Water-saving and drought-resistant rice (WDR) coupled with alternate wetting and drying irrigation (AWDI) possesses a high photosynthetic potential due to higher mesophyll conductance (g(m)) under drought conditions. However, the physiological and structural contributions to the g(m) of leaves and their mechanisms in WDR under AWDI are still unclear. In this study, WDR (Hanyou 73) and drought-sensitive rice (Huiliangyou 898) were selected as materials. Three irrigation patterns were established from transplanting to the heading stage, including conventional flooding irrigation (W1), moderate AWDI (W2), and severe AWDI (W3). A severe drought with a soil water potential of -50 kPa was applied for a week at the heading stage across all treatments and cultivars. The results revealed that severe drought reduced gas exchange parameters and g(m) but enhanced antioxidant enzyme activities and malondialdehyde content in the three treatments and both cultivars. The maximal photosynthetic rate (A(max)) of HY73 in the W2 treatment was greater than that in the other combinations of cultivars and irrigation patterns. The contribution of leaf structure (54%) to g(m) (g(m)-S, structural g(m)) was higher than that of leaf physiology (46%) to g(m) (g(m)-P, physiological g(m)) in the W2 treatment of Hanyou 73. Additionally, g(m)-S was significantly and linearly positively correlated with g(m) under severe drought. Moreover, both the initial and apparent quantum efficiencies were significantly and positively with g(m) in rice plants (p < 0.05). These results suggest that the improvements in photosynthesis and yield in the WDR combined with moderate AWDI can mainly be attributed to the enhancement of g(m)-S under severe drought conditions. Quantum efficiency may be a potential factor in regulating photosynthesis by cooperating with the g(m) of rice plants under severe drought conditions.

High yield, good eating quality, and high nitrogen (N) use efficiency present challenges in cultivating medium hybrid indica rice. We hypothesized that balanced source-sink relationships are key traits for achieving high yield, good eating quality, and high N use efficiency in medium hybrid indica rice under suitable N management regimes. Three field experiments were conducted with two medium hybrid indica rice cultivars. Five distinct N application levels, designated as N0, N75, N150, N225, and N300, were used to investigate varying source-sink characteristics and their impact on yield, eating quality, and N use efficiency. The results indicated that the ratio of dry matter at the heading stage to the number of spikelets per unit area (DM/Spik. R) exhibited a significant decrease with increasing N application rates in both cultivars over three years, except for the cultivar HLY898 in 2021. Conversely, an increase in N application rates generally increased the ratios of accumulated N rate and leaf area at the heading stage to the number of spikelets per unit area (AN/Spik. R and LA/Spik. R) across the cultivars and experimental years. Only AN/Spik. R showed significant relationships with yield, eating score, and N partial factor productivity (PFPN). In addition, significant differences were observed among the three study years for DM/Spik. R and LA/Spik. R, but no significant difference was found for AN/Spik. R across the three study years. Moreover, both N concentration and nitrogen nutrition index (NNI) at heading had significant and linear relationships with AN/Spik. R. Further analysis revealed that the highest yield and maximum eating scores, constituting 92 % of the total, were achieved when AN/Spik. R reached 3.65 mg per spikelet. Correspondingly, the NNI was recommended as 0.93 at heading when 90 % of the highest yield and maximum eating scores were harvested. Additionally, 79 % of the highest yield and maximum PFPN were obtained when AN/Spik. R and NNI were approximate to 2.58 mg per spikelet and 0.78 at heading, respectively. These results suggest that moderate AN/Spik. R corresponding to mild N deficiency at heading could be a key source-sink indicator for the integrated regulation of high yield, good eating quality, and high N use efficiency in medium hybrid indica rice.

