Root architecture of provenances, seedlings and cuttings of Melia volkensii: implications for crop yield in dryland agroforestry

Melia volkensii (Gürke) is being increasingly promoted as an on-farm tree in Kenya. Researchers’ and farmers’ views on its competitiveness with crops differ; research station studies have found it to be highly competitive whereas farmers do not consider it to be so. Because of difficulties in seed germination, it is probable that dissemination programmes will rely upon plants produced from root and stem cuttings, rather than on seedlings. This study evaluates differences in root system architecture of plants raised from seed (of four provenances), stem or root cuttings and the relationships between the competitivity index (CI) and crop yield. Cuttings were more shallowly rooting than seedlings, and had higher competitivity indices, and there was a negative relationship between CI and crop yield. No differences in root architecture between provenances were found. Therefore, to reduce tree-crop competition, the use of seedlings rather than cuttings should be recommended when promoting the use of this species on dryland farms. If cuttings are used to circumvent the problems of seed germination, alternative methods of controlling competition, such as root pruning, need to be considered

Evaluation of chilling requirements for six Arkansas blackberry cultivars utilizing stem cuttings

Woody perennial plants including blackberries (Rubus subgenus Rubus) require certain amounts of chilling or rest hours below 7ºC during the dormant season for successful bud break the following year. Arkansas-developed blackberry cultivars are being grown in various climates worldwide and all cultivars need chilling requirement estimates for accurate recommendations of adaptation. Determining chilling requirement using stem cuttings collected from field-grown plants rather than whole plants is a desirable system. We conducted a study to evaluate both artificial and field chilling of six cultivars. For the artificial-chilling study, 12- node stem cuttings were collected 2 days after the first killing frost. These were then placed in a moist medium in a walk-in cooler at 3ºC. At 100 hour chilling intervals, five cuttings of each cultivar were placed under an intermittent mist system. For the field-chilling study, a biophenometer was placed in the field to measure chill, and ten 12-node stem cuttings of each cultivar were collected at 100-hour intervals of chilling up to 1000 hours below 7ºC and placed under mist. For both studies the mist bench was located in a heated greenhouse (min. temperature of 15ºC), and cuttings were placed according to a completely random design. Budbreak was recorded weekly. Studies were analyzed separately by SAS. Results for Study One, artificial-chilling, were inconclusive due to a lack of clear differentiation among the cultivars and chilling intervals. Study Two, using field-chilling, showed a significant chilling interval x cultivar interaction. ‘Arapaho’ appeared to have a chilling requirement of 400 to 500 hours, ‘Kiowa’ 200 hours, ’Shawnee’ 400 to 500 hours, and ‘Chickasaw’ possibly 600 to 700 hours. The cultivars Choctaw and Apache did not provide clear chilling interval differentiation in the study. Our results indicate that the use of stem cuttings receiving field chilling to evaluate chilling requirement of blackberry cultivars has merit and can be a successful method in this research area

Effect of Vegetative Propagation Materials on Globe Artichoke Production in Semi-Arid Developing Countries: Agronomic, Marketable and Qualitative Traits

Abstract: In Tunisia, globe artichoke is mainly propagated by underground dormant axillary buds (ovoli), which are removed from the field in August during the quiescence period. The high cost of in vitro-plants and the absence of specialized nurseries were among the reasons for the rise of heterogeneity and spread of diseases. The aim was to help farmers to improve artichoke yield and quality by ameliorating their vegetative propagation technique with low cost methods. Three plant cuttings management methods were tested: summer ovoli (T0); spring offshoots nursery\u2019s cuttings forced to pass a vegetative rest period by stopping irrigation (T1); and offshoots nursery\u2019s cuttings not forced (T2). The cuttings management can affect both yield and qualitative traits of artichoke. T1 nursery plants produced the heaviest primary heads, 7% and 23% higher than T2 and T0, respectively. T1 plants exhibited the highest yield during the harvest season, with +17.7% and +12.2% compared to T0 and T2, respectively. T0 and T1 showed the highest total antioxidant capacity and inulin content; the propagation method also affected the short-chain sugars ratio. T1 is a viable and sustainable alternative to the traditional one that does not heavily impact on growing costs and improves yield and quality of artichoke

Propagation of thornless blackberries utilizing adventitious shoots from root cuttings

Studies were conducted in early 2003 to determine the effect of root source and length on yield of adventitious shoots from root cuttings and on subsequent plant yield for University of Arkansasdeveloped thornless blackberries. In the first study, roots from ‘Arapaho’ and ‘Apache’ plants grown in an aboveground bed containing commercial potting soil were compared to field-grown roots. Bed-grown roots averaged 6.9 shoots per 15 cm root cutting while field grown roots averaged 3.4. ‘Apache’ produced more shoots/root cutting compared to Arapaho, (5.9 vs. 4.4 shoots/root cutting, respectively). In a comparison of 15- vs. 30-cm-long root cuttings of ‘Apache’, ‘Arapaho’, and ‘Ouachita’, shoot yield of 30-cm roots was higher than that of 15 cm roots, but total yield of shoots per root unit was not increased by the longer root cuttings. Rooting of adventitious shoots neared 100% in both studies, and resulting quality of plants from these shoots was very good. This minor modification to the traditional method of planting root pieces to yield individual plants could lead to a more efficient and productive yield of propagules. The use of adventitious shoots from root cuttings for blackberry plant propagation appears to be a viable method for nurserymen to consider

