Читать книгу Dry Beans and Pulses Production, Processing, and Nutrition онлайн

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Two contrasting methods are used to harvest beans, depending on plant type and seed size, location, local weather conditions, and irrigation systems. The traditional harvest method widely used throughout the US is to mechanically undercut (pull) beans into windrows of 6–12 rows and then thresh windrows when plants are dry using a pickup header on commercial combines. In the western states, to avoid large seed losses from pod shattering due to low humidity conditions, beans are pulled at physiological maturity when they are still green and left to ripen in the windrow for 7–10 days before being threshed. In the Midwest, where erratic rains are problematic, growers cut/pull and windrow mature plants early in the morning (4:00–11:00 a.m.) when dew adheres to the plant, thus preventing pod shattering, and the windrowed plants are threshed the same afternoon. Prostrate vine‐type varieties or those severely lodged are particularly suited to the traditional pulling system, as they would suffer major seed loss if direct harvested. In those areas where furrow irrigation is used and the soil surface is uneven, the ridged rows facilitate knife‐pulling, as do hilled rows for weed control. Conversely, rod‐pullers have the action of grabbing and pulling the plants out of the ground rather than cutting them. Bean roots are still attached to the plant following both pulling operations and enter the combine at threshing. This extra plant mass has a cushioning effect during threshing, which is particularly advantageous for larger‐seeded kidney beans, which are easily damaged at harvest.