Biochar has been heralded as an amendment to revitalize degraded soils, improve soil carbon sequestration, increase agronomic productivity, and enter into future carbon trading markets. However, scientific and economic technicalties may limit the ability of biochar to consistently deliver on these expectations. Past research has demonstrated that biochar is part of the black carbon continuum with variable properties due to the net result of production (e.g., feedstock and pyrolysis conditions) and postproduction factors (storage or activation). Therefore, biochar is not a single entity but rather spans a wide range of black carbon forms. Biochar is black carbon, but not all black carbon is biochar. Agronomic benefits arising from biochar additions to degraded soils have been emphasized, but negligible and negative agronomic effects have also been reported. Fifty percent of the reviewed studies reported yield increases after black carbon or biochar additions, with the remainder of the studies reporting alarming decreases to no significant differences. Hardwood biochar (black carbon) produced by traditional methods (kilns or soil pits) possessed the most consistent yield increases when added to soils. The universality of this conclusion requires further evaluation due to the highly skewed feedstock preferences within existing studies. With global population expanding while the amount of arable land remains limited, restoring soil quality to nonproductive soils could be key to meeting future global food production, food security, and energy supplies; biochar may play a role in this endeavor. Biochar economics are often marginally viable and are tightly tied to the assumed duration of agronomic benefits. Further research is needed to determine the conditions under which biochar can provide economic and agronomic benefits and to elucidate the fundamental mechanisms responsible for these benefits.

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Biochar: a synthesis of its agronomic impact beyond carbon sequestration.

Qualitative analysis of volatile organic compounds on biochar.

The role of activated charcoal in plant tissue culture.

Haploids are plants with a gametophytic chromosome number and doubled haploids are haploids that have undergone chromosome duplication. The production of haploids and doubled haploids (DHs) through gametic embryogenesis allows a single-step development of complete homozygous lines from heterozygous parents, shortening the time required to produce homozygous plants in comparison with the conventional breeding methods that employ several generations of selfing. The production of haploids and DHs provides a particularly attractive biotechnological tool, and the development of haploidy technology and protocols to produce homozygous plants has had a significant impact on agricultural systems. Nowadays, these biotechnologies represent an integral part of the breeding programmes of many agronomically important crops. There are several available methods to obtain haploids and DHs, of which in vitro anther or isolated microspore culture are the most effective and widely used. This review article deals with the current status of knowledge on the production of haploids and DHs through pollen embryogenesis and, in particular, anther culture.

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Anther culture for haploid and doubled haploid production

Carbon-rich biochar derived from the pyrolysis of biomass can sequester atmospheric CO, mitigate climate change, and potentially increase crop productivity. However, research is needed to confirm the suitability and sustainability of biochar application to different soils. To an irrigated calcareous soil, we applied stockpiled dairy manure (42 Mg ha dry wt) and hardwood-derived biochar (22.4 Mg ha), singly and in combination with manure, along with a control, yielding four treatments. Nitrogen fertilizer was applied when needed (based on preseason soil test N and crop requirements) in all plots and years, with N mineralized from added manure included in this determination. Available soil nutrients (NH-N; NO-N; Olsen P; and diethylenetriaminepentaacetic acid-extractable K, Mg, Na, Cu, Mn, Zn, and Fe), total C (TC), total N (TN), total organic C (TOC), and pH were evaluated annually, and silage corn nutrient concentration, yield, and uptake were measured over two growing seasons. Biochar treatment resulted in a 1.5-fold increase in available soil Mn and a 1.4-fold increase in TC and TOC, whereas manure produced a 1.2- to 1.7-fold increase in available nutrients (except Fe), compared with controls. In 2009 biochar increased corn silage B concentration but produced no yield increase; in 2010 biochar decreased corn silage TN (33%), S (7%) concentrations, and yield (36%) relative to controls. Manure produced a 1.3-fold increase in corn silage Cu, Mn, S, Mg, K, and TN concentrations and yield compared with the control in 2010. The combined biochar-manure effects were not synergistic except in the case of available soil Mn. In these calcareous soils, biochar did not alter pH or availability of P and cations, as is typically observed for acidic soils. If the second year results are representative, they suggest that biochar applications to calcareous soils may lead to reduced N availability, requiring additional soil N inputs to maintain yield targets.

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Biochar and Manure Affect Calcareous Soil and Corn Silage Nutrient Concentrations and Uptake.

