Showing papers in "Journal of Root Crops in 2015"

Effect of Zeolites on Soil Quality, Plant Growth and Nutrient Uptake Efficiency in Sweet Potato (Ipomoea batatas L.)

Abstract: Zeolites (sodium alumino silicates) are effective controlled nutrient release materials that are highly useful to improve soil nutrient use efficiency, plant uptake of nutrients especially NPK because of its twin benefits of high cation exchange and water retention properties. In this paper, we evaluated different types of synthetic zeolites applications viz. fly ash based near neutral agricultural grade (FAZ) and commercial (CZ) zeolites (zeolite 4A) in tropical laterite soils with respect to soil chemical properties, soil water content, sodium adsorption ratio (SAR) as well as plant growth parameters and yield of sweet potato crop (variety ST-14) with an aim of understanding the effectiveness of zeolites on NPK uptake efficiency. A pot study was conducted in farm soils of CTCRI (acidic, sandy loam soils) using six treatments viz. FAZ applied at 1% and 2% levels (w/w, zeolite: soil) (denoted as F1 and F2), pH treated CZ at 1% level, potassium and zinc impregnated CZ (K-CZ and Zn-CZ) at 1% and a control (with out zeolites) each replicated thrice in a completely randomized design. Study showed that 1% zeolite amended soils registered a better soil moisture increase over control to an extent of 20.9 % and tuber yield increase of 57% over control. Soils amended with both FAZ levels are well below the critical limits in terms of SAR. The uptake efficiency of FAZ amended at 1% (F1) rate was significantly superior in respect of N and P as compared to F2 and control. The study also suggested that FAZ at 1% will be beneficial for sweet potato crop.

The Contribution of Tropical Tuber Crops Towards Food Security

Abstract: Tuber crops (with 5.4% energy) are the second most important group of crop plants providing food energy to humans after cereals (49%). Of them, the tropical tuber crops (TTCs) contribute 3.9% of human energy for an average consumption of 28.6 kg capita-1 year-1 (76 kcals capita-1 day-1).Three of the TTCs - cassava, sweet potato and yam - rank among the top 15 crop plants of the world in area under cultivation. Two of the most commonly used terms in development science, Food security and Staple foods, are defined here. The contributions of TTCs to them are highlighted. Cassava and yams are presently among the major crops that show the highest rates of increase in area under cultivation. This may be attributed to their resilience to climate changes. It is proposed that TTCs should double their contribution to food security to 8% by 2030 AD. Towards this, the factors favouring and disfavouring the TTCs are discussed. Moreover additional steps needed to be taken to ameliorate/adapt them are dealt with. These include the present very low yields of TTCs, their low nutritional content, presence of antinutritional factors, high glycaemic index and their prolonged periods of maturity. The ongoing international efforts to mitigate some of them are summarized, including biofortification.

Micropropagation for Rapid Multiplication of Planting Material in Cassava (Manihot esculenta Crantz)

Abstract: Rapid multiplication of planting material in cassava through tissue culture techniques such as shoot initiation, micropropagation and hardening was studied in cassava variety Sree Padmanabha. The effect of nodal segments from axillary bud of the field grown cassava cultured in Murashige and Skoog’s basal medium supplemented with different concentrations and combinations of 6- Benzylaminopurine (BAP) and Naphthalene acetic acid (NAA) were evaluated based on different parameters viz., number of shoots, number of roots, number of leaves and number of nodes. Minimal risk of contamination was observed with sterilization in 0.1% HgCl2 for 7 min, which was found to be an effective surface sterilant. For in vitro regeneration using apical node as explant, MS media with 0.3 mg l-1 NAA was found to be the best in terms of shoot having three nodes. When in vitro shoots were inoculated in MS media with 0.1 mg l-1 NAA, rooting was the most profuse. Nodal explants took one month for development into plantlets having three nodes. Potential number of planting material production from one nodal explant using micropropagation techniques was estimated to be ranging from 16,000 to 17,000 in one year period. Well rooted in vitro plantlets in sterilized vermiculite with 4-5 cm length were found suitable for hardening and subsequent transplanting, which gave 91% success after two months of hardening.

Karyosystematic Studies in Amorphophallus Blume ex Decne.

