Nitrogen-deficient Soils Research Articles

Effect of nitrogen and cobalt application on herbage and seed yields of serradella and subterranean clover

The response of serradella and subterranean clover to soil applications of cobalt in the absence and presence of regular applications of nitrogen fertilizer was measured in a field experiment on a nitrogen-deficient soil near Esperance, Western Australia. In an ancillary experiment, also sited near Esperance on a nitrogen-deficient soil, the responses of three serradella species and two cultivars of subterranean clover to regular applications of nitrogen were measured. Yields of herbage and seed were used to measure the response to the fertilizer treatments. Neither serradella, nor subterranean clover responded to cobalt application. However, in winter, herbage yields of serradella were markedly improved by regular applications of fertilizer nitrogen. Yield increases were three- to eight-fold, depending on the species. However, by springtime, there was no herbage response of serradella to fertilizer nitrogen. Seed yields of serradella and yields of subterranean clover at any harvest were unaffected by regular applications of nitrogen. It is concluded that low winter temperatures limit the rate of symbiotic nitrogen fixation for serradella which in turn limits dry matter production.

Aphids and Plant Fitness: 1984

Virtually all studies of effect of aphids on plant growth involve cultivated varieties of plants growing in unnatural assemblages. Choudhury's report is no exception as he chooses cultivated pea, Pisum sativum, which also happens to fix its own nitrogen and is therefore unlikely to benefit from a sugar input which, according to our hypothesis, stimulates nitrogen fixation by free-living soil bacteria. Choudhury's experiment is a good one in that he measures production of flowers and seeds rather than production of leaves, but like others (e.g. Dyer 1980, Petelle 1980) he uses wrong plant in wrong situation. What is required is an analysis of effect of a natural plant-feeder on a naturally growing plant. Only in this situation will it be possible to demonstrate presence or absence of mutualistic co-evolution. What then, would be a good choice? One is wild cabbage, Brassica oleracea, a relatively long-lived perennial confined to sea coasts of western Europe. In marked contrast to its many annual or biennial cultivars that are often severely damaged when grown under unnatural conditions, wild cabbage shows little evidence of detrimental effects of consumers, even though all cabbage-feeding specialists, together with an array of generalist feeders, are present (Owen unpubl.). As we previously pointed out (Owen and Wiegert 1976), many species of aphids aggregate and drain nutrients from distant parts of plants and in effect act as sinks, competing with natural sinks such as growing parts and storage organs. Even cultivars growing in unnatural conditions may occasionally 'benefit' from feeding by aphids, when 'benefit' is defined in terms of a product useful to man. Way and Cammell (1970), working with cabbage aphid, Brevicoryne brassicae, have shown that in cabbage supply of photosynthetic material exceeds capacity of plant's sink and so sugar accumulates in leaves and slows down photosynthesis which, in turn, decreases productivity. But our original, and continuing position has been that 'benefit' must be defined solely in terms of relative fitness, which is not necessarily related to productivity. Excess sugars released by aphids and deposited below plant could stimulate nitrogen fixation which would be beneficial for a plant unable to fix its own nitrogen and which very often grows in nitrogen deficient soils. We therefore agree with Choudhury that long-lived perennials are more likely to enter into a mutualistic relationship with consumers than short-lived annuals. Indeed we have never agreed with Stenseth's (1978) reasoning that short-lived r-strategists are more likely to benefit than long-lived K-strategists. Stenseth's conclusion stems directly from Leslie matrix model used in his theoretical analysis in which there is no threshold level below which grazing does not affect mortality. Using such a model, grazing can confer benefits to fitness (measured as rmax in Stenseth's paper) only when increased natality more than counteracts increased mortality due to grazing, in Stenseth's words the relative gain... must be greater longer life cycle. But we argue that grazing (or browsing), if regulated below given levels (which would be species specific), seldom if ever increases mortality of long-lived perennials. Thus, increased fitness of these organisms depends entirely on whether grazing produces more propagules with increased relative survival rates. This effect, we argue, is much more likely to be selected for when organism being grazed is long-lived, remaining in place to reap benefit of (in aphid example) whatever increased concentrations of nutrients are produced by action of aphids. Lastly, Choudhury seems to want to join increasing band of ecologists who see consumers as playing roles in ecosystem regulation. Although it may be true that there is some ecosystem effect, we maintain that evolutionary significance of plant-consumer relationships must be sought in terms of benefit, or otherwise, at individual plant level. Any regulatory effect on ecosystem is a by-product of organismorganism interactions whether they are mutualisms or not.

