Normalized difference vegetative index, arthropod density, water and nitrogen interactions in Acala 1517-99 cotton, Gossypium hirsutum (L).

摘要

Nitrogen (N) is very often used to increase yields with little or no regard to the implications it may have on profit, especially when it is used excessively. A three year study was conducted at the Leyendecker Research Center, New Mexico State University to evaluate multispectral reflectance, water, N, and arthropod interactions on irrigated Acala 1517-99 upland cotton, Gossypium hirsutum (L). The objective of this study was to determine the optimal water/N use strategies, profit estimates, and arthropod density estimates using multispectral canopy reflectance, COTMAN(TM) plant modeling, arthropod vacuum sampling techniques, and economic cotton budget analysis.; Multispectral canopy reflectance indices were established throughout the growing season among various N rates. These reflectance indices corresponded to differences in arthropod density.; Plant growth and development was documented throughout each season using cotton management expert system software (COTMAN(TM)). Plant architecture modeling with COTMAN(TM) distinguished morphological plant responses attributed to soil moisture, N, and insect density.; A high clearance vacuum collector, called the Insectavac (IV) was used to sample arthropods from treatment replications. Data showed a significant difference among Lygus spp. in higher N treatments, but not between irrigation treatments. Most predaceous arthropods did not respond to varying, levels of water or N.; Economic analysis for each treatment effect was conducted to determine profit. Although higher N application rates gave higher yields, they did not provide higher profits. N applications, applied at half the recommended rates, gave higher profit with little yield differences.; Infrared reflectance measurements, precision N applications and effective arthropod sampling can increase profits and reduce environmental insults from excessive agrochemical use and inefficient irrigation applications.