Abstract: Cytological studies in 25 accessions revealed the occurrence of three chromosome numbers viz., 2n=28 for all the Amorphophallus paeoniifolius accessions, A. dubius, A. smithsonianus and A. sylvaticus; 2n=26 for A. bonaccordensis, A. hohenackeri and A. commutatus; and 2n=3x=39 for A. bulbifer. Zarco’s asymmetry indices revealed that the accessions T2 (A. bonaccordensis) and T3 (A. smithsonianus) were the more evolved species in terms of karyotype symmetry. According to the classification of Stebbins, A. bonaccordensis included in 3B category was the most asymmetrical and hence considered as most evolved. Amorphophallus paeoniifolius var. campanulatus with A1=0.40-0.43 appeared to be more evolved than A. paeoniifolius var. paeoniifolius based on Zarco’s asymmetry indices. Slight differences observed in the A1 values (0.1714-0.37) in the accessions of A. paeoniifolius var. paeoniifolius demonstrated the close relationship of the accessions. Taxa with asymmetric karyotype tend to have low total form (TF)% and accordingly cv. Gajendra (GJ) and cv. Karunaikizhangu (T10) (both classified as A. paeoniifolius var. campanulatus) having low TF% can be considered as highly evolved among the A. paeoniifolius accessions. UPGMA clustering based on five karyotypic parameters namely total chromosome length (TCL), average chromosome length (ACL), chromosome number, TF% and ratio of longest chromosome (LC) to shortest chromosome (SC) of the complement revealed two principal clusters at a Euclidean distance of 1.3. The two cultivars of A. paeoniifolius var. campanulatus (GJ and T10) along with A. dubius (A.d) were clustered in a single sub-cluster. Such clustering pattern is in tune with the morphological data which leads to make a valid assumption that A. dubius is a possible ancestor of the cultivars GJ and T10.

Economic Analysis of Yam Seed Tuber Systems in Nigeria

Abstract: New seed tuber systems from mini-sett, mini-tubers, and vine cuttings have been developed for yam production to supplant the traditional systems which have been proven inefficient and costly. The new techniques provide producers in tropical countries with the opportunity to minimise production costs reducing seed tuber price and promoting great availability for seed. A discounted cash flow budget with a whole farm perspective was used to analyse the economic performance and risk implications, of a hectare investment in the new seed tuber system over time for a representative farm . Data based on realistic process costs and review of past reported studies were employed to reflect the relative economic worthiness and opportunity cost of investment and operating capital of seed tuber systems in Nigeria. From the NPV and BCR analyses , the new seed tuber systems were more viable than current traditional seed tuber systems through milking of live immature plants. This raises the need to identify which among the new techniques could be the most profitable and recommendable. Therefore, understanding the economics of seed tuber systems would not only help a large section of stakeholders at local, regional and national levels but also prove beneficial to policymakers, funding agencies and non-government organizations embarking upon the yam projects and programmes. Normal 0 false false false EN-US X-NONE AR-SA /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-ansi-language:EN-US; mso-fareast-language:EN-US;}

Influence of Age of Explants and Genotype on Somatic Embryogenesis in African and Indian Cassava Cultivars

Abstract: Potential of eight cassava cultivars viz., TME3, TME4, TMS 30572, TMS 1089A, 96/0160, Albert,Kibaha and H165 for initiating somatic embryos was studied. Two different explants, young leaf lobe pre-cultured on Murashige and Skoog (MS) medium and axillary bud pre-cultured on MS medium containing BAP were tried. The age of explants and type of cultivar highly influenced the frequency and quantity of somatic embryos. Axillary buds of cv. Albert and young leaf lobes of cv. H165 responded well, while the same results were observed for conversion and development. Hardening and establishment in green house was close to 100% for all the cultivars under study. This paper discusses the effect of juvenility of the explants used, duration of pre-treatments and culture on embryogenesis medium, cultivar and its preference of explant, health of the mother plants, on successful regeneration of cassava via somatic embryogenesis, which could be very resourceful for friable embryogenic calli production and successful genetic transformation.

