The Collaborative International Dictionary of English v.0.48:

Truck \Truck\, n. [Cf. F. troc.]
   1. Exchange of commodities; barter. --Hakluyt.
      [1913 Webster]

   2. Commodities appropriate for barter, or for small trade;
      small commodities; esp., in the United States, garden
      vegetables raised for the market. [Colloq.]
      [1913 Webster]

   3. The practice of paying wages in goods instead of money; --
      called also truck system.
      [1913 Webster]

   Garden truck, vegetables raised for market. [Colloq.] [U.
      S.]

   Truck farming, raising vegetables for market: market
      gardening. [Colloq. U. S.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

truck farming
    n 1: growing vegetables for the market

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "truck farming":
   agrarianism, agricultural geology, agriculture, agrology,
   agronomics, agronomy, contour farming, cultivation, culture,
   dirt farming, dry farming, dryland farming, farm economy, farming,
   fruit farming, geoponics, grain farming, husbandry, hydroponics,
   intensive farming, mixed farming, rural economy, sharecropping,
   strip farming, subsistence farming, tank farming, thremmatology,
   tillage, tilth