves of Vigna radiata were observed. Fresh and dry weight, relative water content and K+ ion decreased, whereas, Na+ ion and Na+/K+ ratio increased significantly in roots, stem and leaves. Post-NaCl recovered roots, stem and leaves showed similar results with lower values. Chlorophyll and carotenoid pigments decreased significantly in the leaves. Peroxide and lipid peroxidation level increased significantly with higher ratio in stressed compared to recovered leaves. Ascorbate and proline content increased significantly with no significant change in glutathione content in stressed roots, stem and leaves. Significant decrease in protein content, SOD, CAT, POX, APX and GR activities was observed in roots with no significant change in stem and leaves. The recovered parts showed similar results except increased POX and GR activities showing a tissue-specific response to NaCl-salinity stress. Improved tolerance to salt stress may be accomplished by increased capacity of antioxidative defence system and by lower level of lipid peroxidation and improvement in the plant water status, activities of some of the antioxidants in the recovered parts suggest that significant tissue differences in response to salt stress in V. radiata is closely related to differences in the activities of antioxidants, ion and proline content.  相似文献   

3.
Evaluation of commonly grown cotton (Gossypium hir-sutum L.) genotypes under saline environment may help to cope with the venture of the crop failure in salt-affected soils. In a pot experiment, four cotton genotypes (MNH-93, NIAB-78. S-12, and B-557) were grown to compare their relative performance on a sandy clay loam soil (original ECe = 1.9 dS m−1) salinized with a salt mixture (Na2SO4, NaCl, CaCl2, MgSO4 in the ratio of 9:5:5:1 on equivalent basis) to EQ levels of 10 and 20 dS m−1. The crop was raised to the flower initiation stage. The imposed salinity stress exhibited deleterious effect on the germination and vegetative growth with significant differences among the genotypes. Leaf area, stem thickness, shoot (stem + leaves) and root weights decreased with the increase in substrate salinity. NIAB-78 showed the least decline followed by MNH-93. Leaf thickness showed an opposite trend as an increase in this parameter was observed with the rising salinity, the maximum increase being in the case of NIAB-78. Analysis of the leaf sap showed increased Na+ and Cl− concentrations and decreased K+ concentration with the increase in substrate salinity. A better osmotic adjustment, a lower Na+/K+ ratio and a lower Cl concentration were found in the leaves of NIAB-78 followed by MNH-93. This contributed towards their better growth performance under saline conditions.  相似文献   

4.
Seedlings of a maize hybrid sensitive to chilling initially grew in the growth chamber of the phytotron at 20/ 17°C (day/night) and after the formation of the fourth leaf, the soil temperature was lowered to 5°C. Under such growth conditions the dynamics of dry weight change, gas exchange and the distribution of 14C-assimilates in seedlings were examined. The low soil temperature inhibited daily growth of dry weight of whole seedlings more than their photosynthesis. Simultaneously, it was also responsible for a greater increase in dissimilative losses.
During 37 hours (day-night-day), following exposure to 14CO2, dissimilation in seedlings in cool soil (5°C) and in non-chilling conditions amounted to 35.1 % and 23.4 % of assimilated 14C (AC), respectively. At lower soil temperature relatively high dissimilative losses were observed on the first day after exposure (23.5 %), lower at night (9.9 %) and the lowest on the following day - merely 1.7 % AC. Higher losses of 14C under chilling conditions occurring on the first day were a result of limited photosynthetic refixation of 14CO2 At night, however, they were associated with a prolonged period of intensive translocation of assimilates to the stem. It was assumed that an excessive accumulation of assimilates in leaf blades might be an additional factor responsible for increased dissimilative losses at low temperature during the first twenty-four hours. In the third period of measurements, as a result of a limited transport of 14C, dissimilative losses were lower than in previous ones and were not dependent upon soil temperature.  相似文献   

