Analysis of Yield and Disease Resistance Traits of New Winter Rapeseed Varieties over the Past Twenty Years in China

Based on the results of the national regional trail for winter rapeseed in four groups,including the upper reaches,middle reaches and lower reaches of Yangtze River and Huang-Huai region in the past twenty years,new varieties of winter rapeseed showed upward trend in average yield,the yield level in Huang-huai group was higher than other groups.The changes of average effective pods per plant were not significant in any group,but the number of grain per pod and 1 000-grain weight showed increase trend.However,the increment of grains per pod in three Yangtze River groups was higher than that in Huang-Huai River group,while the increment of 1 000-grain weight was just opposite.The incidence rate of Sclerotinia sclerotiorum and viral disease in new varieties of winter rapeseed obviously decreased,and the incidence rate of S.sclerotiorum decreased lower than 5%.Genetic improvement for winter rapeseed should be focus on the number of grain per pod and 1 000-grain weight in the future,and yield level of new varieties in all four groups is expected to increase.

Adaptation of faba bean varieties for yield, for yield components and against faba bean gall (Olpidium viciae Kusano) disease in South Gondar, Ethiopia

Faba bean(Vicia faba L.) has an important place in the Ethiopian national diet. It is consumed in various forms and contributes to the improvement of soil fertility. However,its production and productivity are affected by biotic and abiotic constraints. Among the biotic constraints, the emerging faba bean gall disease, caused by Olpidium uiciae, is the major and most destructive disease wherever faba bean is grown. Field experiments were conducted at two locations(Farta and Tach Gayint districts) to evaluate the reaction of faba bean varieties to faba bean gall disease and to assess them for yield and yield components during the 2014 and 2015 main cropping seasons. Thirteen faba bean varieties and one local check were plantecd in three replications Lusing a randomized complete block design. The disease incidence and severity of faba bean gall were recorded(on a 1-9 scale) five tinmes at10-day intervals. A combined analysis of variance showed za significant difference(P < 0.05)among faba bean varieties with respect to the incidence and severity of gall disease at both locations. Disease incidence, severity, and AUDPC were lowest for variety Turmsa at both locatiOons, but this variety showed lhigh yield only at tlhe Farta location. 'The lhighest yields were obtained from varieties Degaga(1157.74 kg ha ') and Nc58(828.97 kg ha ') at Farta and Tach Gayint, respectively and these varieties slhowed low faba bean gall severity and AUDPC. Thus, higher-yielding faba bean varieties such as Degaga and Nc58 are recommended for faba bean production areas in northwestern Ethiopia.

Comparison of yield performance between direct-seeded and transplanted double-season rice using ultrashort-duration varieties in central China

Labor scarcity requires double-season rice to be planted by direct seeding as an alternative to transplanting. Only ultrashort-duration varieties can be used in direct-seeded, double-season rice(DSD) in central China where thermal time is limited. Whether ultrashort-duration varieties grown in DSD can be as productive and efficient in nitrogen(N) use as transplanted double-season rice(TPD) remains unclear. Field experiments were conducted in Hubei province, central China with two establishment methods(DSD,TPD) and three N rates in the early and late seasons of 2017 and 2018. Nitrogen treatments included zero-N control(N0), total N rate of 60 kg N ha;with equal splits at basal, midtillering, and panicle initiation(N1), and weekly N application at 15 kg ha;from seeding/transplanting to heading(N2). Both early-and late-season rice under DSD matured within 95 days, on average 9 days shorter than rice under TPD. The grain yield of DSD was comparable to or higher than that of TDP in both seasons, although the daily yield was significantly higher under DSD than under TDP. Before heading, DSD had higher leaf area,stem number, intercepted radiation, and radiation use efficiency than TPD, which compensated for the negative effect of short growth duration on biomass production. Total dry weight and harvest index under DSD were comparable to or higher than those under TDP. In general, the recovery efficiency of fertilizer-N under DSD was higher than that under TPD, but the reverse was true for physiological N use efficiency. Thus, there was no significant difference in agronomic N use efficiency between DSD and TPD. These results suggested that DSD with ultrashort-duration varieties is a promising alternative to TPD in central China for maintaining high grain yield and N fertilizer use efficiency with less labor input.

