Castor Bean Yield Research Articles

Nitrogen uptake, grain yield, and oil concentration of dwarf castor beans under nitrogen rates and inoculation of rhizobacteria in grasses-legumes rotation.

Plant growth-promoting bacteria (PGPB) have been primarily studied for atmospheric nitrogen (N) fixation but they also have the capacity to improve nutrition and yield of crop plants. Therefore, the objective of this research was to investigate the effects of inoculation with PGPB in association with different N rates on N uptake, grain yield, and oil concentration of dwarf castor beans in succession to legumes and grasses in Ilha Solteira, Brazil. The treatments consisted of N rates (0 to 180 kg ha-1 of N) and inoculation with three plant growth-promoting bacteria (Azospirillum brasiliense, Bacillus subtilis, and Pseudomonas fluorescens, applied by leaf) and a control with no-inoculation. The grain and oil yields of castor beans were increased by 20 and 40% at a rate of 103 kg ha-1 of N in succession to grasses as compared to without N application. In addition, the grain yield of castor bean after legumes was increased by 28, 64, and 40% with estimated rates of 97, 113, and 92 kg ha-1 of N in combination with inoculations of A. brasilense, B. subtilis, and P. fluorescens as compared to without N application, respectively. Shoot, grain, and total N uptake were improved with foliar inoculation of A. brasilense, B. subtilis, and P. fluorescens at the N rates of 45, 90, and 135 kg ha-1, respectively. Topdressing of N at the rate of 103 kg ha-1 and foliar inoculation in succession to grasses and 180 kg ha-1 of N without the effect of foliar inoculation in succession to legumes are recommended for higher grain and oil yield of castor beans. Foliar inoculations with A. brasilense, B. subtilis, and P. fluorescens increased grain yield under reduced use of N fertilizer by 44, 37, and 49% in dwarf castor cultivation in succession to legumes, potentially contributing to sustainable agriculture.

Assessment of seed, biodiesel and oil yield of castor bean (Ricinus communis L.) under differential phosphorus doses

Assessment of seed, biodiesel and oil yield of castor bean (Ricinus communis L.) under differential phosphorus doses

Mapping and yield prediction of castor bean (Ricinus communis) using Sentinel-2A satellite image in a semi-arid region of india

Abstract Castor bean (Ricinus communis) indigenous to the southeastern Mediterranean basin, eastern Africa and India is a crop having various industrial and medicinal applications. It is helpful in crop rotation and replenishing the soil nutrients due to less water consumption. The current study explores the utility of Sentinel-2A satellite image for mapping and yield prediction of castor beans. Several classification methods viz. migrating means clustering, maximum likelihood classifier, support vector machine and artificial neural network are used for the classification and mapping of different landscape categories. The overall classification accuracy was achieved to be highest for artificial neural network (85.81 %) subsequently support vector machine (80.12 %), maximum likelihood classifier (74.23 %) and migrating means clustering (73.03 %). The yield prediction is performed using Sentinel-2A-derived indices namely Normalized Difference Vegetation Index and Enhanced Vegetation Index-2. Further, the cumulative values of these two indices are investigated for castor bean yield prediction using linear regression from July 2017 to April 2018 in different seasons (pre-monsoon, post-monsoon, and winter). The regression model provided (adj R2=0.75) value using EVI-2 compared to (adj R2=0.55) using NDVI for yield prediction of Ricinus communis crop in the winter season. The methodology adopted in this study can serve as an effective tool to map and predict the productivity of Ricinus communis. The adopted methodology may also be extended to a wider spatial level and for other significant crops grown in semi-arid regions of world.

Photosynthetic efficiency, gas exchange and yield of castor bean intercropped with peanut in semiarid Brazil

ABSTRACT To evaluate the photosynthetic efficiency, gas exchange and yield of castor bean intercropped with peanut under Brazilian semiarid conditions, a field experiment was set up with six treatments and four replicates arranged in a randomized block design. The experiment consisted of the cultivation of castor bean ‘BRS Energia’ in a monocrop system and intercropped with peanut ‘BR 1’. One treatment was formed by monocropped castor bean and the others by the castor bean intercropped with peanut with different intercrop establishment times, i.e. peanut sowing times (0, 10, 15, 20 and 25 days after castor bean sowing). The castor bean photosynthetic and carboxylation efficiencies were higher in the intercrop system with a 25-day interval between sowings. Peanut sowing at 0 to 10 days after castor bean sowing in the intercropped system affected the photochemical efficiency of the latter, which resulted in its yield reduction. Larger intervals between sowing of peanut ‘BR-1’ and of the main crop increased castor bean yield in the intercrop system.