5.
Interactive effect of NaCl salinity and putrescine on shoot growth, ion (Na+, K+ and CI−) concentration in leaf, stem and inflorescence and yield of rice (Oryza sativa L. var. GR-3) were studied. When rice plants were subjected to salt stress (12 dS/m) the extension growth and dry weight of shoot system as well as total leaf area and chlorophyll content were found markedly reduced. Analysis of leaf, stem and inflorescence of salt-stressed plants showed higher concentration of Na+ and Cl ions and lower concentration of K+ ion compared to the control. Salinization also caused a considerable fall in grain yield.
Foliar application of putrescine (10−5M) significantly increased the growth and yield of salt-stressed plants. Putrescine treatment decreased the influx of Na+ and Cl− ions and increased the K+ level in all the tissues of salinized plants examined. Putrescine also increased the chlorophyll content in salt-stressed plants. These results suggest that exogenous application of putrescine can be used successfully to ameliorate the stress injuries caused by NaCl salinity in rice plants to a considerable extent.  相似文献   

6.
Cowpea ( Vigna unguiculata L. Walp) is an important food legume grown under rainfed conditions in the tropics. However, the yield of this crop varies widely in most tropical ecosystems due to crop and environmental factors. Experiments were carried out to evaluate the effects of seed characteristics, soil moisture at planting and the season of crop establishment on growth and yield parameters of cowpea as these influence the productivity of the crop. Growth and yield of cowpea plants grown from small seeds with a high conductivity of their lea-chates were significantly lower than those grown from large seeds. Root growth of seedlings was most prominent under moderate soil moisture levels. Low soil moisture retarded root growth by reducing dry weights and suppressing the development of laterals. Shoot growth was more sensitive to increasing soil moisture stress than root growth. Planting cowpea in the wet season produced the highest yields. Within a season, growth and yield were higher when the crop was planted early. Establishment of the crop later in the season produced better quality seeds measured in terms of germination after controlled deterioration.  相似文献   

7.
Productivity of maize ( Zea mays L.) legume intercrops is determined by soil, management, and environment. Planting sequence and time and N fertilization are easily controlled management factors but their effects on intercrop yields are not well understood. Maize grown in monoculture or intercropped with polebean ( Phaseolus vulgaris L.) or cowpea ( Vigna unguiculata [L.] Warp.) was studied for two growing seasons at Morgantown, WV. Crops were seeded in the following sequences: maize before legume, both at the same time, and legume before maize. Planting times were early May or mid June. Nitrogen was applied at 0 or 160 kg ha−1. Maize grain and forage, legume grain and forage, and total forage production were determined on a dry matter basis. Intercropping (average of all treatments) reduced maize grain and forage yields compared to maize in monoculture but had no effect on total forage production. However, total forage production was greatest when the seeding sequence was maize intercropped at the same time or before cowpea. Cowpea never produced grain, but forage production was almost double that of polebean. Maize produced most forage when seeded before the legumes, and the legumes produced most forage when seeded before maize. Early planting increased maize production and decreased legume production. Nitrogen increased maize grain, maize forage, and total forage yields but had not effect on legume forage production. It is concluded that maize/legume intercrops show promise for increasing forage production in temperate areas and more research on planting times and densities, weed control, harvesting and management is needed.  相似文献   

8.
NaCl-resistant (selected at 300 mM NaCl) and non-selected cell lines of Vigna radiata were compared for growth, various ions and metabolites at weekly intervals up to 28 days of culture in the presence or absence of NaCl (0–300 mM). The sale-resistant line grew significantly better than the non-selected line at NaCl concentrations higher than 50 mM. The resistant line accumulated significantly more Na+ and maintained higher levels of K+ under NaCl stress than the non-selected line. Both lines accumulated various metabolites, e.g. protein, proline and soluble amino-nitrogen under stress, but this accumulation was greater in the non-selected line than in the resistant one. On the other hand, total content of reducing sugars and sucrose (soluble sugars) was significantly higher in the latter than the former. Moreover, the concentration of soluble sugars in resistant calli was much higher than the other intracellular metabolites. Thus, sugars and ions are likely the major osmoregulants in the resistant line of V. radiata under salt stress.  相似文献   

9.
Excised ears of Triticum durum (HD 4502 and B 449) and T. aestivum (Kalyansona and Kundan) varieties were cultured in 14C-sucrose, and the uptake and distribution of 14C within the ear was examined. Species-level differences in the distribution of 14C to spikelets at basal, middle and apical positions in the wheat ear (vertical distribution) were observed. T. aestivum var. Kalyansona and Kundan showed no limitation in vertical translocation of 14C-sucrose, whereas in T. durum there was a decrease in the distribution of 14C to apical spikelets. Within a spikelet, the distribution of 14C-sucrose to distal grains was significantly less than that to proximal grains in all the genotypes.  相似文献   

