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Increased water scarcity necessitates the implementation of water-conserving irrigation management practices to sustain crop production,especially in water-limited areas. A two-year field study was conducted during 2019 and 2020 to evaluate the effect of deficit irrigation on physiology, plant growth, and yield of cucumber cultivars. The experiment was conducted in a split-plot design with four irrigation levels (100% ETc (crop evapotranspiration), 80% ETc, 60% ETc, and 40% ETc) as main plot factor and two cultivars (Poinsett 76 and Marketmore 76) as subplot factor with three replications. Results showed that stomatal conductance (gs), transpiration rate (E), photosynthesis rate (Pn), intercellular CO2 concentration (Ci), and leaf area were significantly lower in 60% ETc and 40% ETc compared to 100% ETc while stomatal limitations, intrinsic water use efficiency (WUEi), and relative leaf temperature were significantly higher in 60% ETc and 40% ETc compared to 100% ETc. The observed values of these aforementioned parameters were comparable between 100% ETc and 80% ETc. A decrease in leaf area, as well as a decrease in Pn, resulted in a decline in overall photosynthesis per plant in 60% ETc and 40% ETc compared to 100% ETc. As a consequence of this, plant dry biomass and total fruit yield were significantly lower in 60% ETc and 40% ETc compared to 100% ETc. However, photosynthesis per plant was comparable between 100% ETc and 80% ETc due to comparable Pn and leaf area between them. Because of comparable photosynthesis per plant, plant dry biomass and fruit yield were comparable between 100% ETc and 80% ETc. Marketmore 76 had significantly higher gs, E, Pn, Ci, and leaf area and it had significantly lower stomatal limitations, WUEi, and relative leaf temperature than Poinsett 76. Vegetative dry biomass and total above-ground dry biomass were higher in Marketmore 76 but fruit yield was higher in Poinsett 76. These results suggest that 80% ETc irrigation level and Poinsett 76 cultivar can be recommended for successful cucumber production without causing a significant decline in fruit yield in water-limited Southern High Plains of United States.

Background Producing rainfed cotton (Gossypium hirsutum L.) with high fiber quality has been challenging in the Texas High Plains because of extended periods of insufficient rainfall during sensitive boll developmental stages. Genetic variation created by Ethyl MethaneSulfonate (EMS) mutagen has successfully improved fiber quality of cotton. However, little is known about the effect of water deficit environments on fiber quality. Three EMS treated populations were advanced from the first to the fourth generation (M1 to M4) as bulk harvested populations. In 2014, single-plant divergent selection was applied based on perceived morphological and agronomic differences seen during and at the end of the season. Results Analyses from these selections in 2014–2016 showed significant (P

In the semi-arid Texas High Plains, declining irrigation water supply hinders the profitable corn (Zea mays L.) silage production, the principle feed ingredient of the beef and dairy industries. Drought-tolerant and deep-rooting crops like forage sorghum (Sorghum bicolor L.) and pearl millet (Pennisetum glaucum L.) could be an alternative to corn silage under limiting irrigation. A field study was conducted during 2018 and 2019 at New Deal, TX to assess soil water depletion patterns, water use efficiency (WUE), and silage yield of forage sorghum, pearl millet, and corn under limited irrigation. The experiment was conducted in split-plot design with three irrigation levels [I0 (55 and 29 mm), I1 (172 and 147 mm), and I2 (323 and 260 mm) in 2018 and 2019, respectively] as main-plots and five cultivars [P1498AM (corn), AF7401 and Silo700D (BMR sorghum), and Epic and Exceed (BMR pearl millet)] as sub-plots with three replications. The soil water depletion amount was greater in I0 (105 and 57 mm) followed by I1 (60 and 37 mm) and I2 (44 and 13 mm) in 2018 and 2019, respectively. Fresh biomass yield was the greatest in I2 followed by I1 and I0; however, the highest WUE was achieved in I0 and I2 in 2018 and 2019, respectively. Water depletion depth was greater for sorghum and pearl millet plots (0–1 m) than corn plots (0–0.6 m) which resulted in greater water depletion amount in sorghum (75 and 31 mm) and pearl millet (68 and 48 mm) plots than corn (67 and 28 mm) during 2018 and 2019, respectively. Average yield and WUE were the highest in sorghum cultivars, followed by pearl millet and corn. Results confirmed that the higher silage yield and WUE can be achieved by sorghum compared to pearl millet and corn under limited irrigation conditions.