Comparative Test on Spring Medium-sized Watermelon Varieties in Beijing

[Objectives]This study was conducted to select suitable medium-sized watermelon varieties for early spring cultivation in Beijing.[Methods]Seven watermelon varieties were collected,including Beinong Tianjiao 2,Beinong Tianjiao,Hongfuji,Yongfeng 1,Beinong Futian,Beinong Shijia,and Beinong Jinxiu,and Jingxin 2 was used as the control check(CK).The growth period,morphological traits,yield traits and fruit quality of the tested varieties were investigated.[Results]Beinong Tianjiao 2 had an earlier maturation stage,a fruit development period of 38 d and a total growth period of 118 d.It showed stable growth,with a single fruit weight of 7.56 kg,a fruit setting rate of 0.99 per plant,and a yield of 83076.9 kg/hm~2,which ranked,respectively,second,first,and second among all tested varieties,and were significantly superior to the CK.Furthermore,this variety had thin and tough peel,a bright red flesh color,high central sugar content,loose and crisp flesh,and a good taste.[Conclusions]It is preliminarily believed that it is suitable for early spring watermelon production in Beijing area.

Evaluating Two Varieties of Sweet Pepper Using Different Nutrient Sources to Increase Productivity

This experiment aims to increase sweet pepper production sustainably by using manures and a combination of manure and fertilizer. Manures are well known to improve soil health and maintain crop production for a relatively long period. This study was conducted under a tunnel house at the National Agricultural Research and Extension Institute at Mon Repos East Coast Demerara, Guyana. Plots were arranged according to strip plot design with two treatments (Aristotle and Sunsation), four rates (R1: 0 g/plant), (R2: 350 kg NPK/ha + 10 t vermicompost/ha), (R3: 10 t poultry manure/ha + 10 t vermicompost/ha and (R4: 350 kg NPK/ha + 10 t poultry manure/ha) and replicated thrice. These nutrients were applied in a split application at four weeks before planting, and four, eight, and twelve-week intervals after planting. The varieties did not differ from one another for the vegetative parameters tested. Plants treated with Rate 2 achieved significantly better growth parameters such as plant height, plant spread, and number of branches than the other rates. Sunsation obtained a significantly higher yield of 21.4 t/ha at the 5% level as compared to Aristotle (19.9 t/ha). The various rates recorded significant differences in yield. Rate 2 obtained a significantly higher yield of 32.8 t/ha followed by Rate 4 with 24.9 t/ha, then Rate 3 (17.0 t/ha). The lowest yield of 7.8 t/ha was attained by Rate 1. The interaction of varieties and rates showed statistically significant differences in yield. The interaction of Sunsation and Aristotle with Rate 2 achieved a superior yield of 34.8 t/ha and 30.7 t/ha respectively than other rates. Rate 4 also obtained significant interaction with Sunsation and Aristotle to achieve a yield of 25.7 t/ha and 24.1 t/ha respectively than Rate 3. Rate 3 interacted significantly with Sunsation and Aristotle and obtained a yield of 16.5 t/ha and 17.5 t/ha compared to Rate 1. Rate 1 achieved the least interaction for both varieties tested. Rates differed significantly for fruit shelf-life at room temperature. Fruits obtained from Rate 3 recorded a significantly longer fruit shelf-life of 14.7 days for 50% decay when stored at room temperature (30.3˚C) than other rates. The lowest fruit shelf-life of 7.7 days was obtained from Rate 1. This study indicated that the Sunsation variety is better to cultivate because of superior improvement in growth and yield attributes. The application of Rate 2 can considerably increase yield and when combined with Sunsation variety superior yield and yield attributes can be obtained.

Screening Test of Small Seedless Watermelon Varieties in Beijing Area

[Objectives]This study was conducted to select small seedless watermelon varieties with excellent quality and high yield suitable for planting in Beijing.[Methods]Under the conditions of facility cultivation in Beijing,a screening test was conducted on seven small seedless watermelon varieties for growth process,field traits,yield traits,fruit quality,and disease resistance.[Results]Varieties Mitong,Motong and Tianbao Xiaowuzi had a short growth period and relatively stable growth,and bore fruit easily,and their female flowers were closely spaced.Their yields exceeded 60000 kg/hm~2,ranking in the top three among all varieties.The fruit had a thin skin,a bright red flesh color,and a high mass fraction of soluble solids in the center.The flesh was tight or crispy,and tasted good.They also showed good disease resistance.Overall,they showed excellent comprehensive agronomic traits,and are thus suitable for facility cultivation in Beijing and its surrounding areas.[Conclusions]This study provides a theoretical basis for the upgrading of varieties and the increase in production and farmers'income in the suburbs of Beijing.