Effects of Organic and Inorganic Fertilizers on Yield of Elephant Foot Yam and Soil Enzymes Activity

Abstract: A field experiment was carried out for two consecutive years during 2011and 2012, to study the effects of organic and inorganic fertilizers on leaf area and yield of elephant foot yam and soil enzyme activities. The experiment was conducted at the Regional Centre of Central Tuber Crops Research Institute, Bhubaneswar using randomized block design (RBD) with three replications. The experiment comprised of eight treatments involving organic and inorganic fertilizers. Highest leaf area per plant was recorded with the application of FYM 25 t ha-1 and the application of FYM 10 t ha-1 with NPK@ 100- 60-100 kg ha-1. These treatments also resulted in higher light interception and offered lower soil resistance. The application of FYM 10 t ha-1 + NPK@ 100-60-100 kg ha-1 and FYM 25 t ha-1 has produced 105.7% and 97.1% higher corm yield respectively, over control. These treatments maintained higher soil enzyme activities despite poor post harvest soil nutrient status. In alfisols, medium duration elephant foot yam can be cultivated profitably under protective irrigation with the application of FYM 10 t ha-1 + NPK@ 100-60-100 kg ha-1 or FYM 25 t ha-1 with enhanced soil enzyme activity.

Productivity of Cassava (Manihot esculenta) as affected by drip fertigation in humid tropics

Abstract: Field experiments were carried out at Central Tuber Crops Research Institute, Kerala, India during three seasons, 2009-2010, 2010-2011 and 2011-2012 to investigate the response of cassava to precision approaches in irrigation and fertigation. The experiments were laid out in split plot design with three replications. The main plots included three levels of drip irrigation viz., (I 1 - irrigation at 100% pan evaporation (PE), I 2 - 80% PE and I 3 - 60% PE). The sub plots comprised of three fertigation schedules viz., three ratios of recommended nitrogen and potassium fertiliser doses applied at growth stages of 1-40 days, 40-80 days and 80-120 days (F 1 -50:30:20, F 2 -30:50:20 and F 3 -50:40:10). Minisetts of cassava variety 'Sree Vijaya' was planted at a distance of 60 x 45 cm during the dry spell (Dec- May) in all the years. Results indicated that irrigation at 100% PE yielded maximum tuber yield in all the seasons (43.9 t ha -1 ). There was no significant difference in yield among the fertigation schedules. However, interaction effects showed that I 1 F 1 resulted in better growth characters, yield attributes and yield followed by I 1 F 3 . On an average, 280 mm, 224 mm and 168 mm of water were applied in I 1 , I 2 and I 3 irrigation levels respectively during the growing season. Water use efficiency determined was also higher for irrigation at I 1 level of irrigation.

Genetic Variation in Different Cultivars of Greater Yam (Dioscorea alata)

Abstract: Assessment of 27 accessions of greater yam (Dioscorea alata L.), collected throughout north east India, was carried out during 2009-2010 at the Experimental Farm, Department of Horticulture, Assam Agricultural University. Observations were recorded for different morphological characters following International Plant Genetic Resources Institute’s (IPGRI) descriptors for yam. Phenotypic coefficient of variation (PCV) was higher than genotypic coefficient of variation (GCV) for all the characters indicating the influence of environment. High heritability (>90%) coupled with high genetic advance (>50%) was exhibited by total phenol, internode length, petiole length and days to emergence.

Analysis of Genetic Diversity in Edible Aroid Accessions of India Based on Morphological Characters

Abstract: The family Araceae includes the important edible aroids like Amorphophallus peaoniifolius var. campanulatus (elephant foot yam), Colocasia esculenta (taro), Xanthosoma sagittifolium (tannia) etc. Most of these root crops are important source of food in many tropical countries, primarily grown for their corms and cormels, although sometimes the leaves are also used as vegetable. The Araceae family is highly heterogeneous, with enormous variation in morphology, chromosome structure and number. The Central Tuber Crops Research Institute, Thiruvananthapuram, India, is maintaining about 590 taro and 183 elephant foot yam accessions, which represent genotypes collected from different parts of India and forms the backbone of the variability existing within the country. However, there is chance of duplicates being present in the above collection. Hence morphological characterization is resorted to identify the duplicates. National Bureau of Plant Genetic Resources (NBPGR) descriptors were used for both taro and elephant foot yam for this purpose. In the present paper, diversity analysis using cluster package (R package) was done for 45 taro accessions on the basis of six tuber characters and 26 elephant foot yam accessions on the basis of 14 above ground characters. The results showed that five clusters were formed in taro based on six tuber characters, whereas, in elephant foot yam, six major clusters were formed. No duplicates could be identified within the accessions screened.

