Effect of Varied Irrigation Scheduling with Levels and Times of Nitrogen Application on Yield and Water Use Efficiency of Aerobic Rice

More rice needs to be produced with lesser water to feed the increasing human population. Judicious water management practices and appropriate water saving technologies in rice cultivation are in need in the coming decades. Aerobic rice is one of water saving method of rice cultivation. The field experiment was conducted during Summer season of February 2018 to May 2018 at Tamil Nadu Agricultural University, Agricultural College and Research Institute, Madurai, to find out the effect of irrigation schedules with varied doses and time of nitrogen application on yield of aerobic rice. Irrigation scheduling of IW/CPE (Irrigation Water/Cumulative Pan Evaporation) 1.0 up to panicle initiation stage and thereafter IW/CPE 1.2 up to dough stage recorded higher yield attributes viz., number of panicles hill-1 (9.1), number of filled grains panicle-1 (87.9), test weight (15.3 g), grain yield (4462 kg·ha-1), straw yield (5977 kg·ha-1). However, the highest water use efficiency (6.8 kg·ha-1·mm-1) was recorded in the treatment of IW/CPE 1.0 throughout the crop growth period. Lower yield attributes, yield and water use efficiency were recorded with irrigation scheduling of IW/CPE 0.8 throughout the growth stage. Application of nitrogen at 150 kg·ha-1 in 5 equal splits at 20, 35, 50, 65 and 80 DAS (Days after sowing) recorded higher yield attributes viz., number of panicles hill-1 (9.3), number of filled grains panicle-1 (90.5), test weight (15.4 g), grain yield (4746 kg·ha-1), straw yield (6258 kg·ha-1) and WUE (7.5 kg·ha-1·mm-1). Application of nitrogen 100 kg·ha-1 in 4 equal splits at 20, 40, 60 and 80 DAS recorded lower yield attributes, yield and water use efficiency. The interaction effect between irrigation scheduling and nitrogen management on yield was significant. The combination of IW/CPE 1.0 up to panicle initiation stage and thereafter IW/CPE 1.2 up to dough stage along with application of nitrogen at 150 kg·ha-1 in 5 equal splits at 20, 35, 50, 65 and 80 DAS significantly produced higher number of panicles hill-1 (10.7), grain yield of 5419 kg·ha-1 and straw yield of 6906 kg·ha-1. However, IW/CPE 1.0 throughout the growth period along with application of nitrogen at 150 kg·ha-1 in 5 equal splits at 20, 35, 50, 65 and 80 DAS registered the highest water use efficiency (8.4 kg·ha-1·mm-1) in aerobic rice.

Grain yield and water use efficiency of super rice under soil water deficit and alternate wetting and drying irrigation

This study investigated if super rice could better cope with soil water deficit and if it could have better yield performance and water use efficiency （WUE） under alternate wetting and drying （AWD） irrigation than check rice. Two super rice cultivars and two elite check rice cultivars were grown in pots with three soil moisture levels, well watered （WW）, moderate water deficit （MWD） and severe water deficit （SWD）. Two cultivars, each for super rice and check rice, were grown in field with three irrigation regimes, alternate wetting and moderate drying （AWMD）, alternate wetting and severe drying （AWSD） and conventional irrigation （CI）. Compared with that under WW, grain yield was significantly decreased under MWD and SWD treatments, with less reduction for super rice than for check rice. Super rice had higher percentage of productive tillers, deeper root distribution, higher root oxidation activity, and greater aboveground biomass production at mid and late growth stages than check rice, especially under WMD and WSD. Compared with CI,AWMD increased, whereasAWSD decreased grain yield, with more increase or less decrease for super rice than for check rice. Both MWD and SWD treatments and eitherAWMD orAWSD regime significantly increased WUE compared with WW treatment or CI regime, with more increase for super rice than for check rice. The results suggest that super rice has a stronger ability to cope with soil water deficit and holds greater promising to increase both grain yield and WUE by adoption of moderate AWD irrigation.

