Andrew Riseman

Assessment of System of Rice Intensification (SRI) and Conventional Practices under Organic and Inorganic Management in Japan

Abstract The system of rice intensification (SRI) is a production system that involves the adoption of certain changes in management practices for rice cultivation that create a better growing environment for the crop. This system was compared with conventional practices and assessed under organic and inorganic management. SRI practices showed significant response in root number, number of effective tillers per hill, days to flowering and harvest index. In addition, SRI was found effective in minimizing pest and disease incidence, shortening the crop cycle, and improving plant stand. Grain yield was not different from conventional method. Except for harvest index and plant lodging percentage, there were no significant effects from management treatments. Synergistic responses were noted when SRI practices were combined with organic management for plant height, number of effective tillers per hill, days to flowering and to maturity. The improved panicle characteristics, lower plant lodging percentage and higher harvest index that ultimately led to comparable grain yields. Net returns increased approximately 1.5 times for SRI-organic management regardless of the added labor requirements for weed control. However, comparatively higher grain yield from conventional-inorganic methods underscore the need for further investigations in defining what constitutes an optimum set of practices for an SRI-organic system specifically addressing grain yield and weed management.

Nitrogen and carbon transformations, water use efficiency and ecosystem productivity in monocultures and wheat-bean intercropping systems

Enhancing soil organic carbon (SOC), nitrogen (N) and water use efficiency (WUE) are significant challenges in intensive wheat production. An intercropping system combining wheat and grain legumes may help maintain SOC, soil mineral N and WUE while also providing an opportunity to sequester carbon (C) in low input organic systems. We grew wheat (Triticum aestivum cv. ‘Scarlet’) as a monoculture and intercropped with either common bean (Phaseolus vulgaris cv. ‘Red Kidney’, or cv. ‘Black Turtle’), or fava bean (Vicia faba cv. ‘Bell’) in rows of 1:1, 2 wheat: 1 bean or broadcast arrangement without fertilizers for 2xa0years to assess the effects of genotype and spatial arrangement on biological nitrogen fixation and seasonal transfer, WUE, gross ecosystem photosynthesis (GEP), and net ecosystem productivity (NEP). Stable isotope methods (13C and 15N natural abundance) were used to quantify C and N within the plant and soil system. Field CO2 exchange measurements used a dynamic closed transparent chamber connected to a portable CO2 analyzer. Intercropped plots had higher percent N derived from symbiotic N2 fixation, and increased C and N accumulation compared to monocultured wheat. The fava bean cv. Bell intercrops showed increased nodulation (60–80xa0% more nodules) and percent N derived from symbiotic N2 fixation (10–12xa0% higher) compared to common beans resulting in the fixation of 74xa0kgxa0Nxa0ha−1 biologically from the 1:1 arrangement. The highest rate of N-transfer (13xa0%) was observed in the wheat-fava bean cv. Bell combination when planted in the 1:1 arrangement. All intercrops accumulated more N in shoot biomass compared to monoculture wheat with wheat-fava bean cv. Bell (1:1 arrangement) accumulating the highest N (34xa0kgxa0Nxa0ha−1, i.e., 176xa0% higher) and C (214xa0gxa0Cxa0m−2 year−1, i.e., 26xa0% higher). All plots fixed the most CO2 (i.e., greatest GEP) during mid-growth stage (50xa0days after seeding i.e., prior to flowering) however, wheat-fava bean cv. Bell in the 1:1 arrangement displayed the greatest NEP sequestering C at the seasonal daytime average rate of 208xa0mgxa0Cxa0m−2xa0h−1 (i.e., 7xa0% higher than wheat monoculture plots). Intrinsic WUE of wheat, as indicated by δ13C, was also improved when grown with fava bean cv. Bell or common bean cv. Red Kidney. This study demonstrated that intercropping wheat and fava bean is an effective strategy to achieve greater nitrogen fixation and transfer to the wheat counterparts, higher WUE, and ecosystem productivity than wheat monocultures in areas with low soil N and C. Furthermore, the wheat-fava bean cv. Bell (1:1 arrangement) was more productive than either the 2:1 or mixed planting arrangements.

