Impact of Deficit Irrigation on Selected Glandless Cultivars in New Mexico

Water availability for irrigation is a challenge in the Southwest. Therefore, it is important to evaluate the performance of existing cultivars to different levels of irrigation. Glandless cotton cultivars, (Acala GLS and STV Glandless) were subjected to deficit irrigation and compared with conventional Acala 1517-08, a public variety bred for NM conditions. Irrigation treatments consisted of four (R1), five (R2) and six irrigations (R3). Each irrigation event consisted of an application of 3.5 inches of water through furrow irrigation. All cotton cultivars were planted on May 13^th, 2014. The experimental design was a split plot with treatments replicated four times. Measurements collected at intervals during the growing season included plant height (PH), number of squares, number of nodes, total number of bolls (TB) and number of open bolls (OB).  Results at 4.5 months after planting showed significant cultivar effect on PH, with Acala 1517-08 being the tallest. There was also significant interaction effect between irrigation treatment and PH. Although the TB was higher in R3 (23 bolls), it was not significantly different from R2 (18 bolls) and R1 (13 bolls). While Acala 1517-08 had significantly higher TB than Acala GLS, it was not significantly different from the STV Glandless. The irrigation treatment had significant impact on the OB at 4.5 months after planting, with R1 having higher number of OB (9 bolls) compared to R3 (2 bolls). Deficit irrigation led to shorter growing period and earlier cutout in R1 treatment, giving rise to earlier maturity. Lack of sufficient moisture for growth and development, especially under the R1 treatment may affect the yield and fiber quality significantly. Field observations showed lodging under the R1 treatment, due to concentrated boll formation at the upper part of the plants. Final yield and fiber quality will be recorded at the end of the season.