Showing papers in "Journal of Root Crops in 2011"

Survey of Cassava Mosaic Disease in Kerala

Abstract: A survey was conducted on the incidence of cassava mosaic disease (CMD) in Kerala. Cassava mosaic disease occurred throughout the state at low to high incidences (44.5-96.75%) in the 35 regions surveyed. The disease incidence was higher in Thiruvananthapuram and Kollam districts and lower incidence was noticed in Wayanad district. Maximum white fly population was also observed in Thiruvananthapuram district of Kerala followed by Kollam. Survey results alsoindicate that Sri Lankan Cassava Mosaic Virus (SLCMV) is wide spread in Kerala.

In Vitro Growth Response of Different Varieties of Greater Yam (Dioscorea alata L.)

Abstract: A simple, reproducible and efficient micropropagation protocol was developed for three different varieties of greater yam ( Dioscorea alata L.) viz ., Sree Roopa, Sree Keerthi and Sree Shilpa using nodal segments for axillary shoot proliferation at Central Tuber Crops Research Institute, Thiruvananthapuram, India. The effect of different explants, surface sterilants and different combinations and concentrations of Benzyl Adenine (BA) and Napthalene Acetic Acid (NAA) on different parameters viz. , number of shoots, shoot length, number of roots, root length, number of leaves and number of nodal meristems were evaluated. The use of nodes from young, vigorously growing vines of sprouted tubers as well as 4 - 8 nodes from the tip of field grown plants proved to be the best explant source which gave a quick response. Minimal risk of contamination was observed with 0.08% mercuric chloride (HgCl 2 ), which was found to be an effective surface sterilant. For in vitro regeneration, MS media with 0.5 mg l -1 NAA and 0.75 mg l -1 BA with 0.1% activated charcoal was found to be the best. A high percentage of shoots were seen rooted in the same medium containing 0.1% activated charcoal (92%). Regenerated plants were successfully hardened and transplanted. About 90% of plantlets survived under net house conditions.

Variability of Carotenoids and Dry Matter Content in Orange-fleshed Sweet Potato (Ipomoea batatas (L.) Lam.) During Storage

Abstract: Orange-fleshed sweet potatoes (OFSP) possess carotenoids, which is a precursor of vitamin A. Planting time and processing methods are believed to affect carotene content of orange-fleshed sweet potato storage roots. Since OFSP are a rich source of β -carotene, it is essential to determine whether sweet potato carotenoids are stable during storage. The changes in dry matter and carotenoids were studied at regular intervals during 35 days of storage in 10 orange-fleshed sweet potato clones at Central Tuber Crops Research Insititue, Thiruvananthapuram, Kerala, India. There was a significant variation in the content of total carotenoids (10.32 – 13.99 mg 100g -1 f.w) and β -Carotene (9.02 – 12.16 mg 100g -1 f.w) among the clones. A gradual increase in dry matter from 24.1 to 25.5% was observed during storage, due to depletion of moisture. There was no significant change in total carotenoids and β -carotene content in the OFSP clones during the storage period. The results of the study indicated that the total carotenoids and β -carotene in sweet potato storage roots had high stability during storage.

Effect of Time of Planting on Growth, Yield and Economics of Sweet Potato Under Rainfed Conditions

Abstract: Sweet potato (Ipomoea batatas (L.) Lam.) is an important starchy food crop. It is the seventh most important food crop, which produces high edible energy per unit area per unit time as compared to rice, wheat, maize and cassava (Saikia and Borah, 2007). It is eaten after boiling, baking and frying. It is also candied with syrup or used as a ‘Puree’. Tubers of sweet potato are utilized for canning, dehydrating and flour making. Apart from being a food crop, sweet potato is also utilized for feeding livestock. The vines serve as a good source of fodder for livestock. In India, the leading states in terms of area and production of sweet potato are Orissa, Bihar, Uttar Pradesh, Maharashtra, Karnataka and Madhya Pradesh. In India, particularly in the state of Madhya Pradesh, sweet potato is mostly cultivated by small and marginal farmers having low investment capacity. Climate conditions, particularly temperature and photoperiod exert great influence on the growth and development of sweet potato vines and tubers. Besides, under rainfed cultivation, soil moisture is another important factor, which depends upon total quantity and distribution of precipitation. During the growing period, a range of temperature between 20-30C is favourable for tuber formation and high yield, whereas, high temperature between 30-40C, high rainfall, long days and low light intensity promotes vine growth (Verma and Naskar, 1990). Changes in starch properties of sweet potato tubers do occur with different dates of planting and harvesting (Noda et al., 2000).