Rice Yield and Water Use as Affected by Soil Management Practices

A field experiment was conducted at the Shenyang Experimental Station ofEcology, Chinese Academy of Sciences, to study the effects of soil management practices on water useand rice (Oryza sativa L.) yield in an aquic brown soil during 2001 and 2002. A completely randomexperimental design with three replications was employed, having four soil management practices astreatments, namely: an undisturbed plow layer (CK), a thin plastic film (TN), a thick plastic film(TI) and subsoil compacting (CP). Results indicated no significant differences among all treatmentsfor rice biomass and grain yields. Also, water consumption was about the same for treatments TN andCK, however the treatments TI and CP were much lower with more than 45% and 40% of the irrigationwater in the treatments TI and CP, respectively, saved each year compared to CK. Therefore, wateruse efficiency was higher in the treatments TI and CP. These results will provide a scientific basisfor the water-saving rice cultivation.

Response of Gas Exchange and Water Use Efficiency to Light Intensity and Temperature in Transgenic Rice Expressing PEPC and PPDK Genes

Aiming to controvert whether the photosynthetic capacity of transgenic rice expressing C4 genes is enhanced, with the C3-type untransformed rice （WT） and maize （a C4 plant） as controls, the activity of C4 photosynthetic enzymes, gas exchange parameters and water use efficiency （WUE） under different light intensities and temperatures, the stable carbon isotope ratio （8-3C） value and the metabolic index of active oxygen as well as plant yield parameters were determined in transgenic rice carrying the PEPC and PPDK genes （CK） in this study. The results showed that the light-saturated photosynthetic rate of CK was intermediate between that of WT and maize, with a slight bias towards that of maize. Under a high light intensity （1 200 μmol m^-2 s^-1） and high temperature （35℃）, CK still exhibited higher photosynthetic capacity, while the Gs decreased. The WUE of CK was only slightly increased, and was similar to that of WT. The δ13C value indicated that CK functioned as a C3 plant. In addition, the tolerance to photo-oxidation and grain yield of CK was enhanced by sprayed with NaHSO3. In conclusion, CK possesses higher photosynthetic productivity under the conditions of high photon flux density （PFD）, high temperature and spraying with NaHSO3 solution, thereby providing a new technical approach and physiological basis for constructing C4-like rice.

Study on Intermittent Irrigation for Paddy Rice: I. Water Use Efficiency

A field experiment was conducted in a well-puddled paddy field developed on the Tama River alluvial soil in the Farm of Tokyo University of Agriculture and Technology, Japan, to study the effect of intermittent irrigation on water use efficiency of paddy rice. Four treatments were arranged with 2 replicates: continuous flooding irrigation treatments (CFI), and three intermittent irrigation treatments Ⅱ-0, Ⅱ-1 and Ⅱ-2, in which plants were re-irrigated when the soil water potential fell below 0, -10, and -20 kPa, respectively, at soil depth of about 5 cm. Water consumption was lower in treatment Ⅱ-0 than in treatment CFI because the percolation rate was reduced by the reduction in the hydraulic head of ponded water. Intermittent irrigation led to soil repeated shrinking and swelling in Ⅱ-1 and Ⅱ-2 plots and, therefore, soil cracks developed rapidly. Since they became the major routes of water percolation, the soil cracks increased water consumption in treatments Ⅱ-1 and Ⅱ-2. There were no significant differences in dry matter production and grain yields between treatment Ⅱ-0 and treatment CFI, but the dry matter production and grain yields in treatments Ⅱ-0 and CFI were significantly higher than those in treatments Ⅱ-1 and Ⅱ-2. Therefore, the water use efficiency in the treatments was in the order of Ⅱ-0 > CFI > Ⅱ- 2 > Ⅱ- 1.