10.
15N-aided investigations were conducted to ascertain the Nj fixation and the nitrogen (N) contribution by mungbean ( Vigna radiata L.) and groundnut ( Aracbis hypogaea L.) when intercropped with maize ( Zea mays ). The study involved growing seven genotypes of the above legumes with maize in alternate rows in two separate experiments. A sole crop of maize was used as the reference crop to determine N2 fixation by the 15N methodology. Significant genotypic differences in pod yield and stover N content were observed in intercropped mungbean and groundnut. The percentage N derived from the atmosphere showed a genotypic variation of 31 to 45 % (7 to 10 kg N2 fixed ha−1O in mungbean and 47 to 69 % (9 to 18 kg N2 fixed ha−1) in groundnut. Harvest index for N varied from 58 to 77 % in mungbean and 55 to 75 % in groundnut. In groundnut, the uptake of soil N was significantly affected by the genotype. Assuming that the N contribution to the soil by the helow-ground plant parts was negligible, the removal of seeds at maturity resulted in a negative N balance in the soil in all the genotypes of mungbean. In groundnut, some genotypes produced a positive N balance in the soil. Owing to high N2 fixation capacity and low harvest index for N, groundnut showed a greater N supplementing ability than mungbean.  相似文献   

11.
Effect of heat stress on 14CO2 assimilation and translocation by different parts was investigated in Indian mustard ( Brassica juncea (L.) Czern.]. Heat stress reduced 14CO2 assimilation by leaves, stem and pods. Export of radioactive carbon from upper and lower leaves, upper and lower stem and stem of terminal raceme was inhibited in response to heat stress. Import of 14C-photosynthates into pods was also inhibited by heat stress indicating reduction in sink strength of the developing pods.  相似文献   

12.
Rice ( Oryza sativa cv. Koshihikari) seedlings were grown in a sandy dune soil in pots with a basal dressing of N (0.5 g N), P and K. Two N treatments were applied, a +N treatment in which a top dressing of 15N-labeled 0.5 g N was supplied on July 20 and a −N treatment in which no additional fertilizer was supplied. During the grain-filling stage from August 6 to 13, plants were subjected to one of three temperature treatments; controlled low temperature, LT (day/night 28/23 °C), controlled high temperature, HT (35/30 °C) and uncontrolled glasshouse temperature, UT (day/night averages, 38/26 °C). All plants were then exposed to 13CO2 for 1 h on August 11 in a growth chamber at 25 °C. On August 13, all plants were harvested and the 13C and 15N abundances and starch and sugar concentrations in the ears, shoots and roots were determined. The 13C content of the ear was lower in UT than in LT irrespective of the +N or −N treatment. The translocation of 15N to the ears was also slightly depressed in UT compared with LT. Under high-temperature conditions (HT and UT), the starch content per plant was reduced for −N, but for +N, it was not significantly different among the temperature treatments. A high accumulation of sucrose was observed in all plant parts under UT conditions. It is suggested that extreme high day temperatures during the grain-filling period may reduce starch synthesis in the grains and, especially so under N-deficient conditions. High temperatures also induce an accumulation of sucrose and a decrease in carbon and nitrogen transport from the shoots to the ears via the phloem.  相似文献   

13.
The effects of exposure in the vegetative phase of growth to 5- or 10-day spells of soil drought (30% field water capacity) on assimilation, dissimilation and accumulation of 14C and on dry matter growth were studied in two maize hybrids, nos. 8344 and 8388 (Garst Seed Co.) of high and low drought tolerance. Under control water regime in soil there was no difference in 14CO2 uptake and dry matter growth between hybrids. After five days of drought 14CO2 assimilation dropped by about 75% referred to unit weight of dry matter in hybrid 8344 and by 56% in hybrid 8388. After 10 days of drought 14CO2 assimilation rate was reduced by 75% in both hybrids. Soil drought increased the 14C dissimilation. There were no significant differences between hybrids in all treatments, with the exception of 5 days drought; after this treatment the dissimilation rate of hybrid 8344 was higher than that of 8388. Changes of translocation of 14C and its accumulation in particular organs occurred in drought treated plants; the amount of 14C accumulated in roots of plants of hybrid 8344 increased, while that of hybrid 8388 decreased. Changes of 14C accumulation in roots were positively correlated to changes of dry matter of those organs. One day after 10 days of drought assimilation and dissimilation rates in both hybrids were about 60% of controls.  相似文献   

