Detasseling

Abstract: THE influence of detasseling on the performance of corn has been studied since the last decade of the last century. Some of the early research workers found that detasseling decreased yield, while others found that it did not. The early work was reviewed adequately by Grogan. Grogan stated that the removal of immature tassels seemingly results in diversion of some of the energy and nutrients normally expended in pollen production to grain production. He predicted that under the same environment male-sterile plants which produce no pollen would react in a manner similar to their detasseled fertile counterparts.

Abstract: Genetically modified maize (Zea mays L.) produced for regulated products such as pharmaceutical or industrial proteins will require methods to confine transgenic pollen. In one production system, nontransgenic maize would be used to pollinate detasseled transgenic inbred plants. Resulting hybrid kernels would be used for protein extraction or seed increase. The effect of different female inbred detasseling efficiency levels on gene flow was tested at three locations in southeastern Missouri in 2000 and 2001. Pollen sources were yellow inbred isolines representing transgenic females planted in alternating rows with white inbred maize representing nontransgenic males. During detasseling, female plants were intentionally missed at rates of 0, 730, 1460, and 7300 tassels ha -1 . Each detasseling treatment was matched with a maize isoline and traceable marker. White hybrid trap plots were planted on three dates at 200 and 300 m from pollen sources. Dates that maximized silking synchronization with yellow isoline tasseling were selected for sampling. Gene flow was detected by counting yellow kernels in white maize plots. When no tassels were removed from an isoline, the highest recorded gene flow was 0.03% at the 200 m and 0.02% at the 300 m isolation distances. At greater detasseling levels, gene flow decreased. Gene flow was 0.0013% or less when 730 tassels ha -1 remained. When complete detasseling was intended, one positive kernel with a tracer gene was detected at 200 m, and none was detected at 300 m. For effective control of regulated transgenes in pollen by detasseling, complete and timely tassel removal will be necessary.

Abstract: Mechanical detasseling in hybrid seed production fields of corn (Zea mays L.) frequently is accompanied by loss of some leaf material. Little is known about the effect of this practice on seed production in those instances where the seed parent is an inbred line. We investigated the effects of tassel removal and tassel plus leaf removal on 5 short season inbred lines grown at Guelph, Ontario and 5 later maturing lines grown at Harrow, Ontario. Treatments at both locations consisted of a check, and the removal just prior to anthesis of the tassel, tassel plus one leaf, tassel plus two leaves, and tassel plus three leaves. When tassels alone were removed, there was an average increase "of 6.9%g rain yield. When 1, 2, and 3 leaves were removed with the tassel, yield reductions for the 10 inbreds averaged 1.5, 4.9, and 13.5% relative to the yield for tassel removal only. Yield differences were the result of a reduction in both kernel weight and number of kernels per row. However, yield responses to leaf removal varied greatly between inbreds, and therefore, it is impossible to generalize on the effects on grain yield of leaf removal during detasseling. For some inbreds, particularly shorter season ones, the reduction in yield due to removal of 2 and 3 leaves with the tassel is large enough to warrant consideration in seed production. On the other hand, yield of some of the later inbreds was reduced only slightly when 3 leaves were removed with the tassel. This probably reflects the higher percentages of leaf area removed in earlier inbreds as compared to the later inbreds.

Abstract: Three experiments (E1, E2, and E3) were carried out in Mossoro, Brazil, to evaluate baby corn yield, green ear yield, and grain yield, respectively, of two corn hybrids (AG 1051 and BRS 2020), in response to detasseling (with or without tassel). A randomized splitplot block design (with hybrids defined as plots) and ten replicates was used. The three experiments were planted on the same day and in neighboring areas. In the three experiments, the hybrids did not differ from each other on the dry matter mass and number of tassel branches. In E1 (baby corn production at 180 thousand plants ha -1 ), for both hybrids, the following effects were observed due to detasseling: a) an increase in ear total number, in ear total weight, in marketable unhusked ears number and in marketable unhusked ears weight; b) no change was observed in the number and weight of marketable husked ears. Hybrid AG 1051 was superior to BRS 2020 for weight of marketable husked ears, but the two hybrids did not differ in other traits utilized to evaluate baby corn yield. In E2 (green ear yield at 50 thousand plants ha -1 ), detasseling did not change the following traits in both hybrids: total number and weight of ears; number and weight of marketable unhusked ears and marketable husked ear weight. Detasseling reduced the number of marketable husked ears in cultivar AG 1051, but not in BRS 2020. The two hybrids did not differ in total number of ears and number of marketable unhusked ears. Hybrid AG 1051 was superior to BRS 2020 in regard to the total ears weight, marketable unhusked ears weight and number and weight of marketable husked ears. In E3 (grain yield at 50 thousand plants ha -1 ), detasseling did not affect grain yield (RG) and hybrid AG 1051 was superior to BRS 2020 for grain yield.