Screening and Application of Oilseed Rape Varieties with High Yield and High Harvest Index

28 oilseed rape Pol CMS three-line hybrid combinations diallel-crossed were compared in the yield and harvest index and analyzed on the correlation between the experimental yields and harvest indexes in this study. The correlation coeffcient was only 0.365 4, lower than a signifcant level, which indicated that there was no signifcant positive （or negative） correlation between the economic yields and the harvest indexes in oilseed rape. Among them, 8 hybrid combinations including 7 with a harvest index〉0.30 and one with a harvest index〈0.27 increased signifcantly in the yields compared with the control, and then were screened for production experiment. Under different cultivation methods, all the 8 combinations had a stable harvest index, and the combinations with higher harvest indexes also had a stable performance in yields. An oilseed rape variety Fengyou 737 with higher yield and harvest index selected through a further screening was grown with the harvest indexhigher than 0.33 whether transplanted or directly seeded in Yangtze River Basin Demonstration Area, demonstrating stable high yields as well as good ecological adaptability. The combination of yield and harvest index in the study is conducive to breeding a new oilseed rape variety with stable yields and good tolerance to close planting.

Effect of Variety and Plant Spacing on Growth and Yield of Groundnuts (Arachis hypogaea L.)

A field experiment was carried out to determine the effect of variety and plant spacing on yield and growth of groundnuts. The field experiment was laid in a 3 × 3 factorial experiment in a Randomized Complete Block Design (RCBD) with three (3) replications. The factor A included three (3) groundnut varieties (Nkatie Sari, Sum Nutt 22 and Yenyawoso) and Factor B was the three (3) spacing of 30 cm × 15 cm, 30 cm × 30 cm and 30 cm × 40 cm. All recommended agronomic practices were followed. Data was collected from eight (8) tagged plants. Growth data were recorded on plant height, number of branches, number of leaves, and the number of flowers while yield data were collected on the number of flowers, number of pods per plant, 100 seeds weight and the pod yield (kg/ha). The plant spacing significantly influenced (P < 0.05) the growth and yield parameters. Groundnut grown at a spacing of 30 cm × 15 cm produced the maximum plant height, whereas the maximum number of leaves, number of branches and number of flowers were produced from 30 cm × 40 cm. Yenyawoso variety with a wider plant spacing performed better vegetatively among all the varieties. The Yenyawoso variety produced the highest number of pods, 100 seeds weight and pod yield as compared to the other varieties. Also, Yenyawoso at 30 cm × 40 cm spacing and Nkatie Sari at 30 cm × 15 cm spacing produced the maximum pod yield.

Comparative Study on Grain Cadmium Content and Yield in Different Rice Varieties

[Objectives] The rice varieties with a low cadmium (Cd) content and a high yield were screened to provide reference for further experiments on moderate and high Cd-contaminated soils and local promotion.[Methods] Under the soil condition of a Cd content of 0.58mg/kg,differences in agronomic traits such as grain Cd content,yield,number of effective panicles,number of grains per panicle and 1 000-grain weight of 26 different rice varieties such as Huanghuazhan,Y Liangyou 9918 and T You 109,were studied by pot experiment.[Results] Such six varieties as Xiangyou 109,Tianfengyou 316,C Liangyou 651,Y Liangyou 3218,Y Liangyou 9918 and T You 109 had a relatively higher yield and relatively lower Cd content,which was because that their traits including panicle length,number of effective panicles and 1 000-grain weight were superior to other varieties.The correlation analysis between plant Cd content and yield showed that there was a negative correlation between Cd content and yield in rice.[Conclusions] This study provides a theoretical basis for cultivating suitable varieties in this area.

Study on Yield and Traits of Different Maize Varieties in Chuxiong Prefecture

The new maize variety test was conducted to select fine varieties suitable for the ecological environment in Chuxiong Prefecture and speed up the variety upgrading. The results showed that Yunrui 392,Yunrui 407 and Yunrui 7 had good comprehensive traits,great lodging resistance,stable yield and good disease resistance,and their yield was 9531. 3,9312. 5 and 9250. 0 kg/ha,respectively,close to the yield of control variety Beiyu 16,indicating that the yield potential was large and they could be planted in Chuxiong to replace the varieties with low yield and poor resistance.

