[Effect of hyacinth mulching on rice (Oryza sativa L.) uptake and utilization of nitrogen].

Nitrogen is the most important element for rice growth, and hyacinth can absorb large quantities of nitrogen and accumulate in their tissues. The field experiment was conducted to investigate the effects of hyacinth mulching on rice nitrogen (N) concentration, uptake, efficiency and allocation at different growth stages. Taked Yun 2645 as a material, the nitrogen uptake and utilization of rice were evaluated under two different levels of N input: low (LN, 120 kg x hm(-2)) and normal N (NN, 240 kg x hm(-2)) in 2009. Main results showed that: (1) Compared with AMB, hyacinth mulching significantly increased N concentration in rice plant over the season, hyacinth mulching significantly increased nitrogen accumulation in rice plant, and the increasing rate was gradual addition from mid-tillering to heading, but from heading to maturity the increasing rate was gradual decline. (2) Hyacinth mulching had no obvious effect on nitrogen allocation pattern in leaves and stems of rice over the season, significantly decreased nitrogen allocation pattern in spikes. (3) Except mid-tillering, hyacinth mulching resulted in the significant decrease in N use efficiency for biomass (NUEp) over the season and in N use efficiency for grain yield (NUEg) at grain maturity, but no effect was observed on nitrogen harvest index (NHI). (4) Nitrogen concentration and accumulation at most growth stages of rice increased with increasing N supply (p < 0.05 or 0.01), but NUEp and NUEg showed the opposite trends. 1(5) nteractions between hyacinth mulching x N were not observed for N uptake and utilization. Hyacinth mulching increased N concentration and N uptake, decreased NUEp and NUEg at most growth stages of rice.

[Effects of asymmetric warming on the growth characteristics and yield components of winter wheat under free air temperature increased].

In 2007-2009, a field warming experiment was performed in Nanjing of Jiangsu Province, China to investigate the effects of asymmetric warming (all-day warming, AW; daytime warming from 6:00 to 18:00, DW; and nighttime warming from 18:00 to 6:00, NW) on the growth and development of winter wheat under free air temperature increase (FATI). Asymmetric warming increased the effective tillers and decreased the ineffective tillers. In CK plot, the ineffective tillers were 2.6, 1.7 and 3.5 times of those in AW, DW and NW plots, while the effective tillers were decreased by 13.7%, 3.2%, and 0.5%, respectively. Asymmetric warming also increased the plant height, flag leaf area, and the total green leaf area and green leaf ratio at flowing stage. In treatments AW, DW, and NW, the plant height was increased by 5.6%, 4.5%, and 1.3%, flag leaf area increased by 45.7%, 39.4% and 26.1%, total green leaf area increased by 25.1%, 29.8%, and 17.3%, and green leaf ratio increased by 37.7%, 43.3%, and 38.7%, respectively, compared with CK. As for the yield components, the spikelet number per panicle and the filled grain number per panicle in treatments AW, DW and NW were increased by 4.1%, 5.7%, and 1.7%, and by 2.2%, 5.3%, and 2.6%, respectively. Though the grain/leaf ratio in treatments AW, DW, and NW was decreased by 15.3%, 8.5%, and 11.3%, the thousand-grain mass in the treatments was increased by 6.9%, 6.2% and 11.8%, and thus, the yield per unit was increased by 27.0%, 40.1%, and 18.3%, respectively, compared to the CK. Our results suggested that under anticipated warming, the winter wheat productivity in eastern China would be further enhanced.

[Temperature differences of air-rice plant under different irrigated water depths at spiking stage].

With rice cultivars Yangdao 6, Yangjing 9538 and Wuxiangjing 14 as test materials, field experiment was conducted to study the effects of 3 irrigated water depths (0 cm, 2-4 cm, and > 10 cm) on the temperature of different parts of rice plant at spiking stage. The results showed that from 10:30 to 15:00 on sunny days, irrigated water depth on paddy field had significant effects on the temperature of field surface, middle part of rice plant, and rice spike. The higher the water depth on field surface, the lower the temperature of rice plant and rice spike. At the water level > 10 cm, the average temperature differences between air and the rice spike, middle part of rice plant and field surface of these three cultivars were 1.37, 2.98 and 4.12 degrees C higher than those at the water depth of 0 cm, and 0.67, 1.59 and 2.17 degrees C higher than those at the water depth of 2-4 cm, respectively. In addition, the temperature differences were 0.71, 1.39 and 1.95 degrees C higher at the water depth of 2-4 cm than those at the water depth of 0 cm, respectively. Obvious temperature differences of air-rice plant were also observed among the three rice varieties under different irrigated water depths. The analysis of the characteristics of temperature transfer among field surface, middle part of plant and rice spike indicated that the temperature transfer patterns under all test water management regimes accorded with the principles of energy transfer, suggesting that keeping proper water depth on the field surface at rice spiking stage contributed great to the decrease of rice spike temperature and the alleviation of rice heat injury.

[Effects of high temperature on grain filling and some physiological characteristic in flag leaves of hybrid rice].

The effects of high temperature on grain filling rate and some physiological indexes in flag leaves in hybrid rice Teyou 559 were studied. The results showed that chlorophyll content and superoxide dismutase (SOD) activity in flag leaves were lower significantly by high temperature stress (Figs.2A and 3A). The electrolyte leakage and malondialdehyde (MDA) content were higher significantly under high temperature stress (Figs.2B and 3B). The proline (Pro), ascorbic acid (AsA), glutathione (GSH), soluble protein and soluble sugar contents were lower significantly by high temperature stress than those of the control (Figs.4,5 and 6). Both the rate of grain filling and grain dry matter accumulation become lower significantly under high temperature stress (Figs.7 and 8). Therefore, it was suggested that high temperature accelerated the senescence of rice leaf and decreased the photosynthesis rate during grain filling period, and then which was the main reason in physiology which resulted the decrease of grain filling rate, seed setting rate, grain weight and yield.