Maincrop Varieties Research Articles

Assessing boro rice yield variances across varied seedling ages to address early flash flood vulnerabilities in the Haor area of Bangladesh

Haor is one of the most flood-prone areas of Bangladesh and it underlies in water for several months of a year. Boro rice cultivation in this area is challenging due to the flash flood. An experiment was conducted to examine the suitability and productivity of four rice varieties transplanted in different seedling ages. This experiment was carried out at Sunamganj district for two consecutive years of Boro season in 2021-22 and 2022-23. Four Boro rice varieties namely Binadhan-10, Binadhan-17, Binadhan-24, BINA dhan25, and three seedling ages (i.e., 30, 35 and 40 days old seedlings) were used as treatment in the experiment. It was conducted through a split-plot design with three replications placing seedling ages in the main plot and crop varieties in the subplot. Transplanting of 30 days seedlings of Binadhan-24 produced the highest mean grain yield of 7.8 t ha-1 and 8.2 t ha-1 while 35 days seedlings produced 7.6 t ha-1 and 7.7 t ha-1 respectively, in two consecutive years, the highest among all varieties. The maturity period among crop varieties varied due to the changes in seedling age as lower seedling age showed an earlier maturity period. So, transplanting of 30-35 days seedlings can be recommended for Binadhan-24 cultivation in the haor area. Bangladesh J. Nuclear Agric, 38(1): 41-52, 2024

Utilization of Corn Waste as a Media for Cultivation of Janggel Mushroom in Gunungkidul

Corn is the main crop variety in Dadapayu village, Semanu Gunungkidul. Based on village data, it is the largest corn producer in Gunungkidul. It is not surprising that corn plant waste is only used as fuel and even burned at plantation sites because it is considered to have no significant value. but residents only use the corn kernels without realizing that all the residents attached to corn can be utilized so that it has high economic value. The abundant natural potential requires insight for the farming community on how to manage scattered plantation products that are considered useless. The idea that was conveyed to the farmers was received positively and realized, so that the waste that was considered useless became a variant of a plant that produces its own value for the family, namely by utilizing janggel, which so far only functions as fuel. Corn cobs will function as a planting medium for mushroom cultivation, so that apart from having economic value, they are also able to help meet the nutritional needs of the family, namely in the form of cobwebs.

Evaluation of grain yield performance and its stability in various spring barley accessions under condition of different agroclimatic zones of Ukraine

Two extremely urgent problems of biological and agronomic research nowadays are ensuring an optimal balance between usage of natural resources to meet rapidly growing needs for food production and preservation of biodiversity. It is also important to extend the genetic diversity of the main crop varieties in agroecosystems. At the same time, modern varieties should be characterized by a combination of high yield and preserving yield stability under variable conditions. Solving the outlined tasks requires comprehensive research and involvement in breeding process of the genetical diversity concentrated in genebanks of the world. Barley (Hordeum vulgare L.) is one of the most important crops that satisfy the various needs of humanity. In respect to this, in 2020–2022, a multi-environment trial was conducted in three agroclimatic zones of Ukraine (Forest-Steppe, Polissia, and Northern Steppe). We studied 44 spring barley collection accessions of different ecological and geographical origin, different subspecies and groups of botanical varieties which were obtained from the National Center for Plant Genetic Resources of Ukraine. Statistical indices (Hom, Sc) and graphical models (GGE biplot, AMMI) were used to interpret the yield performance and its stability. Both individual ecological sites in different years and combinations of different sites and years of trials were characterized for productivity, discriminating power and representativeness. The environments differed quite strongly among themselves in terms of these indicators. It was established that most of the genotypes were characterized by higher adaptability to individual environmental conditions (stability in different years), compared to adaptability for all agroclimatic zones (wide adaptation). A strong cross-over genotype by environment interaction was found for most studied accessions. Nevertheless, both genotypes with very high stability in only one agroclimatic zone (Amil (UKR), Gateway (CAN)) and genotypes with a combination of high adaptability to one or two ecological niches and relatively higher wide adaptability (Stymul (UKR), Ly-1064 (UKR), Rannij (KAZ), Shedevr (UKR), and Arthur (CZE)) were identified. There were also the accessions which did not show maximum performance in the individual sites, but had relatively higher wide adaptability (Ly-1059 (UKR), Ly-1120 (UKR), Diantus (UKR), and Danielle (CZE)). In general, the naked barley genotypes were inferior to the covered ones in terms of yield potential and wide adaptability, but at the same time, some of them (CDC ExPlus (CAN), CDC Gainer (CAN), and Roseland (CAN)), accordingly to the statistical indicators, had increased stability in certain ecological sites. Among naked barley accessions relatively better wide adaptability according to the graphical analysis was found in the accession CDC McGwire (CAN), and by the statistical parameters CDC ExPlus (CAN) was better than standard. The peculiarities of yield manifestation and its variability in different spring barley genotypes in the multi-environment trial revealed in this study will contribute to the complementation and deepening of existing data in terms of the genotype by environment interaction. Our results can be used in further studies for developing spring barley variety models both with specific and wide adaptation under conditions of different agroclimatic zones of Ukraine. The disitnguished accessions of different origin and botanical affiliation are recommended for creating a new breeding material with the aim of simultaneously increasing yield potential and stability, as well as widening the genetic basis of spring barley varieties.

