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Effects of Genotypes and Seed Quality on Low Temperature Tolerance of Rice During Germination

M G Ali
Agronomy Division, Bangladesh Rice Research Institute, Gazipur 1701. Bangladesh.

A B S Sarker
Agronomy Division, Bangladesh Rice Research Institute, Gazipur 1701. Bangladesh.

M B Rahman
Agronomy Division, Bangladesh Rice Research Institute, Gazipur 1701. Bangladesh

R E L Naylor'
Department of Agriculture and Forestry, University of Aberdeen, 23 Machar Drive, A824 3RY, Scotland. United Kingdom.

S Matthews
Department of Agriculture and Forestry, University of Aberdeen, 23 Machar Drive, A824 3RY, Scotland. United Kingdom.

Abstract/ Executive Summary:

Laboratory experiments wel:f carried out to compare the temperature responses with respect to genotype and seed vigor during germination. Above 90% germination for BR5, BR11, 8R14, BR23, BR24, BRRI dhan2S. BRRI dhan29, BRRI dhan31, BRRI dhan32 and 8RRI dhan33 were recorded between 18-33°C. At 13.7°C. seeds of BR14, 8R24, BR26, BRRI dhan28, BRRI dhan29, 8RRI dhan31 and BRRI dhan32 germinated by 80% while less than 9% germination was recorded in BR1, 8RRI dhan30, Kartiksail and Kalaghora The rate of genninaiion (seeds hr^-1) increased from 13.7°C with increasing temperature and attained a maximum level at optimum temperature (around 30.9°C) for most of the genotypes. However. the slowest rate of germination was recorded for all genotypes at low temperature. The highest rate of germination was found for BR23 while the lower rates of germination were recorded for BRI, BR5, BRRI dhan30, Kartiksail and Kalaghora. The lower germinating genotypes along with BR5 had the shallower slopes (0.0006 to 0.0011), whereas for other genotypes had slopes ranging from 0.0013 to 0.0019. This was found when rates of germination were regressed against sub-optimal temperature range. Distinct differences in germination (at 21 ± 1°C) between genotypes began to seen at and after 48 hours agenig at 24% seed moisture content and 45°C. At this ageing treatment BR I, Kartiksail, Kalaghora were identified as the lowest quality seed lots. The above seed lots had the poorest viability than other genotypes. The calculated viability period (p) ranged from 24.2 hours (for Kalaghora) to 117.3 hours (for BRRf dhan33). Positive and significant tP < O.O1) relationship was seen between germination at low temperatures (13.7 and 15.8°C) and three assessment of physical quality (germination after 48 hours ageing, initial seed quality (K), and viability period) when all genotypes were included, while no significant relationship were existed when the lower germinating BRI, Karriksail and Kalaghora were excluded. Seed quality as well as genotypic variations might influence the final germination and rate of germination of rice genotypes at low temperature.

Keywords: Genotypes, Seed Quality, Low temperature, Rice, Germination

Location: BRRI, Gazipur-1701

Start Date: 20-02-1980

End Date: 20-03-1981

Program Area: Crop-Soil-Water Management

Commodity: Rice

Objectives:

One of the objectives of the present study was to compare the responses of 15 rice genotypes to a range of constant temperature with respect to final germination and rate of germination. The other objective was to assess the physiological quality (i.e. seed vigor) of the genotypes using ageing test (controlled deterioration) so as to separate the influence of seed quality and genotype on low temperature germination

Methodology:

