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101.
Summary Pectic strands are shown to connect the lower stomatal ledges and to develop across the posterior chamber of a number of plant species. Similar strands are formed between guard cells and subsidiary cells, and between epidermal cells. 相似文献
102.
Summary Dry-matter accumulation, and concentration and uptake of nitrogen increased with increasing level of nitrogen at all the stages of crop growth. The differences in nitrogen concentration due to nitrogen levels were greatest at panicle initiation stage and started becoming narrower with the advancement in crop age. Split application of nitrogen with its heavier fractions at tillering and panicle initiation stages either through soil alone or soil+foliage (1/3+1/3+1/3) resulted in higher dry-matter accumulation, and higher nitrogen concentration and uptake than other methods. The crop, on an average, removed 61 kg N/ha. Plants accumulated nearly 15% of the total absorbed nitrogen, up to tillering, 50% up to panicle initiation and 85–90% up to heading. Proportionately lesser nitrogen uptake and dry-matter accumulation at post-heading stage is an indicative of a major constraint for production efficiency of rainfed-upland rice culture. 相似文献
103.
Summary In order to explore interrelations between S nutrition, soluble sugars, leaf area, nodulation and N2 fixation, greenhouse experiments were done with several levels of S added to perlite-sand cultures or to a moderately S-deficient soil. Sulfur had indirect effects on nodulation and N2 fixation, possibly by improving sugars supply and N metabolism.In perlite-sand culture, leaf area increased with concentrations of supplied S up to 50 and 200 M for symbiotic and N-treated plants respectively, then decreased at higher concentrations. Plant yield and total sugars content (mg per plant) for the N-treated plants behaved similar to leaf area in response to added S but in the symbiotic plants maximum values were obtained at 100 M S. In soil, Mo had no effect on growth but interacted significantly with S in affecting total sugars content. High levels of S depressed sugars content at low Mo but raised it at high Mo.Sulfur increased the N content of soil-grown plants. It increased the N content of plants grown in perlite-sand culture except at very high levels of S. There was little effect on concentration of N in the shoots. Nitrogen content correlated significantly with leaf area and sugar content, and highly significantly with S concentration in the shoots. 相似文献
104.
Summary Inclusion of sucrose in the solution applied to soybean (Glycine max L. merr.) leaves much reduced the severity of the damage to the leaves from application of urea and, to a lesser extent, from application of phosphorus (P) as orthophosphoric acid. Sucrose had no evident effect on P absorption. Damage to the leaves from joint application of orthophosphoric acid and urea exceeded the sum of the damage caused by the substances individually. Urea did not seem to influence P absorption, but the effect, if any, was not readily determined because nearly all values for P absorption exceeded 90%.Neutralization of orthophosphoric acid with nitrogen-containing organic bases, including choline, guanidine, and guanyl urea, did not prove useful as a technique for increasing the quantity of orthophosphate that could be applied without damage to the leaves.Absorption and translocation of orthophosphate by corn (Zea mays L.) and soybean leaves were not influenced by the pH of the solution within the range from 2 to 10. Absorption of tripolyphosphate by corn leaves decreased with an increase in pH of the solution applied, but translocation of the absorbed P was not influenced by pH. With soybeans, absorption of tripolyphosphate decreased with an increase in pH of the solution. Translocation of P applied to soybean leaves as tripolyphosphate was less than 5% of the amount absorbed within the first 24 hr and decreased with an increase in pH after 10 days. 相似文献
105.
