Agria Research Articles

Tuber yield and processing traits of potato advanced selections

World potato production continuously requires new cultivars to satisfy farmers’ and consumers’ demand. Tuber yield and quality are some of the main potato breeding targets. In this study, 27 advanced potato clones from 7 hybrid families were evaluated for yield, tuber specific gravity and chipping ability. Variability in tuber yield was found between families as well as between clones. Forty-eight percent of clones showed higher productivity compared to the best control (Agria, 1.1 Kg). Families displayed significant differences also in terms of tubers specific gravity, with about 70% of clones with a score higher than 1.080, which was considered the minimum acceptable value for processing. Chipping ability was evaluated at harvesting time and after cold storage with and without reconditioning. The majority of studied clones showed a good chipping ability score (<4.5) at harvest; five samples chipped well after cold storage with reconditioning, while good chippers were not identified after cold storage without reconditioning. The use of an arbitrary index calculated for each clone is proposed to assist the selection of materials with a good trait combination.

Identifying Irregular Potatoes by Developing an Intelligent Algorithm Based on Image Processing

The objective of this study was to develop an algorithm based on image processing for detecting misshapen potatoes from the mass of potatoes and obtaining homogeneous products. The database used in this research included the digital images acquired from Agria variety of Ardabil (Iranian northern-west) potato with different sizes and shapes. A combination of morphological features including geometrical features like length, width and features related to shape such as roundness were taken into consideration in identifying irregular potatoes from others employing elongation and Fourier descriptors. Using statistical principal component analysis (PCA), seven features were selected as the most prominent for classification. The experimental results showed that the proposed method achieves a high level of accuracy with merely seven selected discriminative features, obtaining an average correct classification rate of 98% for training set. Additionally, regular potatoes were separated into small, medium and large categories with 100% accuracy. According to the results, the developed algorithm based on image processing can be used in classifying products with no proper shape.

مدل سازی سینتیک افت رطوبت قطعات سیب زمینی پیش تیمار شده با اولتراسوند و مایکروویو در طی فرایند سرخ کردن عمیق

مدل سازی فرایند سرخ کردن در جهت آگاهی از روابط بین متغییرهای مختلف، می تواند گامی مناسب در جهت بهبود کیفیت محصول باشد. در این پژوهش، اثر پیش تیمار اولتراسوند تحت فرکانس های 28 و 40 کیلوهرتز به مدت 15 دقیقه و پیش تیمار مایکروویو با توان های 3 و 6 وات بر گرم به مدت 10 دقیقه بر میزان رطوبت سیب زمینی سرخ شده در درجه حرارت های 150، 170 و 190 درجه سانتی گراد به مدت 60، 120، 180 و 240 ثانیه مورد بررسی قرار گرفت. برازش داده های تجربی افت رطوبت نمونه ها در طی فرآیند سرخ کردن با استفاده از شش مدل تجربی پیشنهادی و قانون فیک انجام شد. نتایج نشان داد که هر دو پیش تیمار اولتراسوند و مایکروویو در کلیه سطوح مورد استفاده، میزان رطوبت نهایی نمونه ها را به طور معنی داری در سطح احتمال 5 درصد کاهش دادند. همچنین، با افزایش دما، میزان رطوبت نمونه های سیب زمینی به شکل غیرمعنی دار در سطح احتمال 5 درصد کاهش یافت. از طرف دیگر، با افزایش زمان فرایند، میزان رطوبت نمونه ها به طور معنی دار و بصورت نمایی کاهش پیدا کرد. همچنین، مدل های پیشنهادی در این پژوهش، با داشتن ضریب تبیین بالا (2R( و ریشه میانگین مربعات خطا (RMSE) پایین، به خوبی داده های تجربی را برازش نمودند. ضریب انتشار مؤثر رطوبت برای نمونه های مختلف در دامنه 8-10×57/3 الی 8-10×08/11 متر مربع بر ثانیه به دست آمد. اعمال پیش تیمارهای اولتراسوند و مایکروویو موجب افزایش ضریب انتشار مؤثر رطوبت و کاهش انرژی فعال سازی نمونه ها شدند.