Cotton (Gossypium spp.) production around the world often occurs in water limiting environments. Although Upland (G. hirsutum) and Pima (G. barbadense) cottons have been evaluated under conditions of water stress before; these two species are rarely compared to each other. This may be due to differences in irrigation management and environmental constraints (i.e. season length). In 2014 and 2015, two Upland cultivars and two Pima germplasm lines were evaluated at Lubbock, TX, USA. Plant architecture, boll retention, lint yield and fiber quality were assessed under three deficit subsurface drip irrigation levels. Crop water use was evaluated using soil water balance in conjunction with neutron probe soil water content measurements. In 2014 during flowering at the high irrigation rate, Upland cultivars extracted significantly (p

The Texas High Plains often has extended periods between rainfall events, which can lead to a reduction in the yield and fiber quality of cotton (Gossypium hirsutum L.). It is known that cultivated cotton suffers from low levels of genetic diversity due to the over-use in breeding of similar gene pools, which may hinder breeding for drought tolerance. In this study, for the first time the novel variability or genetic diversity of morphological and agronomic traits possibly created by the chemical mutagen ethyl methanesulfonate (EMS) was evaluated to improve drought tolerance in cotton by traits’ response to different irrigation regimes. EMS is a chemical mutagen that has been shown to cause point mutations in the DNA of many model plants and crop species. Three EMS treated lines were advanced from the M1 to M4 generation as bulk-harvested populations. A diverse selection scheme was applied to capture most of the genetic trait-variability or diversity and superior lines in these populations. In 2014–2016 the diversity of these populations was evaluated based on four agronomic and thirteen morphological traits to determine differences in response to multiple irrigation rates. Analyses of these traits showed statistically significant (p ≤ 0.05) differences between and within populations when compared to the original non-treated EMS source, with most of the variability being observed in the high irrigation rate. However, none of the EMS treated populations had significantly (p ≤ 0.05) better lint yield than the commercial cultivar (control) in 2016. EMS yield performance was possibly constrained by the applied diverse selection scheme of this study. Traits such as total number of bolls, bolls retained at node 7 and below, and those retained between nodes 8 and 12, and bolls retained at node of first fruiting branch may be predictors to improve cotton production (yield) in water limiting environments.

Within the Ogallala Aquifer Region of Texas, the irrigation capacity (IC) for a given field often changes within a growing season due to seasonal depletion of the aquifer, in-season changes in crop irrigation needs in dry years, or consequences of irrigation volume limits imposed by irrigation district rules. Irrigation planning is further complicated by erratic seasonal rainfall. A field experiment was conducted from 2010 to 2013 to determine cotton ( L.) irrigation productivity using a range of ICs common to the Texas South Plains during three irrigation periods. The treatments included in-season ICs (maximums of 0, 3.2, and 6.4 mm d-1) in combination with irrigation periods determined by accumulated growing degree days (GDD15.6) and were designated as period 1 (P1= emergence to 525 GDD15.6), period 2 (P2= 525 to 750 GDD15.6), and period 3 (P3>750 GDD15.6). Combinations of these factor levels resulted in 27 irrigation treatments with applications made by the low energy precision application (LEPA) method. Annual rainfall totals ranged from 137 to 557 mm over the four years. In all years, results indicated that attempting to store water in the soil profile, or irrigating in excess of the cotton evapotranspiration rate, early in the growing season reduced seasonal irrigation water use efficiency (SIWUE), and sometimes yield, compared to treatments with limited or no early irrigations. Treatments with 0 and 3.2 mm d-1 ICs during P1 used up to 20% less seasonal irrigation with minor yield loss (

Published in Agron. J. 107:1355–1364 (2015) doi:10.2134/agronj14.0502 Copyright © 2015 by the American Society of Agronomy, 5585 Guilford Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. ABSTRACT In the semiarid Texas Rolling Plains, the growth and yield of cotton (Gossypium hirsutum L.) is driven by the amount of water available to the crop through irrigation and precipitation. A field study was conducted in 2012 and 2013 at Chillicothe, TX, to investigate the growth, yield, water use efficiency (WUE), and spectral reflectance responses of cotton. A split-split plot design with three replications was used with irrigation as the main plot (three irrigation levels and dryland), tillage (no tillage and conventional tillage) as the subplot, and cultivars (PHY499, DP1044, PHY375, and FM9170) as the sub-subplot treatments. Plant height, lint yield, WUE, and fiber quality were significantly affected by irrigation and irrigation × cultivar interaction. Increasing irrigation level resulted in a linear increase in lint yield and WUE. The irrigation × cultivar interaction showed that the 90% evapotranspiration (ET) replacement treatment with PHY375 produced the greatest lint yield and WUE. Tillage did not significantly affect lint yield, WUE, or fiber quality. Increasing irrigation resulted in a linear increase in fiber length and strength, and a linear decrease in fiber micronaire. Two vegetation indices, normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) were calculated using spectral reflectance measurements in this study. The NDWI increased steadily for all irrigation treatments during the measurement period. However, NDVI exhibited little change during the peak growth period between 79 and 89 d after planting. We suggest further investigation on using NDWI for irrigation management for cotton in the Texas Rolling Plains.