The effects of nitric oxide (NO) on the photosynthetic adaptation mechanisms of wheat plants in waterlogging during the flowering stage are poorly understood. Field and pot experiments using two cultivars were conducted with three treatments: waterlogging (WL), waterlogging plus NO donor sodium nitroprusside (WLsnp), and adequate water (CK). The results indicated that the WLsnp and CK treatments exhibited significantly higher 1000-kernel weight and yield than the WL treatment because of high photosynthetic potential(P<0.05). We found that the photosynthetic performance, including photosynthetic rate (P-n), stomatal conductance (g(s)), mesophyll conductance (g(m)), carbon dioxide concentration at the carboxylation site (C-c), maximum carboxylation rate (V-cmax), maximum electron transfer rate (J(max)), actual electron transfer rate (J), actual PSII efficiency (Phi(PSII)) and potential maximum efficiency in PSII (F-v/F-m), was significantly improved in the WLsnp treatment compared to the WL treatment, both during waterlogging and after de-waterlogging. Little difference was observed in the photosynthetic performance between the WLsnp and CK treatments during waterlogging for cultivar YM15 and after de-waterlogging for cultivar YM24. Further analysis indicated that g(s), g(m) and J were identified as key physiological indicators that synergistically regulate P-n of waterlogged wheat plants. Overall, the improvement of wheat's waterlogging resistance capacity after spraying NO is mainly related to high g(s), great g(m), and high J.

Mechanical transplanting with bowl-type nursery tray (MTB) is a new mechanical cultivation approach to obtain high-yield and superior-quality rice. However, the precision of nitrogen (N) management regimes for obtaining high-yield and good-quality medium indica hybrid rice in MTB is unclear. Therefore, field experiments were conducted with five N application amounts for two medium indica hybrid cultivars in MTB in three studied years. The results indicated that the highest grain yield reached 10.40–12.27 t ha−1 when the N application amount was increased to approximately 245 kg ha−1 across cultivars. In addition, increasing the N application rate significantly decreased the eating quality of both cultivars in the three years in MTB (P < 0.05). The intersections of "high yield" and "good quality" were found at the site with 90% of the maximum yield and optimal eating quality. The corresponding N application amount was 130–140 kg ha−1 across cultivars and years. Critical nitrogen concentration (Nc) models based on total dry matter (TDM), stem and sheath dry matter (SDM), and leaf area index (LAI) had higher fitting precision and predictive abilities for the N content of rice plants (R2 >0.9) than the Nc model based on leaf dry matter (LDM) in both cultivars. However, the stability was poor among the different study years for the nitrogen nutrition index (NNI) calculated using NcTDM compared with those calculated using NcSDM and NcLAI. The reliable NcSDM and NcLAI models were expressed as Nc= 1.97SDM−0.42 (R2 =0.91;RMSE=0.11;n-RMSE=8.94%) and Nc= 3.72LAI−0.34 (R2 =0.93;RMSE=0.37;n-RMSE=15.54%) for medium indica hybrid rice in MTB. The yield increased linearly with NNI from 0 to 0.99 before heading and from 0 to 0.88 at heading in both cultivars. The yield did not increase further with increasing NNI when NNI reached the upper threshold value. However, increasing NNI significantly decreased eating quality (P < 0.05). Finally, the lower threshold value of NNIs obtained 90% of the maximum yield and optimal eating quality were recommended as 0.94, 0.96, 0.90, and 0.80 at the late stage of tillering, initial booting, middle stage of booting, and heading, respectively. This study provides important theoretical references for precise N management of medium indica hybrid cultivars in MTB.

提高学生实验安全意识对于预防和避免安全事故的发生具有举足轻重的作用.通过在实验课前讨论分析近期高校发生的实验安全事故,课中纠正其不规范操作行为,课后让其自主搜集实验室内外存在的安全隐患,并结合优化的考核方式,将安全意识形态、实验操作技能和实验技术原理均规范纳入最终的实验课程成绩中,从而实现"安全意识培养全程化+考核方式过程化"的实验课创新教学模式.该模式近2年在农学类专业应用,表现出良好的教学效果,客观的验证了创新教学模式的先进性,有力的支撑了教学目标的达成.

