| Sweet potato is a multi-use crop in food, feed and economy in China. The waterconsumption defection is more during the early period of sweet potato. During thecrop closing period, the water deficiency has a serious effect on the seed number perplant and yield of sweet potato. The drought resistance of sweet potato could beincreased through fertilizer application. The studies were less on the effect of droughton sweet potato under different fertilizer application conditions at present, and mostof them were centered on the yield of sweet potato in dry land. However the studieswere not found on the growth and development and physiology of sweet potato. Inorder to supply a theory base of drought resistance cultivation of sweet potato, theexperiment was conducted to study the effect of soil drought on the growth anddevelopment and physiology of sweet potato under various fertilizer applicationconditions with two varieties, Qinshu 4 and 619, through pot cultivation. The resultsshowed that: (1) The green leaf number of sweet potato reduced with the decreased of soilmoisture, and the differences of green leaf number among soil moistures weresignificant at the 0.01 level. The differences among different fertilizer levels were alsosignificant at the 0.01 level. The green leaf number increased with the increase offertilizer and was more in the treatments with several fertilizer elements than that inthe treatments with only one element. The interaction between fertilizer applicationand soil moisture was extremely significant in almost all the experiments . The yellowleaf number was not significant in the fertilizer application, soil moisture and theirinteraction in almost all the experiments. The green leaf number was increasing with the growth of sweet potato, and thedifferences among soil moistures were clearer and clearer. The difference amongfertilizer applications had a same change tendency but the tendency was weaker andweaker with the increase of soil drought extent.7 (2) The stem number and total stem length were significantly reduced with theincrease of soil drought extent at the 0.01 level. Among fertilizer applications, thedifferences of stem number were significant at the 0.01 level in almost all theexperiments. The interaction of stem number between fertilizer application and soilmoisture was significant at the 0.05 or 0.01 level in almost all the experiments. Thestem length of two varieties were significant at the 0.01 level among various fertilizerapplications, and increased with the increase of fertilizer and was more in thetreatments with several fertilizer elements than that in the treatments with only oneelement. Fertilizer application extremely significantly interacted with soil moisture inthe stem length. The dynamics changes of the stem length were same as those of thegreen leaf number. (3) The fresh and dry weight of stem were reduced with the decrease of soilmoisture. Both the differences among soil moistures and among fertilizer applicationswere significant at the 0.01 level. In fertilizer application, the stem length increasedwith the increase of fertilizer and was more in the treatments with several fertilizerelements than that in the treatments with only one element. An extremely significantinteraction existed between fertilizer application and soil moisture. (4) After more than 40 days, the growth and development of sweet potato rootbecame slower and slower, and the seed member per plant reduced with the decreaseof soil moisture. The root was different among fertilizer applications. The seed wasonly formed in all the treatments under the condition of common water supply and inHF and HP treatments under the condition of middle drought extent. (5) With the decrease of soil moisture, the leaf area per plant reduced extremelysignificantly. A significant difference existed among fertilizer applications at the 0.01level. The leaf area per plant in fertilizer application showed incr...
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