Changes in DTPA-iron and management of iron chlorosis in rice nurseries

Summary On a Typic Ustochrept soil incorporation of 10 tons/ha of a green manure plus submergence for 10 days followed by raising upland nursery checked iron chlorosis. In contrast, presubmergence with and without FYM and iron sulfate or pyrite were a failure. Nor weekly sprays with 3.0% iron sulfate were found very effective. The success of green manure plus submergence was associated with the mobilization of soil iron as a result of intense reduction and its subsequent retention in available form at a sufficient high level during the growth of upland nursery.     

Major histocompatibility (B) complex and sex effects on the phytohaemagglutinin wattle response

The influence of the major histocompatibility (B) complex and sex on the phytohaemagglutinin (PHA) wattle response was studied in 136 segregants (B2/B2, B2/B5 and B5/B5) of a fourth generation cross between inbred lines 6(1) and 15(1). At 6 weeks of age, chickens were injected with 100 micrograms purified PHA-P. Wattle thickness measurements were taken 4, 24, 48, 72 and 96 h after injection. Analysis of variance showed that 4 h after injection, males had a significantly higher response than females but the sex-genotype interaction was also significant. Females had higher responses than males 24 and 48 h after injection as a consequence of more rapid development and earlier resolution of the reaction in males. B2/B2 chickens had significantly lower responses than B5/B5 chickens 72 and 96 h after injection, signifying a faster late resolution phase in the B2/B2 genotype. The developmental and early resolution phases of the PHA wattle response were influenced by sex while the late resolution phase was influenced by B genotype.     

Peat,zeolite and basalt as adsorbents of ammoniacal nitrogen during manure decomposition

The effectiveness of sphagnum peat, zeolite (clinoptilonite) and basalt in reducing ammonia losses during aerobic manure decomposition was determined in an incubation experiment. Peat placed in the spent air-stream adsorbed all of the ammonia volatilized during the first 8 days of decomposition, and reduced overall ammonia losses by 59%. Zeolite reduced total ammonia losses by 16%, and basalt by 6%.All adsorbents were considerably less effective in reducing ammonia losses when mixed with the manure. Reductions in ammonia losses of 24% and 1.5% were obtained with the peat and zeolite, respectively. The addition of basalt increased losses.Ammonia and ammonium adsorption isotherms were determined for the three materials. The adsorption capacities and affinity terms of the adsorbents calculated from the isotherms, reflected their ability to reduce ammonia losses in the incubation experiment. Zeolite had both the highest affinity for ammonium and the highest ammonium adsorption capacity. The peat had a very high affinity for ammonia and a high adsorption capacity (23.4 mg NH₃–N g^–1), whereas zeolite and basalt had a much lower adsorption capacity (1.8 and 0.05 mg NH₃–N g^–1, respectively) compared with their capacity to adsorb ammonium (18.1 and 0.18 mg NH₄–N g^–1).     

Nitrogen mineralization ofSesbania sesban used as green manure for lowland rice in Sri Lanka

Sesbania sesban was evaluated as green manure crop for lowland rice in the Dry Zone of Sri Lanka. The legume was grown during a fallow period before lowland rice (Oryza sativa) and ploughed under just before transplanting. Weight loss and nitrogen content in litterbags containing leaves, stems and roots of the legume were monitored. Comparisons were made between rice yields from 20 m² plots after green manuring in combination with different nitrogen fertilizer levels (0, 2.4, 4.8 and 7.2 gm⁻²) and nitrogen fertilizer (9.6 gm⁻²) alone. Above-ground biomass ofS. sesban was 440 gm⁻² (dry wt) when ploughed under after 84 days growth. N-content in leaves, stems and roots was 3.76%, 0.41% and 0.73%, respectively. This gave a N-input fromS. sesban of 9.2 gm⁻² (8.3 g from above-ground parts and 0.9 g from roots). The corresponding K and P inputs were 7.3 and 0.6 gm⁻² respectively. The nitrogen rich leaves, which contained 88% of the nitrogen in the above-ground parts, decomposed and released its nitrogen much more rapidly than the stems and roots. After only four days the leaves had released 5.3 g Nm⁻² and after 14 days they had released 6.4 g Nm⁻². The highest rice yield (505 gm⁻²) was obtained usingS. sesban and 4.8 gm⁻² of N-fertilizer. The yields with only N-fertilizer or onlyS. sesban were 442 gm⁻² and 396 gm⁻², respectively. Due to the rapid decomposition of the nitrogen rich leaves,S. sesban did not behave as a slow release fertilizer. Thus, it is not necessary to apply nitrogen fertilizers as a basal dose.     