Water-saving and drought-resistant rice (WDR) is a new type of rice variety. Maintenance of high mesophyll conductance (gm) is one of the main factors promoting high photosynthetic production in WDR in water stress. We hypothesized that suitable irrigation regimes before water stress could further improve gm of WDR by activating some key genes in water stress. Therefore, WDR cultivar (HY73) and drought-sensitive cultivar (HLY898) were used for comparative studies. Three irrigation regimes were set before heading stage. Severe water stress was applied at heading for both cultivars in the three water treatments. RNA-seq, weighted gene co-expression network analysis, and protein interaction analysis were adopted to screen key genes maintaining high gm of WDR in water stress. It was found that when subjected to mild wetting-drying alternate irrigation, cultivar HY73 plants showed the highest net photosynthesis rate (Pn), gm, and SPAD value, as compared with the Pn, gm, and SPAD exhibited by all other combinations in severe water stress. A total of 3071 differentially expressed genes (DEGs) were clustered in 3 modules named midnightblue (734 DEGs), blue (921 DEGs), and turquoise (1416 DEGs) in severe water stress. Weighted gene co-expression network analysis revealed that the three modules (midnightblue, blue, and turquoise) were significantly correlated with gm (p < 0.05). Genes in the midnightblue module were the only enriched genes and positively regulated gm in the photosynthesis process (p < 0.05). In the midnightblue module, 11 hub genes were screened using the co -expression networks method. It was found that OsCSP41B, OsPGLP1A, OsLHCA5, and OsGSTU6 genes had similar variation trends with gm among the 11 hub genes in the three water treatments for both cultivars. Results of the present study showed that OsLHCA5 and OsCSP41B genes were significantly up-regulated in cultivar HY73, as compared with cultivar HLY898 in water stress conditions, especially in mild wetting-drying alternate irrigation (p < 0.05). Therefore, it was evident that high expressions of OsLHCA5 and OsCSP41B genes are important mechanisms for maintaining great gm and improving drought-resistance abilities in WDR in water stress. Mild wetting-drying alternate irrigation has positive effects to increasing expression level of OsLHCA5 and OsCSP41B genes in WDR in severe water stress.

HgCl 2 作为水通道蛋白专用抑制剂,可有效量化水通道蛋白和叶片结构对光合作用的贡献度,对认识提高作物光合作用的潜在途径具有重要意义。然而,有关抑制叶片水通道蛋白的HgCl 2 浓度和时长尚不清楚。本研究以水稻品种Y两优900和徽两优898为试材,采用HgCl 2 溶液离体饲养水稻叶片（叶龄余数为2）,设置不同处理浓度:0、100、200、300和500μmol L -1 及不同处理时间:0、0.5、1、1.5、2、2.5、3、3.5、4和4.5 h。研究表明,不同浓度和处理时长对叶片相对含水量无显著影响（P＞0.05）。随着浓度增加,叶片SPAD值、净光合速率和气孔导度呈明显降低趋势。与对照相比,浓度为100μmol L -1 时长2h时的净光合速率降低至最低值（62.33%）,随着处理时间延长,光合速率趋于稳定。当浓度＞100μmol L -1 时,随着处理时长增加,净光合速率持续降低,且超氧化物歧化酶（SOD）和过氧化物酶（POD）活性及丙二醛（MDA）含量均显著增加（P＜0.05）,表明浓度＞100μmol L -1 ,处理时间较长时, HgCl 2 溶液能对叶片活体造成伤害。与活体测量相比,叶片净光合速率离体稳定数值降幅约15%～20%,因而离体叶片测量光合速率乘以1.25～1.33的矫正系数,可能较准确反映水稻叶片活体原位测定的光合指标。此外, 100μmol L -1 HgCl 2 显著降低水稻叶片水通道蛋白基因表达。这些结果表明, HgCl 2 高效安全抑制水稻水通道蛋白的最佳组合为100μmol L -1 下饲养2 h。