Growth and Yield of Elephant Foot Yam under Integrated Nutrient Management (INM) in Alfisols

Abstract: The field experiment was carried out for consecutive two years during 2011-12 and 2012-13 to study the effect of integrated nutrient management practices on elephant foot yam. The experiment was conducted in randomized block design with three replications. The treatment consisted of N-P 2 O 5 -K 2 O 60-60-60, 80-60-80 and 100-60-100 kg/ha, the above treatments in combination with FYM 10 t/ha, FYM @ 25 t/ha and control. The results revealed that application of FYM @ 25 t/ha recorded longer pseudostem, higher canopy spread, pseudostem diameter and no. of leaflets per plant. However, yield attributes and corm yield were found significantly higher with the application of N-P 2 O 5 -K 2 O 100-60-100 kg/ha along with FYM 10 t/ha. The nitrogen and potassium uptake was highest in the treatment FYM 10 t/ha along with 100-60-100 NPK kg/ha whereas maximum phosphorus uptake was noticed in the treatment FYM 25 t/ha. The post-harvest soil nutrient status revealed that maximum soil nitrogen and phosphorus was available in FYM 10 t/ha + N-P 2 O 5 -K 2 O 100-60-100 kg/ha and potassium was in N-P 2 O 5 -K 2 O 100-60-100 kg/ha.

Genetic Diversity of Phytophthora colocasiae Causing Taro Leaf Blight: Analysis Using Start Codon Targeted (SCoT) Polymorphism

Abstract: The Oomycetous fungus Phytophthora colocasiae that causes taro leaf blight is one of the most devastating diseases of taro and is widely distributed in India. Cultural and molecular techniques were employed for assessing the genetic variability among 30 isolates of P. colocasiae obtained from different geographical origins of India. Cultural characters like pathogenicity assay, mating type and metalaxyl sensitivity showed variation among isolates. Eight Start Codon Targeted Polymorphism (SCoT) markers produced 121 reproducible fragments with 100% polymorphism. The average value of the number of observed alleles, the number of effective alleles, mean Nei’s genetic diversity, and Shannon’s information index were 2.00 ± 0.00, 1.58 ± 0.30, 0.34 ± 0.13, and 0.51 ± 0.16, respectively. Analysis of molecular variance (AMOVA) showed that 89 % of the diversity was present within population of P. colocasiae . Dendrograms based on the molecular data using the unweighted pair group method with arithmetic mean (UPGMA) classified the P. colocasiae isolates into two major clusters. Cophenetic correlation coefficient between dendrogram and original similarity matrix were significant for SCoT marker (r = 0.904). The results of this study displayed a high level of genetic variation among the isolates irrespective of the geographical origin. The possible mechanisms and implications of this genetic variation are discussed.

Cross-compati bility Among Six Improved Cassava (Manihot esculenta Crantz) Varieties

Abstract: Crosses are very vital in the development of populations for breeding purposes and the ease with which a parent can cross with other clones is very important in enhancing successful generation of progeny in a breeding programme. Sexual propagation is a promising technique in cassava breeding programmes due to its manifold advantages such as enhanced multiplication rate, longer seed viability, ease of storage and transportation . Another advantage is the high genetic heterogeneity, leading to variation among seedlings which provides the breeder opportunity to select materials with good qualities of the traits of interest. However, one of the major problems militating against breeding of cassava is the difficulty in producing recombinant seeds due to the associated limitations such as inbreeding depression, high abortion rate, low seed germinability and long breeding cycle of the crop. The objective of this study was to assess crossability among six cassava varieties in terms of seed set capability and germinability of the hybrid seeds. Nine hybrid populations were developed using three female and three male parents in a non-reciprocal cross and the resultant seeds were sown in the nursery. Seed set and germinability were recorded. The results showed that seed set and germinability were influenced by the genotypes used as parents. The percentage seed set ranged between 19.9 and 35.5 and the cross, TMS 98/0505 x NR 8083 with highest percentage seed set was about 178% better than the cross, TMS 97/2205 x TMS 30572 with the least percentage seed set. There was variation in compatibility between each female parent and the male parent. Germinability of seeds among the nine crosses ranged between 25.74 and 51.30% indicating that a broad base of variation existed in crossability among the cassava varieties. It is therefore suggested that varieties with high crossability having good qualities of breeder's trait(s) of interest should be used in cassava breeding programmes to enable breeders to generate large populations within a short period.