Cotton producers on the southern High Plains of Texas face reduced seasonal irrigation capacities as groundwater resources from the Ogallala Aquifer decline. Technological advancements have allowed producers to achieve maximal water use efficiencies (>95 %); however, new management strategies are necessary to sustain producer profitability. By determining the optimal timing of irrigation, producers may be able to conserve irrigation water and reduce their pumping expenses. In a field experiment conduced from 2010 to 2013, cotton (Gossypium hirsutum L.) lint yield and profitability were compared across 27 irrigation treatments using a LEPA irrigation system on Pullman Clay/Olton soils. Irrigation was applied during three growing periods determined by growing degree days (GDD15.6), where P1=emergence to 525 GDD15.6, P2 = 525–750 GDD15.6, and P3 > 750 GDD15.6. Treatments for the experiment included three irrigation capacities of 0, 3.2, and 6.4 mm d−1 in a randomized block design with three replications. Profitability was assessed by calculating gross margin from economic budgets that included the management operations from each year. On average, treatments with an irrigation capacity of 0 mm d−1 in P1 made 6 % less yield, but saved 30 % more water and generated the same profitability as the IC treatments of 3.2 mm d−1. Irrigation during P3 at the 6.4 mm d−1 irrigation capacity (IC) was the most critical for yield potential, generating 114 % more yield than the 0 mm d−1 IC and 27 % more than the 3.2 mm d−1 IC treatments, resulting in a 468 % and 110 % increase in profit, respectively.

An important limitation to cotton (Gossypium hirsutum L.) production in the Texas High Plains is water shortage. A 2-yr study was conducted at two locations in Lubbock, TX, in 2007 and 2008 to determine the optimal irrigation and plant density for cotton production in the Texas High Plains based on yield and fiber quality. A field experiment was conducted by using a split plot design, with irrigation (0, 2.54 and 5.08 mm d–¹) as the main plot, and plant density (75,300; 150,600; and 226,000 plants ha–¹) as the subplot. Two central rows of each plot were machine harvested to determine lint yield. Fiber quality was tested by both High Volume Instrument (HVI) and Advanced Fiber Information Systems (AFIS). The results showed environmental conditions heavily impact lint yield and fiber quality. Irrigation played a significant role in yield and fiber quality. Under appropriate weather conditions at Quaker 2008, 5.08 mm d–¹ irrigation rate increased seed cotton yield by 36.4 and 214.3%, compared with 2.54 and 0 mm d–¹, respectively. Irrigation of 5.08 mm d–¹ increased fiber length by number, uniformity, and short fiber content. The fineness and maturity ratio and subsequently micronaire decreased. Plant density seemed to play a smaller role in determining yield and fiber quality. Based on profitability, higher yield did not necessarily translate to higher net returns. We concluded that weather pattern and irrigation heavily impact yield and fiber quality in the Texas High Plains.

The boll distribution characteristics of upland cotton (Gossypium hirsutum L.) cultivars are related to cotton maturity and can interact with environment and management practices to determine yield and fiber quality. The boll distributions of six cotton cultivars under four irrigation levels were compared in 2011 and 2012 on the Texas High Plains. In 2011, a year of severe drought and heat, all cultivars had relatively compact fruiting patterns and increases in irrigation affected both boll accumulations up the plant and second-position fruiting sites. In 2012, which was less hot and dry than 2011, all cultivars produced more fruit on higher sympodial branches; however many cultivars followed unique patterns of boll accumulation with increased irrigation. Later-maturing cultivars significantly increased boll production at higher portions of the plant while early maturing cultivars retained more bolls at the bottom of the plant. One cultivar, DP1311, increased yield at the second position as irrigation increased. Micronaire was also compared among the cultivars and irrigation treatments. In 2011, micronaire increased with increasing irrigation, while in 2012, micronaire decreased with increasing irrigation. There was a strong irrigation by cultivar interaction for micronaire in both years, which may have been related to boll accumulation patterns for the cultivars. These findings suggest that the cultivars compensate for yield differently in response to increased irrigation, and the choice of a specific cultivar should also take into account fruiting habits and their potential effect on micronaire in respect to environmental and management factors, particularly water availability.

