On the assessment of the sources of inoculum of bacterial wilt in Brazil.

Dispersal of Ralstonia spp. cells by water and contaminated plant material and the importance of weeds as inoculum sources have been poorly investigated. Water of rivers, soil from fields of diverse crops and areas of natural vegetation both from the Amazonia, Cerrado and Mata Atlantica biomes, besides soil of the rhizosphere of weeds present in tomato fields with records of bacterial wilt were sampled and analyzed to detect Ralstonia spp. Seeds of tomato plants artificially and naturally infected with Ralstonia spp. were also processed. All samples were enriched a priori in selective medium South Africa (SMSA) and colonies were isolated in plates containing solid SMSA. Detection of Ralstonia spp. was confirmed by polymerase chain reaction with specific primers. The Co-operational PCR (CO-PCR) was also used to detect Ralstonia spp. Colonies were obtained from soil samples and from a commercial substrate sample. Five soil samples from eggplant fields, one from coffee field, one substrate from potato seed tuber production, two soil samples from the rhizosphere of Amaranthus spp., one from Bidens pilosa and one from Solanum americanum tested positive for Ralstonia spp. Besides these soil samples, five water samples of rivers were positive for CO-PCR detection: two samples from Amazonia, one from Cerrado and two samples from irrigation water collected from tomato fields located in the Mata Atlantica biome. Ralstonia spp. were not detected in tomato seeds. These results revealed potential inoculum sources, especially weeds, in areas with historical records of bacterial wilt. Additionally, rivers may act as dispersal agents of inoculum of Ralstonia spp.

Transplanting Hybrid Potato Seedlings at Increased Densities Enhances Tuber Yield and Shifts Tuber-Size Distributions

To contribute to the development of a novel cropping system for potato grown from greenhouse-derived seedlings from hybrid true potato seeds, planting density trials were carried out under normal Dutch agronomic conditions. For two consecutive years, 5-week-old seedlings of two experimental genotypes were transplanted into farmers’ potato production fields at two contrasting locations: a flat-bed system on sandy soil and a traditional ridge system on clay soil. Planting densities were 6.25, 12.5, 25, 50, 100 and 200 plants/m2 in the flat-bed system, and 3.125, 4.688, 6.25, 12.5, 25 and 50 plants/m2 in the ridge system. In general, increasing planting density of hybrid seedlings per area decreased tuber fresh weight per plant and reduced the number of tubers per plant. On a per hectare basis, an increased planting density resulted in increased total tuber yield and number of tubers up to very high densities, but finally both parameters levelled off. Highest total tuber yields harvested were 107 and 45 Mg/ha for the flat-bed and ridge system, respectively. On flat-beds, the optimal planting density for total yield was 50 plants/m2. On ridges, planting density interacted with year and genotype, resulting in an optimum planting density of 25 plants/m2 to reach the maximum total yield. Obtained yields in the commercial size classes Baby Baker (20 < size class ≤ 35 mm) and Seed Tubers (28 < size class ≤ 50 mm) were in general very high on the flat-beds, with a maximum Seed Tuber yield of 64 Mg/ha at 50 plants/m2. The current study showed that transplanted hybrid seedlings are feasible alternatives for seed-tuber-grown systems for certain potato outlets.

Interactive Effects of Vermicompost and Seed Tuber Size On the Production of Potato (Solanum Tuberosum L.)

An experiment was conducted to find out the effect of vermicompost and seed tuber size on the yield of Potato. The experiment consisted of two factors, i.e., factor A: Vermicompost level (Vc-4): Vc1: 0 t/ha, Vc2: 3 t/ha, Vc3: 6 t/ha and Vc4: 9 t/ha; factor B: Tuber size (T-5): T1: 5 - 10 g, T2: 10 - 20 g, T3: 20 - 30 g, T4: 30 - 40 g and T5: >40 g. Vermicompost was found to have a significant effect on most of the yield contributing parameters. Results showed that yield parameters increased with increasing vermicompost level irrespective of tuber size. Among the 20 treatment combinations, vermicompost @ 9 t/ha with tuber size > 40 g produced the maximum yield (31.33 t/ha) that was 216.82% higher than Vc1T1. Bangladesh J. Bot. 50(3): 695-700, 2021 (September)

