Research On Growth Dynamic Trend, Physiological Indexes And Yield For Broad Bean Under Regulated Deficit Irrigation

The effects of regulated deficit irrigation on growing trends, physiological index and yield effect of broad bean were studied in Qinwangchuan irrigation regions of Gansu Province during March to August in 2006. Nine kinds of soil moisture treatment in various degrees in different growth stage and whole growth stage were designed of broad bean in the field. The each soil moisture lower limit were (the percentage of taking the field capacityθ_f), (70%-75%)θ_f, (60%-65%)θ_f and (50%-55%)θ_f. the test result shows:1. The plant height assume linear increased tendency along with the growth period of each treatment of broad bean. The first three growth stage deficit water make the plant height of broad bean significantly decrease. The more deficit water, the more reduce obvious in height of broad bean. The plant height growth recover very fast after re-watering of slight deficit water but slower of high deficit water treatment .The plant height decreased of broad bean have also related to the deficit water stage duration time and growth stage. The water deficit stage duration short made the effect small of broad bean and deficit water in critical stage for water requirement reduces the plant height of broad bean obviously.The leaf area assume linear increased tendency along with the plant height and growth period of each treatment of broad bean. The LAI of broad bean's increase speed begin drop were related to the deficit degree, the more the deficit degree, the more the decrease obvious and deficit water in critical stage for water requirement can also reduce the LAI of broad bean obviously.From emerging to harvest period the dry matter increment in each day present the change patterns of small-big-small. The dry matter increment in each day of the treatments in water deficit stage was lower than other treatments. The dry matter increment in each day was decrease in large degree compared with other treatments especially the treatment of high water deficit.The dry matter decrease degree was different by deficit water in different growth stage.2. The photosynthesis rate and transpiration rate daily variation discrepancy no too compared with CK even some treatment overtop CK in light water deficit but the photosynthesis rate decrease obviously in high water deficit of broad bean in the whole growth stage. The photosynthesis rate and transpiration rate can be depressed for a long time by regulated deficit irrigation in the whole growth stage of broad bean and in different water deficit stage the depress time of photosynthesis was different. The decrease degree of photosynthesis rate and transpiration rate was related to the water deficit degree and the more the deficit degree, the more the decrease degree. The correlation coefficient of photosynthesis rate and transpiration rate curve regression equation all more than other treatments in light deficit irrigation. It was accounted a certain degree water deficit can enhance ratio of photosynthesis and transpiration. 3. In water controlled stage the actual evapotranspiration all below CK treatment and after re-watering the evapotranspiration increased rapidly even exceed CK. The water requirement rates (WRR) decrease compared with CK in each water deficit treatment stage and the more the deficit degree, the more the decrease. The water deficit alleviation the leaf's aging speed in upper growth stage and it made the water requirement rates more than CK. In water deficit stage the water consumption modulus of these treatments were below then other treatment and the water consumption modulus of the treatment of high water deficit were below CK and other stage of this treatment. Controlled water in different growth stage can depress the growth of broad bean and in water deficit stage the growing speed and growing intensity all below other treatment. Flowering stage was the upper period of water use efficiency. Light dry in seeding, jointing and flowering can increase the water use efficiency (WUE) of biological yield and the biological yield not below CK by dry in jointing and flowering.4. At full irrigation condition the water consumption of broad bean was most but the yield is not highest. Light deficit water in seeding was the best treatment of saving water and increase yield (increase yield 9.09%, saving water 10.92%) and light deficit water in jointing followed it. In the while the two treatments's WUE were also highest (the WUE was 1.40kg/m~3 and 1.36kg/m~3). On the contrary light deficit water in seeding and jointing was the optimal deficit stage and deficit degree of broad bean.5. Additive model and multiplicative model all obtain the sensitivity coefficient was most in flowering stage and mature stage of broad bean. Lack water in flowering stage and mature stage can affect the yield of broad bean mostly. In seeding stage the sensitivity coefficient was least and it is account lack water in this stage insensitivity of the yield effect. The regression equation of the irrigation water and yield was Y=-0.0025X~2+15.083X-15850. The economy irrigation quota was 2500m~3/hm~2 by calculate.