Data/hora: 10/06/2024 11:30:18

Provedor de dados: 	18	
País: 	United Kingdom	
Título: 	Effect of timing of a deficit-irrigation allocation on corn evapotranspiration, yield, water use efficiency and dry mass	
Autores: 	Payero, J.O.; Tarkalson, D.D.; Irmak, S.; Davison, D.; Petersen, J.L.	
Data: 	2009	
Ano: 	2009	
Palavras-chave: 	Soil; Water; Drip irrigation.	
Resumo: 	Water regulations have decreased irrigation water supplies in Nebraska and some other areas of the USA  Great Plains. When available water is not enough to meet crop water requirements during the entire  growing cycle, it becomes critical to know the proper irrigation timing that would maximize yields and  profits. This study evaluated the effect of timing of a deficit-irrigation allocation (150 mm) on crop  evapotranspiration (ETc), yield, water use efficiency (WUE = yield/ETc), irrigation water use efficiency  (IWUE = yield/irrigation), and dry mass (DM) of corn (Zea mays L.) irrigated with subsurface drip  irrigation in the semiarid climate of North Platte, NE. During 2005 and 2006, a total of sixteen irrigation  treatments (eight each year) were evaluated, which received different percentages of the water  allocation during July, August, and September. During both years, all treatments resulted in no crop  stress during the vegetative period and stress during the reproductive stages, which affected ETc, DM,  yield, WUE and IWUE. Among treatments, ETc varied by 7.2 and 18.8%; yield by 17 and 33%; WUE by 12  and 22%, and IWUE by 18 and 33% in 2005 and 2006, respectively. Yield and WUE both increased linearly  with ETc and with ETc/ETp (ETp = seasonal ETc with no water stress), and WUE increased linearly with  yield. The yield response factor (ky) averaged 1.50 over the two seasons. Irrigation timing affected the  DMof the plant, grain, and cob, but not that of the stover. It also affected the percent of DM partitioned to  the grain (harvest index), which increased linearly with ETc and averaged 56.2% over the two seasons,  but did not affect the percent allocated to the cob or stover. Irrigation applied in July had the highest  positive coefficient of determination (R2) with yield. This high positive correlation decreased  considerably for irrigation applied in August, and became negative for irrigation applied in September.  The best positive correlation between the soil water deficit factor (Ks) and yield occurred during weeks  12–14 from crop emergence, during the ‘‘milk’’ and ‘‘dough’’ growth stages. Yield was poorly correlated  to stress during weeks 15 and 16, and the correlation became negative after week 17. Dividing the  150 mm allocation about evenly among July, August and September was a good strategy resulting in the  highest yields in 2005, but not in 2006. Applying a larger proportion of the allocation in July was a good  strategy during both years, and the opposite resulted when applying a large proportion of the allocation  in September. The different results obtained between years indicate that flexible irrigation scheduling  techniques should be adopted, rather than relying on fixed timing strategies.	
Tipo: 	Article	
Idioma: 	Inglês	
Identificador: 	http://eprints.nwisrl.ars.usda.gov/1328/1/1305.pdf

Payero, J.O. and Tarkalson, D.D. and Irmak, S. and Davison, D. and Petersen, J.L.  (2009) Effect of timing of a deficit-irrigation allocation on corn evapotranspiration, yield, water use efficiency and dry mass.   Agricultural Water Management.     96:1387-1397.	
Relação: 	http://eprints.nwisrl.ars.usda.gov/1328/

1305	
Formato: 	application/pdf