Effect Of Irrigation On Physiological And Ecological Indexes And Yield Of Processing Potato

Effects of irrigation on growing dymanics, physiological index and yield of processing potato were studied in Station of Yimin Irrigation Experiment of Gansu Province during March to October in 2007. There were six irrigation treatments at different growth stages: T1 (450m³Â·hm^-2),T2 (750m³Â·hm^-2),T3 (1050m³Â·hm^-2),T4 (1350m³Â·hm^-2),T5 (1650m³Â·hm^-2) and T6 (1950m³Â·hm^-2). Results showed that:1. During the whole growing period, The differences between treatments in soil moisture in 10⁴0cm were the largest at seedling period and tuber initiation period. And that were 40⁶0cm at tuber bulking period and starch accumulation period. Soil moisture with the lowest irrigation treatment (T1) was the minimum during the whole growth period, whereas T6 was the highest. Soil moisture in T5 which had the highest yield kept relatively stable.2. The overall trend of daily water consumption increased first and then decreased in whole periods. The daily water consumption was highest (3.23 mm·d-1) at tuber initiation period, but lowest (1.71 mm·d-1) at the starch accumulation period.3. Irrigation norm had significant effects on water use efficiency (WUE) and irrigation water use efficiency (IWUE). WUE did not increase as water consumption increased, but IWUE decreased.4. There were significant difference among plant height, leaf area index(LAI), dry matter accumulation, the root-shoot ratio, number of tubers per plant, tuber weight per plant, (photosynthetic rate)Pn, (transpiration rate)Tr and (stomatic resistance)Sr. T5 had the highest LAI, dry matter accumulation, number of tubers per plant, tuber weight per plant, Pn and Tr were the highest before 12:00 at tuber initiation period and tuber bulking period.5. The overall trend of soil temperature showed the upper soil was higher than lower. The range of 0¹0 cm was higher than 20²5 cm. There was significant difference among treatments at certain time.6. Water production of processing potato can be fitted with Jensen Model. The sensitive index (λ) was relatively small at early growth period, increased at middle growth period and decreased in later growth period.λreached its maximum at tuber initiation period (0.3943) and lowest at starch accumulation period (0.1018). 7. Results showed that yield increased significantly as irrigation quota increased from 1050 to 1650 m³Â·hm^-2. However, there was no more yield advantage when irrigation quota exceeded 1650m³Â·hm^-2. There was significance correlation between tuber yield and the number of tubers per plant (R=0.89**)and tuber weight per plant (R=0.84*).8. Among six irrigation scheme, T5 (1650 m³Â·hm^-2) had the highest yield, which was regarded as the optimum irrigation norm, but economic irrigation quota by analysis was 1450 m³Â·hm^-2. So it was suggested that irrigation norm was 1500 m³Â·hm^-2. It can be split into three irrigation, the first time at the seedling stage (around May 10th, 450 m³Â·hm^-2); the second at the tuber initiation phase (around June 25th, 550 m³Â·hm^-2); and the third at tuber bulking stage (around July 20th, 500 m³Â·hm^-2). The maximum yield was 27200 kg·hm^-2.