Modeling the Effect of Temperature on Ginger and Turmeric Rhizome Sprouting

Ginger and turmeric are tropical plant species with medicinal, beverage, and edible uses. Both species are typically propagated using seed rhizomes that often lack uniformity when sprouting, ultimately affecting the transplant growth and quality. Our objectives were to (1) develop a model to predict the effect of temperature on rhizome sprouting and transplant growth and (2) characterize the morphological factors affecting the sprouting of ginger and turmeric rhizomes. Two experiments were conducted where the rhizomes were placed in plastic bags with a moist substrate inside dark incubator chambers. Five temperature treatments (21, 25, 27, 30, and 32 °C) were used for calibrating the model, and six temperature treatments (14, 20, 25, 30, 35, and 40 °C) were used in the validation phase. The number of days for rhizomes to develop 1- and 5-cm sprouts were counted; after which, the total number of sprouts, total leaf length, and root quality were measured. A nonlinear regression analysis was used to develop temperature–response curves. Ginger and turmeric had optimal sprouting temperatures of 27.5 and 30.1 °C, respectively. Temperatures close to the optimal reduced the time to sprout and to subsequently reach the transplant stage. No sprouting was observed at 14 °C, and the minimum temperature to develop 5-cm sprouts was estimated at slightly above 17 °C in both species. Temperatures above 32 °C resulted in tissue damage and rhizome loss. The results from this study show the potential to produce uniform ginger and turmeric transplants using temperature treatments that accelerate sprouting.

Changes of organic phosphorus in river waters in northern Bangladesh

The variability in phosphorus concentrations and the decomposition rates of organic phosphorus were measured in five selected rivers through four surveys in July and November of 2012, and February and May of 2013. After collection the water samples were incubated for 20 days in a dark incubator and the change of forms of phosphorus such as particulate organic phosphorus (POP), dissolved organic phosphorus (DOP) and dissolved inorganic phosphorus (DIP) were analyzed. By fitting the changes to two types of models, the decomposition rates of organic phosphorus were determined. The mean total organic phosphorus (TOP) decomposition rate coefficients in the studied rivers was 0.039 day-1. The average POP decomposition rate coefficient (POP?DOP?DIP model) was 0.038 day-1 while the mean DOP decomposition rate coefficient was 0.251 day-1. The decomposition rate coefficients measured in this study might be applicable for modeling of river water quality.Int. J. Agril. Res. Innov. & Tech. 5 (2): 31-36, December, 2015

First Report of Pindo Palm Heart Rot Caused by Ceratocystis paradoxa in China

On January 12th, 2012, a novel disease with an incidence of 50% was discovered in Pindo palm Butia capitata (Mart.) Becc from the Coconut Grant View Garden (19°33.137′ N, 110°47.482′ E) located in Wenchang, Hainan Province. Diseased leaflets at the base of the rotted heart leaves had reddish brown lesions; when the infection progressed, the leaves turned yellow and became blighted from the inner to the outer part of the crown. Once the growing point was destroyed, the entire tree ultimately died. Tissues from the edges of lesions from diseased leaflet samples were placed onto potato dextrose agar (PDA) and incubated at 25°C for 3 days. The color of colonies of five isolates obtained turned from white to black in 48 h. The optimum temperature for mycelium growth was from 20 to 30°C, and no growth occurred at temperatures higher than 40°C or lower than 5°C (n = 5). The cylindrical colorless to pale brown conidia were 7.5 to 17.5 μm long × 5.0 to 7.5 μm wide (n = 100); oval black chlamydospores were 12.5 to 22.5 × 7.5 to 15.0 μm (n = 100). The sequence (497 bp) of the internal transcribed spacer (ITS) region of the representative isolate BX3 (China Center for Type Culture Collection No. CCTCC AF2014002) was amplified using primer pair ITS1/ITS4 (GenBank Accession No. KF939052) and shared 99% sequence identity with Ceratocystis paradoxa strain xie331-4 (JQ039332). Based upon these biological characteristics and ITS sequence, this pathogen was identified as C. paradoxa (Dade) C. Moreau (anamorph Thielaviopsis paradoxa (de Seynes) Höhn.) (3). Pathogenicity tests were conducted on 8-cm-long sections of young leaflets excised from a 12-year-old pindo palm tree. One side of the midrib of 10 sections was wounded with a sterilized scalpel at the center and the other side was non-wounded, then a PDA plug (4 to 6 × 4 to 6 mm) from the edge of an actively growing colony of BX3 incubated for 3 days were inoculated onto each wounded or non-wounded site. As controls, plain PDA plugs were placed on wounded and non-wounded spots of another 10 sections following the above procedure. Pathogenicity was tested twice. Each inoculated section was then put into a 9-cm petri dish in which two filter papers (Φ = 9 cm) were placed and 8 ml of sterile water were added to maintain high humidity, and then all dishes were placed in a dark incubator at 25°C. After 5 days, typical symptoms developed only on the wounded points inoculated with mycelium plugs. C. paradoxa was re-isolated from the margins of the expanding lesions. C. paradoxa causing fruit rot of B. capitata was reported in Uruguay (2), but to our knowledge, there are no previous reports of this species in China or infecting leaves of B. capitata worldwide (1). We report here a new Ceratocystis disease on B. capitata, and it was named as pindo palm heart rot based on its symptoms. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , Feb 21, 2014. (2) V. Gepp et al. New Dis. Rep. 27:12, 2013. (3) F. Y. Yu et al. Plant Dis. 96:290, 2012.