Water-saving and drought-resistant rice (WDR) is widely grown in central China in recent years. However, studies have not explored the interaction effect of WDR and irrigation regimes on drought-resistance capacities under severe drought at sensitive growth periods. A pot experiment was conducted using a WDR cultivar Hanyou73 (HY73) and traditional high-yielding and drought-sensitive cultivar Huiliangyou 898 (HLY898). Three irrigation regimes, including flooding irrigation (W1), mild wetting-drying alternation irrigation (W2), and severe wetting-drying alternation irrigation (W3), were applied before heading. At heading, severe drought with -50 KPa soil water potential was established for all treatments and cultivars. The findings showed that cultivar HY73 under W2 treatment had the highest yield, 1000-grain yield, filled grain, relative water content, and photosynthesis potential compared with the other combinations. The higher net photosynthetic rate (P-n) was attributed to larger mesophyll conductance (g(m)) in drought for cultivar HY73 under W2 treatment compared with that for cultivar HLY898 and the other water treatments. Enhanced photo-respiration rate may be an important photoprotection mechanism for achieving high P-n for cultivar HY73 coupled with W2 treatment than for other combinations in drought. The relative expression level of OsPIP1;1 gene was significantly down-regulated during drought in all cultivars and water regimes. But OsPIP1;2, OsPIP2;3, OsTIP2;2, and OsTIP3;1 genes were upregulated to alleviate the significant decrease in g(s) and g(m) under drought. These results suggest that WDR and mild wetting-drying alternation irrigation (W2) have significant interaction effects in improving photosynthetic production potential by maintaining higher g(m) under severe drought.

Wetting-drying alternation irrigation (WDI) can harvest high grain yield under effective irrigation water saving conditions. However, the kernel cadmium (Cd) content usually exceeds the national standard of 0.20 mg Cd per kg kernel in WDI. Applying a passivating agent with high-efficient repairing capabilities could be a feasible approach to reduce Cd content lower than 0.20 mg·kg-1 in WDI. Therefore, a field experiment was conducted with different irrigation regimes and passivating agents in a mildly Cd-polluted paddy field, of which the irrigation regimes were WDI and traditional flooded irrigation (FI) and the six passivating agents treatments were CK (no passivating agent; T1), slaked lime with 1125 kg·hm-2(T2), 1125 kg slaked lime and 3000 kg biochar per hectare (T3), 1125 kg slaked lime and 3000 kg organic fertilizer per hectare (T4), 1500 kg porous Nano stupalith per hectare (T5), and 1125 kg slaked lime combined with 1500 kg porous Nano stupalith per hectare (T6). Two typical Indica hybrid rice varieties with a high accumulated capacity named cultivar Shenliangyou 1813 and a low accumulated trait named cultivar Liangyou 6206 were utilized. The main reason that Indica hybrid rice cultivars were selected was their higher absorbed and accumulated characteristics than that of Japonica rice. The results indicated that available Cd content of the soil significantly declined with 17.13%-61.01% decreasing amplitude at maturity when compared with pre-transplanting in WDI; however, the reduction was in the range of -43.45%-21.07% for the FI treatment across cultivars and passivating agents treatments. The available Cd content at maturity was significantly greater in FI than in WDI (P<0.05). In contrast, WDI had higher Cd content on stem, leaf, and kernel organs at maturity than with FI treatment of both cultivars and all of the passivating agents (P<0.05). Generally, the T1 treatment had the maximum available Cd content in the soil layer and highest accumulated Cd content on different aboveground organs, followed by the T2, T3, T4, T5, and T6 treatments considering both cultivars and irrigation regimes. The Cd kernel contents were 0.23-0.24 mg·kg-1 and 0.16-0.21 mg·kg-1 for cultivars Shenliangyou 1813 and Liangyou 6206, respectively, in the T6 treatment. The higher Cd kernel content was generally related to a larger Cd content in the stem organ. For the grain yield, no significant differences were observed among cultivars, irrigation regimes, or passivating agents treatments (P>0.05). Under WDI, the kernel Cd content was still slightly higher than 0.20 mg·kg-1 in the T6 treatment (0.24 mg·kg-1 for cultivar Shenliangyou 1813 and 0.21 mg·kg-1 for cultivar Liangyou 6206); however, there is a predictability potential to produce lower than 0.20 mg·kg-1 kernel content in the T6 treatment if a cultivar with low accumulated capacity is used. Thus, the combined mode of the WDI+T6+cultivar with accumulated low Cd content could be considered an optimized cultivation scheme to obtain no Cd contaminated kernels with high grain yield and water-use efficiency in mildly polluted paddy fields.