Calcium Chloride and Salinity Stress Effects on Growth, Dry Matter Allocation and Ion Uptake of Sweet Potato (Ipomoea batatas [L.] Lam.)

Abstract: The effects of NaCl salinity and CaCl2 concentrations on growth, dry matter allocation and ion uptake of sweet potato (Ipomoea batatas [L.] Lam.) plants were examined. Responses of sweet potato to salinity showed that plants growing in low Ca2+ exhibited severe growth reduction under salinity stress of 140 mM NaCl. Growth was reduced by NaCl salinity, and differences in ion uptake were observed between the plants receiving low and high concentrations of CaCl2. Relative growth rate (RGR) of sweet potato was only slightly reduced by salinity in the early stages, with a large reduction occurring in the later stages. Sweet potato had a higher dry matter allocation to its shoots as NaCl salinity reduced root growth more than it did shoot growth. Salinity tolerance of sweet potato appears to be associated with its ability to control rates of Na+, K+ and Ca2+ ion uptake and transport, in order to maintain ionic adjustments within the plant tissues during salt stress. There appears to be a salt tolerance mechanism operating in which, during salt stress, ionic adjustment within the plant tissues of sweet potato cultivar is maintained by controlling the rates of ion uptake and transport.

Isolation and Characterization of N Fixing Bacteria from Elephant Foot Yam (Amorphophallus paeoniifolius (Dennst.)Nicolson) Growing Regions of South India

Abstract: Isolation and screening of 130 bacteria from the rhizosphere region of elephant foot yam ( Amorphophallus ) growing area of South India for their ability to fix atmospheric nitrogen ( Kjeldhal technique) resulted in the identification of 62 isolates having varying levels of nitrogen fixing ability in Jensen's nitrogen free medium. The most potent nitrogen fixing isolates were tested for their efficiency to release plant growth promoting substances like indole acetic acid (IAA), ammonia (NH 3 ), hydrogen cyanide (HCN) and catalase enzyme. Morphological and molecular characterization of the two potent bacterial strains led to the identification of them as Bacillus cereus strain ANctcri-1 (HQ286640) and Pseudomonas aeuroginosa ANctcri-11 (JX974833). A study on the effect of various physiological conditions on growth of this potent bacteria revealed their facultative alkaliphilic halo tolerant nature.

A Highly Sensitive Nested-PCR Method Using a Single Closed Tube for the Detection of Colletotrichum gloeosporioides causing Greater Yam Anthracnose

Abstract: Greater yam is an important species of yam grown in different parts of India. Anthracnose or die back disease caused by Colletotrichum gloeosporioides reduces the yield up to 90 per cent. The pathogen survives in the soil debris and transmits the disease to the next season through tubers. In this study, a sensitive method for the specific diagnosis of C. gloeosporioides in soil and planting material was developed. The standard nested PCR previously described was re-standardized to run a single nested PCR in a closed tube. The problems of cross contamination and the increased risk of PCR product contamination, while handling the product of first PCR could be avoided. This technique could be achieved by adjusting the concentration of primers and the annealing temperature along with the standardization of PCR cycles so as to produce a single amplicon without compromising the limit of detection and specificity. The lowest amount of DNA that could be determined by this method was 200 pg ml-1.

A Comparative Study on the Resistant Starch Content in Starches from Different Botanical Sources in Relation to their Physicochemical Properties

Abstract: Resistant starch (RS), a functional food ingredient and a third type of fiber that provides the benefits of both insoluble and soluble fibers , bags attention due to its unique functional and health attributes. The aim of this study was to investigate the resistant starch content in the starch isolated from different botanical sources such as cereals (maize, rice, oats, wheat, barley), legumes (lentil, mung bean), vegetable (raw banana), and roots & tubers (potato, cassava, sweet potato and arrowroot). The rapidly digestible (RDS), slowly digestible (SDS) and RS contents in the starch samples were determined and related with their physiochemical and functional properties. The study showed that the starch from different sources varied significantly in their chemical, physical and functional properties as well as in RS content. The highest RS content was observed for lentil starch (5.3%) and lowest for starch from oats (1.3%). In general, RS content was lower for starch extracted from roots and tubers compared to that from cereals and legumes. The RDS content of maize starch was the highest (95.2%) and that of barley starch was the lowest (69.5%), whereas the SDS showed a reverse trend. The RDS and RS contents showed a positive correlation with amylose content in the starch. The highest amylose content was possessed by lentil starch (28.5%) which also showed the highest RS content among all the selected starches.