FIRST REPORT OF POTATO BROWN ROT CAUSED BY RALSTONIA SOLANACEARUM IN GEORGIA

Potato is one of the most important constituent of the human diet in Georgia. Potato brown rot caused by Ralstonia solanacearum is an economically important bacterial disease and the cause of severe damage to the potato industry. During 2011-2013 a survey of potato plantations and storage facilities in different potato-producing regions of Georgia, samples were collected of tubers with brown rot symptoms and wilted potato leaves and stems. Since 2010, bacterial wilt presumed to be caused by R. solanacearum has been an important disease in Georgia. The disease was first reported in tomato in Chkorotsku and Kutaisi regions (west Georgia), where it caused up to 100% plant loss in greenhouse- and field-grown crops (Meparishvili, et al., 2012). Since then, several cases of this disease have been documented on potato in home gardens in the Kobuleti region. In 2012 -2013, brown rot symptoms were detected in several commercial potato cultivars. i.e. Jelly, Marfona, Picasso, Finca, Agria, Alliance, Marabely in Khulo (west Georgia) and Akhaltsikhe (south Georgia). Bacteria isolated from wilted potato plants and rotten tubers produced typical pearly white, flat, irregular, fluidal colonies on CPG and fluidal, irregular in shape and milky white colonies with pink centers on SMSA media, respectively. These colonies were presumed to belong to R. solanacearum, thus their identity was sought and confirmed by specific PCR using the primer pair OLI/Y2 (Seal et al., 1993). All tested isolates and positive control DNA extracted from R. solanacearum type strain NCPPB 325 produced the expcted 288 bp product, confirming their identity as Ralstonia solanacearum. To the best of out knowledge, this is the first report on the presence of potato brown rot in Georgia.

تعیین میزان قندهای احیاءکننده در سیب زمینی با استفاده از گلوکزیاب دستی و مقایسه آن با روش آنزیمی

In order to estimate the reducing sugar in tubers of potato by using a manual Glucose determiner, an experiment was conducted in factorial arrangement based on completely randomized design with three replications. In this research reducing sugar of four cultivars of potato – Agria, Sante, with two methods: enzymatic and a manual Glucose determiner. The results Picaso and Kizer – that maintained in two temperatures of germinator, 3 and 7.5oC, were measured indicated that there was no significant difference between determinated glucose by using a manual Glucose determiner and enzymatic procedure, but there was a significant difference between determinated glucose by using a manual Glucose determiner and total reducing sugar measured by enzymatic procedure. The effect of maintenance conditions on glucose content and total reducing sugar in both procedures was significant and treatments that were maintained at higher temperatures had less sugar. The effect of cultivar on glucose content and total reducing sugar in both procedures was significant and in temperature 3oC, Agria and Sante had the highest sugar content, but in temperature 7.5oC, there was no significant difference among reducing sugar content of four cultivars. Keywords: Potato, Enzymatic procedure, Reducing sugars, Glucose

Potato response to potassium application rates and timing under semi-arid conditions

A two-year experiment (2004-2005) was conducted at Tal Amara Research Station in the Bekaa Valley of Lebanon to evaluate the influence of progressive application of K rates and application timing on yield, yield components and tuber quality of potato (Solanum tuberosum L. cv. Agria). Four levels of potassium (0 (K0), 75 (K75), 150 (K150), and 225 (K225) kg K2O ha-1) and two application timings (tuber initiation and tuber bulking stages) were used in a split-plot design. The progressive application of potassium fertilizer from 0 to 225 kg K2O ha-1 significantly affected the yield and yield components of potato. In both years, small grade tubers and aggregate tuber yield increased quadratically with increasing K application rates up to 150 kg K2O ha-1, reaching a plateau thereafter, showing luxury consumption of the nutrient at 225 kg K2O ha-1. In 2004 when averaged over K application rates, large and medium grade tubers and aggregated tuber yield were 120%, 22%, and 12% greater, respectively, with K application at tuber bulking than at tuber initiation. A similar trend was also observed in 2005, when the small grade tubers and aggregate tuber yield were 20% and 12% higher, respectively, with K application at tuber bulking than at tuber initiation stage. Finally, no significant difference among treatments was observed for tuber dry matter (avg. 19.8%) and specific gravity (1.08 g cm-3).