Tissue D T, Nobel P S
Department of Biology and Laboratory of Biomedical and Environmental Sciences, University of California, 90024, Los Angeles, CA, USA.
Oecologia. 1988 Mar;75(2):266-271. doi: 10.1007/BF00378607.
Agave deserti, a monocarpic perennial occurring in the northwestern Sonoran Desert, produces ramets on rhizomes that extend from the base of a parent plant. Shading ramtes to light compensation for two years did not decrease their relative growth rate (RGR) compared with unshaded ramets. However, the parents experienced a 30% decrease in total nonstructural carbohydrate (TNC) level, suggesting that carbohydrates were translocated from parents to ramets. Shaded parents had RGR's similar to unshaded parents, due in large part to consumption of 50% of the TNC reserves of shaded parents, but about 10% of the growth of the shaded parents was attributed to TNC received from their attached ramets. Estimates of parent and ramet growth separately, based on changes in TNC levels (converted to dry weight using a measured production value), net CO uptake of unfolded leaves, and respiration of roots, stems, and folded leaves, were similar to measured growth of parents and ramets combined, suggesting that parents and ramets are physiologically integrated and grow as a unit. Large TNC reserves, which were also shown to support growth during conditions of water limitation in the field, enhance the growth of ramets in an environment where seedling establishment is rare.
沙漠龙舌兰是一种生长在索诺兰沙漠西北部的多年生一次性结实植物，它通过从母株基部延伸出的根茎产生分株。对分株进行两年的遮荫处理，使其光照补偿，与未遮荫的分株相比，其相对生长速率（RGR）并未降低。然而，母株的总非结构性碳水化合物（TNC）水平下降了30%，这表明碳水化合物从母株转移到了分株。遮荫母株的RGR与未遮荫母株相似，这在很大程度上归因于遮荫母株50%的TNC储备被消耗，但遮荫母株约10%的生长归因于从其附着的分株获得的TNC。根据TNC水平的变化（使用测量的生产值转换为干重）、展开叶片的净CO吸收以及根、茎和折叠叶片的呼吸作用分别估算母株和分株的生长，与测量的母株和分株组合生长相似，这表明母株和分株在生理上是整合的，作为一个整体生长。大量的TNC储备在田间水分限制条件下也能支持生长，在幼苗定植稀少的环境中增强了分株的生长。