Influence of Tillage and Wood Ash on Zn and Fe Content of Soil, Castor Shoot and Seed

The effect of tillage methods (Mound, Ridge, Flat) and rates of wood ash on soil properties and yield of castor bean plant were studied in field trial at Abakaliki for 3 years cropping seasons. The experiment was a split plot in randomized complete block design with three tillage methods and four rates of wood ash (0 t∙ha-1, 2 t∙ha-1, 4 t∙ha-1 and 6 t∙ha-1), replicated three times. CropStat Version 7.2 computer software for data management developed primarily for the analysis of data from agricultural field trials was used to analyze data collected from the study and mean separation was done using least significant difference (LSD) at 5% alpha level. The findings from the study showed for soil heavy metal contents, it was observed that tillage methods had no effect on the heavy metals except for 1st year cropping result of Zn and 2nd year cropping result of Fe. The effect of tillage methods on heavy metal contents of castor shoot showed a significant difference P rd year result of Fe. The values obtained from Ridge and Flat were higher when compared with the value of Mound with regard to soil and castor shoot; heavy metal content with higher values was more observed in Flat method. The result of heavy metal content of seed indicated that tillage method had no effect on the heavy metal contents of the castor seed; the results of Fe, Zn in 1st and 2nd year planting season were not significant among the rates of wood ash applied. The effect of tillage and wood ash on heavy metal content of soil, castor shoot and seed was found to be significant (P -1 (Rd2), 4 t∙ha-1 (Rd4) and 6 t∙ha-1 (Rd6) on Fe 2nd year planting result of castor seed was statistically similar, while the result from Mound method was found to increase the seed uptake of the tested parameters. The observed values of the tested parameters (Fe, Zn) in wood ash amended plots in the three years’ study were beyond acceptable limits; hence reservation in the use of wood ash on continuous bases as soil amendment especially at higher rates. The findings also indicated that the use of wood ash as soil amendment on continuous basis on the same piece of land especially at higher rates might constitute pollution problems on the near future.

English

This study aimed to evaluate the morpho-physiology and oil yield of castor bean (cultivar 'BRS Energia') as a function of irrigation water salinity and cationic nature. The experiment was carried out using an Ultisol of sandy loam texture, in Campina Grande, Para ba, Brazil. Six combinations of cations and water electrical conductivity (ECw) were studied (S1 - Control; S2 - Na+; S3 - Ca2+; S4 - Na++Ca2+; S5 - K+ and S6 - Na++Ca2++Mg2+), in a randomized block design, with four replicates and five plants in each plot. Plants in the control treatment (S1) were irrigated using water of 0.6 dS m-1, while the other treatments were irrigated using water of 4.5 dS m-1, prepared using chloride salts of different cations. Gas exchanges, growth and oil yield of castor bean were more affected by ECw variation than by the cationic nature of the water. Among the tested cations, potassium promoted the highest values of gas exchange and growth except in the flowering and fruiting stages. Oil yield is the most sensitive variable to the cationic nature of irrigation water.

Determination of Appropriate Rate of Cattle Dung for Effective Weed Control and Higher Yield of Castor Bean Seed (Ricinus Communis L) At Badeggi, Nigeria

Castor field of National Cereals Research Institute (NCRI) Badeggi is becoming over mined as a result of continuous cropping over a long period of time and thereby leading to high leaching of added inputs such as herbicides, inorganic fertilizer; and water by causing high infiltration of both rain and irrigation water and consequently, affecting weed control and castor yield (kg/ha). Therefore, possible way to reclaim or ameliorate the soil to improve weed control and enable higher productivity of castor seed is necessary. Field trials were established on castor experimental field of National Cereals Research Institute, Badeggi in 2013 and 2014 wet seasons. The treatments evaluated were different rates of air dried cattle dung manure at the following rates 5.0t/ha, 10.0t/ha, 15.0t/ha, 20.0t/ha, NPK inorganic fertilizer at 60-60-20kg/ha and the control where nothing was applied. All the rates of cattle dung evaluated offered better weed control and castor bean yield (kg/ha) than the control where no fertilization took place in both years. The incorporation of cattle dung in both years at all the rates evaluated gave significantly better weed control and yield (kg/ha) of castor seed than plots treated with inorganic fertilizer alone at 60-60-30kg/ha NPK. Among the various rates of cattle dung evaluated for effective weed control and castor seed yield (kg/ha), the weed control and castor seed yield achieved from the incorporation of 10.0t/ha of cattle dung was significantly comparable to the weed control and castor yield (kg/ha) obtained from the incorporation of higher rates of 15.0t/ha and 20.0t/ha in 2013 and 2014.