By ammonium sulfate fractionation and gel filtration an enzyme preparation which catalyzed NAD+-dependent L-lactate oxidation (10-4 kat kg-1 protein), as well as NADH-dependent pyruvate reduction (10-3 kat kg-1 protein), was obtained from leaves of Capsella bursa-pastoris. This lactate dehydrogenase activity was not due to an unspecific activity of either glycolate oxidase, glycolate dehydrogenase, hydroxypyruvate reductase, alcohol dehydrogenase, or a malate oxidizing enzyme. These enzymes could be separated from the protein displaying lactate dehydrogenase activity by gel filtration and electrophoresis and distinguished from it by their known properties. The enzyme under consideration does not oxidize D-lactate, and reduces pyruvate to L-lactate (the configuration of which was determined using highly specific animal L-lactate dehydrogenase). Based on these results the studied Capsella leaf enzyme is classified as L-lactate dehydrogenase (EC 1.1.1.27). It has a Km value of 0.25 mmol l-1 (pH 7.0, 0.3 mmol l-1 NADH) for pyruvate and of 13 mmol l-1 (pH 7.8, 3 mmol l-1 NAD+) for L-lactate. Lactate dehydrogenase activity was also detected in the leaves of several other plants.Abbreviation FMN
flavin adenine mononucleotide 相似文献
106.
Leaf tissues of Zea mays were examined with a transmission electron microscope and a high-voltage electron microscope. Tubular extensions (invaginations) of the plasmalemma were found in vascular parenchyma cells and thick-walled, lateformed sieve elements of intermediate and small veins, and in epidermal, mesophyll, and sheath cells of all leaves examined. No continuity seems to exist between the tubules and other cellular membranes. 相似文献
107.
The period length of the leaf movement rhythm of Trifolium repens L. is lengthened by continuously offered cAMP (0.5–1.0 mol m-3) and theophylline (0.5–4 mol m-3). At the higher concentrations this effect is more pronounced and the rhythm damps out faster. Imidazole (0.5 and 1 mol m-3) has no effect on the period length; however, after 5 mol m-3 the rhythm is abolished. Offered as 4 h pulses the resulting phase response curves for cAMP and imidazole are similar and show delays of up to 4 h during the day position of the leaves. Theophylline pulses lead to delays of up to 5 h during closure and advances of up to 3 h during opening. No phase shift is brought about by 4-(3,4-dimethoxybenzyl)-2-imidazolidone. The results do not support the cAMP-model of the circadian clock which has been proposed by Cummings (J. theor. Biol. 55, 455–470; 1975). The effect of the substances tested could, however, be based upon influences on the transport of Ca2+.Abbreviations ATP
adenosine triphosphate
- cAMP
cyclic adenosine 35 monophosphate
- AMP
adenosine 5 monophosphate
- AC
adenyl cyclase
- PDE
phosphodiesterase
- LL
continuous light 相似文献
108.
Ryoko Imaichi 《Journal of plant research》1983,96(3):159-170
The third petiolar bud ofHypolepis punctata appears on the basiscopic lateral side of the petiole above the fairly developed first petiolar bud. This investigation clarified
the fact that the third bud is formed neither by the activity of the meristem of the first bud nor by the meristem directly
detached from the shoot apical meristem, but is initiated in the cells involved in the abaxial basal part of the elevated
portion of the leaf primordium. Thus the third bud is of phyllogenous origin. This investigation further revealed that the
cells to initiate the third bud are originally located in the abaxial side of the leaf apical cell complex like the cells
to initiate the first bud, but are not incorporated into the meristem of the first.
After the first, second and third petiolar buds have been initiated, they are carried up into fairly high regions on the petiolar
base by the intercalary growth which occurs in the leaf base below the insertion level of the first and the second buds. 相似文献
109.
水生植物叶片的功能性状特征与陆生植物有所不同,同时叶脉类型也显著影响叶片的功能性状。本研究选取9种具有不同叶脉类型的水生植物,通过对叶脉进行直接损伤,分析叶片性状(形态、色素含量和叶绿素荧光指标)在叶脉受损后的变化程度与叶脉类型的关系。结果显示:具有平行脉的3种水生植物对叶脉损伤具有较强的耐受性;具羽状脉的4种植物主脉受损后显著抑制叶片生长,而侧脉受损的影响在不同物种间有所不同,具有物种特异性。本研究可为大型湖泊水生植物修复的水生物种筛选提供参考。 相似文献
110.