Effect of Zinc and Magnesium on Orange Fleshed Sweet Potato in Alfisols of Odisha, India

Abstract: The effect of application of magnesium (Mg) and zinc (Zn) individually and in combination on yield, proximate composition and nutrient uptake of orange fleshed sweet potato was studied in an acidic Alfisol of Odisha, India by conducting field experiments for two kharif (rainy) seasons during 2009-10 and 2010-11. The results revealed that significantly highest mean tuber yield (11.9 t ha -1 ) and vine yield (18.1 t ha -1 ) was recorded due to application of 20 and 30 kg ha -1 of ZnSO 4 and MgSO 4 , respectively. The mean yield response was pronounced to be 12, 19 and 10 % due to application of 10, 20, and 30 kg ZnSO 4 ha -1 over control, while it was 7, 11 and 8 % with respect to 15, 30, and 45 kg MgSO 4 ha -1 . Highest mean starch content (22.4%), total sugars (3.61%) and dry matter (29.4%) was observed due to application of 20 kg ha -1 ZnSO 4 . Combined application of 20 and 30 kg ha -1 of ZnSO 4 and MgSO 4 recorded significantly highest total uptake of N and P (67.4 and 24.7 kg ha -1 , respectively), however, the total uptake of K was highest (93.1 kg ha -1 ) due to 10 and 45 kg ha -1 of ZnSO 4 and MgSO 4 . Addition of Zn and Mg resulted in significant improvement of soil properties. The results emphasized that application of 20 and 30 kg ha -1 of ZnSO 4 and MgSO 4 , respectively along with the optimum doses of NPK produces highest and sustainable crop yields with good quality tubers and maintains the soil fertility.

Screening of Rhizobacteria Associated with Cassava for Plant Growth Promotion and Biocontrol Potential

Abstract: Plant growth promoting rhizobacteria (PGPR) are beneficial bacteria that colonise plant roots and enhance plant growth by a wide variety of mechanisms. The use of PGPR is steadily increasing in agriculture and offers an attractive way to replace chemical fertilizers, pesticides and supplements. In the present study, rhizobacteria associated with five varieties of cassava, viz., Sree Padmanabha, Sree Vijaya, Sree Jaya, Sree Rekha and Sree Prakash were isolated and screened for their plant growth promotion traits and in vitro biocontrol potential. A total of 41 isolates were selected based on colony morphology and designated as RB1 to RB41. These isolates were screened in vitro for their plant growth promoting traits like production of indole acetic acid (IAA), ammonia (NH3), phosphate solubilisation, hydrogen cyanide (HCN) and antifungal activity. Cowpea seeds were treated with rhizobacteria to assess seed germination and growth of seedlings. A pot experiment was conducted with cassava variety, Sree Vijaya, where stem cuttings were treated with rhizobacteria followed by a soil drench. About 88% of the isolates produced IAA, 83% produced ammonia and 50% solublized P. Only one isolate produced HCN and nine isolates showed antifungal activity against the plant pathogen, Sclerotium rolfsii. Rhizobacterial treatments promoted the germination in cowpea and growth in cassava.The present study suggests that PGPR isolates might have potential in future field applications as plant growth promoters or as biocontrol agents.

Effect of NAA and IBA on in vitro regeneration and hardening in cassava(Manihot esculenta Crantz.)

