GB/T 29371.1-2012Technical rules for seed producing system of two-line hybrid rice - Part 1: Terminology (English PDF)

2.1 Photo/thermo-sensitive genic male sterile line

The rice that has the recessive male infertility nuclear genes which are sensitive to photoperiod and temperature conditions of the environment; the variation of the photoperiod and temperature can induce its fertility transition. It is expressed by the capital "S". According to different reactions of the fertility transition to the photoperiod and temperature, photo/thermo-sensitive genic male sterile lines are divided into three categories - photo-sensitive, thermo-sensitive, and thermo-photo co-inducing male sterile line.

2.1.1 Photoperiod-sensitive genic male sterile line

Within the photo-sensitive temperature range, the sterile lines of which the light period is the determining factor for fertility transition. It includes 2 categories - long photo-period inducing male sterile line; and short photo-period inducing male sterile line.

2.1.1.1 Long photo-period inducing male sterile line

The sterile lines of which the long photo-period can induce the sterility and short photo-period can induce fertility, within the photo-sensitive temperature range.

2.1.1.2 Short photo-period inducing male sterile line

The sterile lines of which the short photo-period can induce the sterility and long photo-period can induce fertility, within the photo-sensitive temperature range.

2.1.2 Thermo-sensitive genic male sterile line

The sterile lines of which the fertility transition is mainly controlled by the temperature, within a certain temperature range. It includes 2 categories - high temperature inducing male sterile line; and low temperature inducing male sterile line.

2.1.2.1 High temperature inducing male sterile line

The sterile lines that - when the temperature is above the critical temperature for inducing male sterility of the sterile line, it expresses as the sterility; and when it is lower than the critical temperature for inducing male sterility, it expresses as the fertile.

2.1.2.2 Low temperature inducing male sterile line

The sterile lines that - when the temperature is below the critical temperature for inducing male sterility of the sterile line, it expresses as the sterility; and when it is above the critical temperature for inducing male sterility, it expresses as the fertile.

2.1.3 Thermo-photo co-inducing male sterile line

The sterile lines of which the fertility expression is affected by thermo-photo co-inducing effect sterile line. In which, the temperature effect outweighs the long light effect. The male sterility is obtained under sterile temperature and sterile photoperiod. The fertility obtained under the fertile temperature and sterile photoperiod is lower than that obtained under the fertile temperature and fertile photoperiod. When the critical temperature is appropriately reached, the fertile photoperiod can improve the fertility and the sterile photoperiod can improve the male sterility.

2.2 Restorer of photo/thermo-genic male sterile line

The rice variety (line) that conducts the hybrid with the photo/thermo-sensitive genic male sterile line. Its first hybrid generation (F1) can seed normally. It can be expressed as the capital letter "R".

2.3 Two-line hybrid rice F1 seed production

It is a hybrid seed production process. The photo/thermo-sensitive genic male sterile line acts as the female parent; the restorer of photo/thermo-genic male sterile line acts as the male parent; select and arrange the production base and the season which can make the female parent completely sterile; alternatively plant the female and male parents in accordance with the proper period difference between R and S seeding and line proportion; supplement with chemistry control and supplementary pollination.

2.4 Sensitive period of fertility reversing

The period when the fertility expression of the sterile line is sensitive to the environmental temperature and photoperiod. The sensitive period of fertility reversing of japonica sterile line is during III-V stages of young panicle differentiation (from the secondary panicle branch and spikelet primordium differentiation stage to the pollen mother cell formation stage). The sensitive period of fertility transition of indica sterile line is during IV-VI stages (from the pistil and stamen formation stage to the pollen mother cells meiosis stage).

2.5 Critical photo-length for inducing male sterility

The required daily shortest (longest) effective photoperiod length to induce complete-abortion of the photoperiod-sensitive genic male sterile line.

2.6 Critical temperature for inducing male sterility

The threshold temperature of the inducing photo/thermo-sensitive genic male sterile line from the fertility to complete male sterility. It is expressed by daily average temperature.

2.7 The plant with higher male sterility inducing temperature

It refers to the plants. In high temperature inducing male sterile photo/thermo-sensitive genic male sterile line group, the critical temperature of inducing male sterility of the minority single-plants is changed and affected by the genetic basis. Thus it generates the plants of which the critical temperature of inducing male sterility rises. These plants are easier to generate the male sterility alteration or the higher fertility degree than other plants, under the condition of the critical temperature of fertility transition.

2.12 Safe period of heading and flowering

The period when the environmental conditions has no abnormally high temperature, dry hot wind, low humidity or continuously overcast and rainy weather. It can ensure the seed production parents to flower, pollinate and outcross-fructification normally.

2.13 The period from seeding to 10% heading

The number of days from seeding (referring to the germination seed falling to mud) to initial heading (heading of 10%).

2.14 Day number difference between R and S seeding

The difference value of the number of the days for parents seeding time. It is also known as the sowing period difference. When female parent seeding is earlier than male parent, it is called the "seeding period difference upside-down".

2.15 Leaf number difference between R and S seeding

The leaf age of the stem of the earlier seeding parent, when the latter seeding parent is seeded. It is also known as the leaf age difference.

2.16 Accumulated temperature difference between R and S seeding

The effective accumulated temperature difference between the male and female parents, from the seeding to initial heading. The effective accumulated temperature is defined as the accumulated temperature value between the maximum temperature and the minimum temperature in the biology. The maximum temperature is 27°C and the minimum temperature is 12°C (glaze rice) or 10°C (japonica rice). See equation (2) for the calculation formula of the effective accumulated temperature. Where. […]