| Aims:Rice under drip irrigation with firm mulch(DIFM) has a significant effect on saving water and fertilizer. However, it stresses tolerance may become weak if compared to flood irrigation(FI).The paper aims to study the mian reason why rice seedling died and the yield significantly decreased under DIFM when irrigated water was using well water. By added Na Cl to the soil,lowered or raised the soil temperature, to study on the mechanism of inhibitting growth about salinity, soil temperature and the interaction between salinity and temperature, to provide theoretical basis for drip irrigation with film mulch rice.Methods:The research conducted at Xinjiang Tianye Agricultural Research Institute(plot experiment)and Agricultural Experiment Station in Shihezi University(pot culture), Shihezi, Xinjiang province, China in 2014-2015, respectively. Lowland rice genotype T-43(Oryza sativa L.)(Moderately sensitive to salinity and temperature) was used in this study.The pot experience I consisted of a two factor design with two irrigation treatments(drip irrigation and flood irrigation, abbreviated DI and FI, respectively) and three soil temperature treatments(18℃, 28℃and 36℃, abbreviated T1, T2 and T3, respectively). The pots were moved to one of three water chambers in a water bath with temperature control when rice growth at(1)tillering stage(TS),(2) jointing to booing stage(BS) and(3) grain-filling stage(GS), six pots of rice were placed in the water chamber to receive different temperature treatment for 25 days. The experiment to evaluate(1) effects of irrigation methods on the adaptability of temperature stress in rice and(2) effects of low temperature stress on different growth stages under drip irrigation rice to adaptability.The plot experiment was two factors test. There were two salt content(Low salt 1.50 g kg-1,Medium salt 2.58 g kg-1, abbreviated LS and MS, respectively) and two distant(According to the location of the rice and drip tape, near line(NL) was the distance from the drip irrigation zone 12 cm, far line(FL) was the distance from the drip irrigation zone 22 cm.). The study to explore the effects different salt contents on the drip-irrigated rice growth and yield through the detection of soil salt ion concentration distribution in soil and rice dry matter, Leaf SPAD value and yield.The pot experience II consisted of a two factor design with two soil salinity treatments(0 and1.8 g kg-1 Na Cl, abbreviated S0 and S1, respectively) and three soil temperature treatments(18℃,28℃ and 36℃, abbreviated T1, T2 and T3, respectively). The pots were placed in one of three water tanks when the seedlings had one fully extended leaf. The whole pots are kept in the temperature controlling system(i.e., Figure 2) for 10 days. The experiment was to study the effects of soil temperature and salinity on rice seedlings growth under drip irrigation.Results:The paper aims to study on soil temperature, salinity, the interaction between salinity and temperature to rice under drip irrigation with film mulch,All of the works were to explore(1) The differences of soil temperature on rice growth, nutrient uptake and yield.(2) The soil salinity injury mechanism, the effect of interaction of soil salinity and soil temperature on rice seedlings growth. The main results are as follows:(1) Low soil temperature induced leaf chlorosis in drip irrigation rice, slow growth and yield lose. Low temperature reduce of yield and biomass in the order of BS stage > TS stage > GS stage. And drip irrigation rice had no yield after low temperature treatment at the BS stage.Compared with temperature treatment filling stage, low soil temperature had a greater influence on growth, SPAD value and yield at TS stage and BS stage. And low soil temperature had a greater influence on growth under drip irrigation rice than flood irrigation rice.(2) Increasing soil temperature contributed to the absorption and accumulation of rice root on N, P and K. N, P and K content in shoot were more than in root, indicating they were easy to transport in plants. Flooded culture was conducive to absorb P and K of rice root, and was conducive to accumulate N, P and K of shoot. But drip-irrigated culture was conducive to absorb N of rice root.(3) The migration distance of salt ions was different under the condition of drip irrigation with film mulch, migration distance of K+, Na~+ and Cl~- is farther than other salt ions, so they have a more serious effect on far line rice. Salinity resulted in chlorophyll content and root vigor decreased obviously, the delay of tillering stage, irregular heading date and time of growth.(4) The soil surface layer Na~+ content significangly increased as soil temperature increased.High temperature resulted in more Na~+ in shoot of rice, seedling mortality, proline and MDA concentrations were increased. But rice biomass was decreased. The interaction between salt stress and high temperature decreased physiological activity of rice. The interaction between salt stress and low soil temperature increased physiological activity of rice, and the interaction between salt stress and high temperature was more than the interaction with salt stress and low temperature. So the interaction between salt stress and high temperature had a negative effect on drip-irrigated rice.The main reason why rice is not tolerant of salt is the accumulation of 70% Na~+ in the upper part of the total absorption, which leads to the enhancement of the toxicity.Conclusions:(1) There was a significant difference in chilling injury between drip irrigation rice and flood irrigated rice. After low temperature stress, drip irrigation rice grow slowly, N, P and K uptake decreased, SPAD value decreased significantly, the growth period was prolonged, the yield was decreased. Low soil temperature had a significant influence on flood irrigation rice at tillering stage, but had no significant influence during booting stage and filling stage. So there was a more serious influence in DI rice than FI rice.(2) There was a different stress to rice under low soil temperature in different growth stages,the result was booting stage > tillering stage > filling stage.(3) Under drip irrigation with film mulch condition, Cl~- and Na~+ moved with the water movement, and finally accumulated on the edge of the wetting front, which led to the decline of the rice vigor, the delay of the growth, the biomass and the yield.(4) The interaction of salinity and high temperature led to Na uptake of shoot, proline and MDA concentration increased, biomass decreased, and finally resulted in the increase of seedling mortality. Therefore, drip irrigation rice was very sensitive to salinity and temperature. |
