Spatial Responses of Contrasting Cotton Cultivars Grown Under Semiarid Conditions
- J. D. Bilbro
The southern Great Plains of Texas, New Mexico, and Oklahoma is the largest nonirrigated, semiarid cotton (Gossypiunz hirsutum L.) production area in the world. To determine if plant spacing is an important factor in crop performance under nonirrigated, semiarid conditions, a 5-year study was conducted at Lubbock, Texas, on the effects of 5-, 10-, 15-, 20-, and 25-cm spacings within rows 1 m apart on seven characters (lint yield, lint percentage, bolls/plant, boll size, 2.5% span length of fiber, fiber strength, and coarseness). The soil was fine-loamy, mixed thermic Aridic Paleustalf or Paleustoll. Two cultivars, ‘ Paymaster 111’ and ‘ Stripper 31’ were used.
Differences among years were significant for all characters and were larger than differences between cultivars or among spacings. Year X cultivar, and year X spacing interactions were significant for most characters, but the cultivar X spacing interaction was significant only for bolls/plant. The second-order interaction was significant for only fiber coarseness. The two cultivars differed significantly for all characters except lint yield and lint percentage. Paymaster 111 produced larger bolls and longer, stronger fiber; whereas, Stripper 31 had more bolls/plant and coarser lint. Spacing affected every character, except fiber strength, in at least 1 year. Regression analyses of lint yield-spacing relationship indicated that spacings of about 16 to 19 cm were optimum in the years when yields were near average (250 to 300 kg/ha). When yields were much above average (over 600 kg/ha), the 5cm spacing was superior. In the year when yields were much below average (less than 100 kg/ha), there was no significant yield-spacing relationship. Spacing had no significant effect on fiber strength in any year. Bolls/plant increased linearly as spacing was increased. The effects of spacing on lint percentage, fiber length, and micronaire were not consistent. The 5-cm spacing produced the smallest bolls.
The overall results indicate that under dryland conditions in the southern Great Plains, the optimum within-the-row spacing of cotton plants is probably about 17 cm if the distance between rows is 1 m.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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