Quality Parameters as Influenced by Different Integrated Nutrient Management of Rustica Tobacco (Nicotiana rustica L.) and Its Residual Impact on Succeeding Summer Green Gram (Vigna radiata L.)

The present research work entitled “Quality parameters as influenced by different integrated nutrient management of rustica tobacco (Nicotiana rustica L.) and its residual impact on succeeding summer green gram (Vigna radiata L.) ” a field experiment was conducted during rabi and summer season of years 2020-21 and 2021-22 at Bidi Tobacco Research Station, Anand Agricultural University, Anand, Gujarat. The experimental field had an even topography with a gentle slope having good drainage and sandy loam in texture. The soil of the experimental field at 0-15 cm depth was low in organic carbon and available nitrogen, medium in available phosphorus and potassium and slightly alkaline in reaction. The ten integrated nutrient management treatments viz., T1: 100% RDF (200-00-00 kg/ha), T2: 75% RDF + 25% N from FYM, T3: 75% RDF + 25% N from poultry manure, T4: 75% RDF + 25% N from castor cake, T5: 50% RDF + 50% N from FYM, T6: 50% RDF + 50% N from poultry manure, T7: 50% RDF + 50% N from castor cake, T8: 50% RDF + 25% N from FYM + Azotobacter, T9: 50% RDF + 25% N from poultry manure + Azotobacter, T10: 50% RDF + 25% N from castor cake + Azotobacter were tested in Randomized Block Design with four replications. Rustica tobacco variety GCT 3 was considered as main rabi crop and green gram variety GAM 5 was considered as summer residual crop. The experiment was conducted on the same site during both the years without changing randomization of treatments. Results of the experiment showed that quality parameters viz. nicotine content was found significant due to various integrated nutrient management during both the years (2020-21 and 2021-22) in pooled analysis, while reducing sugar and chloride content was found non-significant during both the years (2020-21 and 2021-22) but significant result was observed in pooled analysis due different integrated nutrient management in both quality parameters under application of 75% RDF + 25% N from poultry manure (T3). In case of residual summer green gram protein content in seed and protein yield exerted significant result due to various integrated nutrient management during the years 2021, 2022 and in pooled analysis under application of 50% RDF + 50% N from FYM (T5). Interaction effect (Y x T) was found non-significant on all the growth parameters during the experiment.

