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are strongly recommended, but when this is not possible, harvest intervals should not be longer than two days to avoid excessive seed exposure to unfavorable environments. Immediately after each harvest, seeds are packaged in plastic bags for storage.

(28) The Recalcitrant Behavior

The term recalcitrance refers to seeds that undergo no maturation drying as the final stage of development, tolerate very little post-shedding desiccation and are often chilling-sensitive. In contrast, orthodox seeds are shed from the parent plant at low moisture contents and their storability is favored by seed drying and decreases in temperature.

Species that produce recalcitrant seeds have adopted a reproductive strategy in which relatively large-sized seeds do not undergo drastic maturation drying as the final stage of development and usually do not exhibit a latent after-ripening period. These seeds are normally shed at regular intervals in humid environments at relatively high moisture content, usually greater than 30% on a fresh weight basis, and germinate almost immediately. Among the recalcitrant species, most are produced in the tropics, including several of economic importance such as mango, avocado, cocoa, coconut, rubber tree, guarana, oak tree, loquat, etc.

(29) The development pattern of orthodox seeds consists of a period of cell division, early expansion and morphogenesis followed by a significant increase in dry weight, and a third phase of rapid desiccation until hygroscopic equilibrium with the surrounding environment is achieved. In contrast, a common feature of recalcitrant seed development is the absence of rapid drying phase after maximum dry weight is attained. These seeds are shed or harvested at relatively high moisture content as shown in this Figure.

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