An experiment was conducted to study the effect of harvesting dates and variety on the yield and processing quality of potato tuber. Three processing potato varieties (BARI Alu-25, Asterix; BARI Alu-28, Lady Rosetta and BARI Alu-29, Courage) were used as test crops and they were harvested at different days after planting [80, 90, and 100 days after planting (DAP)]. The three processing potato varieties showed higher tuber yield of Grade A (9.12 t ha-1) and B (13.64 t ha-1). The highest tuber yield (Grade A+B) [29.62 t ha-1] and total tuber yield (35.97 t ha-1) was found in Courage at 90 and 100 DAP harvest, respectively. The variety Lady Rosetta attained the highest percent of processable tuber yield (86.8% of the total tuber yield), the maximum dry matter content (26.37%), specific gravity (1.102) at 90 DAP harvest and this variety also contained the highest mean starch content (111.75 mg g-1 FW) followed by Courage (111.17 mg g-1 FW) and Asterix (103.95 mg g-1 FW). Optimum dry matter content (24.07%), specific gravity (1.091), starch content (110.15 mg g-1 FW), processable tuber yield (26.62 t ha-1) and total tuber yield (32.76 t ha-1) was found at 90 DAP harvest and therefore, it could be mentioned as suitable harvesting date for processing purposes. Among the varieties, Lady Rosetta and Courage were found preferable potato varieties that could be used for processing of potato products. Bangladesh J. Agril. Res. 44(1): 179-193, March 2019

Liverwort Marchantia polymorpha is considered as the key species for addressing a myriad of questions in plant biology. Exploration of drought tolerance mechanism(s) in this group of land plants offers a platform to identify the early adaptive mechanisms involved in drought tolerance. The current study aimed at elucidating the drought acclimation mechanisms in liverwort’s model M. polymorpha. The gemmae, asexual reproductive units of M. polymorpha, were exposed to sucrose (0.2 M), mannitol (0.5 M) and polyethylene glycol (PEG, 10%) for inducing physiological drought to investigate their effects at morphological, physiological and biochemical levels. Our results showed that drought exposure led to extreme growth inhibition, disruption of membrane stability and reduction in photosynthetic pigment contents in M. polymorpha. The increased accumulation of hydrogen peroxide and malondialdehyde, and the rate of electrolyte leakage in the gemmalings of M. polymorpha indicated an evidence of drought-caused oxidative stress. The gemmalings showed significant induction of the activities of key antioxidant enzymes, including superoxide dismutase, catalase, ascorbate peroxidase, dehydroascorbate reductase and glutathione S-transferase, and total antioxidant activity in response to increased oxidative stress under drought. Importantly, to counteract the drought effects, the gemmalings also accumulated a significant amount of proline, which coincided with the evolutionary presence of proline biosynthesis gene Δ1-pyrroline-5-carboxylate synthase 1 (P5CS1) in land plants. Furthermore, the application of exogenous abscisic acid (ABA) reduced drought-induced tissue damage and improved the activities of antioxidant enzymes and accumulation of proline, implying an archetypal role of this phytohormone in M. polymorpha for drought tolerance. We conclude that physiological drought tolerance mechanisms governed by the cellular antioxidants, proline and ABA were adopted in liverwort M. polymorpha, and that these findings have important implications in aiding our understanding of osmotic stress acclimation processes in land plants.

The present investigation was undertaken to analyze the antioxidant potential of sixteen different potato genotypes. Eleven yellow fleshed potato genotypes namely Forza, Courage, Laura, Rosa Gold, Lady Rosetta, Cumbica, Asterix, Coronada, Granola, Cardinal and Diamant and five purple fleshed potato genotypes namely Jam Alu, KAC 10063, KAC 10064, KAC 10069, KAC 10097 were used as experimental materials. Total carotenoids, anthocyanin, phenolics, flavonoids, ascorbic acid and antioxidant activity in the above mentioned genotypes were determined to compare the antioxidant potentials of the genotypes. Analysis of above mentioned parameters resulted significant variation in their contents in both yellow and purple fleshed genotypes. The results indicate the purple fleshed genotypes showed significantly higher carotenoids, anthocyanin, flavonoids and total antioxidant activity than those of yellow fleshed genotypes. The findings also suggested the antioxidant activity of the genotypes positively correlates to the total content of carotenoids, anthocyanin and flavonoids. Since, purple fleshed genotypes showed higher antioxidant properties, the results of this study claim that the purple fleshed genotypes would be suitable for direct consumption as vegetables which might increase the health and food security of human beings.Bangladesh J. Agril. Res. 43(3): 369-381, June 2018

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