Productivity of Selected Cabbage Varieties under Varying Drip Irrigation Schedules in Humic Nitisols of Embu County, Kenya

Use of controlled irrigation in vegetable production is considered a viable option for optimizing input use and productivity. This study aimed at assessing the effects of different drip irrigation schedules on productivity and profitability of three cabbage varieties grown in humic nitisols of Embu County. The study was laid out in a split plot design arranged in Randomized Complete Block Design (RCBD). The drip irrigation schedules were allocated the main plots and crop varieties allocated the subplot treatments. Cabbage test varieties investigated were Riana F1 (V1), Gloria F1 (V2), and Triperio F1 (V3). Irrigation schedule one (S1) involved application of irrigation water twice a week, S2 once a week, and S3 once every two weeks. Soil water content was determined before irrigation and then replenished to field capacity using a known volume of water. The data were subjected to Analysis of Variance using SAS version 9.4. Mean separation was done using Fisher’s least significant difference at 95% level of confidence. The findings revealed that the yields and net revenue obtained from different cabbage varieties were not significantly different. However, the cabbage yields and subsequent revenue increased as irrigation frequency increased. The study recommends adoption of irrigation schedule S1 whose productivity remained high despite the high cost of production.

Survey of Community Livelihoods and Landscape Change along the Nzhelele and Levuvhu River Catchments in Limpopo Province, South Africa

Landscape-change studies have attracted increasing interest because of their importance to land management and the sustainable livelihoods of rural communities. However, empirical studies on landscape change and its drivers are often poorly understood, particularly, in small rural communities in developing countries such as South Africa. The present study surveyed local community livelihoods and perceptions of landscape change in the Nzhelele and Levuvhu river catchments in Limpopo Province, South Africa. These areas have experienced land reform and are also characterized by environmental degradation, poverty, inequality and environmental justice concerns among other issues. Land-cover maps derived from Landsat satellite imagery were used for purposes of correlating and validating the survey data findings and results. The survey results showed that education levels, working status and marital status have statistically significant effects on community livelihoods (indicated by levels of income, p < 0.05). Maize, fruits and vegetables are the main cultivated crop varieties in the study area, and these crops are mainly used for subsistence to meet household self-consumption requirements. Moreover, local community members and stakeholders argue that the landscape has changed over the past 20 years mainly as a result of urban expansion, deforestation, agricultural diversification and forestry intensification. These landscape changes were largely confirmed by the land-cover change maps derived from satellite imagery. Soil erosion as a result of landscape changes was identified as a major threat and hazard in the study area. Political, natural, economic and cultural factors have been identified as the major underlying drivers for the observed landscape changes. These results have implications for understanding landscape change, coupled with human–nature relationships as well as informing government policy with respect to advancing land management and further promotion of the sustainable livelihoods of rural communities. Overall, the study proposes a multiple stakeholders’ approach and ecosystem-based approach to promote the sustainable management of landscapes in rural areas.

On-farm examination of main-crop potato varieties in Hungary

Characterisation of potato varieties in Hungary is based on conventional breeding and examination processes. Therefore organic growers need experimental data about the performance of new multi-resistant potato varieties under organic conditions. In order to provide sufficient information in 2012 we initiated a participatory-research program for testing resistant potato varieties under local organic conditions. 2012-2014 ten main-crop varieties were tested by participating organic farmers. Among the varieties Bettina, Desiree, Demon, Hopehely, Katica and Tiamo reached the highest yields. In the qualitative assessment the Streptomyces infection appeared to be most frequent. Among red-peel varieties Demon, among yellow-peel varieties Hopehely showed highest resistance to examined infections. The on-farm program is still running, in 2014 participant farmers’ number grew to 22. Achievements and results underline the importance of on-farm participatory research networks. Keywords: potato, resistant varieties, on-farm examination, participatory research, Streptomyces