14.
Four bread wheat cultivars were studied at two salinity levels. Tobari 66 had the lowest uptake of Na+ and Cl−, and the highest K+/Na+ ratio; Pato had the highest uptake of these ions and Lyallpur 73 was intermediate. Intervarietal differences were greater at higher salinity, suggesting that they were not caused by variation at the Kna1 locus. There were significant differences between inbred lines for Na+, particularly in Blue Silver, suggesting the possibility of selecting genotypes with enhanced tolerance from within existing cultivars. Pato, Tobari 66 and their reciprocal F1 hybrids were further evaluated at four salinity levels. The hybrids exhibited similar relative grain yield to Tobari, with better Na+ and Cl− exclusion and higher K+/Na+ ratios than Pato. Overall, Tobari had the highest absolute yield under salinity, and the hybrids were closer to Tobari than to Pato. Tiller and grain numbers, 100-grain weight and yield were more affected by salinity than were height, spike length and spikelet number. We conclude that intervarietal variation for salt tolerance in wheat is controlled by genes which could be transferred to sensitive genotypes to improve their tolerance, and that the K+/Na+ ratio of the youngest leaf could be used to screen for salt tolerance.  相似文献   

15.
Soil salinity is a major abiotic stress which adversely affects the yield and juice quality in sugarcane. However, the mineral nutrient status of plant plays a crucial role in increasing plant tolerance to salinity. We investigated the effects of K and/or Si on plant growth, yield and juice quality in two sugarcane genotypes differing in salinity tolerance. Addition of K and Si significantly (P ≤ 0.05) increased K and Si concentrations and decreased the accumulation of Na+ in plants under salt stress. Cane yield and yield attributes were significantly (P ≤ 0.05) higher where K and Si were added. Juice quality characteristics like Brix (% soluble solids in juice), Pol (% sucrose in juice), commercial cane sugar (CCS) and sugar recovery in both sugarcane genotypes were also significantly (P ≤ 0.05) improved with the supplementation of K and Si. For most of the growth parameters, it was found that K either alone or in combination with Si was more effective to alleviate salt stress in both sugarcane genotypes than Si alone. Moreover, the beneficial effects of K and Si were more pronounced in salt sensitive genotype than in salt tolerant genotype. The results suggested that K and Si counteracted the deleterious effects of high salinity/sodicity in sugarcane by lowering the accumulation of Na+ and increase in K+ concentration with a resultant improvement in K+/Na+ ratio which is a good indicator to assess plant tolerance to salinity.  相似文献   

16.
Field bean planes cultivar Nadwiślański were submitted to soil drought (30 % of field soil water capacity) for 5 days at the stage of pod formation (A) and of rapid pod growth (B) and then exposed for 20 minutes to 14CO2. Radioactivity of leaves, stems, roots, and pods or pod shells and seeds was measured 1, 5, 24 and 48 hours after exposition.
In both stages soil drought reduced by about five times total CO2 assimilation, mainly owing to lower activity of the photosynthetic apparatus and also, though less so, to reduced leaf growth. Photosynthetic activity referred to the dry weight of the leaves dropped to 22-35% of controls. Accumulation of photosynthetates in generative organs was much less depressed than 14CO2 assimilation. 48 hours after exposition to 14CO2 of drought treated plants, the contents of 14C of pods in phase A, and seeds in phase B, amounted to respectively 24% and 36% of assimilated 14C and equalled 91.5% and 74% of the corresponding values for controls.
The progressive decline of radioactivity in leaves and stems after 14CO2 exposition was distinctly correlated to the rise of radioactivity of generative organs both in soil drought treated plants and in controls. Slightly lower values of correlation coefficients in drought treated plants may indicate impairment under drought conditions of synchronization in processes of unloading and accumulation of assimilates.
In plants drought treated in phase A the ability to dissimilate 14C was reduced to about 59% of that in controls, but when drought was applied in phase B, dissimilation rate was about three times as high.  相似文献   

