try:
    consulta = "SELECT "+select+" FROM parametros "
    print(consulta)
    cur.execute(consulta)
    rows = cur.fetchall()
    for row in rows:
        #print(row)
        lista = {}
        lista['temperatura'] = row[0]
        lista['ph'] = row[1]
        lista['oxigeno'] = row[2]
        lista['electroconductividad'] = row[3]
        listas.append(lista)
    #print (listas)

except Exception as inst:
    print("Error en conexion con la base de datos", inst)

return json.dumps(listas)

import sqlite3

def dict_factory(cursor, row):
    d = {}
    for idx, col in enumerate(cursor.description):
        d[col[0]] = row[idx]
    return d

select = ("temperatura", "ph", "oxigeno", "electroconductividad")

conn = sqlite3.connect('test.db')
conn.row_factory = dict_factory

consulta = "SELECT {} FROM parametros".format(", ".join(select))
cur = conn.cursor()

cur.execute(consulta)
listas = cur.fetchall()

import sqlite3


select = ("temperatura", "ph", "oxigeno", "electroconductividad")

conn = sqlite3.connect('test.db')
conn.row_factory = sqlite3.Row

consulta = "SELECT {} FROM parametros".format(", ".join(select))
cur = conn.cursor()

cur.execute(consulta)
listas = [dict(row) for row in cur]

[{'temperatura': 24, 'ph': 7.5, 'oxigeno': 12, 'electroconductividad': 1.2},
{'temperatura': 25, 'ph': 6.3, 'oxigeno': 14, 'electroconductividad': 1.4},
{'temperatura': 26.3, 'ph': 8, 'oxigeno': 15, 'electroconductividad': 1.2},
{'temperatura': 27.5, 'ph': 6.2, 'oxigeno': 17, 'electroconductividad': 1.3}]