The impacts of climate change on agricultural production systems in China

Climate change can bring positive and negative effects on Chinese agriculture, but negative impacts tend to dominate. The annual mean surface temperature has risen about 0.5–0.8 °C. The precipitation trends have not been identified during the past 100 years in China, although the frequency and intensity of extreme weather/climate events have increased, especially of drought. Water scarcity, more frequent and serious outbreaks of insects and diseases, and soil degradation caused by climate change have impacted agro-environmental conditions. However, temperature rise prolonged the crop growth seasons and cold damages have reduced in Northeast China. The projection of climate change indicates that the surface temperature will continue to increase with about 3.9 to 6.0 °C and precipitation is expected to increase by 9 to 11 % at the end of 21st century in China. Climate warming will provide more heat and as a consequence, the boundary of the triple-cropping system (TCS) will extend northwards by as much as 200 to 300 km, from the Yangtze River Valley to the Yellow River Basin, and the current double-cropping system (DCS) will move to the central part of China, into the current single cropping system (SCS) area which will decrease in SCS surface area of 23.1 % by 2050. Climate warming will also affect the optimum location for the cultivation of China’s main crop varieties. If no measures are taken to adapt to climate changes, compared with the potential yield in 1961–1990, yields of irrigated wheat, corn and rice are projected to decrease by 2.2–6.7 %, 0.4 %–11.9 % and 4.3–12.4 % respectively in the 2050s. Climate warming will enhance potential evaporation and reduce the availability of soil moisture, thus causing a greater need for agricultural irrigation, intensifying the conflict between water supply and demand, especially in arid and semi-arid areas of China. With adequate irrigation, the extent of the reduction in yield of China’s corn and wheat can be improved by 5 % to 15 %, and rice by 5 % or so than the potential yield in 1961–1990. Adaptive measures can reduce the agricultural loss under climate change. If effective measures are taken in a timely way, then climate change in the next 30–50 years will not have a significant influence on China’s food security.

The relationship between yield, mainstem number, and tuber number in five maincrop and two early-maturing cultivars

Using data from an 11-year period, total and marketable yield were related, using regression analysis, to mainstem and tuber number for five maincrop varieties (Russet Burbank, Shepody, Atlantic, Norchip, and Norland) and two early-maturing varieties (Conestoga and Carlton), at irrigated and dryland sites in western Canada. Mainstem number by itself was a poor predictor of total and marketable yield. Highly significant regressions of yield on the derived variable tuber number per mainstem were evident for all cultivars grown at the dryland sites. In general, the proportion of the total variation in yield accounted for by the regression models was much higher at the dryland than at the irrigated sites, indicating that the relationship between yield and its predictor variables was more complex for irrigated sites. While the study suggests that the use of tuber number per mainstem may be useful as an early-season predictor of tuber yield for cultivars, particularly under dryland conditions, a model using the predictor variables mainstem and tuber number will generally be superior due to the additional information it provides when competitive effects are present for light energy within the canopy or for assimilates among developing tubers. Contour plots provide a useful way to study the yield response to changes in tuber number at specific stem density levels.

Idiosyncrasies of Pecan Pollination

Pecan orchard productivity and yields often suffer due to pollination problems despite copious pollen produced within or near orchards. The problem is most acute in large block-type orchards of one or two varieties and can be due to pollen not being present at time of stigma receptivity or due to selfing. Fruit-set problems do not appear to be due to excessive pollen on stigmatic surfaces, as is the case in walnut. Pistillate flowers set best when pollen is received within about 1 day after becoming receptive. While stigma receptivity appears to lasts several days, pistillate flowers usually fail to complete development if pollinated after ≈2 days. Flowering dichogamy of given varieties varies with tree age and spring temperatures, thus often leading to poor pollination and low fruit-set. Orchards are therefore likely to benefit from the presence of two complementary pollinizers for the main crop variety. Trees in block-type orchards and are beyond about three rows or 50 m from pollinizers are likely to exhibit pollination related yield losses. Many orchards exhibit pollination problems because adherence to the standard two-class Type I/II flowering system often caused planting of noncompatible varieties. A recently developed 30-class Type I/II system allows for greater probability of avoiding pollination problems. Removal of “off-genotype” trees from orchards may reduce yields in block-type orchards.