普通高校农学类专业核心课"金课"打造是培育高素质新农科人才的重要途径.在适应"教育信息化2.0"基础上,构建农学类专业课"金课"的统一原则;提出农学专业课+思政课互融的双课模式及实现途径;借助于人工智能大数据提供的可朔源和可视化功能,明确了教学内容模块化、教学方式多元化、教学设计详实化以及考核方式多维化的构建原则.

目的 研究安徽省主栽杨树品种间的亲缘关系.方法 通过ISSR分子标记手段,结合NTSYS-pc 2.10 e分析软件,对17个杨树品种进行遗传相似性系数计算,并按UPMGA法进行聚类分析.结果 10条引物共获得扩增谱带67条,其中多态性条带54条,多态性百分比为80.6%,各品种之间的遗传相似系数在0.3773~0.9620,遗传距离为0.0387~0.9747.结论 通过聚类分析将17个杨树品种分为4类,并运用特殊谱带建立杨树品种的分子检索表.由此可知ISSR分子标记技术能揭示材料间的遗传多样性,为杨树的分类、鉴别和选育提供依据.

Wetting-drying alternation irrigation ,which has a higher grain yield than traditional flooded rice because the water regime is more favorable to yield formation ,is considered as an important water-saving cultivation technology in rice plants.In addition ,the two different irrigation regimes have significant effects on ratios of ammonia nitrogen and nitrate nitrogen in the root zone ,and then could alter the grow th and development of rice plants .Therefore ,soil water and nitrogen forms could be critical regulatory fac-tors affecting yield formation of rice plants in wetting-drying alternation irrigation .To investigate the in-teraction effect ,we conducted pot experiments in 2016 with cultivar Ningjeng 8 in different water regimes and N forms .In this study ,water regimes included traditional flooding irrigation (W1 ) and wetting-drying alternation irrigation (W2 ) ,and N forms treatments set three categories :ammonia and nitrate nitrogen ra-tio=0:100 (N1 ) ,ammonia and nitrate nitrogen ratio=50:50 (N2 ) ,ammonia and nitrate nitrogen ratio=100:0 (N3 ) .The results showed that :(1) the grain yield ,yield components ,photosynthetic produc-tion ,harvest index ,N harvest index ,and nitrogen grain production efficiency in the W2 treatment are sig-nificantly higher than that in the W1 treatment (P<0 .05) .But slightly lower N content in the W2 treat-ment was observed when compared with the W1 treatment .From the perspective of N forms ,grain yield in the N2 treatment was the greatest ,and yield in the N1 treatment was the minimum among N treatments , which were mainly from a higher matter translocation from sheath to kernel and photosynthetic produce a-bility during grain filling stage in the N 2 treatment than that in the N3 and N1 treatments .The greater N content and N concentration could be an important physiological basis for high photosynthetic ability in the N2 treatment than the others .The N1 treatment had the highest N use efficiency ,and then followed by the N2 and N3 treatments .Moreover ,there were significant interaction effects between water regimes and N forms for grain yield ,yield components ,and harvest index (P< 0 .05) .The W2 treatment coupled N2 treatment was the optimal combination for yield formation of rice plants .

于2011-2012年在干旱区(新疆石河子市)开展田间小区试验,研究淹灌(W1)、控制灌溉(W2)和旱作(W3)等栽培模式下的产量构成、光合特性及蒸腾效率,以期为干旱区水稻高产高效栽培提供理论依据.研究结果表明:开花前,净光合速率(Pn)在W1和W2处理间差异不显著(p＞0.05),但花后,W1处理Pn分别高出W2、W3处理11.29％ ～ 20.91％和38.65％～52.03％;在饱和土壤含水量条件下,W2处理净光合速率较W1处理轻微降低,羧化效率、光饱和点和光补偿点均可与W1持平,并显著高于W3处理(p＜0.05),W2处理花后光合生产能力受限主要因其在非饱和土壤含水量条件下大幅降低所致;W1处理全天各时间段Pn高于W2和W3处理,午后时段处理间差异较上午更大;最终,W2处理产量仅降低4.43％ ～ 18.72％,而W3处理降低31.23％ ～39.45％;在整个生育期,W2处理蒸腾效率最大,显著高于W1、W3处理(p＜0.05).综上所述,W2处理在干旱区表现出高产高效生产潜力,提升灌浆期午后光合生产能力可能对于进一步提高旱区水稻产量具有重要作用.