Castor (Ricinus communis L.) tolerance and weed control with preemergence herbicides

U.S. castor production is limited in part due to only one labeled herbicide (trifluralin) for effective weed control. Field studies were conducted in south Texas and in the Texas High Plains in 2008, 2009, 2012, and 2013 to evaluate castor tolerance and weed efficacy following the application of preemergence (PRE) herbicides. During years of little or poor rainfall, no castor injury was noted following the application of PRE herbicides. However, when rainfall occurred soon after application of PRE herbicides, linuron doses of 1.12kg/ha or greater resulted in stunting of castor plants and reduced stands when compared with the non-treated control. Acetochlor, clomazone, pendimethalin, and trifluralin consistently caused the least injury to castor plants. However, castor bean yield in many instances was not affected by herbicide injury. Diuron at doses of 1.12kg/ha or greater and the combination of diuron plus linuron at 0.56kg/ha or greater effectively controlled (> 80%) smellmelon (Cucumis melo L. var. Dudaim Naud.) and Palmer amaranth (Amaranthus palmeri S. Wats), but provided inconsistent control (0–99%) of Texas millet [Urochloa texana (Buckl.) R.Webster]. Results of these studies indicated that castor tolerance to PRE applications of acetochlor, clomazone, and pendimethalin was excellent, thus providing the greatest opportunity for future use in castor production.

Yield of castor bean fertilized with sewage sludge and potassium and magnesium sulphate

<title>ABSTRACT</title><p>The aim of this study was to evaluate the yield and nutrition of castor bean in response to fertilization with sewage sludge and potassium (K) and magnesium (Mg) sulphate. The experiment was carried out from January to July 2011. The treatments, in a randomized block design with three replicates, in a Nitosol, corresponded to a factorial scheme (2 x 4 +1): two doses of K and Mg sulphate combined with four doses of sewage sludge (0, 2.60, 5.20 and 10.40 t ha<sup>-1</sup>, dry basis), applied based on its nitrogen (N) content and the N requirement for the crop and an additional treatment with NPK. The castor bean grain yield fertilized with sewage sludge did not differ from conventional fertilization, with the maximum value achieved at a dose of 7.5 t ha<sup>-1</sup> of sewage sludge. The fertilization with sewage sludge increased zinc and copper levels in the soil to values close to or higher than those in conventional fertilization, without any influence on the concentrations in the leaf. Fertilization with K and Mg sulphate increased the levels of these cations in the soil without affecting the concentrations in the leaves. The fertilization with sewage sludge increased the contents of organic matter, sulfur, zinc, iron, copper and boron in the soil, and manganese and boron in castor bean leaves.</p>

Physiology, growth and yield of castor bean under salt stress and nitrogen doses in phenophases

El alto crecimiento de la poblacion durante las ultimas decadas y la disminucion de los recursos hidricos, tanto en cantidad como en calidad, han hecho el uso necesario de agua salina en las actividades agricolas. Esta investigacion se realizo para evaluar la influencia del riego con agua salina en las diferentes fases fenologicas en ricino cv. Energia BRS. La investigacion se realizo bajo las condiciones de campo en Pombal-PB, Brasil, desde septiembre de 2011 a enero de 2012. El diseno experimental fue de bloques completos al azar, dispuestos en un diseno factorial 5x2x2 y fue adoptada con tres repeticiones. Se consideraron cinco niveles de conductividad electrica del agua de riego (ECw = 0,3; 1,2 ; 2,1; 3,0 y 3,9 dS m-1); dos estrategias de gestion de la salinidad del agua (riego con agua de baja salinidad durante la etapa vegetativa y la aplicacion de diferentes niveles de salinidad en la fase reproductiva y riego con diferentes niveles de ECw en todo el ciclo de cultivo) y dos dosis de nitrogeno (100 y 160 mg de N kg-1 suelo). Se evaluo materia seca de hojas (DML) y el tallo (DMS); numero de frutos (NFruPC) y numero de semillas (NSeePC) del racimo principal. El riego con ECw superior a 0,3 dS m-1 afecto negativamente a DML y DMS. La mayor acumulacion de materia seca se observo en las plantas que no fueron irrigados con aguas salinas en la fase inicial de desarrollo. El suministro de nitrogeno en dosis de 160 mg N kg -1 suelo aumento el DMS. No se observo efecto interactivo significativo entre los factores y las variables estudiadas.

