Impact of Planting Position and Planting Material on Root Yield of Cassava （Manihot esculenta Crantz）

Cassava （Manihot esculenta Crantz） is a perennial woody shrub with an edible root, which grows in tropical and subtropical areas of the world. In Africa, cassava provides a basic daily source of dietary energy. It plays an important role in food security and incomes of many rural households in the southern Ethiopia. However, information available on production practices of cassava for the region is insufficient. Hence, field experiment was conducted at Awassa Agricultural Research Center for two successive cropping seasons from 2004 to 2006 to investigate the response of cassava to planting position and planting material. The treatments used were three planting positions （slant, vertical and horizontal） and five planting materials （main stem top part, main stem middle part, main stem bottom part, branch stake top part and branch stake bottom part） were combined in factorial arrangement and laid out in randomized complete block design with three replications. The result revealed that root yield was significantly （P 〈 0.05） affected by the interaction effects of the planting position and planting material. The highest yield （25.2 ton ha^-1） was obtained from the main stem top part planted in slant position whereas the least yield （6.5 ton ha^-1） was obtained from main stem bottom part planted in horizontal position. Based on the findings of this study, areas like Awassa with moderate rainfall slant and vertical planting of main stem top and middle parts could be used as planting material.

Effect of Variety and Size of Stem Cutting on Flesh Root Yield and Yield Components of Sweet Potato

Sweet potato is an important food crop which contributes to food security. Storage roots are stored in the ground and harvested when needed. In coastal Kenya, the production of the crop is limited by lack of adaptable varieties and shortage of planting materials at the onset of long rains. The prevailing prices of sweet potato vines for planting present a hindrance for sweet potato cultivation culminating to low acreages by farmers. This study was carried out during the long rains of 2011 to 2013 to determine the effect of variety and size of sweet potato cutting on root yield. Four sweet potato varieties were planted under four stem cutting sizes of four, six, eight and 10 nodes. The four varieties were K135, Bungoma, SPK004 and Mtwapa 8 （check）. The experimental design was a split plot with varieties assigned to main plots and cutting sizes to sub-plots. The number of roots per plant for Bungoma variety was significantly （P 〈 0.05） less than that for the check, and variety K135 showed significantly （P 〈 0.05） higher number of marketable root per plant than the check. The same trend was observed for root yield per hectare. The check variety had the highest percent of dry matter and was significantly higher than that of SPK004 and Bungoma varieties. There were no significant （P 〈 0.05） differences among the stem cutting sizes as regards to number of roots per plant, number of marketable root per plant and percent of dry matter. The cutting size of six nodes gave similar root yield as the recommended eight nodes, and therefore farmers can adopt shorter vines than the recommended, hence saving on the cost of planting materials.

Effects of Planting Methods on Root Yield and Nutrient Removal of Five Cassava Cultivars Planted in Late Rainy Season in Northeastern Thailand

The objectives of this study were to evaluate growth, yield and nutrients removal of five cassava cultivars planted by different planting methods in late rainy season of northeastern Thailand. A split plot design was used in this study. The planting methods (vertical and horizontal) were assigned as main-plots. Cassava cultivars (Rayong-7, Rayong-11, Rayong-72, Huaybong-80 and E-dum) were assigned as sub-plots with four replications. Results showed that vertical planting gave significantly higher fresh storage root yield than those of horizontal planting, across five cassava cultivars. The cultivar Rayong-7 produced maximum fresh storage root yield across two planting methods, but not significantly different from Rayong 11, Huaybong 80 and Edum cultivars. Irrespective of nutrient removal, N, P and K removed ranges from 2.9 - 3.6, 0.8 - 1.3 and 5.3 - 7.9 kg per ton fresh root weight, respectively depending on cassava cultivar. The cultivar Rayong-7 removed the highest quantities of N, and the cultivar Rayong-11 removed maximum of P and K in the present study. Regardless of nutrient removal at different plant parts;N, P and K removed maximum quantities in leaf, stem and storage root, respectively. Planting method had no significant effect on N and P removal, but significant effect on K removal. The vertical planting removed K higher than those of horizontal planting.

