'Tamcot Pyramid' cotton (Gossypium hirsutum L.) was developed in the multi-adversity resistance (MAR) cotton genetic improvement program and released in May 2000 by the Texas Agricultural Experiment Station (TAES). The established MAR system was the breeding procedure used to develop Tamcot Pyramid (Bird 1982; El-Zik and Thaxton 1989). The MAR techniques and procedures utilize specific seed, seedling and plant selection in the laboratory and greenhouse in the fall and winter, followed by an extensive four-stage field testing and evaluation at ten locations throughout Texas, from the Rio Grande Valley to the Rolling and High Plains. These procedures make it possible to identify superior cotton germplasm with the simultaneous genetic improvement for resistance to pests (insects and plant pathogens) and abiotic stresses, in addition to drought tolerance, and improved yield, earliness, and fiber and seed quality (Thaxton and El-Zik 1994, 1996, 1999, 2000).

Tamcot Pyramid was developed from a cross between the MAR lines CD3PIHP45H-2-89 and CD3HGCBU8S-1-91. Individual F3 plants were selected using the MAR laboratory-greenhouse procedures. An F4 single seed descent field progeny row was selected in 1995 and given the strain designation SPNXCDUG8H-1-95. CD3PIHP45H-2-89 was released as Tamcot Sphinx in 1995 and originated from the cross between CDP37HPIH-1-1-96 and a selection from Paymaster 145. CD3HGCBU8S-1-91 originated from the cross between the MAR lines CD3HCAHUGH-2-88 and CABUCAG8US-1-88.

Tamcot Pyramid is a hairy (pubescent), glanded, normal leaf and normal bract cotton. It is nectaried and leaves are dark green. It has a cylindrical shaped growth habit, short internodes, and storm resistant bolls. Plants are of medium height, taller (4 cm) than Tamcot Sphinx (El-Zik and Thaxton 1994) and shorter (2.5 cm) than Paymaster 330. Flowers from plants of Tamcot Pyramid will have cream pollen.

Tamcot Pyramid was tested extensively throughout Texas and in Oklahoma for four years for resistance to insects and pathogens, drought tolerance, agronomic characteristics, earliness, productivity, and fiber quality performance (Thaxton and El-Zik 1996, 1999, 2000). Data were collected from 36 tests conducted in Texas over four years, 1996-1999, at 12 sites (Weslaco, Corpus Christi, College Station, Temple, Thrall, McGregor, Hill County, Chillicothe, Halfway). The tests included the 1996 Early Field Planting (EFP) test at four locations (32 genotypes and four replications) and the 1997-1999 Uniform MAR (UMAR) test at eight locations with 24 genotypes and four replications. Data were abstracted from the above described tests and statistically analyzed to compare Tamcot Pyramid performance with Tamcot and commercial cultivars.

Tamcot Pyramid had field stand ability and vigor equal to the recent Tamcot cultivar releases. Tamcot Pyramid had stand of 61% seedling survival as percent of planted seed as compared to 43.1% for the susceptible genotype (Table 1). Tamcot Pyramid was similar to Tamcot Sphinx and Paymaster PM330 for seedling survival. Tamcot Pyramid is highly resistant to the bacterial blight pathogen. It carries the B _2B3B7 genes that confer high levels of resistance to Xanthomonas campestris pv. malvacearum (Smith) Dye the causal agent of bacterial blight. Tamcot Pyramid was evaluated in the Verticillium wilt nursery at Halfway from 1996 to 1999. Tamcot Pyramid has similar levels of resistance to Verticillium wilt (38.2%) as Tamcot Sphinx (38.2%) and Paymaster PM330
(30.2%), compared to 27% for the highly resistant genotype and 80% for the susceptible genotype (Table 1). Based on weekly counts of Phymatotrichum root rot disease symptoms, Tamcot Pyramid had a similar level of resistance as Tamcot Sphinx and Paymaster PM330 (Table 1). In the 1997 National Fusarium wilt nursery at Tallassee, Alabama, Tamcot Pyramid averaged 58% plants with wilt symptoms compared to 89.0% for the susceptible genotype Rowden and 21% for the highly resistant genotype M-315 (Table 1).

In a reniform nematode infested (RN) field test at Weslaco, Tamcot Pyramid produced 1102 lb of lint per acre (ranked 9 ^th highest yield out of 36 entries) in the non-treated RN plots and 1237 lb/acre in the treated plots (5 ^th highest yield). Yield ranged from 755 to 1272 lb/acre in the non-treated RN plots, and from 825 to 1391 lb/acre in the treated plots. Tamcot Pyramid produced high yields in both the RN infested and fumigated plots indicating it has levels of resistance to the reniform nematode.

Levels of resistance to insects were determined by including cultivars and genotypes with known levels of resistance and susceptibility in the tests for comparison with Tamcot Pyramid, Tamcot Sphinx, and Tamcot CAB-CS. Presence of cotton insects and damage caused was noted in the MAR Strains, EFP and UMAR tests throughout the season, and tests were evaluated and a grade of one (very little damage) progressing to five (severe insect damage) was assigned to each plot. Tests were harvested sequentially to determine early and total lint yield, which are indicators of early, mid- and late season insect damage. Extensive grading and evaluation indicated that Tamcot Pyramid has higher resistance levels to seven insects: aphids, thrips, fleahopper, boll weevil, budworm, bollworm, and whitefly, and to spider mites than Tamcot CAB-CS (Bird et al. 1986) and similar resistance levels to Tamcot Sphinx (Table 2).

Eight genotypes; Tamcot Pyramid, Tamcot Luxor, Tamcot Sphinx, four elite MAR-7 lines and a susceptible genotype, were evaluated for levels of resistance to four insects at Chillicothe, Texas in 1996 (Parajulee et al. 1997). No insecticides were applied throughout the season. Sampling consisted of weekly monitoring of plots from plant emergence to late August. Tamcot Pyramid had the lowest levels of damage to thrips, fleahopper, boll weevil and boll worm (Table 3). Boll weevil punctured bolls ranged from 4.2% for Tamcot Pyramid to 19.3% for the susceptible genotype.

Results from 38 tests conducted over four years (1996-1999) were used to compare Tamcot Pyramid (SPNXCDUG8H-1-95) lint yield per acre with other advanced MAR lines, Tamcot and commercial cultivars. Tests included the EFP, UMAR, and tests conducted in the Texas High Plains and Oklahoma. The MAR tests were grown at 10 locations across Texas in the major cotton growing regions, which represent a wide range of diverse environments including pest pressures and water stress.

The summary results from 17 tests over four years showed that Tamcot Pyramid produced the highest lint yield (836 lb/acre), significantly 10% more than Tamcot Sphinx and Paymaster PM 330, both averaging 763 lb/acre (Table 4). It is an early maturing cultivar similar in maturity to Tamcot Sphinx (Table 4). Tamcot Pyramid produced the highest lint yield at each location and year, indicating its wide adaptation and stability over the diverse growing and environmental conditions in Texas. Tamcot Pyramid has a significantly larger boll (82 bolls per pound of seed cotton) than Tamcot Sphinx and Paymaster 330 (Table 4). Its lint percentage and gin turnout were similar to those of Tamcot Sphinx and Paymaster 330.

Yield components of Tamcot Pyramid in comparison with Tamcot Sphinx and Paymaster PM 330 are presented in Table 5. Tamcot Pyramid and Paymaster PM330 produced similar number of seeds/boll and both