Effect of time of sowing and nitrogen fertilization on growth and yield of castor in vertisols under rainfed conditions

A field experiment was conducted at Regional Agricultural Research Station, Nandyal during kharif 2012 to study the effect of time of sowing and nitrogen fertilization on growth and yield of castor in vertisols under rainfed conditions. The experiment was laid out in a split-plot design with three replications. The treatments consisted of four main plots (Time of sowing - II fortnight of June, I fortnight of July , II fortnight of July and I fortnight of August and four sub plots (Nitrogen levels :0,40,60,80 Kg/ha). Significantly highest castor bean yield was recorded with I F.N. of July sowing but it was at par with II F.N. of June sowing. Significantly lowest castor yield was recorded with I F.N of August sowing. Irrespective of time of sowing, increase in N fertilization from 0 to 80 kg/ha increased the castor yield significantly, highest being with 80 kg N /ha. Interaction effect of I F.N of July sowing with 80 kg of N/ha recorded the highest yield but was at par with II F.N. of July sowing at the same level of N. I F.N of July sowing with 80 kg/ha of nitrogen application recorded the highest gross and net returns and B: C ratio.

Teor de óleo e produtividade da mamoneira de acordo com a adubação nitrogenada e irrigação com água salina

O objetivo deste trabalho foi avaliar o teor de óleo e a produção de sementes da mamoneira 'BRS Energia', submetida a doses de adubação nitrogenada e irrigação com água com diferentes índices de salinidade. O experimento foi realizado em lisímetros, em condições de campo, em delineamento de blocos ao acaso, com três repetições. Os tratamentos consistiram dos índices salinos da água de 0,4 (controle), 1,4, 2,4, 3,4 e 4,4 dS m-1, associados a 50, 75, 100, 125 e 150% das doses de N recomendadas para ensaio. A interação entre salinidade da água de irrigação e doses de N não foi significativa para nenhuma variável estudada. A salinidade da água até 1,4 dS m-1 propiciou teor de óleo das sementes de 47%. Doses de N acima de 64% da recomendada promoveram teor de óleo inferior a 48%. A maior produção de matéria seca da parte aérea foi obtida com 150% da dose de N recomendada. O incremento salino a partir de 0,4 dS m-1 aumenta o tempo para emissão do racemo primário e reduz os valores dos componentes de produção, dos quais a massa de matéria seca da parte aérea e o número de frutos são os mais afetados. Condutividade elétrica da água de até 1,9 dS m-1 e doses de N a partir de 134% da recomendada propiciam maior número de racemos.

Custos de produção e lucratividade de cultivares de mamona em diferentes arranjos de plantas

A combinação ótima de espaçamento entre fileiras e populações de plantas pode levar à maximização econômica da produção da cultura da mamona. Este trabalho objetivou analisar o custo de produção e a lucratividade por hectare de duas cultivares de mamona (IAC 2028 e FCA-PB), em oito diferentes arranjos de plantas, na safra de verão dos anos agrícolas 2007/2008 e 2008/2009, em Botucatu (SP). Os melhores resultados econômicos foram obtidos quando se utilizou espaçamento entre fileiras mais estreito (0,45 m). O maior custo de produção ocorreu em 2007/2008, para a população de 70.000 plantas ha-1, devido à utilização de maior quantidade de sementes e aplicações de fungicidas, em relação a 2008/2009. A cultivar FCA-PB apresentou o melhor índice de lucratividade (27,46%), obtido com a utilização da combinação do espaçamento entre fileiras de 0,45 m e 55.000 plantas ha-1, no ano agrícola 2007/2008, com lucro operacional de R$ 1.147,08 ha-1.