Stalk Rot Resistance Analysis and Yield Loss Evaluation on 25 Maize Varieties and Utilization of Resistant Germplasm Jun M9

Stalk rot outbroke in Henan Province in 2014 on maize,and the disease conditions of 25 varieties were investigated.According to national maize variety disease resistance identification standards,Jundan 509 was a resistant variety; Yudan 606,Jinsai 38 and Jundan 3136 were moderately-resistant varieties; and other 21 varieties were all highly susceptible.Based on the yield loss rate of 5% determined as the critical value for division of disease tolerance,disease-tolerant varieties included Jundan 509,Yudan 606,Jinsai 38,Jundan 3136,Huaiyu 5288,Qiaoyu 8,XY046,Zhengyu 10,lile 66,weike 702 and Jundan 29.Varietal disease resistance and tolerance were mainly divided according to incidence and yield loss rate,respectively,and the correlation between them was showed by a Venn diagram.With the male parent Jun M9 of Jundan 509 as a backbone material,multiple maize combinations resistant to stalk rot were formed,and Yongyou 618 among them was approved by Henan Provincial Crop Variety Approval Committee.

A Comparism of Sorghum Yield between Local Varieties in Turare,Katsina State and Sorghum Hybrids from IAR Zaria,Kaduna State

Nine sorghum varieties comprises of five hybrids from IAR,Zaria and four local varieties from Turare local community were evaluated at Turare village in Dutsin-Ma,Katsina state to compare their performance with the aim of selecting the sorghum with the best performance in yield for multiplication and distribution to the local farmers.The experiment field was laid using randomized complete block design(RCBD)with three replications.Random table number was used to allocate sorghum varieties to plots.Among the nine varieties,Samsorg 45 was the best performed variety in agronomic characteristics and yield followed by Samsorg 46 and then Samsorg 40.These three varieties were selected among the nine varieties.The study concludes that Samsorg 40,45 and 46 have a better attributes of early maturity,yield and higher nutritive value.This will relatively translated to higher income for the farmers.It is therefore recommended that farmers should be sensitized and educated on their planting.

Comparative Effects of Organic Cocoa Shell-Based and Inorganic NPK Fertilization on the Growth and Yield of Four Cassava Varieties

Looking of finding an alternative to the use of chemical fertilizers to increase yields of cassava (Manihot esculenta), trials were carried out in the Lamto zone in central Côte d’Ivoire. Thus, the effects of compost and ash from cocoa shell and NPK were tested on the agronomic parameters of cassava. The trial was conducted for two years with four varieties of cassava: Yacé, Alleda agba, Six mois and Bonoua, grown on elementary plots treated with one of these fertilizers. The experimental design was complete randomized blocks with three replicates. Analysis of the results showed that the Six mois variety gave the longest stems (131, 67 cm) with the cocoa shell compost. The Bonoua variety, on the other hand, gave the largest diameter of the stem base (21.56 mm), a higher number of leaves (77.30) and a large wingspan (136.89 cm) with cocoa shell compost. The leaves developed by the plants of this variety were wider (19.30 cm) and longer (17.96 cm) with cocoa shell compost. Also, this Bonoua variety treated with shell compost yielded a high number of tuberized roots (5.11), high average weight per plant (5.83 kg/plant) and higher yield (58.29 t/ha). This compost of cocoa shell has also allowed a better conservation of the cultivated soils quality.

Field Evaluation of Growth and Yield of Two Local Rice Varieties (Tox-728-1 and Madjitolngar) in Response to Indogenous Mycorrhizal Inoculation in South-Chad

This study was carried out to find out how dependent are two local rice varieties (Magitolngar and Tox-728-1) to inoculation with selected endogenous arbuscular mycorrhizal fungi (AMF) in a field where they were isolated. The multi-indigenous endomycorrhiza spores previously isolated and identified were the active ingredient in the production of bioinoculants used for this purpose. Spores massively multiplied from the rhizosphere of each rice variety in each of the four locally collected soils substrates were harvested to constitute 08 AMF inoculants (Kema = T1;Lama = T2;Latox = T3;Ndjatox = T4;Koloma = T5;Kolotox = T6;Ndjama = T7;Ketox = T8). These inoculants were field tested on the two rice varieties at Kelo, under a complete randomized block design, comprising 10 treatments (8 inoculants, 01 positive control = T9, 01 negative control = T10), each of which was repeated thrice. The analysis of data indicates that AMF-inoculated plants were taller, developed more tillers/plant, and produced more rice grains/panicle than non-AMF-inoculated plants for both studied rice varieties. The rice variety Madjitolngar yielded more grains (7.5 t/ha) than the Tox-728-1 variety (5.8 t/ha). Moreover, inoculants Koloma (T1), Latox (T3) and Kolotox (T6) on the one hand, Koloma (T1) and Ketox (T8) on the other hand, were best suited for the improvement of growth and yield of the rice varieties Madjitolngar and Tox-728-1 respectively, tested under field conditions at Kelo. In this study, the two rice varieties have shown a dependency to endomycorrhizal symbiosis at Kelo, and therefore, an industrial-scale production of efficient endomycorrhal inoculants is necessary to sustainably boost the productivity of this important crop in Chad.

