Tolerance to acid soil conditions of the velvet beans Mucuna pruriens var. utilis and M. deeringiana

Velvet beans, fast growing leguminous cover crops used in the humid tropics, are shallow rooted on acid soils. This might be due to an inherent branching pattern, to an intrinsic toxicity of the acid subsoil or to a relative preference for root development in the topsoil. Such preference could be based on soil chemical factors in the subsoil or on physical factors such as penetration resistance or aeration. In a field experiment with two species of velvet bean (Mucuna pruriens var. utilis and M. deeringiana) all topsoil was removed and plants were sown directly into the acid subsoil. Root development was neither affected by this treatment nor by P fertilization or liming. In the absence of topsoil good root development in the exposed upper layer of subsoil was possible, so the hypothesis of a toxicity per se of the subsoil could be rejected. To test whether poor root development in the subsoil in the presence of topsoil is due to an inherent branching pattern of the plant or to a relative preference for topsoil, a modified in-growth core technique was used. Local topsoil and subsoil and an acid soil with a higher exchangeable Al content were placed in mesh bags at different depths and at different bulk densities, with and without lime and/or P fertilizer. A comparison of root development in mesh bags placed in the topsoil or subsoil showed that position and thus inherent branching pattern is not important. Root development in the subsoil was poor when this soil was placed in a mesh bag in the topsoil, but in an acid soil of much higher exchangeable Al content and higher percentage Al saturation more roots developed. In a second experiment in mesh bags, bulk density of the repacked soil in the range 1.0–1.5 g cm^-3 had no significant effect on root development. P fertilization and a high rate of liming of the soil placed in the mesh bag had a positive effect on root length density. It is concluded that poor root development in the acid subsoil under field conditions is due to a relative preference for topsoil. Al saturation and bulk density of the soil are not directly involved in this preference, but differences in availability of P and Mg or in Ca/Al ratios might play a role.     

Tolerance to acid soil conditions of the velvet beans Mucuna pruriens var. utilis and M. deeringiana

Fast growing, climbing leguminous cover crops such as the velvet beans can be used to reclaim weed-infested, degraded soils in the humid tropics, especially land covered by the grass Imperata cylindrica; they climb over the grass leaves and shade the grass out if their cover lasts long enough. Tolerance of two species of velvet bean to eroded soils was investigated by removing topsoil and directly sowing into the subsoil; plots where topsoil was not removed were used as a control. The response to small amounts of P fertilizer and lime was also tested. Removal of the topsoil resulted in retarded growth of both species, in increased dry matter content of the shoot, in decreased specific leaf area and in increased leaf weight ratio, due to shorter internodes. Six weeks after planting the leaf area index (LAI) was about 1.2 where topsoil was retained, sufficient for a shading effect on Imperata. Where topsoil had been removed, the LAI was only 0.6. Mucuna pruriens var. utilis showed a faster aboveground growth than M. deeringiana; the species did not differ in tolerance to eroded soil. Small amounts of P fertilizer had no significant effect on the growth of both Mucuna species. Shoot: root ratios, on a dry weight basis, were much lower when topsoil had been removed, about 3.7 and 2.4 for M. p. utilis and M. deeringiana respectively, compared to 6.2 and 3.3 where topsoil was retained. Removal of topsoil led to reduced Mg and to increased Al concentrations in roots, and to increased levels of Mn and Al in shoots. In the second year no effect of lime or residual effect of P application was found on growth of Mucuna or Imperata. Removal of the topsoil had little effect on the growth of weeds after the cover crop had been harvested. Due to the high Al tolerance of Imperata, reclamation by Mucuna will be less effective if the topsoil has been lost by erosion.     

In vitro shoot culture of wild Oryzae and other grass species

A method was developed for the in vitro clonal propagation of shoots from a range of wild rice and other grass species that have important genetic traits such as drought resistance and salinity tolerance. The axenic multiple shoot cultures, which were suitable for DNA and protein extraction or direct protoplast isolation, could be maintained without subculture for between 2 and 3 months or rapidly multiplied for the subsequent production of mature plants and seeds. Basal sections of the micropropagated shoots also provided novel explants for the production of highly embryogenic callus, from some species, that could be regenerated into green plants. It is envisaged that this clonal propagation technique could aid the genetic manipulation of cultivated rice by providing a means to vegetatively conserve valuable genetic resources, a technique to rapidly multiply novel hybrid material and a source of embryogenic callus that will allow the application of biotechnological techniques, such as somatic hybridization and genetic transformation, to previously unexploited species.Abbreviations BA N⁶-benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - NAA -naphthaleneacetic acid - PAR photosynthetically-active radiation     

Protoplast culture in high molecular oxygen atmospheres

The effect of a molecular oxygen atmosphere on protoplast culture, compared with normal cultural procedures, was investigated for tomato, rice and jute protoplast systems. Protoplasts, in unsealed Petri dishes were cultured in a sealed 250 ml volume container in which the atmosphere was replaced with sterile molecular oxygen (O₂ 100% v/v) achieved by a one minute oxygen flow (10 mBar). Controls were cultured in a similar way but with a normal atmosphere (20.5% v/v oxygen). For all three species a major improvement in plating efficiency and colony formation was observed in the oxygen-enriched atmospheres. In the case of rice, cultivar Taipei 309, a significant increase in plant regeneration capacity, from protoplast-derived colonies, was observed for the high oxygen cultures.Abbreviations MES 2-N-morpholinoethane sulfonic acid - PE plating efficiency     