Deficiency symptoms and uptake of micronutrients by castor bean grown in nutrient solution

Castor bean is a nutrient-demanding species, but there is still little information on its micronutrient requirements. The objectives of this study were to evaluate the effects of levels of B (2.5, 12.5 and 25.0 µmol L-1), Cu (0.05, 0.25 and 0.50 µmol L-1), Mn (0.2, 1.0 and 2.0 µmol L-1) and Zn (0.2, 1.0 and 2.0 µmol L-1) in a nutrient solution on plant B, Cu, Mn and Zn concentrations and uptake, vegetative growth and fruit yield of castor bean "Iris", grown in greenhouse. The experiment was arranged in a completely randomized block design with three replicates. The first deficiency symptoms were observed for B, followed by Zn, Cu and Mn. The main changes in the cell ultrastructure due to lack of B were thickening of the cell walls and middle lamellae, distorted chloroplasts and tightly stacked thylakoids, besides the absence of starch grains. The Mn, Zn and Cu deficiencies led to disruption of chloroplasts, disintegration of thylakoids and absence of amyloplasts. The concentration and uptake of B, Cu, Mn, and Zn in castor bean plants increased with micronutrient supply in the solution. Fruit yield was drastically reduced by B and Mn deficiencies. On the other hand, the dry matter yield of the shoot and root of castor bean plants was not. In the treatment with full nutrient solution, the leaves accumulated 56 and 48 % of the total B and Mn taken up by the plants, respectively, and the seeds and roots 85 and 61 % of the total Cu and Zn taken up, respectively. This shows the high demand of castor bean Iris for B and Mn for fruit yield.

Effect of pruning lateral branches on four varieties of medicinal castor bean plant ( Ricinuscommunis L.) yield, growth and development

In order to study the effect of pruning lateral branches on four varieties of castor bean yield, growth, and development, an experiment was conducted at the Agricultural Research Station of Saatlo in Urmia, Iran, during 2010 growing season. Experimental design was split plot, completely randomized block design with three replications. The main plots were varieties of castor bean (that is, 80-23, 80-29, 80-121 and 80-17), and sub plots included three types of pruning (that is, no pruning, pruning of two lateral branches, and pruning of four lateral branches). The plant characteristics were studied in terms of main panicle length, number of seeds per plant, 100 seed weight, seed weight per main panicle, weight of main panicle, grain yield, biological yield, harvest index, days from planting to maturity and oil yield. Results of the data review showed that, the effect of the varieties was significant on all of the characteristics. Also, the effects of pruning and interaction of two factors (variety and pruning) were significant on seed weight per main panicle, weight of main panicle and days from planting to maturity. Maximum grain yield (1307.78 kg ha -1 ) was in 80-12-1 variety, and minimum yield (770.83 kg ha -1 ) observed in 80-17 variety. According to the results, the variety of 80-12-1 and pruning of four lateral branches in this region were recommended for cultivation.

Espaçamento e população de plantas de mamoneira de porte baixo para colheita mecanizada

O objetivo deste trabalho foi avaliar o efeito do espaçamento entre fileiras e da população de plantas sobre a produtividade e outras características agronômicas da mamoneira de porte baixo, para a colheita mecanizada, na safra de verão. O experimento foi realizado durante os anos agrícolas 2007/2008 e 2008/2009, em um Latossolo Vermelho distroférrico, em Botucatu, SP, com uso da cultivar FCA-PB. Utilizou-se o delineamento de blocos ao acaso com parcelas subdivididas e quatro repetições. As parcelas foram constituídas por quatro espaçamentos entre fileiras (0,45, 0,60, 0,75 e 0,90m), e as subparcelas por quatro populações iniciais de plantas (25.000, 40.000, 55.000 e 70.000 plantas por hectare). O aumento da população de plantas, independentemente do espaçamento entre fileiras, diminuiu a sobrevivência de plantas, o diâmetro do caule, o número de racemos por planta e de frutos por racemo. As maiores produtividades de grãos e de óleo da cultivar FCA-PB são obtidas com populações iniciais entre 55.000 e 70.000 plantas por hectare, nos espaçamentos entre fileiras de 0,45 a 0,75 m.

Produtividade e nutrição de mamona cultivada em área de reforma de canavial tratada com lodo de esgoto