Evaluation of Agronomic Characteristics,Drought Tolerance and Yield of Some Rice Varieties in Central Vietnam

The aim of the study was to evaluate the drought tolerance,agro-morphological characteristics and yield of 10 rice varieties collected from different locations.In experiment one,drought tolerance of rice varieties under artificial drought condition in the greenhouse was assessed through root and leaf characteristics.In experiment two,the growth and yield of rice varieties in the rainfed rice field was estimated.The results showed that drought has affected the root characteristics,leaf rolling and leaf drying of these varieties.In rainfed rice field of Thua Thien Hue and Quang Nam province,summer-autumn 2016 and winter-spring 2016-2017 crop season,these rice varieties grew and developed well.The growth time was 90-119 d in summer-autumn crop season,while in winter-spring crop season was 107-131 d.The yield of these rice varieties ranged from 37.02 quintals/ha to 56.33 quintals/ha and from 42.33 quintals/ha to 66.60 quintals/ha,respectively.Some rice varieties with high yields in both two crop seasons were OM4900,GSR38,IR93340 and OM7347.It is sugessted to conduct production experiment on a large area in rainfed field for these four varieties to evaluate them objectively and early put them into structure of rice varieties in Central Vietnam.

Yield and Profit from New and Old Wheat Varieties Using Certified and Farmer-Saved Seeds

Wheat is a strategic crop for food security in Pakistan with predominance of smallholder farmers. Farmer-saved seed （FSS） is used nearly by 75% of farmers for wheat production. Frequent variety or seed replacement is uncommon even among large-scale farmers, and certified seed （CS） is mostly bought to verify the value of new varieties. Replacing old and obsolete varieties by new high yielding disease resistant varieties is key to transferring new genetic gains to farmers. For the first time in Pakistan, on-farm factorial experiments involving seven new and five old wheat varieties and their corresponding CS and FSS were conducted. A total of 49 farmers representing major wheat cropping patterns throughout the country participated in these trials in the 2014 and 2015 wheat growing seasons. Analysis of variance revealed that there was highly significant difference between wheat varieties and between seed classes. New variety ＋ CS gave 33.8% more grain yield as well as higher marginal return over farmers＇ variety ＋ FSS. Grain yield and returns from new variety ＋ FSS and farmers＇ variety ＋ CS were at par. Scientific knowledge generated in this research demonstrated that use of CS ＆new wheat varieties is best option, while growing new varieties with FSS is a second choice for the advantages accruing from their built-in genetic traits of economic importance over growing CS of old and obsolete varieties. Having more flexible seed system will help accelerate the delivery of new genetic gains to farmers＇ fields.

Comparative Experiments on Different Varieties of Phaseolus vulgaris L. under Dry Farming Conditions

[Objective] The aim was to screen varieties of Phaseolus vulgaris L.for cultivation in arid,semi-arid areas.[Method] The cultivation experiments of seven varieties of P.vulgaris under dry farming conditions were carried out in typical dry farming agriculture region Yangqu County in North China.[Result] The plants of Teyoutejiadou,Chaojiwujing and Xinxinyichiqingyuanlong were relatively strong;the growth rate of Aifeng,Jingxuanjiadouwang and Chaochangsijidou was relatively rapid;the transpiration rate of functional leaves of Aifeng was the lowest.The yield of Tianma 95-33 jiadouwang was significant higher than that of other varieties,the unit yield was up to 36.33 t/hm2,which was 1.39 times higher than that of Aifeng and 1.9 times higher than that of Xinxinyichiqingyuanlong;followed by the yield of Aifeng（26.07 t/hm2）,which was 1.37 times higher than that of Xinxinyichiqingyuanlong.[Conclusion] The yield of Tianma 95-33 jiadouwang and Aifeng was relatively high,as well as the protein content,indicating that they were suitable to be applied and cultivated in the experimental plot and surrounding areas.

