农业工程学报Issue(5)：1-13,13.DOI:10.11975/j.issn.1002-6819.2016.05.001
基于茎直径变化的精准灌溉技术研究进展
Overview of precise irrigation scheduling based on stem diameter variations
摘要
Abstract
The growing scarce water resource has promoted the scientists to develop new technologies for scheduling irrigation. Of these, the ones relying on plant-based water-stress indicators have been found to have the greatest potential. Thus, measurements of stem water content and water potential, canopy temperature, sap flow (SF), and stem diameter variation (SDV), among other variables, have proved useful not only for research purposes, but also for precise irrigation scheduling in commercial production sites. In this work, we systematically reviewed the research achievements and growing trends of precise irrigation scheduling based on SDV. Of those mentioned above, the water-stress indicator had received most attention from the scientific community in terms of its potential for irrigating commercial production sites.Apart from being capable of an early detection of water stress, even if this was mild, SDV could be continuously and automatically recorded. This was a clear advantage over conventional indicators such as stem water potential, canopy temperature and leaf gas exchange parameters (net photosynthesis rate, stomatal conductance, intercellular carbon dioxide, transpiration rate, and so on). The principle of SDV, the history of dendrometers and dendrographs, relationships between SDV-derived index and the other water-stress indicators (water potential and sap flow) were introduced and analyzed in this paper. Among the SDV-derived indices that were useful for scheduling irrigation, the maximum daily shrinkage (MDS) and stem growth rate (SGR) were the most widely used. For young trees and in their periods of rapid stem growth, SGR could be a better indicator than MDS. In periods of negligible stem growth, however, SGR could not be used as an indicator of plant water stress. SDV outputs were affected by seasonal growth patterns, crop load, plant age and size, and the other factors, apart from water stress. Thus, expert interpretation of SDV records was required before using them for scheduling irrigation, which limited their potential for automation of the irrigation. Therefore, the characteristics of an SDV-derived index for irrigation scheduling must be evaluated for the local conditions. In this study we described the characteristics that must be taken into account in the evaluation, such as variability, signal strength, sensitivity, earliness, reliability and robustness. Furthermore, methods to schedule irrigation from SDV records were summarized as using absolute values of SDV-derived indices, the signal-intensity approach and combining SDV with SF. Although SDV-derived indices showed a high variability among plants, in most cases the signal intensity was high enough to achieve an acceptable sensitivity. Accordingly, the signal intensity was important for the realization of precision, digitization and the intelligentization management of the irrigation, and was successfully used to schedule low-frequency irrigation in orchards of a variety of species, for both full-and deficit-irrigation treatments. The hot spots in this field were also proposed at last and they should be focused on the following aspects: 1) To explore more effective sensor shelters to decrease the noise produced by physical contact; 2) To determining the appropriate SDV-derived index according to the actual environment to achieve the high enough signal intensity and sensitivity; 3) To quantify the effects of other factors except water stress on SDV outputs; 4) To combine SDV with other water stress index (such as SF) to enhance the explanations for how the plants absorb and utilize the water; and 5) To combine SDV measurements with aerial or satellite imaging for scheduling irrigation in large orchards with high crop-water-stress variability.关键词
灌溉/水分/生长率/茎直径变化/日最大收缩量/水分胁迫/液流Key words
irrigation/moisture/growth rate/stem diameter variation/maximum daily shrinkage/water stress/sap flow分类
农业科技引用本文复制引用
林琭,汤昀,闫万丽,张纪涛,籍增顺..基于茎直径变化的精准灌溉技术研究进展[J].农业工程学报,2016,(5):1-13,13.基金项目
山西省农业科学院博士研究基金项目（YBSJJ1205）；山西省科技攻关项目 （）