Calibration and validation of FAO-AquaCrop model to estimate the total biomass and yacon root yield

Due to the current water scarcity in the world,it is extremely important to improve the use of this natural and exhaustible resource in agriculture,by contributing to increase agricultural production and sustainability.Several models of crop growth simulation were developed to predict the edaphoclimatic effects on crop yield.These models are calibrated and validated for a given region using the data generated from field experiments.Therefore,the objective of this study was to calibrate and validate the FAO AquaCrop model for yacon(Smallanthus sonchifolius)crop in a tropical climate.The experiment was conducted in an experimental area located in the municipality of Ibatiba,state of Espírito Santo(Brazil)during the years of 2013 and 2014.The calibration was done using the Autumn planting and validation with the Winter and Spring plantings.For the statistical analysis,the coefficient of determination,Willmott concordance index,bias for the systematic error,root mean square error and the mean absolute error to test the model performance were used.In general,the FAO AquaCrop model predicted the root yield,total biomass and harvest index with acceptable accuracy,and with deviations of less than 6%for total and root biomass.Late planting of yacon showed a reduction in yield as well as total biomass.

Effect of Selenium on Root Oxidizing Ability and Yield of Rice under Ferrous Stress

To study the effects of selenium on root oxidizing ability and yield of rice under ferrous stress, a pot culture experiment was conducted, the activity of glutathione peroxidase (GSH-Px) and the concentration of malonaldelyde (MDA) were determined. The root oxidizing ability and yield characters of rice were examined. Results showed that appropriate amount of Se enhanced the activity of glutathione peroxidase and the oxidizing ability of rice roots significantly, reduced the concentration of MDA, increased 1000-grain weight of rice, F = 26.96**, decreased empty and blighted grain rate, increased the rice yield, F = 11.53**, and enhanced the rice resistance under ferrous stress.

Single-seed sowing increased pod yield at a reduced seeding rate by improving root physiological state of Arachis hypogaea

Double-seed sowing(two seeds per hole)is the dominant pattern of peanut sowing in China,but within-hole plant competition usually limits their growth and yield formation.Besides,the traditional double-seed sowing method does not facilitate mechanization during sowing.The objective of this study was to determine if single-seed sowing at a proper seeding rate yielded better than traditional double-seed sowing pattern and the differences of physiological metabolism of roots.A field experiment was conducted in two consecutive years to compare pod yields of single-seed sowing at 180000(S180),225000(S225),and 270000 seeds ha^-1(S270)with that of double-seed sowing at 270000 seeds ha^-1(D270)using a completely randomized block design with four replications.And the root bleeding sap rate,nutrient content,and the main hormone contents in root bleeding sap were also comparatively investigated.Although the pod yields of single-seed sowing at the three densities were higher than that of traditional double-seed sowing(D270),S225 yielded better than the other two single-seed sowing treatments(S180 and S270).The increased pod yield in single-seed sowing at 225000 seeds ha^-1 was mainly due to the higher pod dry weight per plant and harvest index.The improved pod dry weight and shoot growth had closely relationship with the enhanced root physiological traits such as the increased root bleeding sap rate,content of free amino acids,soluble sugars,K^+,Mg^2+,Zn^2+,and Ca^2+of the individual plant root.The improved activity of root reductive,nitrate reductase(NR)and ATPase and higher zeatin and zeatin riboside(Z+ZR)content of root bleeding sap were alsocrucial to the pod and shoot growth of peanut.Single-seed sowing at a moderate seeding rate(S225)is a potential practice to increase pod yield and to save seed cost.

Effect of subsoil tillage depth on nutrient accumulation, root distribution, and grain yield in spring maize

A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen(N), phosphorus(P), and potassium(K) uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development,increased nutrient accumulation, and increased yield. Compared with conventional soil management(CK), root length, root surface area, and root dry weight at 0–80 cm soil depth under subsoil tillage to 30 cm(T1) and subsoil tillage to 50 cm(T2) were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.