Rice Cultivation under Film Mulching Can Improve Soil Environment and Be Beneficial for Rice Production in China

Rice cultivation under film mulching is an integrated management technology that can conserve water, increase soil temperature, improve yield, and enhance water and nitrogen use efficiencies. Despite these advantages, the system does have its drawbacks, such as soil organic matter reduction and microplastic pollution, which impede the widespread adoption of film mulching cultivation in China. Nonetheless, the advent of degradable film, controlled-release fertilizer, organic fertilizer, and film mulching machinery is promoting the development of rice film mulching cultivation. This review outlines the impact of rice cultivation under film mulching on soil moisture, soil temperature, soil fertility, greenhouse gas emissions, weed control, and disease and pest management. It also elucidates the mechanism of changes in rice growth, yield and quality, water use efficiency, and nitrogen use efficiency. This paper incorporates a review of published research articles and discusses some uncertainties and shortcomings associated with rice cultivation under film mulching. Consequently, prospective research directions for the technology of rice film mulching cultivation are outlined, and recommendations for future research into rice cultivation under film mulching are proposed.

Effects of Irrigation and Nitrogen on the Performance of Aerobic Rice in Northern China

Aerobic rice is a new production system in which specially-developed varieties are grown under non-flooded, non-puddled, and non-saturated soil conditions. In 2003-2004, irrigation x Nitrogen experiments were carried out near Beijing using variety HD297. Water treatments included four irrigation levels, and Nitrogen treatments included different fertilizer N application rates and different numbers of N splits. The highest yields were 4460 kg/ha with 688 mm of total （rain plus irrigation） water input in 2003 and 6 026 kg/ha with 705 mm of water input in 2004. Because of the quite even distribution of rainfall in both years, the four irrigation treatments did not result in large differences of soil water conditions. There were few significant effects of irrigation on biomass accumulation, but yield increased with the total amount of water applied. High yields coincided with high harvest index and high percentages of grain filling. The application of fertilizer N either reduced biomass and yield or kept it at the same level as 0 N and consistently reduced the percentage grain filling and 1 000-grain weight. With the highest water application, five splits of N gave higher yield than three splits, whereas three splits gave higher yield than five splits with lower water applications.

A STUDY ABOUT SOIL WATER CHARACTERISTIC,CONDUCTIVITY OF WATER AND EQUILIBRIUM ADSORPTION OF CUPRIC ION IN SOIL——A UTILITY EQUIPMENT USED IN SOIL SCIENCE AND ITS ILLUSTRATION OF USE

A utility equipment used in soil science is designed and installed.The equipment can be used in research pro- grams of soil water and solute transport.Pressure in pressure chamber of the equipment in which a tested soil sam- ple is laid can be adjusted exactly so that we can determine the water content of soil sample.With the equipment we can not only study the problems related water movement in soil but also measure some solute,such as cadmi- um,plumbum and so on,adsorption on surface of soil in saturated and unsaturated state.As an illustration of the use of the equipment,we give the isothermal of cupric ion adsorption in soil.This equipment can be used in the re- search work and application of soil science.

Improving the Predictive Capability of Popular SWCCs by Incorporating Maximum Possible Suction

Soil-water characteristic curve (SWCC) that represents the relationship between the soil moisture and matric suction is one of the important constitutive models required for numerical modeling of unsaturated soils. An effective SWCC model should be capable of calculating the moisture-suction variation for the entire range of degree of saturation. Applicability of popular SWCC models such as Brooks and Corey, van Genuchten, and Fredlund and Xing is limited, especially in low (< 20%) degree of saturation range. In this study, all these models are modified by incorporating maximum suction as one of the model parameters, so that these models can be effectively used over the entire range of degree of saturation. The Fredlund et al (1994) permeability function is also modified based on the modification to the Fredlund and Xing SWCC model. The applicability of the improved models is investigated by calibrating the SWCC of various types of soil and presented in this paper. Based on this study it can be concluded that the modified models are flexible enough to fit the experimental data for the entire range of degree of saturation.

