"In my view, the acceptance of campaign donations puts the elected member at risk of a perception of lack of independence," Ms Bowers said.
According to the regional council's return of electoral donations and expenses, fruit-growing groups were major contributors to the campaigns of the three Hastings councillors, and Ngaruroro councillor Peter Beaven.
All but Mr Barker declared contributions from Bostock Group, totalling $15,784. Apatu Farms donated a total $7868, and the Crasborn Group, a total $6747.
Ms Bowers said if the same people were funding the councillors in their re-election bids, it raised some serious questions.
"If you're getting significant funding from one group of people in successive elections, how can you possibly sit there and be truly independent? I'm not saying that they're not being independent, but I'm just saying that it raises a big question."
The three councillors have denied the contributions from the horticulture sector have, or could, influence them in their roles.
This election, Mr Belford said he had received around 18 contributions, two of whom were from growers.
"To say I am beholden to any part of the community is just ridiculous," he said. "If Cynthia or anyone else has the perception that Tom Belford is bought by the growers of Hawke's Bay for two $1500 contributions, well, they're welcome to that perception."
Although he had received $4257 in support from growers in the 2013 election, he said people would be stunned by the breadth of support, including financial, that he had in the community.
"It's ridiculous to try to pin something on me that I'm going to be influenced by where these contributions come from," he said. "I haven't had my nose in the public purse for 21 years like Cynthia to build up a campaign war chest, so I go out to the community and ask for that support. I'm proud of the support I receive."
"This is an attack on my integrity, that's the way I'm treating it. As I say the breadth of my support speaks for itself."
Mr Graham, who recorded donations of $16,455, said receiving contributions from the horticulture industry did not influence his thinking on it at all.
"Lots of people help me in my election," he said, "and I am very honoured that they do, that they think I'm worthy of their help whether it be financial or otherwise".
"I take them on when I think they're doing wrong," he said, "and I have been the strongest advocate for stopping burning fires in orchards."
He said Ms Bowers comments were "a slight on my integrity, and an insult to the people that do contribute".
"She's attacking us on transparency, she's deflecting from the fact that she was part of a council decision to give $50,000 to a water bottling plant in secret."
Although Mr Barker recorded a $1967 contribution from Apatu Farms on his return, he said this was not cash but what others had spent endorsing his candidacy. Assistance he received was from "horticulture growers who were grassed off" at how the regional council had handled water issues in their areas.
"They wanted regional councillors who would listen to the public, and go see them," he said. "It doesn't mean to say we would always agree with them."
He took exception to the notion that this meant he might not be seen as being independent.
"I'm bought by no one," he said.
Ms Bowers said although she had been offered financial assistance during her campaign, she had not accepted any donations.
"I made a campaign pledge right at the very outset that, firstly, I was going to run a positive campaign. That's getting increasingly difficult, but also that I was going to be independent and that I wouldn't be seeking funding," she said.
In an opinion piece in Hawke's Bay Today last week, Mr Belford accused Ms Bowers, currently the deputy mayor of Hastings District Council, of a flip-flop on her stance on water bottling now she was standing for the regional council.
In a letter to the editor, current Napier regional councillor Christine Scott cited this piece, and said maybe it was time Mr Belford was accountable.
"In the interest of transparency Mr Belford needs to come clean on who his funders are, why last election he spoke against maintaining minimum flows protecting aquatic ecosystems, and why after initially supporting the Water Conservation Order [WCO] on the Ngaruroro, lodged by Fish & Game, raising the minimum flows, he then voted for council to oppose the WCO," she said.
In response, Mr Belford said he did not understand what Ms Scott was talking about.
"From the first time [the WCO] was put forward I was very clear that I thought it was a legitimate use of [sponsors] right to force a set of issues about water quality in the Ngaruroro," he said.
He said he had worked to get all involved, sponsors and the heretaunga growers community, on the same page, and to help them understand the process.
"So I'm not sure what Councillor Scott is talking about in terms of, what did I vote for on day 3 versus day 15. I have no idea what those votes were, or when they occurred," he said.
Ms Scott, who is not standing for re-election, also disputed comments made by him in a Talking Point earlier this month that he, and councillors Beaven, Barker, and Graham, had voted against awarding the Ruataniwha Water Storage Scheme, only to be "again over-ruled by the Dam Five".
She said: "Mr Belford's comment is so misleading that it is ludicrous. But he was present and should know the results of the voting".
"The vote on proceeding with the Ruataniwha Water Storage Scheme subject to 4 conditions, was 6 to 3. The vote to approve all but the last condition was 7 to 2."