Effects of Different Tillage Systems on Soil Properties,Root Growth,Grain Yield,and Water Use Efficiency of Winter Wheat (Triticum aestivum L.) in Arid Northwest China

Studies on root development, soil physical properties, grain yield, and water-use efficiency are important for identifying suitable soil management practices for sustainable crop production. A field experiment was conducted from 2006 through 2008 in arid northwestern China to determine the effects of four tillage systems on soil properties, root development, water-use efficiency, and grain yield of winter wheat （Triticum aestivum L.）. The cultivar Fan 13 was grown under four tillage systems：conventional tillage （CT） without wheat stubble, no-tillage without wheat stubble mulching （NT）, no-tillage with wheat stubble standing （NTSS）, and no-tillage with wheat stubble mulching （NTS）. The soil bulk density （BD） under CT system increased gradually from sowing to harvest, but that in NT, NTSS, and NTS systems had little change. Compared to the CT system, the NTSS and NTS systems improved total soil water storage （0-150 cm） by 6.1-9.6 and 10.5- 15.3% before sowing, and by 2.2-8.9 and 13.0-15.1% after harvest, respectively. The NTSS and NTS systems also increased mean dry root weight density （DRWD） as compared to CT system. The NTS system significantly improved water-use efficiency by 17.2-17.5% and crop yield by 15.6-16.8%, and the NTSS system improved that by 7.8-9.6 and 7.0-12.8%, respectively, compared with the CT system. Our results suggested that Chinese farmers should consider adopting conservation tillage practices in arid northwestern China because of benefits to soil bulk density, water storage, root system, and winter wheat yield.

Effects of Phosphorus Application in Different Soil Layers on Root Growth, Yield, and Water-Use Efficiency of Winter Wheat Grown Under Semi-Arid Conditions

Deep phosphorus application can be a usefull measure to improve crops＇ performance in semi-arid regions, but more knowledge of both its general effects and effects on specific crops is required to optimize treatments. Thus, the aims of this study were to evaluate the effects of phosphorus（P） application at different soil layers on root growth, grain yield, and water-use efficiency（WUE） of winter wheat grown on the semi-arid Loess Plateau of China and to explore the relationship between root distribution and grain yield. The experiment consisted of four P treatments in a randomized complete block design with three replicates and two cultivars： one drought-sensitive（Xiaoyan 22, XY22） and one drought-tolerant（Changhan 58, CH58）. The four P treatments were no P（control, CK）, surface P（SP）, deep P（DP）, and deep-band P application（DBP）. CH58 produced larger and deeper root systems, and had higher grain yields and WUE, under the deep P treatments（DP and DBP） than under SP, clearly showing that deep P placement had beneficial effects on the drought-tolerant cultivar. In contrast, the grain yield and root growth of XY22 did not differ between DP or DBP and SP treatments. Further, root dry weight（RW） and root length（RL） in deep soil layer（30-100 cm） were closely positively correlated with grain yield and WUE of CH58（but not XY22）, highlighting the connections between a well-developed subsoil root system and both high grain yield and WUE for the drought-tolerant cultivar. WUE correlated strongly with grain yield for both cultivars（r=0.94, P〈0.001）. In conclusion, deep application of P fertilizer is a practical and feasible means of increasing grain yield and WUE of rainfed winter wheat in semi-arid regions, by promoting deep root development of drought-tolerant cultivars.

Root Morphology and Physiology in Relation to the Yield Formation of Rice

Root system is a vital part of plant and regulates many aspects of shoot growth and development. This paper reviews how some traits of root morphology and physiology are related to the formation of grain yield in rice （Oryza sativa L.）. Higher root biomass, root oxidation activity, and cytokinin contents in roots are required for achieving more panicle number, more spikelets per panicle, greater grain-filling percentage, and higher grain yield. However, these root traits are not linearly correlated with yield components. When these traits reach very high levels, grain filling and grain yield are not necessarily enhanced. High numbers of mitochondria, Golgi bodies, and amyloplasts in root tip cells benefit root and shoot growth and yield formation. Proper crop management, such as an alternate wetting and moderate soil drying irrigation, can significantly improve ultra-structure of root tip cells, increase root length density and concentration of cytokinins in root bleedings, and consequently, increase grain-filling percentage, grain yield, and water use efficiency. Further studies are needed to investigate the mechanism underlying root-shoot and root-soil interactions for high grain yield, the roles of root-sourced hormones in regulating crop growth and development and the effects of soil moisture and nutrient management on the root architecture and physiology.

