GB/T 29371.5-2012Technical rules for seed production system of two-line hybrid rice - Part 5: Technical rules for identification of variety purity & male sterility of MS line (English PDF)

3.1 Monitoring of phytotron

3.1.1 Monitoring materials and requirements

3.1.1.1 Monitoring materials

The photo/thermo-sensitive genic male sterile line of rice that passes the examination or technical identification by the provincial or above-level Crop Variety Approval Committee, and being used in production.

3.1.1.2 Material requirements

Identification materials require 300g-500g of seeds; germination rate >=80%; and purity

>=99.5%. And provide the breed standard when the sterile line passed the approval or identification.

3.1.1.3 Sampling requirements

It shall execute the provisions of GB/T 3543.2-1995.

3.1.3.5 Temperature and light setting during transitional period

2d before and after the processing, if the natural daily average temperature is >= 30°C or <=

25°C, then the processing materials shall be transited for 2d under the conditions - day-time temperature of 28°C, night-time temperature of 24°C, and light intensity of

1.0×10

4 lx, and then move them into the phytotron or place them in a natural conditions.

3.1.4 Fertility observation

3.1.4.1 Observed object

When the process in phytotron is completed, tag and mark the rice spikes of which the distance between flag-leaf and top-second leaf is 0 cm - 2 cm.

3.1.4.2 Observation method

When the marked spikes grow into the initial heading stage, every morning take the glumous flowers that will be flowering on that day (anthers length stretching to two-thirds of glumous flower) to conduct pollen observation under microscope. Randomly pick 5-6 glumous flowers from each ear; their anther is made into 1 observing piece. Use I 2-KI solution to dye the pollens and press into piece. Under the optical microscope, amplify

100 times to inspect. Choose 3 representative views for each piece. Pollen particles of each view shall be more than 50. Observe and count the numbers of different type of pollens of 3 views (non-pollen abortion type, typical abortion type, spherical abortion type, stained abortion type, and normal). Calculate the percentage of different type of pollens in each piece. If stained pollen is found in an observation piece, then it is deemed as male sterility alteration.

3.1.4.3 Times of observations

Observation under microscope shall be conducted once a day, until the marked spikes end the flowering.

3.1.4.4 Pollen classification

3.2.4 Fertility examination

3.2.4.1 Pollen observation under microscope

From the beginning of flowering to the latest normal heading, observation under microscope shall be conducted once every 2d-3d. If there are staining pollens found during this period, the pollen observation under microscope shall be conducted every day, from that day until two days after the day without staining pollens.

3.2.4.2 Examination of self-seeding rate

Randomly select 10 single-plants from the seeding period when staining pollens are found in observation under microscope. Completely isolate them to cultivate. 20d-25d after full heading, examine the self-seed rate.

3.2.5 Investigation for sterile line group uniformity

Select two completely sterile seeding periods for each sterile line. Investigate the growth period, plant height, plant leaf and ear grain type, color, and other characters.

3.2.6 Comprehensive evaluation

3.2.6.1 Agronomic characters

According to the monitored materials' field's fertile property, plant morphological characteristic, ear grain shape, outcross characteristics, resistance, and other performances, evaluate the stability and conformity of monitored materials group, in combination with breed introduction.

3.2.6.2 Critical temperature for inducing male sterility

Correspondingly analyze the daily average temperature BETWEEN the date occurred in fertility alteration AND fertility sensitive period of each natural ecological point. Judge the sterility critical temperature of monitored materials.

4.1 Identification materials

They are sterile line seeds and hybrid seeds.

4.2 Identification procedures

4.2.1 Take samples

According to the related provisions of GB/T 3543.2-1995.

4.2.2 Field selection

4.2.5.3 Field management

Select the field of medium soil-fertility as the planting identification field. And use lower fertilizer level management. Pay attention to the pest control, snail control, and rat control in growth period.

4.2.6 Identification

4.2.6.1 Identification period

Identification shall be conducted in the period of obvious characteristics. The heading and flowering period and maturation period shall be identified.

4.2.6.2 Identity for breed authenticity

According to the character description of control samples and identification breeds, identity the breed authenticity of samples.

4.2.6.3 Determination for hybrid strains type

Hybrid strains type of sterile line breeds include isomorphic fertile strains, special strains, precocious strains, late maturing strains, and other hybrid strains.

Hybrid strains type of hybrid seeds include sterile line strains, isomorphic fertile strains, different-variety strains, male-parent stains, and other hybrid strains.

4.3 Result calculation and judgment

4.3.1 Result calculation

The seed purity is expressed by the percentage of standard breed plants TO the identification total plants. Keep one decimal place.

4.3.2 Quality determination

The quality of breed purity shall be executed according to the relevant provisions of GB 4404.1-2008.

__________ END __________ […]