Ideal desiccation periods of Urochloa ruziziensis for a no-till sunflower crop

Abstract

> <span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">Sowing crops following cover crops on forage may cause injuries and<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">productivity reduction, due reasons as allelopathy or glyphosate residues. The<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">objective of this study was to evaluate the influence of differing periods between<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">cover crop (<span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;"><em>Urochloa ruziziensis</em><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">) desiccation with glyphosate and sunflower<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">(Aguará 4) sowing in a no-tillage system on crop development and productivity.<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">Two assays were performed in two seasons, one in pots and the other in a field.<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">Treatments in field assay consisted on 5 desiccation times of <span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;"><em>U. ruziziensis </em><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">(with an<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">application of glyphosate at 1.08 kg ae ha<span style="font-family: TimesNewRomanPSMT; font-size: 6pt; color: #000000; font-style: normal; font-variant: normal;">-1<span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">) preceding the sowing of no-till<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">sunflower (0, 3, 7, 10 and 30 days). At the pot assays, 6 times were studied: 0, 3, 7,<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">10, 15 and 20 days between cover crop desiccation and sunflower sowing. A<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">control without cover crop was also included in this assay. Biometric evaluations<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">were performed at the vegetative stage and at harvest. As the period between<br /><span style="font-family: TimesNewRomanPS-ItalicMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;"><em>U. ruziziensis </em><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">desiccation and sunflower sowing was shortened, achene production<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">in sunflower was exponentially reduced. Glyphosate application at 3 or 0 days<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">pre sowing diminished sunflower development and achene production by<br /><span style="font-family: TimesNewRomanPSMT; font-size: 11pt; color: #000000; font-style: normal; font-variant: normal;">approximately 30% compared to desiccation periods greater than 7 days.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /></span></span></span></span></span></span></span></span>