Recovery at Morvin: SERPENT final report

Recovery from disturbance is poorly understood in deep water, but the extent of anthropogenic impacts is becoming increasingly well documented. We used Remotely Operated Vehicles (ROV) to visually assess the change in benthic habitat after exploratory hydrocarbon drilling disturbance around the Morvin well located at 380m depth in the Norwegian Sea.An ROV, launched directly from the rig drilling the well in 2006 was used to carry out video transects around the well before drilling and immediately after. On a return to the site three years after disturbance a larger survey was conducted with a ship-launched ROV in 2009. Transects were repeated at the disturbed area and random background transects were taken. Visible drill cuttings were mapped for each survey, and positions and counts of epibenthic invertebrate megafauna were determined, revealing a fauna dominated by Cnidaria (45% of total observations) and Porifera (33%).Immediately after disturbance a visible cuttings pile extended to over 100m from the well and megafaunal density was significantly reduced (0.07 individuals m-2) in comparison to pre-drill data (0.23 ind. m-2). Three years later the visible extent of the cuttings pile had reduced in size, reaching 60m from the well and considerably less in some headings. In comparison to background transects (0.21 ind. m-2), megafaunal density was significantly reduced on the remaining cuttings (0.04m-2), but beyond the visible disturbance there was no significant difference (0.15m-2). The investigation at this site shows a return to background densities of megafaunal organisms over a large extent of the area previously disturbed. However a central area, where the initial cuttings pile was deepest, demonstrated reduced sessile megafaunal density which persisted three years after disturbance. Elevated Barium concentration and reduced sediment grain size suggests persistence of disturbance beyond the remaining visibly impacted area which may result in changes to the infaunal communities undetectable by ROV video survey

Aspects of energy requirements for rock drilling

Development of laboratory rock breakage techniques to relate energy and surface area produced by slow compression, drop hammer and stamp mill. A detailed study of laboratory rotary-percussive drilling in a wide range of rocks under different conditions, with the collection of drill cuttings and measurement of the drill parameters. The correlation of drill parameters with rock indices by energy concepts and the developed empirical formula. Field rotary-percussive drilling studies and collection of drill cuttings on the basis of laboratory analysis

Nitrogen use efficiency of cereals in arable organic farming

The effect of nitrogen (N) supply and weeds on grain yield of spring barley, winter wheat and winter rye was investigated from 1997 to 2004 in an organic farming crop rotation experiment in Denmark on three soil types varying from coarse sand to sandy loam. Two experimental factors were included in the experiment in a factorial design: 1) catch crop (with and without), and 2) manure (with and without). The apparent recovery efficiency of N in grains (nitrogen use efficiency, NUE) from NH4-N in applied manure varied from 29 to 38% in spring barley and from 23 to 44% in winter cereals. The NUE of above-ground N in catch crops sampled in November prior to the spring barley varied from 16 to 52% with the largest value on the coarse sandy soil and the smallest value on the sandy loam soil. The NUE of N accumulated in grass-clover cuttings varied from 14 to 39% with the lowest value on the coarse sandy soil, most likely due to high rates of N leaching. The NUE declined with increasing amounts of N accumulated in the grass-clover cuttings. This indicates that grain yields can be improved by removing the grass-clover cuttings and applying the N contained in the cuttings in spring to the cereal crops, possibly after fermentation in a biogas reactor

Unsuccessful Cassava Brown Streak Disease (CBSD) evaluation attempts in western Democratic Republic of Congo and implications with cassava root necrosis disease (CRND) etiology

Open Access ArticleCassava brown streak disease (CBSD) is the second most important virus disease after Cassava mosaic disease (CMD), infecting cassava (ManihotesculetaCrantz) in Africa. The disease is caused by two distinct viruses, Cassava brown streak virus [2, 3] and Ugandan Cassava brown streak virus (family, Potyviridae: genus, Ipomovirus). Transmission of CBSV from one plant to another is reported to occur through grafting CBSV-free with infected cuttings and subsequent dissemination by infected cuttings. The basic approach to control of CBSD is selecting planting material from symptomless mother plants. Graft inoculation is the most efficient and effective of the techniques for CBSD virus transmission and consequently cuttings are the most effective way of the disease spreading. In early 2000s, cassava root necrosis similar to those of CBSD were reported in western provinces of Democratic Republic of Congo (RDC) (Kinshasa and Kongo Central) and up to date PCR diagnoses did not detect any causal agent related to the observed symptoms and the disease which was still referred as ‘CBSD-like disease’. Due to lack of molecular data and the similarity of root symptoms with CBSD, the existence of a virus has always been suspected to be the cause of CBSD-like propagation. Thus, 2 field experiments were proposed in order to verify the existence of a systematic transmission of a possible CBSD related virus, knowing that CBSD viruses are transmitted efficiently by cuttings. The first trial focused on the field evaluation of CBSD – like infected and apparently uninfected planting materials, while the second trial involved the importation of tanzanian CBSD resistant genotypes for evaluation in INERA Mvuazi research center under CBSD-like infection conditions. Results of the first trial did not show a systemic transmission of any CBSD-like pathogen while CBSD-resistant parents involved in the second trial all succumbed to CBSD-like disease