Abstract: As the cassava is a delicate plant to harden during in vitro regeneration, huge losses occur during transfer from in vitro laboratory to in-situ field conditions. One month old in vitro plantlets of cassava varieties “Sree Vijaya”, “H-226” and “H-165” released by Central Tuber Crops Research Institute, India grown from in vitro nodal explants using MS media supplemented with NAA or IBA along with a control were used for hardening studies. For in vitro rooting with shoot regeneration, MS media supplemented with 0.3 mgl-1 IBA was found to be the best for all the three varieties. Cassava plantlets grown using 0.6% agar in the in vitro growth medium with NAA supplement produced least root damage (3%) during washing before hardening. All the varieties grown in MS media supplemented with NAA, showed good results during hardening. Cassava varieties Sree Vijaya and H-226 grown in vermiculite + soil as potting mixture using both Hoagland and fertilizer solution showed maximum success of 87% and 80% respectively. Cassava var. H-165 showed best result from the potting media sand + vermiculite + soil using both Hoagland and fertilizer solution, which gave 100% success. The hardened plantlets could be successfully acclimatized in the green house and transplanted to open field conditions.

Impact of Irrigation and Fertigation Levels on the Growth and Yield of Elephant Foot Yam (Amorphophallus paeoniifolius (Dennst.) Nicolson)

Abstract: Elephant foot yam is gaining popularity as a commercial or cash crop in Andhra Pradesh, West Bengal, Uttar Pradesh, Bihar, Jharkhand and Tripura. Its area is expanding in Tamil Nadu, Gujarat and Maharashtra. However, lack of scientific studies on fertigation hinders its further expansion in the nontraditional and water scarce areas. Judicious and optimal use of water and fertilizers are prerequisites to maximize the productivity and return. Hence, field experiments were carried out at Department of Vegetable Crops, Horticultural College and Research Institute, Tamil Nadu Agricultural University, Coimbatore during 2010-2013 through AICRP on Tuber Crops to standardize drip with fertigation technology for elephant foot yam. The experiment was laid out in factorial RBD and replicated thrice. For standardizing the fertigation system, five irrigation levels (I1-25% cumulative pan evaporation (CPE); I2-50% CPE; I3-75% CPE ; I4-100% CPE and I5-Flood irrigation) and four fertigation levels (F1 - fertigation with 100% recommended dose of fertilizers (RDF); F2-fertigation with 75% RDF; F3-fertigation with 50% RDF and F4-absolute control) were followed.. The greatest plant height (78.89 cm), pseudostem girth (12.29 cm), canopy spread EW (65.58 cm) and NS (64.47 cm) were observed under application of 100% RDF along with flood irrigation. There was significant difference in yield among fertilizer levels and irrigation levels. The highest corm yield (47.66 t ha-1) was observed under application of 100% RDF along with irrigation at 100% CPE.

Efficacy of cassava by-products as carrier materials of Trichoderma harzianum, a biocontrol agent against Sclerotium rolfsii causing collar rot in Amorphophallus.

Abstract: The ability of cassava (Manihot esculenta Crantz) by-products such as cassava leaf powder, cassava seed oil and cassava thippy as carrier materials to preserve the viability and antagonistic potential of Trichoderma harzianum, a potent strain against Sclerotium rolfsii was investigated during February 2011 to August 2012 at Central Tuber Crops Research Institute, Thiruvananthapuram, India. The shelf life period of Trichoderma harzianum was highest for cassava seed oil (1x106 cfu ml-1) without severe reduction in the initial population at the end of incubation period of 18 months, which fulfills the minimum recommended population of fungal bioagent in any formulation for seed treatment, while cassava leaf powder maintained the recommended population for nine months. The inhibitory effect of T. harzianum against tested pathogenic fungi was maximum when stored in cassava seed oil (81.57%) than cassava leaf powder (79.2%) after 18 months. The study indicated that T. harzianum mixed in cassava seed oil had the longest shelf-life and antagonistic activity extending to more than an year, whereas this was least for the antagonist formulated in cassava thippy.

