Influence of corn hybrids and water stress on yield and nutritive value

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Title: Influence of corn hybrids and water stress on yield and nutritive value
Author: Montgomery, Randall
Abstract: Silage corn (Zea mays ) in Texas has increased from 16 ,000 ha harvested in 1985 to 53 ,000 ha harvested in 2005 . All corn in the Texas High Plains is irrigated with water from the Ogallala Aquifer . Due to the declining water level of the Ogallala Aquifer and rising energy costs , corn silage producers need new hybrids that require less water and respond to improved crop management practices . As the dairy industry continues to grow in West Texas , producers must supply a high -quality , high -yielding corn forage that meets the nutritional demands of the dairy industry . The objective of this study was to compare the responses in regards to grain yield , forage yield and quality of five Texas Agricultural Experiment Station (TAES ) corn hybrids and three widely grown commercial hybrids (Garst 8288 , P31B13 , and DKC66 -80 ) under full and limited irrigation treatments . This experiment was conducted in 2005 and 2006 , at Halfway , TX and Etter , TX . There were two irrigation treatments (well -watered and drought -stressed ) at Etter and Halfway in both years . Drought stress was imposed by reducing the amount of irrigation water by one -half compared to well -watered plots from V10 to R3 growth stages . Plots were two -rows 5 .5 m long and spaced 1 m apart at Halfway and 0 .76 m apart at Etter . After planting , plots were thinned to 66 ,947 plants /ha at Etter and 57 ,383 plants /ha in Halfway . Data was collected on grain yield , silage yield , plant height , ear height , days to pollen , neutral detergent fiber (NDF ) , acid detergent fiber (ADF ) , crude protein and numerous other forage quality traits . Whole plant corn samples were collected and sub -samples were analyzed by Dairy One Forage Laboratory (Ithaca , NY ) using Near Infrared Reflectance Spectroscopy (NIRS ) . The basic experimental design for this analysis was a randomized complete block design with two blocks (locations ) ; irrigation treatments (100ET and 50ET ) represented the main plot factor of a split -plot arrangement , and hybrid was a subplot factor . No three -way interactions were observed among year , irrigation , and hybrid for any of the variables analyzed . Additionally , interactions between irrigation and hybrid , and between irrigation and year , were not present for any of the variables analyzed . Effects of hybrids depended on the year of the experiment (year X hybrid interaction ) for percentage ADF , NDF , TDN , and DM . For grain yield , per plant fresh weight (FW plant -1 ) , DTP , PHT and EHT , differences among hybrids were independent of other factors included in this study . Thus , differences among hybrids were averaged over each yr and effects of hybrid and irrigation treatment were examined . Differences among hybrids were observed for grain yield (kg ha -1 ) , FW plant -1 , DTP , PHT , and EHT . When analyzing grain yield , the commercial check P31B13 (8703 kg ha -1 ) was the highest yielding hybrid with the exception of C3A654 x B110 (7800 kg ha -1 ) and DKC66 -80 (8044 kg ha -1 ) . In terms of FW plant -1 , S1W x CML343 yielded a greater fresh weight per plant than any other hybrids except DKC66 -80 , while C3A654 x B110 yielded the least fresh weight per plant . Also , S1W x CML343 was the latest maturing hybrid when compared to all others and took an average of 80 d to anthesis (DTP ) . In terms of plant height , S2B73 x NC300 was a taller hybrid than Tx205 x B110 (230 .6 ) and C3A654 x B110 (210 .3 ) as it averaged 244 .4 cm , while , C3A654 x B110 was statistically the shortest when compared to all other hybrids as it measured just over 210 cm on average . Drought stress (50 % ET irrigation ) did affect both ADF and NDF in terms of forage quality . Both cell wall (NDF ) and cell wall minus hemicelluloses (ADF ) were higher in hybrids subjected to water stress than hybrids irrigated at 100 % ET . Irrigation level did not affect percentage CP and TDN . Grain yield was reduced about 50 % by the low irrigation treatment compared with full irrigation . Surprisingly , there were no statistical differences found in the forage yield (FW plant -1 ) or in DTP with the imposition of drought . Effects of year and hybrid interacted with each other for ADF , NDF , TDN and DM . For DM , hybrids were similar (P > 0 .1560 ) in 2005 and differed (P < 0 .0001 ) in 2006 . However , for ADF , NDF and TDN , hybrids differed in each year . In future studies the integration of brown mid -rib hybrids should be made a priority . Some hybrids from this study did show promise and should be considered for future studies as well . Although S1W x CML343 lacked the quality traits that some of the other hybrids , it should not be ruled out on that premise alone . It did appear to be one of the higher yielding hybrids and should be considered for future studies . While C3A654 x B110 did appear to produce higher quality forage , it also had the shortest plants and might lack the overall forage production when being considered for future studies . Also , SPG3 x B110 appeared to have quality traits that would be very desirable and at the same time may include some higher yielding traits and should be used in potential studies . A major limitation in this study was the inclusion of only two blocks , although the two locations did serve as valid blocks . More research and detailed analysis must be performed in order to select for high yielding , high producing corn forage that might potentially use less water . This study may help to serve as a reference to future researches .
URI: http : / /hdl .handle .net /2346 /18065
Date: 2009-05


Influence of corn hybrids and water stress on yield and nutritive value. Master's thesis, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /18065 .

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