Population Construction and Super-high Yield Characteristics of Japonica Super Rice in Cold Regions

[Objective] This study was conducted to construct a super-high yield population of Japnica rice in cold regions of North China and to explore its characteristics. [Method] The super rice variety Longjing 21 was selected as the experimental material. Different row spacing（two levels）, plant spacing（three levels） and seedling number per hill（three levels） were designed in field trials. Then, the growth stages,dry matter accumulation, leaf area, yield and yield components of these different treatments were measured. [Result] Rice yield had significantly negative correlation with plant spacing and row spacing, but no significant correlation with seedling number per hill. Rice yield was mainly affected by plant spacing, and less affected by seedling number per hill. The best recommended specifications for plant spacing of super rice variety Longjing 21 were 24 cm for row spacing, 12 cm for plant spacing and five seedlings per hill, and the expected yield was 10 473.0 kg/hm^2.The increased number of total spikelets（4.5×108hm2or more） in populations was the major reason for high yield. Super-high yield populations had fewer tillers at the early growth stage and achieved the expected number of productive tillers at critical leaf-age（June 25）, and tiller number peaked at jointing stage（July 6） and was about 1.2 times of the expected number. The percentage of productive tillers in total tillers of super-high yield population was more than 85% at heading stage. At middle growth stage（from jointing to heading stage）, the dry matter accumulation, leaf area index（LAI） at heading stage, effective leaf area, spikelet number of population,spikelet number per leaf area unit（cm2）, and culm-sheath weight per stem of super-high yield population were significantly higher than those of other populations.At late growth stage（from heading to maturity stage）, the leaf area decreasing rate of super-high yield population was significantly smaller than that of other populations. At late growth stage（from heading to maturity stage）, the leaf area decreasing rate, crop growth rate, net assimilation rate, biomass accumulation, number of filled grains per leaf area unit（cm^2） and grain weight per leaf area unit（cm^2） of high-yield population were significantly higher than those of other populations. Output and translocation of dry matter（weight per stem and sheath and total filling rate at maturity） from heading to milky stage of super-high yield population were significantly higher than those of other populations. [Conclusion] The characteristics of superhigh yield rice in cold region of North China are enriching the amount of actual filling of sink through improving photosynthetic efficiency from heading to maturity stage on the basis of enough panicle numbers.

Screening of Winter Rape Varieties Suitable for Northern Guangxi

[Objective] The study was conducted to provide a reference for develop- ment of fine winter rape varieties in northern Guangxi. [Method] In 2012 and 2013, 11 winter rape varieties were evaluated in northern Guangxi using randomized com- plete block design, Data such as yield and diseases were collected and analyzed. [Result] Among all the 11 varieties tested, the highest yield was recorded in variety Chuanzao NHl105. Dadi 95, FDl102, Chuanzao NHl105 and SWUl112 exhibited disease resistance better than Qinghai 131. [Conclusion] The winter rape varieties of FD105 and Qianza J102 were found suitable for planting in northern Guangxi.

Effect of Potassium Levels on Growth and Productivity of Potato Varieties

Potato is one of the priority vegetable crops in the highlands of Eritrea growing as a key component in the livelihood systems of farmers. Potato requires a variety of balanced plant mineral nutrients for growth and development without which yield and qualities of tubers are reduced. Potato growers in Eritrea commonly use Di-ammonium Phosphate, Urea and Farmyard manure while potassium fertilizers are overlooked assuming that the soil is developed from K rich parent material and contains sufficient amount of K to support crop growth. However this assumption is based on the result obtained forty-seven years ago. As a result the yield and quality of potato produced is very low as compared with international standards. Therefore the present experiment was conducted to assess the effect of potassium levels on growth and productivity of potato varieties at Hamelmalo Agricultural College, Eritrea. The experiment was conducted in factorial Randomized Complete Block Design with fifteen treatment combinations of three varieties (Ajiba, Zafira and Picasso) and five potassium levels (0, 75, 150, 225 and 300 kg K2O/ha) replicated thrice. The results of the study showed that both variety and potassium had significant effect on growth and yield parameters. Aerial stem number, leaf number per plant and plant height were increased with increasing K levels from 0 to 150 kg while number of days to maturity was increased in the range of 0 - 300 kg K2O/ha. The result also indicated that variety Ajiba treated with 300 kg K2O/ha produced significantly highest tuber weight (1.14 kg) per plant and tuber yield of 49.38 t/ha. The economic analysis result revealed that maximum gross margin 13,665.816 USD/ha was obtained from the application of 300 kg K2O/ha. On the whole, it gives an impression that using potassium fertilizer according to soil requirements will have good influence on growth and tuber yield.