17.
Accumulation of assimilates in stem-rust-infected wheat leaves
Using wheat plants (cv. 'Prelude'), the effects of stem-rust infection on photosynthesis and assimilate partitioning were studied with the aid of the short-lived carbon isotope 11C. Photosynthesis of strongly infected leaf parts declined by about 30 % within 1 day. This rapid inhibition was caused by the formation of appressoria and the growth of infection tubes into the stomata, leading to a reduction in gas exchange. Further decline of photosynthesis to 5–10 % was accompanied by the degradation of chlorophyll. Nevertheless, during sporulation, the dry weight of the infected leaf area increased by about 50 %. With the use of 11C, the reduced export of photosynthate from the infected leaf part and the capture of labelled compounds from the apical leaf section were quantified. The enhanced storage of assimilates in stem-rust-infected leaves can be attributed to the increase in invertase activity.  相似文献   

18.
In a soil lacking indigenous Bradyrhizobium japonicum , soybean ( Glycine max [L.] Merr.) nodulation depends upon the number of rhizobia applied with the inoculum. This field study reports the effect of different rates of applied rhizobia on nodulation, dry matter and nitrogen content in soybean in a Mediterranean soil lacking B. japonicum.
Treatments included six rates of B. japonicum , ranging from 2.5 × 104 to 6.075 × 106 rhizobia cells per seed applied to the seed as peat inoculant at planting, 100 kg N ha−1 and an uninoculated control. The experiment was conducted in an Entisol soil. Regression analysis showed linear relationship between the rate of applied rhizobia and the number of the nodules per plant or the dry weight per nodule. In early stages of development (32 and 68 days after planting) plant dry weight was not affected by inoculation rate. At harvest a rate of 7.5 × 104 rhizobia cells per seed was necessary for maximum total and stover dry weight. A higher rate, 6.75 × 105 rhizobia cells per seed, was required to obtain maximum grain yield, total N content in plant tops and grain N content. Grain percentage N was increased up to 2.025 × 106 rhizobia cells per seed. Nitrogen application increased grain yield, total N content and grain N content at the same level as the lower inoculation rate.  相似文献   

19.
Investigations about the distribution of assimilates during flowering in broad beans ( Vicia faba L.)
The distribution of assimilates during flowering was studied on single plants exposed to 14CO2 in the field. The plants were harvested 1, 3, 15 days after exposition and at ripening. Results:
1. At the begin of flowering the nodes with flowers assimilated much 14C with a tendency of higher contents in the more above situated nodes. The concentration of 14C was similar in blades, stalks and flowers.
2. The assimilates incorporated after 24 hours were only to a small amount translocated afterwards. Only 3 % went to the apical region. An intensive restorement out of the blades took place at the time of ripening.
3. In the midst of flowering the concentration of 14C was lower in the nodes with open flowers than in those with shut or with pods. At that time pods are already strong sinks that withdraw assimilates from blades and stalks.
4. At the time when large and small pods are growing on the lower and middle nodes, the nodes in the apical region will be deprived of assimilates (effects of dominance).
5. Roots and nodules had low but stable contents and concentrations of 14C during flowering. These descended distinctly at ripening.  相似文献   

20.
When one of the crops is a legume, intercropping has potential to reduce fertilizer nitrogen (N) needs and increase food quality. Total dry matter (DM) and grain yields of different plant populations of intercropped maize ( Zea mays L.) and climbing beans ( Phaseolus vulgaris L.), cowpeas ( Vigna unguiculata [L.] Walp.), or velvet beans ( Mucuna pruriens [L.] DC. var utilis [Wight] Bruck.) were compared in two experiments. Maize populations were 40,400 and 50,500 plants ha−1 in combination with climbing bean populations of 0, 20,200, 40,400 and 80,800 plants ha−1 in Experiment 1. In the second experiment, climbing beans, cowpeas and velvet beans at 215,200 plants ha−1 were intercropped with maize at 64,600 plants ha−1. Climbing beans contributed up to 5% to total DM yields in the first experiment. In the second experiment legume contributions to total DM were 20% for climbing beans, 12% for cowpeas and 8% for velvet beans. Increasing populations of maize and climbing beans increased grain and DM yields. Dry matter yield of maize was lowered by intercropping. However, DM yields of the intercrop were not different to maize sole cropped. Maize/cowpeas produced more total DM than maize/climbing beans. Cowpeas increased the total yield of crude protein by over 15% without lowering total DM yield of the intercrop compared to maize alone and are promising as a legume for intercropping with maize. Climbing beans show little promise as a possible legume for intercropping with maize.  相似文献   

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