LED Light Pre-Treatment Improves Pre-Basic Seed Potato (Solanum tuberosum L. cv. Golden King) Production in the Aeroponic System

Production of plants under artificial light conditions is an innovative and smart concept to grow food year-round in any location. However, pre-basic seed potato production in the greenhouse from LED pre-treated seedlings under an aeroponic system is a new and creative idea. Therefore, the objective of the study was to optimize the effect of LED pre-treatment and determine the best LED spectral composition on growth performance and tuberization of potato plants. Potato variety ‘Golden King’ was treated under 9 LED light spectra for 30 days—L1 (natural light), L2, (R:B), L3 (R:B:G), L4 (R:B:FR), L5 (R:B:G:FR), L6 (R:B:G:FR:UV), L7 (R:B:FR:UV), L8 (R:B:W:FR), and L9 (R:B:W:FR:UV) under 300 µmol m−2 s−1 photosynthetic photon flux density (PPFD), 23/15 °C (day/night) temperature, and 70% relative humidity. The study revealed that growth characteristics and tuber number for plants were increased most by the light spectrum L4 (R:B:FR). Furthermore, photosynthetic pigments increased in L4, L7, and L8, while TSC and sucrose accumulated more in L1 treatment. In contrast, higher seed tuber fresh weight was recorded in L8, L9, L4, and L7. Overall, it can be concluded that potato seedlings pre-treated with the L4 (R:B:FR) LED spectral composition performed best for growth, establishment, and tuberization.

Yield and Yield Contributing Attributes Of Potato as Influenced by Vermicompost And Seed Tuber Size

Low yield is crucial bottleneck for potato production in Bangladesh. The application of vermicompost may enhance the yield of potato. The experiment was consisted of two factors, i.e., Factor A: - Vermicompost level (Vm1-4): Vm1: 0 t ha-1, Vm2: 3 t ha-1, Vm3: 6 t ha-1 and Vm4: 9 t ha-1; Factor B:- Tuber size (T1-5): T1: 5-10 g, T2: 10-20 g, T3: 20-30 g, T4: 30-40 g and T5: > 40 g. The experiment was conducted in a split-plot design with three replications. Vermicompost had significant effect on most of the yield contributing parameters investigated under present study. Results revealed that yield parameters increased with increasing vermicompost level irrespective of tuber size. Among the twenty (20) treatment combinations, vermicompost at the rate of 9 t ha-1 with tuber size > 40 g produced the maximum yield (31.33 t ha-1) that was 53.53 % higher than that of control with 3273.01 $ of monetary advantage. Therefore, present study suggests that potato growers may use vermicompost for increasing yield of potato in Bangladesh. SAARC J. Agric., 19(1): 71-79 (2021)

Agro-techniques for Production of Seed Size Tubers in Conventional Seed Potato Production System–A Review

The seed potato cost is very important component in total potato production and account for 30 to 70% which varies depending on the country or region. Tuber size is an important factor to decide the seed requirement per unit area. Seed size affects total yield, graded or marketable tuber yields. Standard seed tuber of 25–125 g weight (30–55 mm) is known as seed size tubers in India. Obtaining seed size tuber is important for achieving higher potential of the cultivars. The tuber size profile can be reduced or expanded by altering inter and intra row seed spacing, controlling days of growth by planting late or killing vines/haulm early, regulating inputs like fertilizer and water etc. An ideal combination of plant population, row width, and in-row seed spacing for a particular variety were the major factors for optimizing tuber size. Variation in tuber bulking ability in different genotypes results in variation in proportion of seed size tubers among different varieties. 70–80 days haulm killing found most suitable for getting higher proportion of seed size tubers in high bulking varieties. Proper management of N, P and K fertilizers is considered very important to maximize tuber yield and attain desirable quality. Variability in nitrogen dose/ha was observed which ranged from 100–150 between different regions of the world. Hence proper combination of above Agro-techniques should be adopted in seed production programme as per the region for getting higher proportion of seed size/plantable seed tubers.