不同土壤水分处理对水稻光合特性及产量的影响

为探明土壤水分对水稻生长发育的影响机理,以武香粳14和两优培九为试验材料,分析了不同土壤水分处理下(W1、W2、W3和CK分别表示土壤体积含水量为20%、30%、40%和5cm水层灌溉)的水稻光合特性、产量及水分生产率等。结果表明,轻度水分胁迫(W3)具有处理间最大的叶片气孔导度、蒸腾速率和净光合速率,其他处理规律不显著。灌浆初期各水分处理下叶位间光合指标均表现为:剑叶>顶2叶>顶3叶>顶4叶,其他生育期规律不显著。与对照处理(CK)相比,武香粳14的W1、W2和W3处理的产量分别减少61.14%和29.13%、增加0.96%,水分生产率分别减少10.69%、增加1.53%和20.61%;两优培九的产量分别减少64.11%和28.76%,增加2.08%,水分生产率分别减少16.39%,增加2.46%和22.13%。研究结果为水稻精确灌溉和节水生产提供了技术支撑。

不同土壤覆盖物对旱作水稻生长和产量影响

在四川盆地通过田间试验研究了不同覆盖物对旱作水稻植株生长及产量的影响。结果表明 ,在有效铁含量较高而有效锰含量较低的土壤上 ,覆地膜及传统淹水处理在整个生育期没有表现缺锰症 ,而覆麦秆处理前期分蘖能力差 ,生长缓慢 ,表现严重的缺锰症。在覆麦秆处理裂区灌施 2‰的 Mn SO4 溶液 (每次 4 5 0 kg/ hm2 )两次后 ,水稻株高、分蘖和生物量都迅速增加 ,说明覆麦秆处理水稻受到了锰的胁迫。其原因与地膜处理明显提高土壤温度 ,而覆麦秆处理却具有降温作用有关。试验还发现 ,灌施锰肥能够补偿温度降低所造成的不利影响。水稻产量以覆地膜处理最高 ,其次是覆麦秆灌锰处理 ,再次是传统淹水处理 ,覆麦秆未灌施锰肥处理产量最低 ,后者与其它处理差异也达极显著水平。覆地膜条件下 ,水稻产量随施氮量的提高而提高 ,但当施氮量为 1 5 0 kg/ hm2后产量变化不大。与传统淹水相比 ,覆盖旱作处理显著降低总耗水量 ,节水率达 6 3.1 % ;并在产量基本不变或有所提高的前提下 ,提高水分利用效率 2～

不同水分和施磷量对旱作水稻耗水量和水分利用率的影响

通过温室盆栽试验研究了土壤水分和磷素对旱作水稻的耗水量和水分利用率的影响。研究表明 :土壤水分和施磷量对旱作水稻耗水量和水分利用率有极显著的影响 ,且相互间的交互作用明显。旱作水稻 (包括种子 )的耗水量均以中水到高水和中磷到高磷时最高 ,耗水量在生长前期占全生育期的1 5 %～ 1 8% ,生长中期占 63 %～ 68% ,生长后期占 1 6%～ 2 0 %。水分利用率在苗期 (1 2 5～ 1 60gL- 1) ,以低水到中水和低磷到中磷时最高 ;中期 (2 2 2～ 3 5 6gL- 1)到后期 (1 68～ 2 0 8gL- 1) ,以低水到中水和中磷到高磷时最高 ;不同生长阶段的耗水量和水分利用率均以生长中期 >后期 >前期。