The objectives of this field experiment were to study the growth characteristics and yield potential of rice plants under non-flooded irrigation in arid area. Non-flooded treatments included drip irrigation with plastic mulching treatments (DIs), furrow irrigation with plastic mulching treatment (FIM) and furrow irrigation with non-mulching treatment (FIN). Conventional flooded cultivation (F) was check treatment (CK). The four drip irrigation treatments differed in the amount of water applied before and after panicle initiation. Root length density, leaf dry weight, shoot dry weight and root activity were generally higher in the non-flood-irrigated treatments (especially the drip-irrigated treatments) than in the flood-irrigated treatment at mid-tillering. However, the growth and development of rice plants were limited after jointing in the non-flooded irrigation treatments. Increasing the root/shoot ratio and root length density in the 20–40 cm depth and decreasing specific root length at 0–20 cm soil layer were important mechanisms for helping the rice plants to adapt to the non-flooded environmental stresses. Finally, the grain yield in the non-flooded irrigation treatments was lower than that in the F treatment. These low yields were mainly attributed to the low root length density at 0–20 cm depth and root activity. Generally speaking, the restricted degrees in the DIs were smaller than that in the FIM and FIN treatments. Among the DIs, both the highest grain yield (8223–8900 kg ha−1) and the highest water use efficiency (WUE) (0.63) were observed when the soil water content was kept at −30 kPa before panicle initiation and at −15 kPa after panicle initiation (referred to as the DI2 treatment). The yield in the DI2 treatment was not significantly different than that in the flood-irrigated treatment. However, WUE was 2.5 times higher in the DI2 treatment than in the F treatment. These results suggest that drip irrigation technology can be considered as a better water-saving cultivation of rice plants in arid region.

水稻规模化种植已成为水稻集约化生产的重要标志,本研究对安徽省霍邱县300个种植大户展开系统问卷调查,分析水稻规模化种植者年龄结构分布、种植规模大小、种植模式及其产量水平以及经济效益.结果表明,种植者年龄分布主要介于40～60岁,合作社经营模式(H3)年龄更趋于年轻化,且H3模式的产量水平和经济效益均明显高于普通大户(H1)和家庭农场(H2)种植模式;平均种植面积以H3最大,其后依次为H2和H1.深入分析认为:年龄偏老龄化和种植面积过大是限制高产形成的重要因子之一.在机插及直播水稻条件下,经济效益分别较人工手插秧高出27.13％36.85％和17.45％～22.40％.综上所述,在增大轻简栽培水稻(机插和直播水稻)比重基础上,以合作社经营模式为主的种植大户可能是进一步提高水稻规模化生产潜力的重要突破口.

Rice production, especially of good quality, must be increased to feed the world’s growing population in the future. Meanwhile, water scarcity and nitrogen over-fertilization is threatening rice production of irrigated region because of fresh water and fertilizer nitrogen crises. Therefore, a major challenge in rice production is to save both water and fertilizer nitrogen while increasing grain yield and improving quality characteristics. Rice production must synchronously focus on high grain yield and good-quality when rice is planted under both water and nitrogen saving cultivation. In brief, rice production and sustainable development are considered not only for high yield and good quality, but also to ensure high water/nitrogen use efficiencies. Based on this background, the paper reviews (1) the effect of water regimes, nitrogen managements, and water-nitrogen interaction managements on grain yield, water/nitrogen use efficiencies, and grain quality of rice plants, respectively; (2) eco-physiological mechanisms obtaining high-yielding and good quality with high water/nitrogen use efficiencies when irrigated rice plants are managed in different water treatments, nitrogen treatments, and water-nitrogen interaction treatments. Finally, some potential research points including theory and technology researches, which could increase yield and improve quality of rice plants with high resources (water and nitrogen ) use efficiencies, were presented in this review.

