The relation between some growth parameters and yield components of rice as influenced by nitrogen level and genotype

The effects of three levels of nitrogen (0, 2 and 4 g (NH₄)₂SO₄ per pot) were evaluated in four rice varieties, differing in grain size, under flooded conditions in a tropical environment. Addition of nitrogen increased plant height and leaf number on the main culm, and hastened flowering significantly in all varieties. It also increased the dry weights of leaf, and culm plus sheath at the maximum tillering stage, anthesis and harvest. The average dry weights of both leaf, and culm plus sheath increased significantly in all varieties until anthesis. Following anthesis, the dry weights of both leaf, and culm plus sheath of the large-seeded varieties, Zhu Lian and PP₆R, further increased mainly due to emergence of the late tillers, but decreased in the small-seeded varieties, IR 747 and P₃C₂₆. During grain-filling, vars Zhu Lian and PP₆R accumulated dry matter more than the other two varieties and did not use their reserve starch present in the culm plus sheath, presumably because of the lack of demand. By contrast, current photosynthesis and ‘reserve’ contributed about 70% and 30%, respectively, of the grain yield in IR 747 and P₃C₂₆. Addition of nitrogen increased grain yield significantly in all varieties. The yield increase in IR 747 and PP₆R was essentially due to increase in grain number, but that in P₃C₂₆ and Zhu Lian was due to increases in both grain size and grain number, the latter having much greater influence. Neither the percentage of filled spikelets nor the 1000-grain weight was influenced by nitrogen addition. It was concluded that grain number is the single most important yield component in rice. Path-coefficient analysis indicated that in a breeding programme involving these four rice varieties, the cross between Zhu Lian and P₃C₂₆ would be most successful in an effort to combine high spikelet number and large grain size.     

A statistical investigation into the relationship between meteorological parameters and suicide

Many previous studies of relationships between weather and suicides have been inconclusive and contradictory. This study investigated the relationship between suicide frequency and meteorological conditions in people who are psychologically predisposed to commit suicide. Linear regressions of diurnal temperature change, departure of temperature from the climatic norm, mean daytime sky cover, and the number of hours of precipitation for each day were performed on daily suicide totals using standard computer methods. Statistical analyses of suicide data for days with and without frontal passages were also performed. Days with five or more suicides (clusterdays) were isolated, and their weather parameters compared with those of nonclusterdays. Results show that neither suicide totals nor clusterday occurrence can be predicted using these meteorological parameters, since statistically significant relationships were not found. Although the data hinted that frontal passages and large daily temperature changes may occur on days with above average suicide totals, it was concluded that the influence of the weather parameters used, on the suicide rate, is a minor one, if indeed one exists.     

An investigation into the mechanism for reduced seed yield inLotus corniculatus

Summary A study of seed position in the pod ofLotus corniculatus L. cv. Mirabel (Fabaceae) suggested that reduced seed set after self-pollination is not due to an inability of the self-pollen tube to reach the end of the ovary. As in other cultivars, it has been demonstrated that cultivar Mirabel produced less seed per pod and shorter pods after self- than after cross-pollination. No differences were noted for percent germination of seeds produced by both types of pollination indicating that the number of seeds per pod is a reliable index of the ultimate productive potential of the pollination.     

An investigation into the effects of iodide and iodate on plant growth

Summary An experiment was carried out in water cultures to compare the effect of iodide and iodate on plant growth. The experimental crop was oats which is known to be very sensitive to an overdose of iodine.Iodide led to a more pronounced growth depression than did iodate. The rate of uptake of iodine from iodide was more than double that from iodate. There appeared to be a fairly quantitative relation between the iodine content of the oat roots and their growth with high supplies of KI and KIO₃. This indicates that iodide and iodate, after being absorbed by the plant, have about the same effect on growth and that differences in effect during the initial stages of growth can be largely ascribed to differences in iodine contents.     

Effects of aerial pollutants on the growth and yield of spring barley

Open-topped chambers were used to determine the effect of field concentrations of aerial pollutants on the growth and yield of spring barley. Experiments were conducted in the Marston Valley, Bedfordshire, where sulphur dioxide and fluoride are the major pollutants. The charcoal filtered chambers enabled pollutant concentrations to be reduced by 60–70%. Cleaning the air increased straw and grain yields. The filtration was non-selective and did not identify the injurious agent. The chambers were found to accelerate the crop's development by 7–8 days and reduce yield by suppressing tillering.     

