Comparison of production systems for potato (Solanum tuberosum L.) minituber production with different cultivars : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Applied Science in Nursery Production

The purpose of these studies is to determine the effect of different production systems (Aeroponic (AP), Deep flow (DF), Nutrition film technique (NFT) and Bark) on production of first generation (prebasic) potato (Solanum tuberosum L.) minitubers with different cultivars (Russet Burbank, Rua, Kenebec, Atlantic and Diésrée). Prebasic tubers usually multiplied in a greenhouse in a bark medium. Replacing the bark based system by a highly intensive aeroponic system is viable. The aeroponic system significantly produced higher tuber numbers per plant and produced a higher percentage (82%) of 1 -2g size tuber than other systems evaluated. In aeroponic and deep flow systems, the time to tuberization is higher. When tuberization is delayed, stolons grow continuously in the deep flow and aeroponic systems. In hydroponic systems a developing stolons did not encounter sufficient mechanical resistance to limit growth, they grew extremely vigorously and very wide of diameter (1.92- 2.42 mm). When roots and stolons filled the aeroponic and deep flow containers some root rustication occurred then tubers were initiated. Acid treatment efficiently synchronised tuberization in the aeroponic systems, tubers were visible four days after acid treatment. Optimum acid treatment depends on the specific cultivar or stage of stolon development. Rua produced the highest yield per plant and highest tuber number per plant. The pH and treatment time significantly affected the tuber number per plant. Acid treatment at pH 3.5 produced the highest tuber number (19.8) per plant. Minitubers show a dormant period immediately after they are harvested. Application of GA is a useful method to break minituber dormancy. Fifty percentage of the GA treated tubers sprouted within 20 days after treatment, while untreated control took 37 days. Overall, sprouting was highest for 100 ppm treatment, but was not significantly different from 30 ppm. The highest and lowest sprouting cultivars were Russet Burbank and Atlantic respectively. Potato cuttings can be propagated in an aeroponic system. Application of IBA treatment at 0.1 to 0.3% significantly induced root formation and root growth. About 80% of the IBA treated cuttings rooted and produced longer roots than untreated cuttings. From these studies we found the aeroponic system to be suitable for minituber production as well as the propagation of potato cuttings. Production of high tuber number per plant in aeroponic systems will reduced the production cost and reduce the number of field multiplications required before final cropping

Adaptability Study of Irish Potato (Solanum Tuberosum L.) Varieties for Yield and Yield Components Under Kaffa Zone, South Western Ethiopia

Potato is one of the most important food crops grown in mid and high altitude areas of Ethiopia. To meet the production need several potato genotypes have been introduced and evaluated at different areas of the country. However, the performances of different released potato varieties were not yet assessed in the study area. To this end, the present study was undertaken with the focus on determining the adaptability of Irish potato varieties for yield and yield components. It was conducted at Kaffa zone Adiyo District in Alarigeta experimental sub-station in 2013 and 2014 Belge cropping season. Seven improved potato varieties; namely Bule, Marachare, Wochecha, Dancha, Jallanie, Gudanie and Belete were used as treatment. Treatments were arranged in randomized complete block design with three replications. Average tuber diameter, average tuber number, average tuber weight, marketable tuber number, unmarketable tuber number, total tuber number, marketable tuber yield, unmarketable yield and total tuber yield data were recorded and submitted to analyze using SAS software version 9.0. Analysis of variance for each year showed significant (p< 0.05) difference among the varieties for all studied traits except Average tuber diameter and marketable tuber number in 2013, and Average tuber diameter and unmarketable tuber yield in 2014. The highest and consistent tuber yield was found in variety Belete (40.54 t/ha and 39.98 t/ha) in 2013 and 2014 respectively.  Therefore, variety Belete, which was given high yield in both years, could be used instated of currently cultivating varieties to increase production and productivity of the crop for better enhancement of food security and livelihood income of the locality. Keywords: potato, varieties, tubers, adaptabilit

Evaluation of Yield and Yield Related Attributes of Potato (solanum tuberosum L.) Varieties in East Gojjam Zone, Ethiopia