Vegetation indices based solely on visible reflectance may simplify and decrease the cost of crop growth estimates compared to visible and near-infrared (NIR) indices. Ground-based and aerial visible and visible/NIR vegetation indices based on aerial images were compared for sensitivity to ground cover fraction (GCF) of cotton (Gossypium hirsutum L.) under four irrigation treatments in 2004 and five treatments in 2005 and 2006. In-season cotton imagery was collected using an unmodified Nikon COOLPIX 4300 camera and a COOLPIX 4300 camera modified for NIR imaging attached to a tethered blimp. GCF imagery was collected at 45 to 60 m and compared with normalized difference vegetation index (NDVI) and green/red ratio values from imagery collected at 180 to 250 m. Ground-based (1.5 m) spectrometer NDVI measurements using multiple spectral regions were also evaluated. Spectrometer (r 2 = 0.40 to 0.80) and camera (r 2 = 0.68 to 0.90) indices were highly correlated with season-wide GCF between fractions of 0.20 and 0.80 and were sensitive to irrigation treatments. Camera green/red ratio was linearly correlated with GCF throughout the 3 yr. The pooled comparison for the 3 yr was strongly linear (r 2 = 0.86). Our results suggest that the green/red ratio index might allow quick, simple, and accurate crop growth estimates for production.

Although subsurface drip (SSD) is used as a water-efficient alternative to overhead irrigation in many crops, the effects of SSD on the distribution of bolls on cotton plants (Gossypium hirsutum L.) have not been thoroughly examined. The purpose of this study was to add to the current knowledge about the effects of SSD on cotton yield dynamics. Cultivar DP 488 BG/RR was grown in three studies during 2 yr with irrigation treatments consisting of overhead irrigation (Overhead), a nonirrigated control (Nonirrigated), SSD matched to overhead irrigation amounts and frequency (SSD Matched), and SSD based on soil moisture (SSD Fed) irrigated cotton. The cotton was grown in two locations in 2004 and one location in 2005 in Georgia. Crop height, maturity, and soil moisture status were monitored throughout the growing season in each location. At harvest, a subplot consisting of one harvest row measuring 3 m in length was removed from each plot and handpicked to determine cotton boll distribution in each plot. Irrigation method had a significant impact on boll distribution on the plants, with the overhead irrigation treatment consistently having less cotton near the bottom of the plant and more cotton near the top than either of the SSD methods. We conclude that SSD irrigation decreases early-season fruit loss, resulting in heavier carbohydrate sinks and decreasing overall growth and upper boll filling on the crop.

Subsurface drip (SSD) is used as a water-efficient alternative to overhead irrigation in many crops. This study compared soil water, water use, crop maturity, lint yield, and fiber quality of cotton (Gossypium hirsutum L.) grown with SSD to cotton grown with overhead irrigation. Three experiments were conducted at two Georgia locations in 2004 and 2005. Treatments consisted of overhead irrigated, nonirrigated, SSD matched to overhead irrigation rates (SSD Matched), and SSD based on soil water (SSD Fed). Cotton maturity was affected by irrigation treatment as nonirrigated cotton matured earliest, whereas overhead irrigated cotton matured latest. Subsurface drip irrigated cotton produced similar or higher lint yields than overhead irrigated cotton. Subsurface drip provided adequate soil water and irrigation amounts were 4.4, 8.2, and 0.5 cm less than overhead irrigation at the three locations. Water use efficiency (WUE) of cotton SSD irrigated was 23 and 15% higher than overhead-irrigated cotton in two experiments. Irrigation method did not substantially affect fiber quality; however, micronaire was higher in cotton from the SSD Fed treatment than cotton in the Overhead treatment in two locations. We conclude that SSD irrigation provides the same positive effects as overhead irrigation in cotton production while reducing irrigation water use and may allow for improved irrigation efficiency.

New transgenic cotton (Gossypium hirsutum L.) technologies Bollgard II/Roundup Ready Flex (BGII/RRF) provide additional mechanisms for the cotton crop to retain early initiated fruiting structures positioned in the lower canopy. It may be possible, therefore, for early fruit retention to become too high with these new technologies resulting in early cutout and reduced yield. The objective of this investigation was to determine if glyphosate-induced differences in early season retention occur between BGII/RRF and the older Bollgard/Roundup Ready (BG/RR) technologies and if so, to test if these differences in retention impact crop maturity, yield, or quality under irrigated and nonirrigated conditions. A study was conducted in 2004 and 2005 at two locations in southwestern Georgia to compare the two technologies under dryland vs. irrigation with or without flower removal. The BG/RR matured later than BGII/RRF when glyphosate was applied late at the seventh and 11th leaf stages. The BG/RR compensated for fruit loss by producing heavier remaining bolls. The BGII/RRF maturity was unaffected by the late glyphosate applications and produced a higher percentage of plants having a harvestable boll in the lower canopy than BG/RR. The BGII/RRF cotton had increased boll number and weight at the first sympodial position at lower main stem nodes while BG/RR produced more and heavier bolls on upper main stem nodes. Flower removal did not negatively affect BGII/RRF or BG/RR yields. Few differences in fiber quality were observed. The BGII/RRF retained more early reproductive structures than BG/RR but also cutout earlier. Yield differences between the two technologies may be due to agronomic performance of the variety backgrounds used.