江淮丘陵季节性干旱区灌溉与施氮量对土壤肥力和水稻水分利用效率的影响

采用防雨棚池栽试验,研究灌溉模式和施氮量对水稻土壤肥力和水分利用效率的影响。结果表明,灌溉模式与施氮量对土壤化学特性、土壤微生物学特性、产量及水分利用效率有着显著影响。与常规灌溉相比,控制灌溉条件土壤有机质含量、全氮含量、全钾含量、速效磷含量、速效钾含量、细菌数量、真菌数量和水分利用效率增加,碱解氮含量和放线菌数量降低。随着施氮量增加,土壤有机质含量、全氮含量、碱解氮含量、放线菌和真菌数量增加,而全磷含量、全钾含量、速效磷和速效钾含量降低,产量和水分利用效率呈现先增加后降低的趋势。在本研究条件下,以控制灌溉模式,施氮量180 kg.hm-2,产量达到11 495 kg.hm-2,节本增效效应最佳。

不同土壤水分含量对水稻水分利用特征的影响

采用控制土壤水分含量的盆栽实验,研究了土壤水分含量对水稻水分利用特性的影响。结果表明,常规水作累积耗水量显著高于覆膜未淹水处理,但稍低于覆膜淹水处理;覆膜轻度水分胁迫或无胁迫处理不仅能够维持和提高产量,水分利用效率也有所提高。随着土壤水分含量的降低,全生育期水稻累积耗水量、各生育期耗水量及耗水强度逐渐降低,且田间持水量与全生育期累积耗水量呈极显著二次曲线相关。无水分胁迫覆膜处理下拔节孕穗期耗水量及模比系数高于其他生育期,其他处理耗水量和模比系数在乳熟期最高。随着土壤水分含量降低,抽穗开花期前各生育期水稻耗水模比系数有降低趋势,其后则有升高趋势;耗水强度下降;有效穗数和实粒数减少,产量逐渐降低,水分生产率先上升后下降。水稻产量与水分利用率具有显著二次曲线相关性。

旱稻农田土壤水分变化特征研究

试验研究旱稻不同灌溉处理土壤水分变化特征结果表明,不同供水条件下农田土壤水分变化的主要层次均为80cm以上,120cm以下土层土壤水分处于相对稳定状态,且维持在相对较高水平;供水较多时旱稻水分耗散量、耗水强度也较大,而相同供水条件下旱稻水分耗散量和耗水强度又小于水稻对照;相同灌溉处理旱稻产量和水分利用效率均高于水稻对照;而充足供水有利于旱稻根系在0～20cm表层发育,但不利于其根系在下层生长,而W2可促使根系下扎,更充分利用下层水分.

水和磷互作对红壤丘岗地区旱作水稻生物量和产量的影响

通过盆栽和大田试验研究了水和磷互作对旱作水稻生物量和产量的影响。研究表明:土壤含水量和施磷量对旱作水稻生物量和产量有极显著的影响,且二者的交互作用十分明显,影响程度以籽粒> 茎>根。上壤含水量为饱和持水量的60%时对旱作水稻生物量和产量影响较大,而80%和100%时几乎没有影响。旱作水稻生物量和产量均随施磷量的增加而增加。这说明控制土壤水分为饱和持水量的80%时就能完全满足旱作水稻的生长,但要求获得较高的产量时必须注意磷肥的投入,或者采取一些凋控措施提高土壤磷的利用率。

不同节水稻作模式对土壤理化特性和土壤酶活性影响研究

针对南方丘陵区季节性干旱现状与目前稻田单一化的连作耕作制度对农田环境造成的不利影响因素,通过4a田间定位试验研究了节水稻作模式下土壤理化性状和土壤酶活性变化规律影响。结果表明,与该区常规稻作模式相比,在试验设计范围内,节水稻作模式下稻田的土壤理化性状明显改善,随着耕种年限增加,土壤容重下降,而孔隙度增加,土壤通透性增强,有效阻止土壤次生潜育化和土壤酸化,提高了土壤pH值;就土壤酶活性而言,节水稻作模式处理酶活性常规稻作模式相比,除转化酶外,其它酶活性均有不同程度的增加,尤其对磷酸酶与脲酶影响最大。