Influence of Planting Density on Root Growth and Yield in Potato.

The influence of planting density on root growth and its relationship to leaf and tuber growth were investigated with two maincrop varieties in the potato. Three levels of planting density were examined ; 23810, 47620 and 95240 hills ha-1. The root length (RL) was investigated to a depth of 1 m at 90 days after emergence (DAE). The root length density (RLD) to a depth of 30 cm was also investigated at 30 DAE. The leaf area and tuber dry weight were measured at several stages. Total RL to a depth of 1 m at 90 DAE in the sparse, intermediate and dense plots was 12.5, 15.9 and 24.1 km m-2 in Norin 1 and 6.4, 7.0 and 10.4 km m-2 in Konafubuki, respectively. These differences were mainly due to those in RL at a depth of 0-30 cm. RL below a depth of 30 cm did not increase in Norin 1, or decreased in Konafubuki in the dense plot. The similar differences were also seen in RLD at 30 DAE. Total RL at 90 DAE showed significant positive correlations with leaf area index (LAI, r=0.929**) and tuber growth rate (GR, r=0.913**) at the late stage. These results confirmed the importance of longer RL to maintain larger LAI and tuber GR at the late stage. They also suggested that poorer deep roots at the dense plot might cause severe drought in dry soil conditions.

An evaluation of small seed for ware-potato production

SUMMARYSixteen experiments over six seasons (1981–87) compared the growth and yield of up to 16 seed-tuber weights, ranging from 1–5 to 110–120 g, in one second-early and four maincrop varieties. Four of the experiments (1986–87) examined effects in seed tubers from seed crops planted in July; the remaining experiments used seed from crops planted at the normal time, April–May. Effects were similar for seed from the different planting dates. Plants from seed < 5 g (and occasionally up to 15 g) emerged slightly later and produced a smaller crop canopy that those from larger seed. The later emergence from the smallest seed was a consequence of a slower rate of sprout elongation. There were no effects of seed weight above 15 g on stem emergence or growth of the canopy. In 1982, a severe frost completely defoliated all plants in four experiments but within 2 weeks complete plant emergence was re-achieved from all seed weights except the smallest (1–5 g). The results suggest few differences between seed weights > 5 or 10 g in emergence from similar depths of planting or in recovery from frost damage.Tuber yields were little affected by seed weight > 5 or 10 g, even at constant within-row spacings. Consequently, seed rates from 0·59 to 5·4 t/ha produced similar yields and the results suggest considerable economic benefits and potential for using seed tubers of much smaller weight than may be sold under current legislation. The use of small seed tubers from late-planted crops may result in further economies in production costs and reduction in disease in seed tubers.

Sprout and stem development from potato tubers of differing physiological age: the role of apical dominance

A series of experiments over three years (1984–1987) is described in which tubers of a range of early and maincrop varieties were exposed to two different storage-temperature regimes to give different physiological ages. Tubers exposed to 10–15°C from the break of dormancy and then held at 5° had a final age at planting of ca. 500 day-degrees > 4°C. Tubers held at 5°C throughout storage were physiologically younger, having accumulated only 100 day-degrees > 4°C. These temperature regimes, in the light, were considered to be representative of the treatment of tubers for commercial production of early and maincrop potatoes. For each treatment, the number and lenght of all sprouts longer than 2 mm at planting, and the number of stems produced in the field, were recorded. In a parallel study in 1985–1986, tubers of a single variety, aged in the same way, intact or with the apical sprout removed, were held in the laboratory to give full expression of sprout production. The use of physiologically younger tubers did not necessarily give more sprouts at planting, nor mainstems after planting in the field. However, the younger tubers held in the laboratory did carry significantly more sprouts, and sprout production from additional eyes was induced by desprouting. Overall, younger tubers produced at least one more mainstem than older tubers in only three out of twelve comparisons and, when the total number of stems per tuber was assessed, the younger tubers carried the same number or fewer stems in all cases. It is concluded from this investigation that, although apical dominance plays an important role in determining the number of sprouts produced per tuber, there is a high degree of variation between varieties and seasons, and within batches of tubers, in its expression. Extrapolation from a single variety, and in general from experiments confined to the laboratory, may bot be justified in the prediction of numbers of stems in the field.