Seeds of 13 rice genotypes were produced in Bangladesh Rice Research Institute (BRRI) between March and December 1997 and two traditional cultivars were collected from the farmers' of Barisal region (Table I). The well dried and pure seed samples were brought to the United Kingdom (UK) from BRRI and were stored in the Department of Agriculture and Forestry, University of Aberdeen, UK in sealed aluminium foil packets at 4°C and were used to carry out the present experiments. Experiment 1 Germination tests at a range of constant temperatures Thirteen modern rice genotypes, developed by BRRI along with two traditional cultivars were used in this experiment (Table I). Germination was assessed on temperature gradient plate at a range of constant temperatures from 13.7-37.3°C. A temperature gradient plate (Grant Instruments, Cambridge, UK) was prepared for use as described in Naylor (1993). Each genotype was placed by randomized complete block design with three replications. Each replication consisted of 12 separate cells with 30 seeds. The surface of the temperature gradient plate was covered with a single continuous piece of plastic backed filter paper (Benchkote, Whatman, England). A 90 mm diameter filter paper (Whatman, England, grade 1) was folded and placed into each cell and the seeds were placed on the filter paper. Prior to start the experiment, 250 ml of deioniscd water was added to the Benchkote and additions of 3.5 ml of deionised water were made during the experiment to ensure that filter papers were kept moist at all times. The top of the temperature gradient plate was covered with a piece of Benchkote (plastic side down) to prevent excessive evaporation and covered with Perspex sheets. The temperature gradient plate was run to give a desired range of constant temperatures (13.7-37.3°C). The temperatures were checked by an electronic thermometer in the front, middle and back rows. Temperature monitoring, seed inspection and germination recording were carried out approximately every 12 hours. This was continued till no further germination was recorded for five consecutive days for a total period of 28 days. Germination was defined as 2 mm radicle extension and germinated seeds were counted and removed. Ungerminated seeds were counted at the end of the experiment. Four runs of temperature gradient plate were required to achieve three replications of all genotypes. The time series data of 144 cells were analyzed to provide estimates of final germination percentage, median germination time (t50) and Experiment 2 Ageing tests Seed samples (Table 1) were screened for mechanical and insect damaged ones. Initial seed moisture content (rnc) was determined by the high temperature oven method (ISTA, 1999) and expressed on fresh weight basis. A controlled deterioration test (ISTA, 1995) was carried out with test genotypes. using mc of 24% and ageing temperature of 45°C for 0, 24, 48, 72 and 96 hours. Germination tests on aged seed lots at 21°C A standard germination test using sterile petri dishes (90 mm diameter) was carried out using four replicates of 25 seeds per genotype x ageing treatment (following controlled deterioration as previously described). Seed test papers (Whatrnan, England, grade 181, 90 mm diameter) were placed in petri dishes and wetted with 5 ml of deionised water and seeds were placed on it. The dishes were stacked in plastic trays with water saturated cloths above and below, enclosed in polythene bags. The bags were placed in a germination room at 21 ± 1°C in dark. Germination counting was done at 24 hours intervals for 14 days. Number of normal and abnormal seedlings was recorded at final counting (14 days). In addition to final germination percentage, the mean germination time (MGT) was calculated as MGT = O(nd)/N where, n is the number of germinated seeds on each day, d is the number of days from the beginning of the test and N is the total number of germinated seeds (Younsheng and Sziklai, 1985). The rate of germination was determined as IIMGT. The predicted initial viability (K) was calculated by the probit intercept method for each genotype. Analyses of variances were carried out using MSTAT The correlations and regressions were studied by using graphical routine in Microsoft Excel. Both germination percentage data and their angular transformation were analyzed: this usually made no change to the statistical significance of the results and so untransformed data are presented. rate of germination (1/t50) in GENSTAT Analysis of variance to compare genotypes, and regressions to determine relationships with temperature was also done in GENSTAT and MSTAT

Source of Information: Bangladesh Rice J. 13 (1): 15-21, 2008

Article Link (Online Journal):

Funding Source:

1. Government

Budget: 50000/-

Total Budget (Tk.) : 50000/-

Achievement/Findings:

The differences in germination after ageing is the indication of the differences in initial seed quality and seed vigor of the genotypes. Germination of seed lots of 14 rice genotypes in low temperature was influenced more by genotype than seed quality. There is no doubt that reduced seed vigor decreases field emergence. The magnitude of the decrease, however, depends on the severity of the stresses encountered in the field.

Knowledge Management: Journal