An investigation of phase relations between theta-rhythm potentials in the neocortex and hippocampus of rabbits

Phase relations between rhythmic activity recorded from the hippocampus and from various levels of the neocortex were calculated on a two-dimensional model on the assumption of the passive spread of hippocampal activity. The calculation showed that if such a spread of activity takes place an appreciable phase shift, caused by the spatio-temporal structure of the hippocampal source of the theta-rhythm, may exist between the rhythmic components of potentials recorded from the neocortex and hippocampus. In some series of electrophysiological experiments on rabbits various consequences of the model calculations were tested. Phase relations of the theta-rhythm recorded in the neocortex and in the hippocampus in the presence of maximal correlation between cortical potentials cannot be explained, in the overwhelming majority of cases, purely by the passive spread of hippocampal activity to the surface of the neocortex.     

Effects of net blotch on growth and yield of spring barley

The effect of net blotch on the growth and yield of cv. Beatrice spring barley was examined in a greenhouse experiment. Separate inoculations at growth stages 21 and 34 reduced green leaf area, root weight, leaf sheath and stem weight and tiller number. The early inoculated plants, which responded and recovered more rapidly than later treated ones, suffered a loss in grain yield and this was related to the amount of disease, the loss in green leaf area and the reduction in unit leaf rate.     

The salmonid elastic fibril. An investigation of some chemical and physical parameters.

Elastic fibrils were isolated, as electron microscopically homogeneous preparations, from salmon (Salmo salar) and trout (Salmo gairdneri) bulbus arteriosus by extraction of other tissue components with guanidinium hydrochloride. The preparations exhibited compositions widely at variance with that of bovine elastin, the differences including both the overall concentration and the relative proportions of the crosslinks. Absorption and fluorescence spectroscopy ruled out the presence of tyrosine-derived crosslinks. The wide-angle X-ray diffraction pattern of the salmonid preparations showed broad reflections corresponding to spacings of 9.8, 4.5, and 2.2 Å, similar to bovine elastin. The mechanical behavior of the salmon preparation was characterized by a linear response to stress, with minimal hysteresis, a Young's modulus of 5.5 × 10⁵ N m^?2, and a breaking strain of 1.5.     

The relationship between leaf canopy development and yield of barley

A study was carried out into the relationship between sowing date, canopy development and yield of four barley genotypes sown in autumn and spring. Yield was considered as the product of PAR absorbed by the crop canopy up till anthesis, the dry matter: radiation quotient, the ratio of grains m²at maturity to the weight of the crop at anthesis and the mean grain weight. Equations were derived to predict the time course of the proportion of PAR absorbed in relation to date of sowing using thermal time as predictor. In crops that were not short of water and were fully vernalised, genotypic differences were detected in plant population density, date of anthesis, and the four yield components identified above. All attributes except plant population density were affected by shortage of water but genotypes differed in their response.     

An investigation of the mineral content of barley grains and seedlings

The Ca, Mg, K, and P content of dry barley (Hordeum vulgare) grains and seedlings was investigated using energy dispersive x-ray analysis and neutron activation analysis. Energy dispersive x-ray analysis of protein bodies in aleurone cells showed that these bodies contained very little Ca in relation to P, Mg, and K. Neutron activation analysis also showed that the endosperm contained very little Ca in relation to the other three elements. Surface sterilization and soaking treatments brought about slight loss of Ca but substantial loss of K from embryos. Over 6 days of growth the seedling plant gained minerals from the endosperm.     

An investigation into the interaction between nitrogen nutrition,photosynthesis and photorespiration

Photosynthetic CO₂ assimilation, photorespiration and levels of glycollate oxidase and ribulose bisphosphate (RuBP) carboxylase were measured in barley, wheat and maize plants grown on media containing nitrate or ammonium or in plants transferred from nitrate to ammonium. The CO₂ compensation point and photorespiratory CO₂ release were not altered by the nitrogen growth regime nor by transfer from nitrate to ammonium. In barley and wheat plants grown on ammonium the levels of glycollate oxidase and RuBP carboxylase per unit leaf area were higher than in nitrate grown material. These differences were not evident when the results were expressed on a protein or chlorophyll basis. The ratio of glycollate oxidase activity to RuBP carboxylase activity was not altered by the nitrogen regime.     