This study was made to clarify the effects of cytokinin type and their concentrations on shoot proliferation and hyperhydricity in in vitro Pyrus pyrifolia N. (`Hosui' and `Kosui') shoots. The shoots were subcultured in a woody plant medium supplemented with 0.5 μM 3-indolyl-butyric acid, 3% (w/v) sorbitol, 0.8% (w/v) agar, and with cytokinins kinetin, 6-benzylaminopurine (BA), N-(2-chloro-4-pyridyl)-N9-phenylurea (CPPU), 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea (TDZ) added at concentrations 0.44, 4.40, 11.0 and 44.0 μM. The highest number of shoots was induced by adding BA at concentration 11.0 μM, then by 4.4 μM BA, in both cultivars. TDZ and CPPU caused greater hyperhydricity in cultured explants than BA and kinetin. `Kosui' was more susceptible to hyperhydricity compared with `Hosui'.

Effects of cytokinin types and their concentrations on shoot proliferation and hyperhydricity in in vitro pear cultivar shoots

Effects of charcoal with pyroligneous acid and barnyard manure on bedding plants

Improvement of micropropagation of Japanese yam using liquid and gelled medium culture

Triploid plants were grown from the diploid pear scion cultivar (Pyrus pyrifolia Nakai) by anther culture. Androgenic callogenesis occurred at about 10 days after anther excision, and most calli formed within four weeks and stopped growing at less than 1–3 mm in diameter. Androgenic embryogenesis occurred within 8–12 weeks after anther culture. The formed embryos were generally white, globular or heart-shaped. To increase callogenesis and embryogenesis, the effects of cold pre-treatment, light and activated charcoal (AC) on anthers collected from buds were investigated. Cold pre-treatment, dark and lack of AC increased callogenesis more than no cold pre-treatment, light and adding AC. A decisive condition was not found for embryogenesis. The embryogenesis frequency was extremely low and only six embryos were grown. Two embryos expanded greenish cotyledons and developed foliage, and they proliferated when transferred monthly to fresh proliferation medium. The proliferated shoots were rooted and acclimated. Flow cytometric analysis and investigation of the number of chromosomes of regenerants showed that all cells were triploid.

Production of triploid plants of Japanese pear ( Pyrus pyrifolia Nakai) by anther culture

Effects of PA on in vitro shoot proliferation and root formation were investigated using shoot cultures of three Japanese pear (Pyrus pyrifolia Nakai) cultivars. PA inhibited shoot multiplication and promoted initiation and development of roots in the cultured shoots of three cultivars, resulting in increasing the proportion of rooted shoots. Chemical name used: pyroligneous acid (PA). by distillation. The distillation duration was ≈10 h and the rate of temperature increase was 2 °C per min., with maximum temperature of ≈500 °C. Crude PA was obtained as a dripping solution from the base of an opening of a gas spillage and was kept for 6 months in a dark, cool room. The top clear layer was removed from the deposited tar by filtering through a coffee filter paper (Karita Co., Tokyo) and was used in the following experiment. Shoot proliferation and rooting investiga- tion. To investigate the effect of PA on shoot proliferation, shoot tips were transferred to a proliferation medium containing 0%, 0.001%, 0.01%, or 0.1% (v/v) PA. The number of new shoots formed from each initial shoot and the rate of fresh weight increase after 30 d were recorded. To investigate the effect of PA on rooting, 10 mm shoot tips were cut and trans- ferred to a root initiation medium consisting of half-strength MS with 4.9 µM IBA, 58.5 µM sucrose, 1.35 mM phloroglucinol (1,3,5- trihydroxybenzene), 0.8% powder agar and 0%, 0.001%, 0.01% or 0.1% (v/v) PA and were kept in the dark at 25 °C. After 5 d, they were transferred to the same medium without IBA (root development medium). Rooting frequency, the average root length and sur- vival rate were recorded after 45 d. All media were adjusted to pH 5.7 and were autoclaved at 121 °C for 20 min. The PA solution was adjusted to pH 5.7 using 1.0 N NaOH, and the PA solution and phloroglucinol were filter- sterilized and were added to the medium after autoclaving. All cultures were incubated at a 16-h photoperiod illuminated by a cool-white fluorescent light (50 µmol·m -2

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Masanori Kadota

Papers

Effects of cytokinin types and their concentrations on shoot proliferation and hyperhydricity in in vitro pear cultivar shoots

Effects of charcoal with pyroligneous acid and barnyard manure on bedding plants

Improvement of micropropagation of Japanese yam using liquid and gelled medium culture

Production of triploid plants of Japanese pear ( Pyrus pyrifolia Nakai) by anther culture

Pyroligneous acid improves in vitro rooting of Japanese pear cultivars