In Ethiopia, a number of improved potato varieties have been released by different research centers; with much emphasis for productivity, while it has been given less or no emphasis to adaptability to different agro ecologies and resistance against late blight resistance. Therefore, field experiments at Debre Markos university and Abazash nursery site and laboratory experiments at Debre Markos university were conducted to evaluate yield, yield component and tuber qualities of five released varieties (Belete, Bubu, Gudenie, Gera and Jalenie) and one local cultivar (Demmie) for two consecutive years. The experiment was laid out as a Randomized Complete Block Design with three replications. quality attributes were studied in laboratory using standard procedure. The results revealed that the highest significant different has been recorded for most of traits. On the basis of overall means, the highest total yield (51.2t/ha), marketable tuber yield (46.69t/ha), average tuber weight (99.85gm), large sized tuber number (48.71%), large sized tuber weight (77.52%), were observed for Belete variety. The highest marketable tuber number (87.62%) and unmarketable tuber weight (4.08t/ha) were observed for gera variety. The highest unmarketable tuber number (45.5%), small tuber number (56.03%), small sized tuber weight (28.291%) were observed for farmers’ local cultivar Demmie. The highest medium sized tuber number (37.173%) and medium sized tuber weight (42.197%) were observed for bubu varieties. Jalene are highly affected by late blight disease.  In conclusion, the result of the study reviled that the variety and growing environment has a great influence on yield and yield components and quality of potato This study suggested that the importance of testing varietiesacross location to recommend varieties for specific end uses. Keywords: Irish potato, Varieties, Location, Yield and Yield Attribute

Effect of Integrated Soil Amendment Practices on Growth and Seed Tuber Yield of Potato (Solanum tuberosum L.) at Jimma Arjo, Western Ethiopia

A field experiment was conducted to study the effect of integrated soil amendment practices on growth and seed tuber yield of potato at Jimma Arjo during the 2013 main cropping season.  Totally, there were sixteen different treatments consisting of different organic and inorganic fertilizers. The experiment was laid out in a randomized complete block design with three replications. The results showed that integrated use of organic and inorganic fertilizer had significant effect on plant height, leaf area index, and total fresh biomass and stem number per hill. Tuber yield and its attributing characters like total tuber number per hill, average tuber weight, large tuber medium and small tuber size number and weight, marketable and  unmarketable tuber number, marketable tuber yield, unmarketable tuber yield, total tuber yield and tuber dry matter were also significantly influenced. It was observed that integration of different organic and inorganic fertilizer had no significant effect on the days to maturity, harvest index and specific gravity. In general the application of wood ash, compost and farmyard manure alone or in combination in the absence of inorganic fertilizer did not prove much beneficial in promoting the growth, yield attributes and yield of potato. Application of 2 t/ha wood ash (WA) +5 t/ha farmyard manure (FYM) along with +111 kg N +92 kg P2O5/ha (RDF) resulted in the highest marketable tuber yield (12.74 t /ha) but was statistically in parity with RDF, however maximum total tuber yield was obtained with a combined application of 2 t/ha WA+5 t/ha compost (C) along with 100% RDF. The marketable and total tuber yield was positively and significantly correlated with growth components like plant height, total fresh biomass and stem number per hill. Similarly the marketable tuber yield was positively and significantly correlated with yield components like total tuber number per plant and marketable tuber number but negatively and significantly correlated with unmarketable tuber number. Keywords: compost, farmyard manure, growth, soil amendment, wood ash, yiel

Associations among Yield and Yield-related Characters in Potato (Solanum tuberosum L.)

Twenty potato (Solanum tuberosum L.) genotypes were tested at Ankober (3100 masl), Ethiopia, during the 2002 main rainy season to estimate the nature  and magnitude of correlations and path coefficient analysis among eleven characters. The experiment was laid out in RCB design with three replications  on a plot size of 6.75 m2. Highly significant differences (P < 0.01) were observed among the genotypes for all the characters studied. The result of the  experiment indicated that though genotypic correlations were higher in magnitude than that of phenotypic correlations, the direction of phenotypic  correlation coefficients were the same as that of corresponding genotypic ones for majority of the characters. At genotypic level, tuber yield per plant  was positively and significantly (P < 0.01) correlated with stem number per hill (rg = 0.588) and leaf area per plant (rg = 0.759). Path coefficient analysis at  genotypic level also indicated that these characters had positive indirect effects on tuber yield via tuber number per plant. This result suggested the  possibility of simultaneous selection of stem number per hill and leaf area per plant with tuber number per plant to maximize tuber yield. Path coefficient  analysis at genotypic level further indicated that average tuber weight, tuber number per plant, above ground biomass and internode  number are important components of tuber yield per plant. Positive and high magnitude direct effect of average tuber weight and tuber number per  plant, and their relatively high negative indirect effects on tuber yield per plant via each other indicated the need to be cautious during simultaneous  selection for improving tuber yield per plant.&nbsp

Yield component analysis and diversity in Jerusalem artichoke (Helianthus tuberosus L.)