The estimation of growth yield and maintenance parameters for photoautotrophic growth

Methods are presented for examining the consistency of experimental data for microbial growth where light energy is converted to chemical energy through photosynthesis. True growth yield and maintenance parameters are estimated for several sets of available experimental data. Methods of parameter estimation are presented which allow all of the measured variables to be used simultaneously for parameter estimation. The results show that a wide range of values have been found for the true growth yield and maintenance parameters. Values of the true growth yield range from 0.04 to values above those predicted by the Z-scheme model for photosynthesis.     

Influence of growth temperature on the structure and thermodynamic parameters of barley starches

Barley starches grown at different temperatures were investigated using high sensitivity differential scanning microcalorimetry and X-ray diffraction. By applying physico-chemical approaches, thickness of crystalline lamellae, thermodynamic and structural characteristics (such as gelatinisation) of cooperative units and parameters characterising thermodynamic properties of crystal surfaces were determined. It was established that a difference of growth temperature experienced by plants during development does not lead to changes in the thickness of amylopectin crystalline lamellae and hence constituent double helix length. The role of defects in structural organisation of native barley starches is discussed. It is suggested that not all fatty acids necessarily form crystalline inclusion complexes.     

Effects of drought and salinity on some growth-contributing parameters in wheat and barley

Summary This study is mainly concerned with some parameters contributing to growth as indicators of difference in drought resistance and salt tolerance of wheat and barley cultivars. Parameters made use of are: transpiration efficiency (‘dry matter/transpiration’ ratio), ‘leaf/root’ ratio, chlorophyll content, chlorophyll stability to heat and anatomical modifications. The results revealed that transpiration efficiency is much higher in mexican ‘super-x’ wheat than in the egyptian ‘Giza-155’ cultivar under reduced soil water matric- or osmotic potentials. Chlorophyll content increased in super-x with decreasing soil water potential while chlorophyll heat stability decreased. The reverse is true in Giza-155 cultivar. Decreased leaf/root ratio in super-x is interpretted in favour of more beneficial water balance in this cultivar. Development of more sclerenchyma in its stems supports this judgement. Of barley cultivars tested, Borg El-Arab is favoured for drought resistance and Giza-117 for salt tolerance. re]19751014     

Effects of some non-pathogenic micro-organisms on the growth of gnotobiotic barley plants

Summary Mated cultures of Blakeslea trispora, which produce trisporic acid, inhibited root and shoot extension of barley plants grown in gnotobiotic cultures, where the carbon from roots was the sole source of carbon available to the microorganism. Unmated cultures of B. trispora and Mucor hiemalis, which do not synthesize trisporic acid, inhibited root extension only. Azotobacter chroococcum had a variable effect in different experiments on both root and shoot extension but could at least partially relieve the inhibitory effect of B. trispora on root growth. Plant growth regulators, applied to roots exogenously, produced effects on plants which, although comparable with some of the inhibitory effects of the micro-organisms, were not comparable with the stimulatory effects of A. chroococcum. re]19751127     

An investigation of boron toxicity in barley using metabolomics

Boron (B) is an essential micronutrient that affects plant growth at either deficient or toxic concentrations in soil. The aim of this work was to investigate the adaptation of barley (Hordeum vulgare) plants to toxic B levels and to increase our understanding of B toxicity tolerance mechanisms. We used a metabolomics approach to compare metabolite profiles in root and leaf tissues of an intolerant, commercial cultivar (cv Clipper) and a B-tolerant Algerian landrace (cv Sahara). After exposure to elevated B (200 and 1,000 microM), the number and amplitude of metabolite changes in roots was greater in Clipper than in Sahara. In contrast, leaf metabolites of both cultivars only responded following 1,000 microM treatment, at which B toxicity symptoms (necrosis) were visible. In addition, metabolite levels were dramatically altered in the tips of leaves of the sensitive cultivar Clipper after growth in 1,000 microM B compared to those of Sahara. This correlates with a gradual accumulation of B from leaf base to tip in B-intolerant cultivars. Overall, there were always greater differences between tissue types (roots and leaves) than between the two cultivars. This work has provided insights into metabolic differences of two genetically distinct barley cultivars and information about how they respond metabolically to increasing B levels.