膜下滴灌旱作水稻水肥耦合模型及组合方案优化

为了研究膜下滴灌旱作水稻灌溉定额和施肥量对产量的影响。采用通用旋转组合设计试验方法,建立膜下滴灌旱作水稻水肥耦合模型。结果表明,在供试土壤膜下滴灌条件下,灌溉定额、氮、磷与水稻产量之间符合三元二次回归模型,其一次项、二次项及水氮交互项回归系数均达极显著水平,三因素的增产作用大小依次为:灌溉定额>施氮量>施磷量。采用此模型计算的预测产量与实际产量之间呈高度正相关(R2=0.981),并可由此计算得出目标产量灌溉定额及其施肥量。经模型寻优,得出不同目标产量下的水、氮、磷最佳组合方案,通过2 a验证试验,验证产量与水分生产效率与模型优化组合目标产量和水分生产效率相吻合,此最优组合方案可以为膜下滴灌旱作水稻节水节肥、水肥一体化技术和高效栽培技术提供科学依据和理论支持。

不同水氮处理对水稻荧光参数和光合特性的影响

在大田栽培条件下,利用LI-6400XT型光合仪测定不同水氮调控对水稻典型生育期主要荧光参数和光合特性的影响。结果表明:水稻光化学量子效率F_v/F_m、光化学淬灭系数q_P与非光化学淬灭系数q_N随着灌水量的减少而降低,随着施氮量的增加F_v/F_m在抽穗开花期、q_P在拔节孕穗期呈倒V形变化趋势,说明寒区黑土水稻叶片PSII反应中心因不同水氮处理而得到调节,使PSII反应中心潜在活性、光合原初反应中心开放程度及热耗散能力受到不同程度的抑制或改善。在控制灌溉条件下气孔限制值L_s高于全面淹灌,但并没有影响水稻叶片的光合作用而表现出一定的气孔限制。对施氮量110~160 kg/hm^2处理光响应曲线模拟得出,随着施氮量的增加曲线升高,光饱和点LSP、光补偿点LCP明显降低,而表观量子效率α、光响应曲线曲角θ和最大净光合速率P_(nmax)有所回升,灌水处理间对比得出全面淹灌条件下LSP、LCP和θ低于控制灌溉,而P_(nmax)显著增加,暗呼吸速率R_d、α结果不明显。这表明高肥有利于水稻叶片对弱光的利用,减少耗水量对强光利用效果显著。因此,水氮胁迫会改善水稻叶片对光的适应能力,适量增加施氮量可以有效改善水稻叶片光响应特征。

华北地区旱稻产量适应性及耗水特征分析

本研究利用2001-2002年的试验结果,分析了北京昌平旱稻的产量及产量构成要素、水分利用效率和耗水特征。结果表明：在水分输入为300-522 mm条件下,北京地区“旱稻297”和“旱稻502”的产量水平分别为3 876-5 289 kg.hm^-2、3 977-5 664 kg.hm^-2,灌溉水的水分利用效率分别为1.01-1.29 g.kg^-1、1.03-1.33 g.kg^-1,同一品种不同水分处理之间存在差异。“旱稻502”的产量和水分利用效率均高于“旱稻297”,表明“旱稻502”更适宜在北京地区种植。对产量分析可以看出,在损失7.9%-29.8%产量前提下,水分利用效率可以提高1.9%-27.7%,其中前期限量灌溉处理的水分利用效率提高幅度最大,为3.6%-23.1%,而产量仅降低7.9%-15.5%。表明前期限量后期充分灌溉处理为北京地区气候条件下的旱稻节水灌溉模式。同时利用北京地区昌平气象站1951-2005年的气侯资料,分析了旱稻生长季内的降水特点,根据person-Ⅲ分布法确定了旱稻生长季内的3种降水年型,并分析了不同降水年型下旱稻生长季内的降水与作物需水的耦合度。结果表明：旱稻在正常年和干旱年型下生长季内各生育阶段均需灌溉水补充,而湿润年型只需在开花-成熟阶段适当补充灌溉。