The size distribution of potato tubers and its application to grading schemes

SUMMARYThe weight, length, breadth and depth were measured for each of 10 000 potato tubers. These were samples over 3 years of the 10 most commonly grown UK maincrop varieties. Volume, square‐mesh riddle size and average projected area were also measured in the final 2 years. A multivariate log‐normal distribution was found to give a good fit to the data. Illustrations are presented of how this distribution can be used to assess grading schemes.

Effects of site of seed production on seed yields and regrowth of progeny tubers in potatoes

SUMMARYNine experiments are reported in which effects of site of seed production on dormancy, sprout and field growth of progeny tubers were recorded. The experiments used early varieties, Home Guard (four experiments), Red Craigs Royal (three experiments) and Arran Comet (two experiments) and in each, seed crops were grown with similar husbandry at sites differing in altitude and location in western England and Wales. There was no consistent effect of site of seed production on the timing of the end of dormancy, and the maximum effect in any year was 11 ± 1·2 (S.E.) days. The small effects of site on dormancy influenced initial sprout lengths, and this effect usually persisted up to planting in Home Guard and Red Craigs Royal, although the effects were small in magnitude. There was no effect of site of seed production on sprout lengths at planting or on field growth and yields in Arran Comet. In the other two varieties there was no effect of site of seed production on yield at early harvests, but at later harvests seed from cooler upland sites sometimes significantly outyielded lowland seed. There was, therefore, no evidence to support the view that locally produced seed was advantageous for early potato production. The results, together with those of the concurrent series with maincrop varieties reported by Wurr (1979), show that on half the occasions on which yields were measured covering the whole of the harvesting period, site of seed production had no effect on yields. In these experiments with early varieties effects of site occurred only at harvests later than the commercial harvesting of such old seed. It is therefore suggested that site of seed production is a much less important determinant of tuber yield than hitherto suggested, and of little practical significance.

Comparisons of growth and early yields of potato varieties of contrasting maturity classification at three sites

SUMMARYSix experiments which compared a range of contrasting varieties are reported. Two experiments were at a very early, coastal site in N. Pembrokeshire (Trefin), two at a site in South Pembrokeshire (Trefloyne) and two at a coastal site in N. Norfolk (Brancaster). No variety was in every experiment but several were in the majority of experiments. In some experiments sprout growth was manipulated by control of storage temperatures. A variety classified as early or second early produced the highest yields in all experiments but the yields of the best maincrop varieties were high and substantially better than many early varieties. The highest-yielding variety at the first harvest maintained this advantage throughout June and July. At two sites (Trefin and Brancaster) the highest-yielding variety was consistent from year to year but overall the ranking order of varieties for yields was inconsistent, e.g. Arran Comet was the highest-yielding variety at Trefin in both years and one of the lowest yielding at Brancaster.The results suggest that it is unwise to attempt to rank varieties for early yields by an overall score. The maturity classification of varieties is not necessarily an accurate guide to the utility of a variety. A consideration of the physiological age of the seed and growing conditions provided some explanation of these effects and their implication for breeding are discussed.

