| (a) Pollen rows in each field must be identified by stakes at each end. (b) Upon request, a representative of the firm applying for certification of hybrid corn seed will accompany the inspector to each field, subject to certification at least 10 days prior to detasseling. (c) Single cross fields submitted for inspection for the foundation class will not be approved if, at any one inspection more than one-fifth of 1.0% of the stalks of the female parent have shed pollen and at the same time more than 1.0% of the stalks of the female parent have receptive stalks. Any plant in an inbred or single cross field submitted for inspection for the foundation class that is shedding pollen in male sterile rows must be completely destroyed at pollinating time to eliminate the possibility of its seed production. (d) Commercial hybrid seed fields submitted for inspection for certification will not be accepted if at any one
inspection more than 1.0% of the stalks of the female parent have shed pollen and at the same time more than 5.0% of the stalks of the female parent have receptive silks. The total for three inspections shall not exceed 2.0%. (e) Detasseling. (1) Tassels shall be removed thoroughly enough so that not more than 1.0% of the plants in seed rows on any one inspection, or not more than 2.0% of the total of any three inspections, shall have shed pollen while more than 3.0% of the seed parent plants have receptive silks. Such percentage is to be determined on the basis of stalks large enough to be in the detasseling stage. (2) The following shall be used in defining a shedding tassel and a receptive silk. (A) Shedding tassel. In fertile fields, a shedding tassel shall be considered as shedding or having shed pollen when there are two inches or more of the exposed center spike and/or panicle branches showing
exerted anther sacs. One- fifth of a shredding tassel shall be counted if a total of less than two inches of the center spike and/or panicle branches show exerted anther sacs. In sterile fields, tassels shedding less than 50% pollen shall be counted as one-tenth of a full tassel. The exerted anther sacs on cytoplasmic male sterile seed parents must be shedding if classed as a shedding tassel. (B) Receptive silks. Receptive silks shall be regarded as susceptible for fertilization when any fresh turgid silks are showing on the ear. As soon as a silk wilts it is regarded as fertilized, although it may not become brown or dry for one or two days after fertilization. (f) A male sterile ear parent can be used to produce certified hybrid corn seed by either of the following two methods. (1) Seed of the normal fertile ear parent must be mixed with the seed of the male sterile ear parent of the same pedigree, either by blending in the
field at harvest or by size at processing time. The ratio of male sterile ear parent seed to normal ear parent seed shall not exceed two to one. (2) The pollen parent must involve a certified pollen restoring line or lines so that not less than one-third of the plants grown from hybrid corn seed produces pollen which appears to be normal in quantity and viability.
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