The field and laboratory experiments were conducted to assess and improve the health and quality of farmer’s stored rice seed and to preserve high quality rice seed. The laboratory experiments were conducted in the Department of Plant Pathology laboratory, Patuakhali Science and Technology University Dumki, Patuakhali and the field experiments were conducted at Agriculture Farm, Patuakhali Science and Technology University Dumki, Patuakhali and farmers field, Dumki, Patuakhali during 2008-2011.
Assessment of health and quality of farmers stored rice seeds of different cultivars before sowing in the field.
Collection of seed samples
Seed samples (1 kg/farmer) were collected after storage from the selected farmers during July, 2008. Each sample was contained in a brown paper bag with proper labeling. The seed samples were preserved in cool room at the PSTU, Dumki for subsequent use in the study. Those seed samples were treated as submitted samples and subjected to different tests for assessing the health and quality. The collected samples were divided into two portions. One portion was used for purity analysis, moisture, germination, vigour and seed health test. The other portion was used for growing in the field to determine the productivity test.
Purity analysis: The purity analysis was done following the standard procedure (ISTA, 2003). Working sample of about 40g was prepared from each submitted sample. The working sample was separated into three components as follows: i) Pure seed ii) Other seeds and iii) Inert matter. Weight of individual fraction was taken with the help of an electric balance. The results were expressed in percentage.
Determination of moisture content:
The moisture content of seed samples were determined by using low constant oven method following the guidelines of International Seed Testing Association (ISTA). The moisture was measured just after collection of seed from the respective farmers. For each treatment 15 g seed was taken into a crucible and weighed. Then the crucible was kept in an electric oven maintained at a temperature of 105±2 0C for a period of 48 hours for proper drying of the seed sample. After cooling the weight of dish plus its cover and contents were taken. Then the moisture content of the seed sample was calculated on wet basis with the help of the following formula (ISTA, 2007).
M2-M3
Seed moisture content (wet basis) = --------- X 100
M2-M1
Where,
M1 = Weight of Aluminum disk + Cover
M2 = Weight of Aluminum disk + Cover + Seed before drying
M3 = Weight of Aluminum disk + Cover + Seed after drying
Germination Test: Four hundred seeds were counted from pure seed fraction of purity analysis. Plastic tray was filled with fine sand moistened with clean tap water. One hundred seeds were sown in each tray and used as a replication. After 5, 7 and 14 days of sowing each seedling was evaluated in accordance with the general principles laid down in ISTA rules. At the end of the germination test, the sample was categorized as normal seedlings, abnormal seedlings and diseased seedlings. The results were expressed as percentage by number of healthy seedlings, abnormal seedlings and diseased seedlings.
Vigor Test: This test was carried out following ISTA rules (2003). Seeds were planted in a single row in a plastic tray filled with sterilized moistened sand for germination for 14 days. Root and shoot length of randomly taken fifty seedlings per replicate were measured after 14 days. The seedling vigor was determined following the formula of Baki and Anderson (1972) as follows:
Vigor index = (Mean of root length + Mean of shoot length) x Percentage of seed germination.
Dry inspection of seeds: Working samples (150 gm) were prepared from the submitted samples. Individual seed was observed with the help of a hand lens and the seeds were grouped into the following category i) healthy, ii) spotted, ii) discolored, iv) deformed and iv) Partially filled seed and others. The number of seeds in each category was counted and the results were expressed in percentage.
Incidence of seed- borne pathogens: Three layers of well-moistened blotter paper were placed at the bottom of 9 cm plastic petridish. Four hundred seeds of each sample were counted at random and placed on the moist blotter paper at the rate of 25 seeds per plate. The plated seeds were incubated at room temperature under 12 hr. cycle of alternate near ultra violate light and darkness in the incubation room. Observations on the presence of fungi were made after 7 days of incubation.
Detection of seed-borne pathogens: Four hundred seeds of each sample were tested. Seeds were surface sterilized in 2% Clorox solution for 1 minute and rinsed with sterile water and placed on PDA plates (10seeds/plate). The seeds were incubated at room temperature for 7 days with 12 / 12 hours alternate cycles of near ultraviolet light (NUV) and darkness. Number of seed infected was counted and seed-borne infection was expressed in percentage. Fungi identified by using temporary and permanent slides when necessary. Photographs were taken on the important event of the study.
Improvement of health and quality of rice seed produced by the farmers
Eight experiments were conducted in this study during the T-Aman seasons of 2009-2010 and 2010-2011. In each season, seeds were sown on seedbed in June and the crop was harvested in January. Experiments were conducted in the farmer’s field of Jhatra, Dumki, Patuakhali.The laboratory experiments were conducted at Central laboratory and Plant Pathology Laboratory, Department of Plant Pathology, Patuakhali Science and Technology University, Dumki, Patuakhali.
Area Under Disease Progress Curve (AUDPC): Area Under Disease Progress Curve (AUDPC) for brown spot, leaf blast, narrow brown spot and bacterial leaf blight were calculated based on data at different days after transplanting and integrated over time using the following model developed by Campbell and Madden (1990)
Y = Σ[(Xi + Xi+1)/2](ti+1 – ti)
where Y is AUDPC, Xi is the disease incidence rating for the ith evaluation, Xi+1 is the disease incidence rating of the i + 1th evaluation, and (ti+1 – ti) is the number of days between two evaluations.
Harvesting and threshing: The crop was harvested and threshed from uncleaned, urea cleaned and manually cleaned seed plots separately to avoid mixture. Threshing was done by two medium strong biting in two sides of the bundle to avoid threshing of unfilled or partially filled grain. This collected seed was used in the next season. The rice plants were harvested at the center of each plot of Dudkolom, Maulata and BR-23 on 10 January and Sadamota and Lalmota on 2January 2010.
Grain yield and yield components: Yield component data were collected from 1m2 harvested areas at the centre of each plot. From each plot 25 hills were collected randomly and then it bundled. Grain yields were taken from each plot. Grain yield was adjusted to 14% moisture content (Savary et al., 1997) and expressed as ton/ha. Data on yield components were as follows:
? Number of effective tillers / hill
? Number of filled grain /panicle
? Number of unfilled or sterile grain/panicle
? 1000 grain weight
? Grain yield/plot
Effect of storage containers on the health and quality of stored seeds
Farmers were selected from village; Jhatra, upazilla; Dumki, District; Patuakhali to find out the effect of storage containers on health and quality of rice seed. Seeds of Dudkolom cultivars harvested from T-Aman, 2009-2010 were used in the experiment.
The experiment was conducted at farmer’s house following CRD. The seeds were kept in different storage containers viz. motka (earthen container), motka painted with cowdung and plastic dram. One set of these containers were closed with lid and made air tight with a thick layer of clay soil around the margin of the lid and another set were covered loosely.
There were six treatments
- Motka-Loose lid
- Motka-Air tight lid
- Motka painted with cowdung- Loose lid
- Motka painted with cowdung- Air tight lid
- Plastic dram- Loose lid
- Plastic dram- Air tight lid
Three farmers were participated in this study. One farmer used as one replication. From each storage container, 500g seed sample was taken from the middle portion of each container which was kept in brown paper and labeled properly and preserved at 5-8 0C in a refrigerator for subsequent use. Germination, health status and moisture contents of the seed samples were determined.