Soil reinforcement by a root system and its effects on sediment yield in response to concentrated flow in the loess plateau

The importance of roots in soil conservation has long been underestimated due to a lack of sys-tematic studies conducted to evaluate root dis-tribution patterns and their effects on soil ero-sion. Current knowledge regarding root mor-phology and its impact on soil erosion by water is limited;therefore, detailed analysis of the role that root systems play in controlling soil ero-sion is needed. In this study, stratified runoff scouring at different soil depths in the field was conducted in a grassland area. The results in-dicated that both root biomass and soil wa-ter-stable aggregates decreased as soil depth increased at all three sites, while there was al-most no change in soil bulk density at 1.3g/cm3. Sediment yields under different runoff dis-charge at different sites showed similar trends, and the sediment yield increased as the soil depth increased at all three sites. Further analysis revealed that close relationships ex-isted between root biomass and the amount of water-stable aggregates and soil organic matter content, and that these factors greatly influ-enced soil erosion. Based on the data generated by the experiment, equations describing the relationship between sediment production at different soil depths and root biomass were determined.

Correlation between Root Trait and Yield of Alfalfa

Growth traits of root system of 13 autumn-sowing alfalfa cultivars were analyzed. The results indicated that there were significant difference in growth pa- rameters of root system among alfalfa cultivars （ P 〈 0.05 ）. The cultivars, Prime and WI323, showed the highest root biomass （ higher than 32 g） ; cuhivar WI323 had the largest lateral root number （17.8 branches）. Cultivars Prime, WI323, Super7 and L90 had better root traits than other cultivars based on comprehensive evaluation. Among three times of mowing within a year, root growth and development of alfalfa had mutual promotion with the first and second time growth of abovegraund part, but had competition with the third time growth. Overwintering alfalfa root restricted the grass yield in the following year, especially the third-cut yield in the next year.

Root Growth, Nutrient Uptake and Yield of Medicinal Rice Njavara under Different Establishment Techniques and Nutrient Sources

Field experiments with medicinal rice Njavara were conducted at Cropping Systems Research Centre, Karamana, Thiruvananthapuram, Kerala during summer of 2007 and 2008. The experimental design was split plot with three replications. The treatments consisted of four establishment techniques viz., System of Rice Intensification SRI (M1), Integrated Crop Establishment Method (ICM) (M2), Package of practices (PoP) (M3) of Kerala Agricultural University and Conventional Management Practices (CMP) (M4) in main plot. Three nutrient sources viz., (1) organic, 2) integrated use of organic and inorganic, 3) chemical fertilizers only) were used under different establishment techniques. Root dry matter production was determined at weekly intervals and plant nutrients uptake was determined by calculating from the product of dry matter, straw dry weight, grain yield and percentage of nutrients. Results revealed that at early stages (4-6 WAT/WAS) (Weeks after transplanting/Weeks after sowing), root dry matter production hill-1 was in the order of SRI > ICM > CMP > PoP which changed to SRI > ICM > PoP > CMP from 7th week onwards. Maximum root dry matter (at 9th WAS/WAT) was recorded in SRI (0.51/0.50 g.hill-1 in 2007/2008). The total nutrients uptake (N, P, K, Fe, Mn and Zn) in conventional management practices was significantly higher than other establishment techniques. Among the nutrient sources, higher total (N, P, K, Fe, Mn and Zn) uptake by crop was recorded under integrated nutrient source than organic and inorganic sources.