A Cowpea Seed Rot Disease Caused by Fusarium equiseti Identified in Nigeria

Fusarium equiseti (Corda) Sacc., reported on cowpea (Vigna unguiculata (L.) Walp.) seeds in India (2), was isolated for the first time in Nigeria from naturally infected cowpea seeds. Cowpea, cv. IT90K-76, seeds (400) from plants grown in Nigeria were surface-disinfested in 0.05% NaOCl and placed on moist filter paper in petri dishes (10 seeds per dish) and then in a dark incubator for 4 days at 27°C. After incubation, some seeds had fungal mycelia growing on their surfaces. When cultured on potato dextrose (PDA) and Spezieller Nährstoffarmer (SNA) agars, the fungi produced macroconidia characteristic of F. equiseti (1). Septate macroconidia were three to six celled with extended apical and distinctive foot-shaped basal cells. F. equiseti was recovered from 4.25% of seeds, and incidence correlated positively with development of seed rot symptoms. To confirm pathogenicity, 80 cowpea seeds were surface-disinfested with NaOCl, and 40 were soaked for 6 h in a suspension of 3 × 105 conidia of F. equiseti per ml of water. The remaining seeds were soaked in sterile distilled water. After incubation, white mycelia developed on 87.5% of seeds soaked in the conidial suspension and rotted without germinating. Only 5% of seeds soaked in sterile water developed seed rot symptoms. When cultured on PDA and SNA, fungi isolated from artificially infested seeds with rot symptoms again were identified as F. equiseti. References: (1) P. E. Nelson et al. 1983. Fusarium species: An illustrated Manual for Identification. Pennsylvania University Press, University Park. (2) O. K. Sinha and M. N. Khare. Seed Sci. Technol. 5:721, 1977.

Sorption, Mobility and Degradation of Triclopyr and 2,4-D on Four Soils

Laboratory studies were conducted to determine the relative sorption, mobility, and degradation rates of triclopyr and 2,4-D on two surface soils and two subsoils from the rice-producing areas of Arkansas. Triclopyr sorption was slightly greater than 2,4-D sorption. However, mobility of the herbicides on a given soil did not differ. Sorption of both herbicides was greatest and mobility lowest on a subsoil with the lowest pH. Triclopyr degradation rates were lower than 2,4-D degradation rates in a dark incubator. The average half life was 138 d for triclopyr and 21 d for 2,4-D. High soil moisture content (0 versus 100 kPa water tension) increased the rate of 2,4-D degradation. Triclopyr degraded more rapidly at 30 C than at 15 C. The dissipation rates of both herbicides were lowest on the soil on which sorption was greatest.

TRANSFORMATION OF ONION CALLUS VIA PARTICLE BOMBARDMENT

Particle bombardment was investigated as a potential transformation method for onion. Seeds of Allium cepa `TG 1015' were planted onto BDS medium and placed in a dark incubator at 25C for germination. Two to 3 weeks after the seeds were germinated, meristems (1 to 2 mm) were excised and placed onto BDS medium containing 2 mg 2,4-D/liter for callus initiation. Callus was transferred monthly onto fresh BDS medium containing 2,4-D until bombardment. The reporter gene for B-glucuronidase (GUS) expression was used to assess efficiency of gene delivery in all particle bombardments. Characteristics examined were target distance and helium pressure (particle velocity). Tissues were subjected to the 5-bromo-4-chloro-3-indoyl-B-D-glucuronide (xgluc) test for detection of GUS activity. Measurements were taken on particle dispersion as affected by target distance and helium pressure. GUS expression was detected in putatively transformed tissues.