A utilização de lodo de esgoto (LE) em solos agrícolas é uma das maneiras mais viáveis de destinação desse resíduo. O objetivo deste trabalho foi avaliar o efeito da aplicação de LE na nutrição e na produtividade da mamona cultivada em área de reforma de canavial, num Argissolo Vermelho-Amarelo distrófico textura argilosa. Os tratamentos testados constaram de quatro doses de lodo de esgoto: 0, 5, 10 e 20 t ha-1 (base seca), calculadas para fornecer N equivalente a 0, 37,5, 75 e 150 kg ha-1; um tratamento com fertilização mineral N-P2O5-K2O (75-40-80 kg ha-1respectivamente) e um controle sem qualquer fertilização. Os tratamentos com LE também receberam 40 kg ha-1 de P2O5 e 80 kg ha-1 de K2O. A mamoneira, cultivar IAC-Guarani, foi cultivada por cerca de 180 dias entre novembro de 2004 e maio de 2005. A aplicação de LE resultou em incremento estatisticamente significativo (p < 0,05) na produtividade e em outras características biométricas da mamona. A aplicação da dose equivalente a 10 t ha-1 de lodo resultou em um índice de eficiência agronômica de 85 %, em relação à adubação mineral. A disponibilidade de N foi o fator mais limitante no crescimento e na produtividade da mamona, e a taxa de mineralização do N utilizada subestimou o fornecimento de N pelo lodo em campo. Houve aumento significativo de Cu e Zn no solo com a aplicação das doses de lodo, mas tanto os teores no solo quanto na planta estiveram dentro dos limites aceitos pela legislação ambiental.

Growth and yield responses of castor bean (Ricinus communis L.) at two enhanced CO<sub>2</sub> levels

Growth and yield responses of castor bean (<I>Ricinus communis</I> L.) to two elevated CO<sub>2</sub> levels (550 and 700 ppm) were evaluated up to the maturity of first order spikes in open top chambers (OTCs). The growth characteristics – root and shoot lengths, root volume, root:shoot ratios, leaf area, dry weights of different plant parts, leaf area duration and crop growth rate increased with 550 and 700 ppm of CO<sub>2</sub> levels compared with ambient control. The spike length, pod and seed yield of first order spikes increased under enhanced CO<sub>2</sub> levels over ambient control. Elevated CO<sub>2</sub> levels significantly increased the total biomass and yield of castor bean, however enhanced CO<sub>2</sub> levels <I>per se</I> did not changed the content and quality of the castor oil. A positive response of castor bean to increased CO<sub>2</sub> concentrations is a good indication for its future existence in potentially changed climatic conditions.

Absorção e translocação de fósforo em dois cultivares de mamoneira (Ricinus communis L.), 'Campinas' e 'Guarani', com uso de 32p

Com o objetivo de estudar a absorção e translocação do fósforo na cultura da mamoneira, instalou-se um ensaio em vasos com os cultivares 'Campinas' e 'Guarani' e empregou-se o fósforo radioativo (32p) como traçador. Os quatro tratamentos constaram da aplicação ao solo de 65 ppm de P contendo 32p, quando as plantas apresentavam seis, nove, doze e quatorze folhas, respectivamente e cortadas com nove, doze e quatorze folhas e as do quarto tratamento após 21 días da aplicação do fertilizante marcado. Através dos dados obtidos, pode-se concluir que, neste solo com baixo teor de fósforo, a aplicação deste elemento, na época da emissão de ínflorescências primárias, não influi no desenvolvimento das inflorescências, uma vez que se formam as expensas de fósforo previamente acumulado no pecíolo e no limbo, e que para lá se desloca a fim de participar do metabolismo de formação e desenvolvimento. Em outros termos, o fósforo, quando aplicado tardiamente, não incrementará a produção dos cachos primários e, consequentemente, não pode esperar que o potencial máximo do cultivar seja atingido, pois os cachos primários representam, no mínimo, 30% da produção total da mamoneira.

Effects of Plant Population on Castorbean Yield1

AbstractPlant population effects on yield and growth of irrigated and non‐irrigated castorbeans (Ricinus communis L.) was tested for 3 years. The optimum plant population of irrigated dwarf‐internode castorbeans was about 58,000 plants per ha. Row spacings from 0.5 m to 1.0 m did not significantly affect yields, if plant population was held constant. The optimum plant population for nonirrigated castorbeans was near or higher than the highest population in our tests. It was clearly higher than the current recommendation of 20,000 plants per ha. Linear regression of yield on plant population was significantly different among cultivars and among tests for the nonirrigated castorbeans. Cultivars with bushy growth and small racemes had greater yield depression from low populations than did more erect cultivars with large racemes. Plant population effect on yield was reduced as the yield level of the nonirrigated tests decreased.Low plant population in nonirrigated tests increased plant height, hypocotyl diameter, length of primary raceme, number of racemes per sequential set, and yield of all sets of racemes. Low population reduced height of the primary raceme from the soil. Population had no effect on nodes to the primary raceme. Oil content of the seed or test weight were not affected by plant population of nonirrigated castorbeans.