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Northwest University of Science and Technology (2008)

Study on Water Consumption Characteristics, Growth Patterns and Regulated Deficit Irrigation Patterns of Alfalfa in Arid-Hungriness Oasis Area

YangLei

Titre : Study on Water Consumption Characteristics, Growth Patterns and Regulated Deficit Irrigation Patterns of Alfalfa in Arid-Hungriness Oasis Area

Auteur : 杨磊; Yang Lei

Grade : Master’s Theses 2008

Université : Northwest University of Science and Technology

Résumé partiel
This paper introduces alfalfa’s growth patterns, water consumption characteristics and regulated deficit irrigation model in desert oasis of Gansu province. The experiment was conducted in the farm of the center of agriculture and technology in Minqin county, Gansu province. According to the production practical in Minqin, carried out the experiment in the different growing periods(70%, 55%, 40% of field capacity) of different cutting and the first cutting under water deficit, which controlled by lower limit of soil water content. When soil water content under 80cm reached the lower limit to irrigation, the upper limit soil water content is 90% field capacity. According to the cultural characteristics and physiological feature of alfalfa, the harvest of alfalfa have three cutting. The first cutting for growth period are : growth stage, branching stage, budding stage, initial flower stage. The experiment set up 11 treatment groups, three repetitions were required in each intensity. We use first cutting single stage combination with whole growth period water deficit, and whole year different cutting in single stage combination with every cutting water deficit. The experiment were carried out from Apr. 15th to Sep. 30th, the experiment periods last 168d, the results as follow :(1) According to the study of alfalfa’s growth in the aerial and underground parts of the plants show that : different growth have inhibition role to height, stem diameter, area of leaves, root crown diameter, depth in soil. Milder deficiency irrigation level increase a lot of lateral root and branch number, after the rehydration, height and area leaves present compensatory growth. As to the first stubble, especially for light water stress(55%θf)before budding stage, it have benefit to root growth, optimal canopy structure. It is important to alfalfa have a whole harvest.(2) Different water deficit in different degree will reduce the growth of leaves transpiration, photosynthesis and leaf conductance. Different water deficit in different stage will increase the WUEL in this stage. Transpiration, photosynthesis and leaf conductance are double-peak curve except for branch photosynthesis is unimodal. The appearance time of wave crest and the wave trough have little different. Leaves transpiration and photosynthesis have a different degree to leaf conductance. With the increase of leaf conductance, leaves transpiration have a same increasing extent with photosynthesis. But when the leaf conductance exceeds some value, the increasing rate of photosynthesis is slowered obviously and even have a large decrease. The alfalfa begin to enter luxurious transpiration stage from the perspectives of photosynthetic product. WUEL is increased by water deficit before budding stage.(3) There is changes in soil moisture : alfalfa can obtain effective water use in the 0 180cm soil moisture, the changes of the high water treatment is more obvious, draws water the function to be more obvious.(4) The water consumption analysis indicated that water consumption rate express a tendency which the cutting decreases progressively, there is a number of water consumption in the first cutting, water consumption reaches maximum value in the budding stage, branching stage next best. Relationship between irrigates quantity and the water consumption are analyzed that the water consumption is increased with irrigates the quantity increased, but the same irrigate quantity, different time of the irrigation will have the tremendous influence to the water consumption.

Mots clés : Arid-hungriness oasis area; alfalfa; Regulated Deficit Irrigation; growth Pattern; Water consumption characteristics;

Présentation (CNKI)

Page publiée le 11 septembre 2014, mise à jour le 18 novembre 2017