Please select the most similar patent number from A, B, C and D. Which number is?
A hybrid rice seedling mechanized transplantation and cultivation method with a high hill density and single seedling per hill. A photoelectric color sorter is used to remove non-germinating hybrid rice seeds, such that a germination rate of sowing seeds is ≥ 98％. A manual sower or printing sower is used to position individual seeds for seed-sowing and seedling-growing. Next, a seedling-transplanting machine transplants seedlings with a high hill density and single seedling per hill, the transplanting density being 24,000-25,000 hills per acre for double-cropping rice and 18,000-20,000 hills per acre for single-cropping rice. After tillering, high productivity management measures are taken to perform field crop management. The method can save the cost of seeds and cultivate strong seedlings, thus significantly improving production and increasing comprehensive benefits of rice plantation.
A: The invention discloses a small-grain type sterile rice line breeding method, and a simple seed production method for a hybrid rice. The small-grain type sterile line rice breeding method comprises the following steps: hybridizing C815S as a female parent with Qi-Gui B as a male parent to produce a F1 hybrid; growing the F1 and hybridizing the F1 with a H155S as a female parent to produce a F1&#39; hybrid; growing the F1&#39; to obtain a F2&#39; generation, then isolating, from the F2&#39; generation and a F3&#39; generation, an individual plant with an ideal plant architecture, strong tillering, shorter height, and smaller grain size; and performing, for two or more generations, directional breeding to obtain a small-grain type sterile line. The small-grain type sterile rice line bred using the sterile rice line breeding method has the advantages of a high out-crossing setting rate, high germination potential and seedling survival rate, excellent storage stability, and a low black smut incidence. Using the invention as the basis for seed production for a small-grain type sterile rice line and large-grain type restorer rice lice allows simultaneous harvesting of the male parent and the female parent and selection based on grain thickness, thereby simplifying seed production for a hybrid rice.
B: A rice ridge-type plant-hole position-setting cultivation method, relating to a rice cultivation method and solving the technical problem of current rice cultivation land having low yields. The present rice ridge-type plant-hole position-setting cultivation method is the product of photosynthetic physics research and photosynthetic chemistry applied research in regard to the photosynthetic efficiency of rice growth, and can achieve, according to economic yields, a calculated efficiency of the ability of rice photosynthesis to utilize solar energy of 0.7%~1.5% per 1hm 2 . For seedlings using a rice vegetative body early-fertility single plant-hole position-setting cultivation method, short maturation time and medium maturation time rice varieties achieve stage-two tillers, and long maturation time varieties achieve stage-three tillers. For rice fields using a rice ridge-type plant-hole position-setting cultivation method, rice achieves a 100% tiller rate of 100% tillering ability, early maturation time varieties achieve stage-four tillers, medium maturation time varieties achieve stage-five tillers and late maturation time varieties achieve stage-six tillers. The number of tillering plants is controlled, and the vegetative growth period is converted to a reproductive growth period in an early stage for young ears to differentiate into large ears. The range of increased yield per mu for early maturation time rice varieties is 700kg〜1300kg, for medium maturation time rice varieties is 800kg〜1400kg, and for late maturation time rice varieties is 900kg〜1500kg.
C: An agricultural hand-held seed planter, comprising a cylinder (1); a top portion thread of the cylinder (1) is sleeved with a quantitative receiving cylinder (2), a top portion thread of the quantitative receiving cylinder (2) is sleeved with a funnel (3), and a valve device (4) is fixedly mounted at a middle portion at a side of the funnel (3); a fixed tip (5) is fixedly connected to a side of a bottom portion of the cylinder (1), and a movable tip (6) is hinged to the other side of the bottom portion of the cylinder (1), a side of the movable tip (6) being movably connected to a side of the fixed tip (5).

In the present agricultural hand-held seed planter, by means the top portion thread of the cylinder (1) being sleeved with the quantitative receiving cylinder (2) and the top portion thread of the quantitative receiving cylinder (2) being sleeved with the funnel (3), the number of quantitative receiving cylinders (2) is purposefully increased according to the size of the seeds to be planted, while the valve device (4) is provided on the funnel (3) and a blocking device (25) is provided at a top portion of an inner cavity of the cylinder (1) so as to facilitate the quantitative metering of seeds planted each time, and thus a quantitative control function of the agricultural hand-held seed planter may be achieved.
D: The present invention relates to agricultural technical field. A parental purification method, improved maize variety, and maize seed production method. The maize seed production method comprises: land selection, parent purification, seeding time setting, seeding space setting, fertilization management, roguing, watering management, maternal emasculation, flowering management, harvesting, and post-harvest processing. The hybrid maize seed production technology provided by the present invention enables the purity and the germination rate of the hybrid seeds to reach more than 98% and the quality to reach the international advanced level.
Answer: B