Tolerance and avoidance of Al toxicity by Mucuna pruriens var. utilis at different levels of P supply

Previous laboratory experiments showed that velvet bean Mucuna pruriens is moderately tolerant to the presence of Al (up to 185 µM) in the root environment, but that it only develops a shallow root system in acid soils. Field experiments showed that Mucuna can tolerate acid subsoil conditions in a homogeneous root environment, but avoids subsoil if topsoil is present. Subsequent split-root experiments with a recirculating nutrient solution showed that this subsoil avoidance may be based on an Al avoidance mechanism in the root system. This Al avoidance mechanism, however, was not evident when phosphorus (P) supply to the whole plant was adequate. We thus hypothesized that surface application of P may help to overcome Al avoidance in the subsoil.In a field experiment on an ultisol in Lampung (Indonesia), only a moderate increase in aboveground biomass production was found for a wide range of P application rates, although the soil was low in available P, and the P adsorption isotherm was very steep. An increased P status of the topsoil and an increased P concentration in the aboveground biomass (from 50 to 75 mmol kg^-1) had no effect on root development in the subsoil.     

Sago Palm (Metroxylon Sagu, Arecaceae) production in the Eastern Archipelago of Indonesia: Variation in morphological characteristics and pith dry-matter yield

Eleven local varieties of sago palm (Metroxylon sagu Rottb.) in southeast and north Sulawesi and in northern Maluku were studied: one variety with a weak black band on the back of the petiole: three varieties with a brown band on the back of the petiole: seven bandless varieties comprising two spineless, four short spine and one long spine types. Large variation in morphological characteristics and pith dry-matter yield were estimated at 13 to 34% and 55%, respectively. The difference in pith dry-matter yield is mainly attributed to trunk diameter and dry-matter percentage of pith. Trunk diameter was not affected by the length of growth period, which might reflect the palm’s own characteristics, such as genetic background and growth environment. The dry-matter percentage of pith was not related to any characteristics measured. The pith dry-matter yield was highest in the short spine type, followed by the spineless and the long spine types.

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Produksi Palma Sagu (Metroxylon Sagu, Arecaceae) Di Kepulauan Timur Indonesia: Keragaman Karakteristik Morfologi Dan Hasil Bahan Kering Empulur Batang

Résumé  Dalam survey tersebut dipelajari sebelas varitas sagu lokal (Metroxylon sagu Rottb.) di Sulawesi Tenggara, Sulawesi Utara, dan Maluku Utara: satu varitas dengan pita sedikit hitam pada bagian belakang dari tulang daun: tiga varitas dengan pita coklat pada bagian belakang belakang dari tulang daun: tujuh varitas tanpa pita terdiri dari dua varitas tanpa duri, empat varitas duri pendek dan satu varitas duri panjang. Terdapat adanya keragaman pada karakteristik morfologi dan hasil bahan kering empulur batang yang diperkirakan beriurut-turut berkisar 13 sampai 34% dan 55%. Perbedaan pada hasil bahan kering empulur batang terutama tergantung pada diameter batang dan proporsi kering empulur batang. Diameter batang tidak dipengaruhi oleh panjangnya periode tumbuh; namun nampaknya lebih terkait dengan gambaran karakteristik khusus, seperti latar belakang genetik dan lingkungan tumbuhnya.Persen bobot kering empulur batang tidak ada hubungannya dengan berbagai karakteristik yang diteliti. Hasil bahan kering empulur batang tertinggi adalah pada tipe duri pendek (511kg/batang), diikuti tipe tanpa duri (417kg/batang) dan tipe duri panjang (329kg/batang).

     

Identification of a Novel Vanadium-binding Protein by EST Analysis on the Most Vanadium-rich Ascidian, Ascidia gemmata

Ascidians are known to accumulate extremely high levels of vanadium in their blood cells (up to 350 mM). The branchial sac and the intestine are thought to be the first tissues to contact the outer environment and absorb vanadium ions. The concentration of vanadium in the branchial sac and the intestine of the most vanadium-rich ascidian Ascidia gemmata were determined to be 32.4 and 11.9 mM, respectively. Using an expressed sequence tag (EST) analysis of a cDNA library from the intestine of A. gemmata, we determined 960 ESTs and found 55 clones of metal-related gene orthologs, 6 redox-related orthologs, and 18 membrane transporter orthologs. Among them, two genes, which exhibited significant similarity to the vanadium-binding proteins of other vanadium-rich ascidian species, were designated AgVanabin1 and AgVanabin2. Immobilized metal ion affinity chromatography revealed that recombinant AgVanabin1 bound to metal ions with an increasing affinity for Cu(II) > Zn(II) > Co(II) and AgVanabin2 bound to metal ions with an increasing affinity for Cu(II) > Fe(III) > V(IV). To examine the use of AgVanabins for a metal absorption system, we constructed Escherichia coli strains that expressed AgVanabin1 or AgVanabin2 fused to maltose-binding protein and secreted into the periplasmic space. We found that the strain expressing AgVanabin2 accumulated about 13.5 times more Cu(II) ions than the control TB1 strain. Significant accumulation of vanadium was also observed in the AgVanabin2-expressing strain as seen by a 1.5-fold increase.