Extranodular growth ofFrankiaonCasuarina equisetifolia

17 genera of non-leguminous angiosperms bear NI-fixing root nodules initiated by an actinomycete known as Frankia [1,11]. The expanding volume of current literature attests to the significance vested in this symbiosis. However, to the best of our knowledge, no publications up to this point have dealt with the occurrence and behaviour of Frankia outside its specific niche, the nodule. Reported here are observations indicating that Frankia is able to grow outside the nodule of Casuarina equisetifolia and to proliferate in its vicinity. Our study is focused on Casuarina because these tropical and subtropical non-legumes play a major role by virtue of their ability to thrive on nitrogen-deficient soils.

Distribution of certain species of utricularia in relation to their habitats in and around Jamshedpur, India

Species of Utricularia grow in nitrogen-deficient soils and low-nitrogen-containing waters. This compells them to adopt to a carnivorous habit which may affect fish production adversely. The chemical characters of the habitats indicate that an acidic medium is essential for their proper growth. Cu, Zn, Mn and Mo are not essential for the growth of these species.

Transport of Nutrients to Tree Root Systems

Calculations suggest that nutrient transport through the soil to roots by mass flow accounts for less than 22, 37, and 80%, respectively, of the N, K, and Ca uptake by a Douglas-fir stand growing on a nitrogen-deficient soil derived from glacial outwash. Diffusion and dispersion, though limited by soil water content, are evidently especially important in nitrogen transport to root systems in this soil.

Nodule and Plant Development in Stylosanthes humilis H.B.K.: Symbiotic Response to Phosphorus and Sulphur

The effect of phosphorus and sulphur on the initiation and subsequent course of development of effective nodulation was determined for young seedlings of Stylosanthes humilis over the period days 1 1 to 26 from sowing. The plants were inoculated with an effective strain of Rhizobium and grown under controlled conditions in a small amount of nitrogen-deficient soil. Phosphorus had a beneficial effect on the initiation of nodules, which were first detected at day 11 in high-phosphorus plants, but not until day 14 in low. Thereafter, nodule development was greatly enhanced by phosphorus, nodule numbers, volumes and dry weights being increased. Nodule relative growth rates were stimulated from 0 . 3 g/g/day at low phosphorus levels to 0 . 7 g/g/day at high phosphorus levels over days 23-26. The nodules became pink earlier, and developed more rapidly as nitrogen-rich organs, in response to phosphorus. This suggested that from the earliest stages, phosphorus not only promoted the development of an increased mass of nodular tissue but also favoured an effective symbiosis. This enhanced nodule development led to greatly stimulated growth, with increasing amounts of total nitrogen and phosphorus in high-phosphorus plants. The assimilation of nitrogen by the whole plant was increased from 17 mg/g nodule dry weightlday at low to 53 mg/g/day with high phosphorus over days 23-26. Sulphur caused an increase in dry weight, but the response to sulphur mainly occurred late in development and was smaller than the response to phosphorus in the young seedlings of this trial.

