Dodd Ian C
The Lancaster Environment Centre, Lancaster University, LA1 4YQ, UK. Email.
Funct Plant Biol. 2007 Jun;34(5):439-448. doi: 10.1071/FP07009.
The effects of different irrigation techniques on leaf xylem ABA concentration ([X-ABA]) were compared in tomato (Lycopersicon esculentum Mill.). During partial rootzone drying (PRD), water was distributed unevenly to the root system such that part was irrigated while the remainder was allowed to dry the soil. During conventional deficit irrigation (DI), plants received the same volume of water as PRD plants, but water was distributed evenly to the entire root system. When the plant root system was allowed to explore two separate soil compartments, DI plants had a higher [X-ABA] than PRD plants with moderate soil drying, but PRD plants had a higher [X-ABA] than DI plants as the soil dried further. The difference in [X-ABA] between the two sets of plants was not because of differences in either whole pot soil water content (θ) or leaf water potential (Ψ). To investigate the contribution of different parts of the root system to [X-ABA], individual shoots were grafted onto the root systems of two plants grown in two separate pots, so that the graft union had the appearance of an inverted 'Y'. After sap collection from detached leaves, removal of the shoot below the graft union allowed sap collection from each root system. Again, DI plants had a higher [X-ABA] than PRD plants when the soil was relatively wet, but the opposite occurred as the soil dried. Root xylem ABA concentration ([X-ABA]) increased exponentially as soil water content (θ) declined. In DI plants, [X-ABA] from either pot (or the arithmetic mean of [X-ABA]) accounted for a similar amount of the variation in [X-ABA]. In PRD plants, [X-ABA] from the watered side underestimated [X-ABA], whereas [X-ABA] from the dry side overestimated [X-ABA]. The arithmetic mean of [X-ABA] best explained the variation in [X-ABA], implying continued sap flow from the dry part of the root system (J) at soil water potentials (Ψ) at which J had ceased in previous studies of PRD plants (Yao et al. 2001). Evaluating the relationship between J and Ψ may assist in maintaining export of ABA (and other growth regulators) from the drying part of the root system, to achieve desirable horticultural outcomes during PRD.
在番茄（Lycopersicon esculentum Mill.）中比较了不同灌溉技术对叶片木质部脱落酸浓度（[X-ABA]）的影响。在部分根区干燥（PRD）过程中，水分不均匀地分配到根系，使得一部分根系得到灌溉，而其余部分则让土壤干燥。在传统亏缺灌溉（DI）过程中，植株获得的水量与PRD植株相同，但水分均匀地分配到整个根系。当植株根系能够探索两个独立的土壤隔间时，在土壤适度干燥的情况下，DI植株的[X-ABA]高于PRD植株，但随着土壤进一步干燥，PRD植株的[X-ABA]高于DI植株。两组植株之间[X-ABA]的差异并非由于整盆土壤含水量（θ）或叶片水势（Ψ）的差异。为了研究根系不同部分对[X-ABA]的贡献，将单个地上部嫁接到种植在两个单独花盆中的两株植株的根系上，使得嫁接部位呈现倒“Y”形。从离体叶片收集汁液后，去除嫁接部位下方的地上部，从而能够从每个根系收集汁液。同样，当土壤相对湿润时，DI植株的[X-ABA]高于PRD植株，但随着土壤干燥情况相反。根系木质部脱落酸浓度（[X-ABA]）随着土壤含水量（θ）的下降呈指数增加。在DI植株中，来自任一花盆的[X-ABA]（或[X-ABA]的算术平均值）对[X-ABA]变化的解释量相似。在PRD植株中，浇水一侧的[X-ABA]低估了[X-ABA]，而干燥一侧的[X-ABA]高估了[X-ABA]。[X-ABA]的算术平均值最能解释[X-ABA]的变化，这意味着在先前对PRD植株的研究（Yao等人，2001年）中，在土壤水势（Ψ）下，当根系干燥部分的汁液流动（J）停止时仍有持续的汁液流动。评估J与Ψ之间的关系可能有助于维持脱落酸（和其他生长调节剂）从根系干燥部分的输出，从而在PRD期间实现理想的园艺效果。
