Nash and his team-mates had attended a pre-match ceremony when Hobden’s parents and his two brothers planted a tree in memory of the 22-year-old, who died in January, before both teams stood in a minute’s silence at the start of play.
Wearing Hobden’s No.19 shirt, Nash made 119 out of a first-wicket stand of 188 with Ed Joyce.
Six wickets then fell for 101 to a mixture of good bowling and rash strokes before Ollie Robinson made an aggressive half-century to help Sussex reach 355 for 9 at stumps.
Nash spent the winter tweaking his technique with former South Africa opening batsman Gary Kirsten and it paid an early dividend as he raced to his half-century off 52 balls, hitting Matt Dixon for four boundaries in the Australian seamer’s second over.
Joyce was more cautious and was dropped on three by Jesse Ryder, diving to his right at third slip, off Jamie Porter.
But Essex’s attack were guilty of bowling too much loose stuff before lunch and Nash was untroubled as he reached his century off 113 balls, including 18 fours, with a single off Graham Napier shortly after lunch.
Joyce went to 50 with a boundary off Dixon soon afterwards and it was only when skipper Ryan ten Doeschate brought himself on as the seventh Essex bowler that they made a breakthrough when Joyce (61) feathered a thin edge to wicketkeeper James Foster off his third delivery.
As often happens after a big stand another wicket fell quickly with Nash departing two balls later, lbw to one which looked a tough high after facing 144 balls and hitting 21 fours.
Sussex struggled to pick up the momentum again either side of tea. Ross Taylor’s first innings for the club ended on 12 when he was caught behind off an inside edge and Essex picked up two more wickets in successive overs immediately after tea.
Off-spinner Tom Westley caught Matt Machan (35) off a leading edge with the first ball after the resumption before late inswing from Graham Napier defeated skipper Ben Brown (0).
Luke Wells (25) squandered a good start when he thick-edged to slip off Westley, who at one stage had figures of 9-6-14-2, before Robinson and Ajmal Shahzad counter-attacked in a stand of 51 in 14 overs for the eighth wicket.
Robinson, who made a century on his Sussex debut batting at No.10 a year ago, played some impressive shots through the off side as Essex rather squandered the new ball. He reached his fifty off 60 balls with nine fours before becoming Napier’s third victim, lbw playing across a straight one.
Ravi Bopara picked up George Garton (1) but Shahzad and Danny Briggs took Sussex to their fourth batting point just before the close.
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