The interaction of wheat genotypes with a specific factor of the environment

SummarySeveral alternative statistical approaches to the analysis of genotype-environment interactions are summarized, and their inter-relationships are presented mathematically and graphically. An experiment was designed to test the ability of these analyses to satisfactorily describe genotype-environment interactions and to locate genotypes causing or contributing significantly to such interactions in a situation where environments differed in only one factor, i.e. soil nitrogen status.Twenty-five lines of wheat were grown at each of 5 levels of applied nitrogen (0–270 kg N/ha) in a sandy, nitrogen-deficient soil, and their grain yields and yield components (ears per unit area, grains per ear, weight per grain) were determined. Designating the nitrogen levels as ‘environments’, linear yield responses, and deviations from linear responses, of individual wheat entries to environment mean yield were calculated according to the various statistical procedures previously outlined. The results suggested that the linear response to environment mean yield was similar for all wheat entries. However, further inspection of the data revealed that the responses of eight entries to environment mean yield departed significantly from linearity. Although several analyses satisfactorily identified these aberrant entries, classifying them as ‘unstable’, it was concluded that the degree of departure from linearity of response was not an adequate measure of instability. Furthermore, as previously suggested by Knight (1970), it was confirmed that the relative ranking of an entry for yield stability according to such a concept varied according to the average response of the group of entries with which it was being compared.The general effects of applied nitrogen on yield components were to increase the number of ears and the number of grains per ear, and to decrease grain weight. However, only the first of these effects occurred consistently for all entries. The number and weight of individual grains per ear varied with the nitrogen treatment, often unpredictably, in a complex pattern which differed significantly between entries.

A Study of the Interaction of Cold Stress, Age, and Phosphorus Nutrition on the Development of Lotononis Bainesii Baker

The effects that specific amounts of cold stress had on the development of the tropical legume L. bainesii were assessed for plants of four ages grown in a nitrogendeficient soil. They were dependent primarily upon symbiotically fixed nitrogen, when receiving phosphorus at five treatment levels. The plants received normal lighting and a 12-hr day length under controlled environment, and the cold stress was gradually increased from nil to frosting.

Mycorrhizal Nodules and Growth of Podocarpus in Nitrogen-poor Soil

MOST genera with nodulated roots are legumes, and the nodules form after infection by nitrogen-fixing bacteria. Thirteen other genera of dicotyledons may also develop root nodules, which form only after infection, and in which nitrogen fixation has been proved or inferred, but in these the endophytes seem to be actinomycetes1,2. Among the gymnosperms, however, in Araucariaceae and Podocarpaceae, nodules develop without any stimulus from microorganisms3 although in nature they usually contain a coarse phycomycetous mycelium. This infection has been synthesized using Endogone spores4 and, like typical Endogone mycorrhizas, infected nodules sustain the growth of seedlings in phosphorus-deficient soils5. There is also a long standing belief that they fix nitrogen, supported recently by some experiments with 15 N (ref. 1). I have tested this hypothesis by attempting to grow seedlings of Podocarpus totara in a nitrogen-deficient soil.

Ecological Importance of Snowbrush Ceanothus Velutinus in the Oregon Cascades

Twelve stands of snowbrush were selected for a biomass study to estimate nitrogen fixation under field conditions west of the summit of the Oregon Cascades. Total nitrogen in the upper 2 ft of soil was higher under snowbrush than in the open, but the difference may have been caused by loss of nitrogen from open areas rather than by nitrogen fixation. Total nitrogen in the upper 15 cm of soil under snowbrush did not differ from that found under nonfixing shrub species. Various shrub species may increase the total soil nitrogen under their canopies, however, if only by accumulation from sites that lack vegetation. More nitrogen may be tied up in the biomass of mature snowbrush stands than in stands of other shrubs. The difference could be explained by nitrogen fixation, which may range from zero to about 20 kg/ha per year under conditions of this study. Nodulated snowbrush seedlings produced 2.5 times the dry weight that non—nodulated seedlings produced in a nitrogen deficient soil. Sixty—one per cent of the nitrogen in nodulated greenhouse seedlings was fixed. Such fixation rates may be reached on infertile soils in the field, but they seem unlikely on soils of medium or better fertility. This point seems to be substantiated by delay in nodulation of snowbrush in soils with increased levels of organic matter. Bioassay tests using Douglas fir seeds and hemlock seedlings showed that snowbrush did not add to the soil any significant amount of nitrogen by nitrogen fixation. The species contributes to the formation of a new organic layer, however, through large amounts of nitrogen—rich litter.