Evaluation of the leaf juice of some higher plants for their toxicity against soil borne pathogens

Out of the leaf juices of eighteen plant species screened, only Eupatorium cannabinum exhibited complete toxicity against Pythium debaryanum, Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii. Shade drying of the leaves had no adverse effect, while oven drying produced an adverse effect on the fungitoxicity of the leaves of E. cannabinum. The crude leaf juice of E. cannabinum successfully inhibited damping-off (Fusarium oxysporum) infection of Pisum sativum seedlings.     

Cytometry and flow cytometry of 4',6-diamidino-2-phenylindole (DAPI)-stained suspensions of nuclei released from fresh and fixed tissues of plants

Cytometry and flow cytometry were used to study characteristics of fluorescence of the DNA-DAPI complex in nuclei released from different fresh and formaldehyde-fixed pea ( Pisum sativum L. cv. Lincoln) tissues. The two methods of isolation are compared and discussed as well as their possible use for quantitative analysis of DNA in plant tissues. With fixed tissues it is possible to obtain a number of nuclei sufficient for the flow cytometric analysis, even using small amounts of plant tissue.     

Conserved organization of an avian histone gene cluster with inverted duplications of H3 and H4 genes

Summary The organization of histone gene clusters of the duckCairina moschata was studied in the DNA inserts of two recombinant phage that overlap and feature identical histone gene arrangements but differ in sequence details and in the extent of repetition of an AT-rich motif in one of the nontranscribed spacer regions. These few but substantial differences between otherwise nearly identical histone gene groups suggest that we have independently isolated alleles of the same site of the duck genome or that this gene arrangement occurs (with slight variations) more than once per haploid genome. Within the histone gene cluster described, H3 and H4 genes are duplicated (with inverted orientation), whereas one H1 gene is flanked by single H2A and H2B genes. The arrangement of duck histone genes described here is identical to a subsection of the chicken genome but differs from any other published histone gene cluster.     

Simulated and measured nitrogen conditions in a manured and fertilised soil

The governing factors for soil nitrogen dynamics were identified with a simulation model. In addition, the model was used to interpret measurements from a plot fertilisation experiment in southwest Sweden.Simulated moisture and temperature conditions were the driving variables for the simulation of soil nitrogen dynamics and leaching during a 6-year period. The results of the simulation were compared with monthly observations on two plots with grain crops, one with liquid manure and commercial fertilisers applied and one with commercial fertilisers only.Simulated temporal variations of the nitrate and ammonium storages generally agreed with observations. The dominant role of the crops as a determinant of soil nitrogen conditions was demonstrated. A higher leaching loss from the plot with application of commerical fertilisers only occurred both in simulations and measurements compared to the plot with application of both commercial fertilisers and manure. The main reason was the higher N-application in the former treatment.The effect of water flows in macropores was interpreted as a delay of simulated leaching compared to observed leaching on some occasions in summer and early autumn. No direct effect of the macropores on the yearly rates of leaching could be seen.     

Evaluating second year cropping on jhum fallows in Mizoram,north-eastern India—Phytomass dynamics and primary productivity

Cropping on jhum fallows in north-eartern India is predominantly done for one year in a jhum cycle. If second year cropping is done, expanse of the forest land required for slashing and burning could be reduced significantly. We tested this hypothesis in a young (6 yr) and an old (20 yr) jhum fallow. We also evaluated if the productivity during second year cropping could be alleviated by auxiliary measures such as tilling the soil or application of fertilizers (chemical or farm-yard manure or both in combination). The results demonstrate that the ecosystem productivity (total dry matter production) and economic yield (rice grain production) decline with shortening of jhum cycle. Second year cropping causes a further decline in ecosystem productivity in old jhum field, but not in young jhum field. Economic yield from second year cropping in its traditional form (without any fertilizer treatment) is not much lower than that in the first year, and can be improved further by manuring the soil. Tilling of soil improves neither ecosystem productivity nor economic yield. Different fertilization treatments respond differently; while inorganic manuring enhances ecosystem productivity, a combination of inorganic and organic manuring improves economic yield