Nonflooded irrigation is an important water-saving rice cultivation technology, but little is known on its photosynthetic mechanism. The aims of this work were to investigate photosynthetic characteristics of rice during grain filling stage under three nonflooded irrigation treatments: furrow irrigation with plastic mulching (FIM), furrow irrigation with nonmulching (FIN), and drip irrigation with plastic mulching (DI). Compared with the conventional flooding (CF) treatment, those grown in the nonflooded irrigation treatments showed lower net photosynthetic rate(PN), lower maximum quantum yield(Fv/Fm), and lower effective quantum yield of PSII photochemistry (ΦPSII). And the poor photosynthetic characteristics in the nonflooded irrigation treatments were mainly attributed to the low total nitrogen content (TNC). Under non-flooded irrigation, thePN,Fv/Fm, andΦPSIIsignificantly decreased with a reduction in the soil water potential, but these parameters were rapidly recovered in the DI and FIM treatments when supplementary irrigation was applied. Moreover, The DI treatment always had higher photosynthetic productivity than the FIM and FIN treatments. Grain yield, matter translocation, and dry matter post-anthesis (DMPA) were the highest in the CF treatment, followed by the DI, FIM, and FIN treatments in turn. In conclusion, increasing nitrogen content in leaf of rice plants could be a key factor to improve photosynthetic capacity in nonflooded irrigation.

Plot experiments and field investigations were conducted with NingGeng28 ( japonica) in 2011 and 2012 to investigate rice root spatial distribution at flowering and grain yield u nder PMDI. The results showed that fewer roots at the 0 -20 cm soil layer were present under PMDI than under flooding irrigation, but more roots were observed at 20 -60 cm soil layer under PMDI than under flooding irrigation. In the horizontal direction, the root length density (RLD) at the 0-20 cm soil layer decreased with increasing horizontal distance away from the hill sites (A1 > B1 > C1) and signi ficantly decreased with decreasing irrigation application amount in each soil column . At the 20-40 cm and 40-60 cm soil layers, RLD were relatively constant under flooding irrigation but increased with increasing horizontal distance away from the hills under PMDI (C2 > B2 > A2ˇ� C3 > B3 > A3) and significantly increased with decreasing irrigation application amount in each soil column. Significant differences in roots and aboveground performance were observed between the near and far rows. Moreover, the grain yield ranged from 3.35×10 3 Kg ha -1 to 6.86×10 3 Kg ha -1 under PMDI, which was 19.3-60.31% lower than that under flooding irrigation. Correlation analysis showed that the roots at the A1 and B1 sites were positively significantly correlated with yield components and aboveground agronomic traits. Therefore, improving root development at the A1 and B1 sites at flowering stage could be a key factor to obtain high er grain yield and good agronomic performance under PMDI.

Plastic mulching with drip irrigation is a new water-saving rice cultivation technology, but little is known on its productivity and water-saving capacity. This study aimed to assess the production potential, performance, and water use efficiency (WUE) of rice under plastic mulching with drip irrigation. Field experiments were conducted over 2 years with two rice cultivars under different cultivation systems: conventional flooding (CF), non-flooded irrigation incorporating plastic mulching with furrow irrigation (FIM), non-mulching with furrow irrigation (FIN), and plastic mulching with drip irrigation (DI). Compared with the CF treatment, grain yields were reduced by 31.76-52.19% under the DI treatment, by 57.16-61.02% under the FIM treatment, by 74.40-75.73% under the FIN treatment, which were mainly from source limitation, especially a low dry matter accumulation during post-anthesis, in non-flooded irrigation. WUE was the highest in the DI treatment, being 1.52-2.12 times higher than with the CF treatment, 1.35-1.89 times higher than with the FIM treatment, and 2.37-3.78 times higher than with the FIN treatment. The yield contribution from tillers (YCFTs) was 50.65-62.47% for the CF treatment and 12.07-20.62% for the non-flooded irrigation treatments. These low YCFTs values were attributed to the poor performance in tiller panicles rather than the total tiller number. Under non-flooded irrigation, root length was significantly reduced with more roots distributed in deep soil layers compared with the CF treatment; the DI treatment had more roots in the topsoil layer than the FIM and FIN treatments. The experiment demonstrates that the DI treatment has greater water saving capacity and lower yield and economic benefit gaps than the FIM and FIN treatments compared with the CF treatment, and would therefore be a better water-saving technology in areas of water scarcity.