Review of Potato Molecular Markers to Enhance Trait Selection

Noncommercial varieties of potatoes (Solanum tuberosum L.) harbor genetic potential for improvements of disease resistance and abiotic stress tolerance in commercial potato cultivars; however, introducing traits from noncommercial varieties to breeding stock can be extremely labor intensive. Molecular genetic markers closely associated with a trait can be used to decrease the time spent phenotyping varieties. Here we review genetic markers that have been used for marker-assisted selection (MAS) in potato. Most MAS markers have been used to detect disease resistance genes, and our review focuses on those markers. Complex traits such as cold, drought and viral tolerance can be studied by comparing expressed genes; next-generation sequencing technologies will help in the discovery of trait-specific molecular markers. This review aids in summarizing the potential of these molecular tools when breeding for complex traits in potato.ResumenLas variedades no comerciales de papa (Solanum tuberosum L.) poseen potencial genético para mejoramiento de resistencia a enfermedades y tolerancia al agobio abiótico en variedades comerciales de papa; no obstante, la introducción de caracteres de variedades no comerciales al acervo de mejoramiento puede involucrar extremadamente intensa mano de obra. Se pueden usar marcadores genéticos moleculares cercanamente asociados a un carácter para disminuir el tiempo que se usa en la descripción fenotípica de variedades. Aquí revisamos los marcadores genéticos que se han usado para selección asistida con marcadores (MAS) en papa. La mayoría de los marcadores MAS se han usado para detectar genes de resistencia a enfermedades, y nuestra revisión se enfoca en ellos. Caracteres complejos como tolerancia al frío, a la sequía y a virus se pueden estudiar mediante comparación de genes expresados; las tecnologías de secuenciación de la siguiente generación ayudarán en el descubrimiento de marcadores moleculares específicos por carácter. Esta revisión ayuda a resumir el potencial de estas herramientas moleculares cuando se hace mejoramiento para caracteres complejos en papa.

In vitro propagation of seven Daphne L. species

Cultures of seven Daphne species: Daphne caucasica, D. cneorum, D. giraldii, D. retusa, D. jasminea, D. laureola and D. tangutica were established inxa0vitro on MS/WPM based media. Five of the species responded best on MS-based media (D. tangutica, D. laureola, D. caucasica, D. retusa and D. giraldii), while the remaining two species performed best on WPM-based media (D. cneorum, and D. jasminea). Shoot proliferation was achieved from both apical and nodal explants. Shoots were sub-cultured from stock cultures, cut into nodal explants 3–5xa0cm long and place vertically on basal media supplemented with different concentrations and combinations of cytokinins and auxins. Individual species displayed different responses to the various cytokinins and auxins. Among species, D. jasminea produced the greatest proliferation rate with an average of 7.84xa0+xa00.6 shoots per explant on WPM supplemented with 2.32xa0μM BAxa0+xa00.0045xa0μM TDZxa0+xa00.054xa0μM NAA, while the best multiplication rate for the same species grown on the same media supplemented with a single cytokinin (BA) and no auxin was 2.60xa0+xa01.3 shoots per explant. Following multiplication, new shoots transferred to the elongation trails and then 50–100xa0mm Shoots used for rooting experiments. Increased rooting efficiencies were observed on inxa0vitro-generated shoots with the two-layer medium or dipping methods over when PGRs were uniformly incorporated into the medium. Maximum rooting frequencies (average) ranged from 59% in D. tangutica to 85% in D. jasminea. Following inxa0vitro rooting, rooted shoots immersed in 0.01% solution of humates and planted into a standard horticultural substrate composed and watered weekly with a solution containing half-strength MS salts.

Root architecture variation in wheat and barley cultivars.

Aims: We analyzed root architecture varia tion among heirloom and commercial cultivars of wheat and barley to improve our understanding of the quantitative variation present within small grain root architectures. We also compared lab-based root architecture measures with cultivarshoot:rootratiosand field data. Study Design: This study had a c

How an Entry-Level, Interdisciplinary Sustainability Course Revealed the Benefits and Challenges of a University-Wide Initiative for Sustainability Education.

Purpose – Delivery of sustainability-related curriculum to undergraduate students can be problematic due to the traditional “siloing” of curriculum by faculties along disciplinary lines. In addition, while there is often a ready availability of courses focused on sustainability issues in the later years of students’ programs, few early entry-level courses focused on sustainability, broad enough to apply to all disciplines, are available to students in the first year of their program. Design/methodology/approach – In this paper, we describe the development, and preliminary implementation, of an entry-level, interdisciplinary sustainability course. To do so, the authors describe the development of a university-wide initiative designed to bridge units on campus working and teaching in sustainability areas, and to promote and support sustainability curriculum development. Findings – The authors describe the conceptual framework for organising course content and delivery. The authors conclude with an informal ...

First report of Thielaviopsis basicola on Daphne cneorum

A previously undescribed fungal disease, coined daphne sudden death syndrome (DSDS), was reported on Daphne cneorum from several nurseries and research centres in British Columbia, Canada. Diseased and healthy plants were obtained from several sources, and from these plants, the following fungi were isolated: Fusarium roseum, Fusarium oxysporum, Trichoderma sp., Aspergillus sp., and Thielaviopsis basicola. However, only Thielaviopsis basicola was recovered from every diseased plant while being absent from healthy plants. All isolated fungi were grown as pure cultures and individually inoculated, via topical application of a spore suspension, to the roots of either healthy, 2-year-old D. cneorum plants or healthy rooted plantlets grown in vitro. The Thielaviopsis basicola isolate was the only recovered fungus to induce symptoms that matched those previously observed from DSDS-infected plants. Therefore, we conclude that Thielaviopsis basicola is the causal agent of DSDS.