(trial court determined that defendant, provider of labor in joint venture with plaintiff with respect to tomato crop, not liable for loss of part of the tomato crop; defendant responsible for selling the tomatoes on commission basis with parties splitting net proceeds; joint venture agreement did not make defendant a commission merchant under state law because defendant had no ownership interest in tomatoes; defendant not required to be licensed as commission merchant; state law licensing requirements for commission merchants applicable only to sales of produce of another producer).