Taproot Restriction Effects on Growth, Earliness, and Dry Weight Partitioning of Cotton
- A. Ben-Porath and
- D. N. Baker
Cotton (Gossypium hirsutum L.) is an indeterminate, woody perennial, whose primary axis remains vegetative throughout the life of the plant. During the boll-filling period, the growing mainstem and taproot compete with reproductive organs for limited supplies of assimilates. In a series of experiments, the effects of taproot restrictions on growth and development of drip irrigated cotton plants were explored. Cotton (‘Stoneville 825’) plants were grown outdoors and in sunlit growth chambers. Taproots were restricted to various degrees by using different pot sizes (I, 2.5, 7, 12, and 18 L) during the years 1982 to 1983. The pots were arranged in a row crop configuration (10 plants m−1 of row, 1m between rows). Dry matter distribution was measured destructively. The restriction of the taproot apical dominance by small pots (I or 2.5 L) accelerated the formation of secondary and tertiary roots compared to roots in larger pots (7 L or more). Taproot-restricted plants started to flower earlier and they flowered faster. Their heavier load of developing bolls caused a greater slowing of vegetative growth of the main axis. As a result, taproot-restricted plants were more compact due to shorter internodes on fruiting branches and at the top of the plant. Taprootrestricted plants were earlier and higher yielding in short seasons because of better partitioning of assimilates into fruit rather than into storage organs.
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