Optimize nitrogen fertilization location in root-growing zone to increase grain yield and nitrogen use efficiency of transplanted rice in subtropical China

The optimized nitrogen fertilization location differs in different rice-growing regions. We optimized nitrogen deep-point application in root-growing zone（NARZ） for transplanted rice in subtropical China. Field plot experiments were conducted over two years（2014–2015） in a double-rice cropping system to evaluate the effects of nitrogen（N） fertilizer location on grain yield and N use efficiency（NUE）. Four different nitrogen deep-point application methods（DN） were compared with traditional broadcast application（BN） using granular urea. The results showed that grain yield, recovery efficiency of N（REN）, agronomic efficiency of N（AEN）, and partial factor productivity of N（PFP_N） significantly increased 10.3–63.4, 13.7–56.7, 24.7–201.9 and 10.2–63.4%, respectively, in DN treatment compared to BN, respectively. We also find that DN treatments increased grain yield as well as grain N content, and thus grain quality, in comparison with conventional BN treatment. Correlation analysis indicated that significant improvement in grain yield and NUE mainly resulted from increases in productive panicle number and grain N content. In our proposed NARZ method, granular urea should be placed 0 to 5 cm around the rice seeding at a 12-cm depth druing rice transplanting. In NARZ, balanced application of N, P and K further improved grain yield and NUE over treatments with a single N deep-point application. High N uptake by the rice plant did not cause significant soil fertility depletion, demonstrating that this method could guarantee sustainable rice production.

两种微生物菌剂不同灌根次数对马铃薯疮痂病防效试验

马铃薯疮痂病是影响天水地区马铃薯产量和商品属性最主要的土传病害。为了防治该病,本研究选取格兰克和菌动力两种微生物菌剂,比较不同灌根次数对天薯13号马铃薯疮痂病的防效。结果表明,与不灌根对照相比,微生物菌剂灌根处理均能提高马铃薯的产量,增产率为0.5%~21.5%;且能有效降低马铃薯疮痂病的发生率,对疮痂病的防效为44.8%~88.2%。其中,格兰克灌根两次(现蕾期和开花期各灌根1次)和菌动力灌根1次(现蕾期灌根1次)两个处理的效果较好,马铃薯产量分别较对照增加14.5%和21.5%,对马铃薯疮痂病的防效分别为88.2%和78.7%。

Root morphological traits and their relations with yield components of dry-raised mid-season indica rice

Research on root morphological traits of dry-raised seedlings (D-RS) at different growth stages of rice have so far attracted less attention. In this study, using mid-season indica hy-

生根粉浸种对木薯生长与产量的影响

为探索木薯的抗逆增产技术,设置5个生根粉浸种浓度(0、10.0、20.0、40.0、60.0 mg·L^(-1))、2个浸种时间(6、12 h)、以不浸种处理为对照(CK),研究其对木薯农艺性状、薯块产量与品质的影响。结果表明:与不浸种比较,20.0、60.0 mg·L^(-1)浸种6 h和20.0~60.0 mg·L^(-1)浸种12 h显著增粗茎径,20.0 mg·L^(-1)浸种6 h显著提高薯长和薯径,0、10.0、60.0 mg·L^(-1)浸种12 h显著增长薯长,0、40.0、60.0 mg·L^(-1)浸种6 h及40.0、60.0 mg·L^(-1)浸种12 h显著增粗薯径,20.0 mg·L^(-1)浸种6 h鲜薯产量显著增加42.3%、淀粉产量显著提高49.9%、收获指数显著提高10.5%。综上,推荐20.0 mg·L^(-1)生根粉溶液浸泡木薯种茎6 h的增产技术。

