Metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] has considerable potential for yellow nutsedge (Cyperus esculentusL.) control in crops commonly produced in the Texas High Plains. Little information is available, however, concerning adsorption characteristics of metolachlor in soils of this region. Adsorption and movement of metolachlor were determined in three commonly occurring soils of the Texas High Plains. Organic carbon contents of the soils by weight varied from 0.3 to 0.5%, and the clay fraction ranged from 16 to 33%. Freundlich adsorption isotherms exhibited two linear regions for each soil, suggesting the possibility of multilayer adsorption. K′ocvalues and coefficients of determination for organic carbon and clay content vs. Freundlich K values indicated that organic matter was the predominant adsorbent for metolachlor in the soils studied. Desorption, soil column leaching, and thin-layer plate studies demonstrated metolachlor to be sufficiently mobile in scils low in organic matter to cause possible crop injury or loss of efficacy.

Four different night temperature regimes were maintained on two varieties of field‐grown cotton Gossypium hirsutum L., during the 1964 and 1965 seasons. Elongation of fiber was found to be closely associated with both temperature and variety. As night temperature was lowered, fiber elongation rates decreased and fiber elongation periods increased for both varieties. Rate of elongation was not uniform over the entire elongation period, but was dependent upon fiber age and night temperature. Temperature coefficients of elongation decreased with increased fiber age and night temperature. Thus, the initial stages of fiber elongation were highly temperature dependent, while the latter stages tended to become temperature independent.

Five cotton varieties were grown in the field under four different night temperature regimes (10, 15, 20, and 25 C). The influence of temperature on the rate and extent of fiber elongation was studied. Temperatures below 20 C reduced fiber length; and generally, the reduction was greater in varieties having the longer fibers. Lowering night temperature increased the fiber elongation period and slowed the fiber growth rate. The temperature coefficients of elongation indicated the rate of elongation for all varieties was extremely temperature‐sensitive up to 15 days age. Beyond 15 days age, however, the coefficlents of elongation quickly approached one, indicating temperature independence.

Different night temperature regimes were maintained throughout the boll development period on cotton growing in the field during the 1963, 1964, and 1965 seasons. Both fruiting and boll development were found to be closely associated with night temperature. Decreased night temperature resulted in the formation of more flowers and, in some cases, increased fruit set. Relative fruitfulness increased as night temperature decreased between the interval of 21 and 8.8 C and 21 and 14.4 C with ‘Paymaster’ and ‘Acala’ varieties respectively. Temperatures above 19.4 and below 13.3 C reduced fruiting index. Rate of boll development was inversely related to temperature, with a decrease of either day or night temperature resulting in slower boll dvelopment, thus, increasing boll periods. However, in this work night temperature was the dominant environmental factor associated with boll periods. In general, the Paymaster variety appeared to be better adapted to low night temperatures than the Acala variety.

The seeds used in this study were produced by growing cotton (Gossypium hirsutum L.) plants from first flower through boll maturation in growth chambers where tire night temperatures were 11, 15, 21, and 27 C. These seeds were used to evaluate the effect of seed quality on the growth and productivity of matured plants. The cultivars used were ‘Acala 1517 Br2,’ ‘Stoneville 7A,’ ‘Lankart Sel 57,’ ‘Stripper 31,’ and ‘CA 491.’ Characters or traits measured were 1) seed weight and percentage of germination of the seed produced in the temperature controlled growth chambers; and 2) rate of seedling emergence, vegetative growth rates, seed cotton per plant, bolls per plant, and production rate index of the plants grown from the seed produced in the chambers.Low night temperatures during the seed maturation period had a detrimental effect upon seed quality (seed weight and percentage of germination). In field plantings, seedlings from seeds produced under low night temperatures (11 and 15 C) emerged more slowly than those from seeds produced under high night temperatures (21 and 27 C). The plants that developed from seeds produced under low night temperatures (11 C) grew more slowly and were less productive than plants from seeds produced under high night temperatures (21 and 27 C).