PENINGKATAN PERTUMBUHAN DAN HASIL BAWANG MERAH (Allium ascalonicum, L) DENGAN APLIKASI PERBEDAAN KONSENTRASI BIO SLURRY DAN PEMOTONGAN UMBI BIBIT

ABSTRACT This study aims to determine the effect of bio slurry and cutting of seed tubers on the growth and yield of shallot plants in the Dukuh Kepoh Food and Horticultural Garden, Tohudan Village, Colomadu District, Karanganyar Regency with a height of ± 105 m above sea level, from April until June 2020. This study used a factorial method with a complete randomized block design (RAKL), consisting of two treatment factors, while the two treatment factors with 12 treatment combinations, each treatment was repeated (3) times. The first treatment, the concentration of bio slurry (S) which consists of 4 levels, namely (S1: Bio slurry 0 ml / l, S2: Bio slurry 50 ml / l, S3: Bio slurry 100 ml / l, S4: Bio slurry 150 ml / l). The second treatment was cutting the seed tubers (P), which consisted of three levels (P1: Cutting 1/4 part of seed tubers, P2: Cutting 1/3 parts of seed tubers, P3: Cutting 1/2 parts of seed tubers). The results showed that the treatment with bio slurry (S) had no significant effect on all observed parameters. Treatment by cutting seed tubers (P) had a very significant effect on plant height, weight of fresh tubers per plant, weight of fresh tubers per plot and had a significant effect on the number of fresh tubers per plant, but had no significant effect on the number of tubers per plot and weight of fresh stems. The combination between the treatment of bio slurry and cutting of seed tubers (SxP) did not significantly affect all observed parameters, The highest yield of fresh tubers per plot was obtained in treatment (S2P2) with a yield of 800.00 g, while the lowest tuber weight per plot was obtained in treatment ( S1P3) with a yield of 433.33 g. Keywords: shallot, bio-slurry, seed tuber cutting

Pectobacterium parmentieri (black leg disease of potato).

Pectobacterium parmentieri is a bacterial pathogen of potato present in Europe since the 1960s. The bacterium was earlier classified as Pectobacterium carotovorum. After reclassification of P. carotovorum subsp. carotovorum SCC3193 to P. wasabiae and later on to P. parmentieri, several studies devoted to identification of pectinolytic bacteria in international collections and identification of the strains isolated from infected potato plants have indicated that this bacteria commonly occurs in several regions of Europe, Canada, USA, New Zealand and South Africa. P. parmentieri can cause symptoms of blackleg and soft rot on potato tubers. These diseases are usually a consequence of latent infection of seed potatoes. In the majority of countries pre-basic and basic seed tuber potatoes intended for the production of seed tuber crops should be free of Pectobacterium spp. and Dickeya spp. P. parmentieri is not present on any international or national alert lists.

Co-occurrence of latent Dickeya and Pectobacterium species in potato seed tuber samples from northern Finland

Recent methodological developments have uncovered the etiological diversity of the potato blackleg and soft rot Pectobacteriaceae. At least five species in the genera Dickeya and Pectobacterium have been confirmed to cause blackleg on potatoes in Finland. The bacteria are seed borne and remain latent in the tuber until conditions favourable for growth, multiplication and infection prevail. Tubers could be infected by one or more of these species. This short communication is based on the results of molecular detection data collected for more than 14 years from potato seed lots produced in Finland. Diagnostic PCR assay specific to Dickeya solani, Pectobacterium atrosepticum, Pectobacterium carotovorum, P. brasiliense and P. parmentieri revealed that potatoes are infected by one or more of these species; it also revealed that single species infection is more common than multiple colonization. An event of simultaneous occurrences of different strains from the Pectobacterium species appears to be more frequent than that observed between Dickeya and Pectobacterium species. The absence of co-occurrence of Dickeya solani and Pectobacterium atrosepticum is intriguing.