垄沟集雨覆盖种植对红豆草根系特征和产量的影响

【目的】为选择集雨垄的环境友好型覆盖材料,提高中国西北半干旱地区的降雨利用效率。【方法】通过随机区组大田试验,以传统平作为对照,研究3种材料(土壤结皮、生物可降解地膜和普通地膜)覆盖垄的垄沟集雨种植对土壤水热条件、红豆草根系特征、根瘤特征、干草产量和水分利用效率的影响。【结果】垄沟集雨种植显著改善土壤水热状况,增加红豆草根系和根瘤特征值。土壤结皮覆盖垄沟集雨种植显著提高红豆草水分利用效率,但降低红豆草干草产量;生物降解地膜和普通地膜覆盖垄沟集雨种植显著提高红豆草的干草产量和水分利用效率。与传统平作相比,土壤结皮、生物降解地膜和普通地膜覆盖垄沟集雨种植的土壤贮水量分别提高10.64、9.36和2.09 mm,垄上表层土壤温度分别增加2.0、3.4和4.2℃,红豆草根干重分别提高27%、72%和87%,有效根瘤数分别增加2.1、9.1和12.4个,水分利用效率分别提高11.9、23.3和30.0 kg/(hm^(2)·mm)。土壤结皮覆盖垄沟集雨种植的红豆草干草产量比传统平作降低13%,生物降解地膜和普通地膜覆盖垄沟集雨种植的红豆草干草产量比传统平作分别提高11%和23%。由于普通地膜残留极易导致土壤结构恶化和环境污染,不利于农业生产可持续性。【结论】在我国半干旱地区,生物可降解地膜覆盖垄沟集雨种植可作为一种高效、可持续的农业节水生产技术。

不同时期水分胁迫对大豆根系特性及产量的影响

为揭示抗旱基因型大豆根系应答干旱胁迫的响应机制,于2020年在辽宁省沈阳市开展盆栽试验,以抗旱基因型和干旱敏感型大豆为试材,探讨干旱(W1,土壤含水量为田间持水量的50%)、轻度干旱(W2,土壤含水量为田间持水量的60%)、适宜水分(W3,土壤含水量为田间持水量的80%)对大豆根系特性和产量的影响。结果表明:同一时期控水,W1和W2条件下,抗旱品种“辽豆14”的总根长和根表面积优于干旱敏感型品种“辽豆21”。一般情况下,平均根直径为0~0.5 mm的根长比例表现为:“辽豆21”>“辽豆14”,而平均根直径为0.5~1.0 mm的根长比例却表现为:“辽豆14”>“辽豆21”。随着生育进程的推进,大豆地上部鲜重、地上部干重、根干重逐渐累积,鼓粒期达最大值;一般情况下,同一控水时期,随着土壤含水量的增加,同一品种地上部鲜重、根鲜重、地上部干重、根干重值逐渐增加,但抗旱品种“辽豆14”的值一般优于干旱敏感型品种“辽豆21”。随着生育进程的推进,根冠比鲜重和根冠比干重值降低;土壤干旱提高了植株的根冠比。各个时期控水,品种和水分均显著影响了大豆的单株产量,干旱(W1)和轻度干旱(W2)均降低了2品种的单株产量,但抗旱品种“辽豆14”引起产量下降的值更低。干旱胁迫条件下,抗旱基因型大豆在总根长、根表面积、地上部干重、根干重、产量以及平均根直径为0.5~1.0 mm的根长比例方面,表现出优于干旱敏感型品种的优势。

潮土与滩涂盐土环境下甘薯块根产量及营养成分差异分析

甘薯[Ipomoea batatas (L.) Lam.]具有高产稳产特性及较好的耐逆能力。为了探究甘薯盐碱地推广的适宜性,本研究对比分析113份甘薯材料在潮土与盐土两种土壤环境下的块根产量,并对其中10份材料的营养成分进行差异分析。结果表明,在含盐量4.4‰的盐土中,约30%的参试材料没有产量,有产量材料的产量平均值相对潮土环境减少79.98%。与潮土相比,除个别材料外(XY153和XY205),盐土中甘薯块根干物率、淀粉含量、蛋白质含量降低,可溶性糖含量增加,具体表现为:盐土中薯块干物率、淀粉含量、蛋白质含量平均值分别减少3.86、6.15、1.73个百分点,可溶性糖含量平均值增加4.38个百分点;盐土中多数材料薯块类胡萝卜素含量降低,平均值相对减少22.34%;除栗子香外,其余材料直链淀粉含量在盐土中均降低,所有材料直链淀粉含量平均值降低1.89个百分点。X射线衍射(XRD)分析表明,普薯32淀粉为C型晶体型,其余材料为CA型晶体,两种土壤环境中的淀粉晶体型无明显差异。此外,筛选到高耐盐品系XY33、XY44,耐盐系数分别为0.69和0.61,可作为耐盐种质利用。本研究结果为甘薯在滩涂盐土中的种植推广提供了理论指导。