Influence of variety, site and storage on physical, sensory and compositional aspects of mashed potato

AbstractOver two seasons, eight potato varieties were grown locally and the three principal UK maincrop varieties at different sites. After periods of storage domestically prepared mashed potato was made from this material and assessed for back extrusion, adhesion, particle and cell size and distribution, ‘free’ starch, dry matter and cell wall polysaccharides in conjunction with sensory textural assessments for mealiness, moisture and structure. The results indicate that there are strong correlations between the physical measurements of work done during back extrusion (EWD) and the deformation to peak adhesion force (ADP) with both dry matter (DM) and the mean sensory scores for mealiness, moisture and structure. The sensory characteristics were also highly interdependent. The r value of these relationships declines after prolonged storage. No significant correlations were found between particle size or cell size and distribution and any of the physical, sensory or compositional data at any storage time. With the three principal UK maincrop varieties, site influenced DM and hence physical and sensory texture more strongly than variety.

Effects of date of planting on plant emergence, leaf growth, and yield in contrasting potato varieties

SUMMARYFive experiments which studied the effects of a wide range of dates of planting on contrasting potato varieties in Pembrokeshire are reported. In three experiments (1976–7) four early varieties (Home Guard, Arran Comet, Irish Peace and Ulster Sceptre) were sprouted from the end of dormancy and compared at four dates of planting, which began as soon as soil conditions allowed (February in 1975 and 1976 and March in 1977). In these experiments all early-emerging treatments were damaged by frost and in 1975 and 1976 date of planting had little effect on leaf area index or yield. In 1977 planting in late April delayed and increased peak leaf area index but reduced yields throughout harvesting. In all experiments the emergence of varieties was affected by date of planting. The varieties with the longest sprouts emerged first only from the earliest plantings; at late plantings all varieties emerged together, which suggests that rate of post-planting sprout elongation decreased in this old seed as planting was delayed despite increasing soil temperatures. The implications for testing of early varieties are discussed.In two further experiments two early varieties (Home Guard in both years and Red Craigs Royal and Arran Comet in 1 year) were compared with three maincrop varieties (Désirée, Maris Piper, Stormont Enterprise) using seed which did not begin to sprout until January at dates of planting beginning in March. Sprout length was again poorly related to earliness of emergence. Delaying planting delayed and increased peak leaf area index in all varieties but only increased yields in the early varieties which had the smallest leaf areas. In maincrop varieties date of planting had little effect on final yields. In these years there were long periods without rain and in 1976 yields were limited by the amount of water available from the soil, for as each treatment exhausted this supply bulking ceased.

The commercial acceptability of three old potato cultivars following latent virus eradication

The potato cultivars, Pinkeye, Bismark and Brownell have a long history of culture in Tasmania, and contain, respectively, the latent virus complements potato viruses S and Y, potato virus S, and potato viruses S, X and Y. Forms that had been freed of these viruses were compared with virus infected seed lines in two trials that followed local recommendations for optimum tuber yield. Virus-free forms were taller, leafier, darker green, and slightly later in flowering than infected plants. There was greater production of tubers (1 4- 198%) in smaller size grades at immature crop harvests by the virus-free forms of Pinkeye and Bismark; this was offset to some extent by an increase in fertilizer rate. At crop maturity, virus-free forms generally gave a higher yield; this averaged 9.1 % for Pinkeye, 4.6% for Bismark, and 10.3% for Brownell. The increased vigour after virus eradication has not affected commercial acceptance of Pinkeye and Bismark for the production of new, immature potatoes; it has increased second growth problems of Bismark and Brownell when grown to maturity and in part has led to their decline as commercial main crop varieties.

An investigation into the damage sustained by different varieties of potatoes during riddling to remove soil

Previously reported riddling experiments were carried out with one potato variety only. This paper describes a further series of riddling experiments carried out according to the previously reported procedure on potato ridge samples containing tubers of 6 maincrop varieties. The standard SIAE potato damage analysis technique was adapted to enable both surface damage and internal bruises to be assessed from the same small sample of tubers, and these were expressed as a single figure indicating the amount of crop lost. The results showed that, compared with abuse level, potato variety has only a small influence on damage during riddling. Hence a greater reduction in potato damage could be achieved by redesign of a harvester riddling system to provide a horizontal instead of a vertical shaking motion, than by growing damage resistant varieties.