Nitrogen immobilization by rice straw incorporated in lowland rice production

The nitrogen supplying power of rice straw for flooded rice production was studied in three field experiments. The net nitrogen immobilization was observed to be 0.54 per cent of the original dry weight of the straw as determined by grain yield responses over single growing seasons. Straws with higher nitrogen concentrations increased grain yield on nitrogen deficient soil, and straws with lower nitrogen concentrations depressed yield.

SPLOTCH, A PHYSIOLOGICAL LEAF DISEASE OF WHEAT: I. NUTRITIONAL STUDIES

A leaf disease observed in Golden Ball and other durum wheats for a number of years is described and named splotch. It was reproduced in the greenhouse by growing these varieties in nitrogen-deficient soils and was reduced or prevented by the use of nitrate fertilizers. Chemical analysis of leaves demonstrated that splotch increased as the total nitrogen decreased below 4 per cent. Phosphatic fertilizers were found to influence splotch, sometimes increasing it, especially where yields were increased, and at other times decreasing it. Their effects are considered to be indirect and related to the ratio of nitrogen to phosphorus. The addition of the minor elements boron, manganese, magnesium, iron, zinc, molybdenum, and copper to the soil as a mixture increased splotch.

Effect of Nitrogen Fertilizer on the Nitrogen, Phosphorus, and Cation Contents of Bromegrass

AbstractHeavy applications of nitrogen fertilizer produce large increases in growth of bromegrass on nitrogen deficient soils in eastern Nebraska. Such a marked effect of nitrogen fertilizer upon growth may also be reflected in the composition of the forage according to results obtained on Rokeby soils at Lincoln, Nebr. Rates of 0, 60, 120 and 240 lbs. N/acre were applied to a sodbound field of Lincoln bromegrass. Yields of forage and plant samples were obtained four times during the growing season during one year, and once at the regular time of harvesting hay during other years.Plant samples were analyzed for nitrogen, phosphorus, calcium, magnesium, potassium and sodium. There was a general decrease in percentage of all elements throughout the growth period sampled, although the trends varied with the element and with the treatment. Nitrogen percentage was higher for fertilized than nonfertilized bromegrass at all stages of growth. During early stages of growth, phosphorus percentage was greater in the fertilized than the nonfertilized forage, but at final harvest there was a tendency for the reverse to be true. There was a noticeable increase in potassium percentage with some decreases in percentages of calcium and magnesium due to fertilization. The increase in potassium percentage was, however, greater than the decreases in calcium and magnesium percentages so that there was an increase in milliequivalents of total cations.

Bacterial Symbiosis in Some New Zealand Plants

A large number of species of Coprasma (Rubiaceae) show bacteria-containing stipular ndules. Hairs which contain bacteria are also present. In other species, for example Myoporum laetum, bacteria are present in superficial and in immersed leaf-glands. It is suggested that the bacterial symbionts, which can readily be obtained in culture, may function in the fixation of atmospheric nitrogen and thereby be of importance to the plants when growing in nitrogen-deficient soils.

Root Nodules of Bog Myrtle or Sweet Gale (Myrica gale L.)

PREVIOUS investigations1 on the root nodules which commonly occur on Myrica spp. have referred chiefly to the structure and cytology of the nodules and to the identification of the endophyte. Little attention appears to have been paid to the possibility of fixation of nitrogen being associated with the nodules. Bottomley2, after visual comparison of the growth made by plants (some with nodules, some without) transplanted from the natural habitat into a nitrogen-deficient soil, concluded that fixation of nitrogen had occurred. This finding deserves confirmation and amplification.