The objective of this study was to analyze the variability and mutual dependence of the tuber weight per plant, tuber number per plant, average tuber weight and total sugars content in the tubers of 20 Jerusalem artichoke genotypes included in a varietal trial conducted in the period 1994-2008. The variability of tuber weight per plant, tuber number per plant and average tuber weight was significantly affected by environmental conditions, while the total sugars content in the tubers depended primarily on the genotype. As the tuber weight per plant increased, the content of total sugars in the tubers decreased. Maximum tuber weight per plant was achieved with the genotype BT-4 and highest contents of total sugars in tubers were found in the genotypes Violet Rennes, UKR 5/82 and Topianca

A study of some factors affecting tuber number in Solanum tuberosum L.

A series of field experiments were carried out to investigate the effects of differences in the previous history of the mother crop, sprout number, sprout development and in the environment in the early stages of post -emergence growth on stem and tuber production.1. There was no effect of sprouting in the winter preceding the production of the mother crop, or burning off the mother crop on sprout, stem or tuber production in the current season in either Arran Pilot or Majestic.2. Delay in setting up previously cold -stored tubers to sprout resulted in an increase in sprout and mainstem number in both varieties. Early- sprouted tubers showed a greater degree of lateral- branch development of the sprout and mainstem than late -sprouted tubers. The response in tuber number and yield varied from year to year but, on average, late -sprouting produced more tubers than unsprouted seed: 10% more in Arran Pilot and about 3% more in Majestic. Late- sprouted seed usually produced more tubers than early- sprouted seed. Where crops matured naturally, yields at harvest in both sprouted and unsprouted seed were similar. In 1965 tuber bulking rates in unsprouted seed were not constant and appeared to show changes in rate associated with the pattern of foliage growth and the prevailing weather conditions.3. Efforts to induce differences in the number and type of lateral branches on the sprout and thus stem and tuber production in Arran Pilot, by clipping off the apex of the sprout at different stages of development, were not successful. An increase in an index of sprout development (the number of lateral branches + sprouts per tuber) led to an increase in stem numbers at ground level and tuber number but the relationship was not a close one. It was difficult to induce lateral - branch development of the sprout in Majestic. Although an increase in the number of lateral stems led to an increase in tuber number this was not as large as an increase per stem as from a unit increase in mainstem number.4. It was clear from the results of a planting date experiment and a shading experiment that differences in tuber number occurred irrespective of changes in mainstem number. It was suggested that these differences were brought about by differences in the environment, particularly soil water content, light intensity and air temperature, at the time of tuber initiation.5. It was argued that differences in the response in tuber number to sprouting from year to year could be related to differences between the treatments in 1) lateral -branch development of the sprout at planting, and 2) the environment at tuber formation

How Planting Density Affects Number and Yield of Potato Minitubers in a Commercial Glasshouse Production System

Commercial potato minituber production systems aim at high tuber numbers per plant. This study investigated by which mechanisms planting density (25.0, 62.5 and 145.8 plants/m2) of in vitro derived plantlets affected minituber yield and minituber number per plantlet. Lowering planting density resulted in a slower increase in soil cover by the leaves and reduced the accumulated intercepted radiation (AIR). It initially also reduced light use efficiency (LUE) and harvest index, and thus tuber weights per m2. At the commercial harvest 10 weeks after planting (WAP), LUE tended to be higher at lower densities. This compensated for the lower AIR and led to only slightly lower tuber yields. Lowering planting density increased tuber numbers per (planted) plantlet in all grades. It improved plantlet survival and increased stem numbers per plant. However, fewer stolons were produced per stem, whereas stolon numbers per plant were not affected. At lower densities, more tubers were initiated per stolon and the balance between initiation and later resorption of tubers was more favourable. Early interplant competition was thought to reduce the number of tubers initiated at higher densities, whereas later-occurring interplant competition resulted in a large fraction of the initiated tubers being resorbed at intermediate planting densities. At low planting densities, the high number of tubers initiated was also retained. Shortening of the production period could be considered at higher planting densities, because tuber number in the commercial grade > 9 mm did not increase any more after 6 WA