Changes in leaf water potential, chlorophyll content and runner yield of swamp taro (Colocasia esculenta) grown in waterlogged environment

Abstract: Growth and yield performance of five swamp taro ( Colocasia esculenta ) cultivars viz ., BCST2, BCST4, BCST15, BCST21 and BCST23 were assessed under natural, swampy, waterlogged conditions. Despite decline in leaf water potential (LWP) due to pre-monsoon dry spell, the cultivar BCST15 showed consistently better runner yield in all the harvests as compared to the other cultivars. The cultivar BCST15 maintained greater plant height, greater leaf area for longer period of crop growth and greater leaf chlorophyll content. The total runner yield was highest in BCST 15 (5.96 t ha -1 ) followed by the cultivar BCST4 (3.15 t ha -1 ) and lowest in BCST 21 (1.72 t ha -1 ). Therefore, the cultivar BCST15 was found suitable for cultivation in swampy, waterlogged environment due to better growth and higher yield than other cultivars.

Variation in the Exine Ornamentation Patterns in Taro (Colocasia esculenta (L.) Schott.) with respect to Geographical Distribution

Abstract: Light microscopic (LM) and scanning electron microscopic (SEM) observations were carried out in taro (Colocasia esculenta) pollen grains for detecting intra-specific variability as reflected in pollen features at Central Tuber Crops Research Institute, Thiruvananthapuram, Kerala, India. The pollen grains were found to occur in monads and were inaperturate. Pollen diameter was found to be below 25I¼m and the shape was globular or spheroidal. Despite the uniformity in aperture type, pollen shape and size, wide intraspecific variations were observed with regard to the exine sculpturing. The echinate excrescence characteristic of the family Araceae was observed in all the accessions studied. The exine surface showed tilate (tile shaped) appearance with the arrangements of basal plates holding the column and wide variations were observed in the size, shape, arrangement and pattern of these basal plates. Based on these features five basic types of exine ornamentation pattern were observed in taro. The variations observed in the exine ornamentation pattern were correlated with the geographical distribution of the plants under study

Evaluation of White-fleshed Sweet Potato Clones for Storage Root Yield and Dry Matter Content

Abstract: Sweet potato (Ipomoea batatas (L.) Lam.) is an important vegetatively propagated crop cultivated for its edible storage roots. It produces the highest energy (194 MJ ha day) and considerable yield with low inputs even in marginal lands (Woolfe, 1992). The storage roots and young leaves are used as a vegetable. The flesh colour of the storage roots varies from white to different shades of cream and yellow to dark orange depending on the carotene content. However, the white-fleshed sweet potatoes, which have no β-carotene content, are traditionally grown and preferred by the local population all over India. The choice of sweet potato variety is strongly correlated with the dry matter and starch content (Simmone et al., 1993). The present study was undertaken to assess the storage root yield and dry matter content of promising white-fleshed sweet potato clones identified from the poly-cross breeding programme.

Physico-Chemical Analysis of Colocasia esculenta Starch

Abstract: The physico-chemical properties of Colocasia esculenta (var. Ghee Kochu) starch was studied in detail. The starch was isolated and analyses were done for microscopy, X-ray diffraction (XRD), furier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) characterizations. The chemical characterizations were done using the investigation parameters like amylose content, both apparent and total, amylose leaching, acid and enzymatic hydrolysis and solubility and 1’-1’diphenylpicryl-hydrazyle (DPPH) scavenging in methanol, water and dimethyl sulfoxide (DMSO). The crystallinity of the starch (41.20%) was found to be high as reported for C. esculenta starches and the starch was A-type. The amylose content of the starch was found to be very poor as compared to the previous reports. The size of the starch granules was found to be 0.50-3.5 μm. An average of 42.27% of degradation was observed during 15 days of acid hydrolysis process. The enthalpy of gelatinization was found to be 13.1 J g -1 . Swelling power of the starch granules at room temperature was found to be 81.99±4.32%.