[Clonal water integration contributes to more survival advantages for Populus euphratica young ramets in the...

The proposed investigation was carried on the characteristics of clonal water integration between the Populus euphratica mother tree and its young ramets, as well as its effects on the phy-siological traits of young ramets at the lower reaches of Tarim River. The results showed that there was obvious water integration characterized by acropetal water transport between P. euphratica mother tree and its young ramets. The mean daily flow by water integration from the mother tree to its young ramets was three times as the seedlings with similar growth status at the same habitat by getting water by itself roots. Compared with the P. euphratica seedlings, the young ramets could take much more water from relatively deeper soil layers just like their mother tree. It indicated the young ramets maintained a better water acquisition ability due to clonal water integration. There was obviously higher leaf water content of young ramets than seedlings, and especially the water potential in the predawn and midday was increased by 10.0% and 29.7%, respectively. The advantaged water status of young ramets made the photosystem 2 electron transport rate and actual photochemical efficiency of photosystem 2 in light-adapted leaves increase by 23.4% and 11.5% than seedlings, respectively, and also made the young ramets maintain a significantly lower excess excited energy in photosystem 2 and a lower risk of photoinhibition than seedlings. All of the above cha-racteristics would impel the P. euphratica young ramets had higher survival advantages than seedlings at hyper-arid habitats.