Worm Power Against Fungal Diseases in Aroids: Prospects and Future Strategies

Abstract: Organic growers have limited options for plant disease control since most of the effective fungicides are synthetic, toxic and potentially polluting Vermicompost and vermiwash have been widely explored as eco-friendly options for controlling plant diseases We explored the possibility of utilizing vermicompost to manage Phytophthora colocasiae and Sclerotium rolfsii that cause taro leaf blight and collar rot of elephant foot yam, respectively Microbial diversity was assessed in terms of quality and quantity in 35 vermicompost samples collected from different parts of the country The distinct isolates were screened against the target pathogens under in vitro conditions Potent organisms were identified by ITS and rRNA sequencing Induced systemic resistance (ISR) was quantified in terms of phenol content, chitinase and glucanase activities The variability in disease suppression by various vermicompost samples was studied under in vitro conditions Pot culture studies were conducted in taro and elephant foot yam for two years to assess the potential of vermicompost/vermiwash for disease suppression A total of 309 culture dependant isolates of vermicompost origin were obtained and 189% and 364% of these organisms showed >50% inhibition against S rolfsii and P colocasiae, respectively The disease suppression potential varied with the source of vermicompost Vermicompost/ vermiwash treated plants showed <10% TLB incidence and 0-50% collar rot incidence Yield increase of 14–70 % was also noted in both crops There is scope for utilizing vermicompost for eco-friendly management of taro leaf blight and collar rot of elephant foot yam

Influence of Nursery Media and Mulching on Sprouting and Growth of Greater yam (Dioscorea alata) Minisetts

Abstract: The experiment conducted at FSRS Sadanandapuram under Kerala Agricultural University to assess the influence of different potting media including soilless media and seed treatments on the sprouting and early growth of Dioscorea alata minisetts revelaed the significant influence of soil in the potting media for minisett germination. Sprouting was significantly earlier when planted in the media containing soil compared to the soilless media. Seedling growth and vigour were significantly higher in the soil media followed by the combination of soil and coir pith compost in 1:1 ratio. The observations remained similar for the cow dung treated and non treated minisetts. However, among the latter two, seed treatment with cow dung slurry proved to be superior. The influence of mulching the minisetts in the nursery was also examined and statistical analyses of the data revealed significantly earlier germination in the mulched minisetts compared to the non mulched treatments. The experiment has proven that soiless media of coir pith compost enriched vermicompost was not comparable with soil in raising Dioscorea alata minisett seedlings in nursery and, cow dung slurry treatment and mulching were absolutely essential for seedling growth in the minisetts.

Geospatial Assessment and Mapping of Selected Soil Physical and Chemical Properties at Farm Level: A Case Study in an Ultisol

Abstract: Analysis and interpretation of spatial variability of soil properties is important in site specific nutrient management, precision farming and sustainable land management. The study assessed the spatial variation of soil physical and chemical properties of the experimental farm of Central Tuber Crops Research Institute (CTCRI), Thiruvananthapuram, Kerala, India. Georeferenced surface (0-15 cm) and subsurface (15-30 cm) soil samples were collected from 130 locations, 50-60 m apart, in an irregular grid. Spatial variability analysis was done for selected soil physical and chemical properties like bulk density, water holding capacity, porosity, soil texture, organic C, available N, available P and exchangeable K. Descriptive statistical analysis was carried out to study the variability of different soil properties. The spatial analysis was done using geostatistical analyst extension of ArcGIS 10.0 software. Results showed that majority of the farm area are sandy clay in texture. Among the soil physical properties studied, bulk density and porosity showed low spatial variations (CV <10.00) in both soil layers. Among the soil chemical properties studied, very high spatial variability was observed for available P followed by exchangeable K. Gaussian and exponential models fitted well with the experimental semivariograms of most of the soil physico-chemical properties. The nugget to sill ratios, which gives the degree of spatial dependence, was observed to be weak to strong for the soil properties. Spatial distributions of soil physico-chemical properties in the farm were estimated using kriging interpolation. The semivariogram parameters were used for kriging that produced interpolation maps of the soil properties which can be used as very good tools for farm planning at regional scale.

In vitro propagation and microtuber induction in Dioscorea belophylla (Prain) Voigt ex Haine

Abstract: A protocol was developed for the in vitro propagation and microtuber induction in Dioscorea belophylla using nodal explants at Central Tuber Crops Research Institute, Thiruvananthapuram, India. MS medium with benzyl adenine (BA) at 3 μM and Kinetin (Kin) at 4 and 5 μM were found to be the best concentrations for developing shoots with good number of nodes and leaves. The addition of 1- naphthaleneacetic acid (NAA) along with cytokinin resulted in healthier leaf production. Among the different concentrations of sucrose tested, MS medium with 4% sucrose was the best for shooting, having the highest shoot length of 11.8 cm and mean number of 17.4 nodes and 11.4 leaves/shoot within 15.4 days of inoculation. Microtuber induction was recorded in the presence of BA (3-5 μM), Kin (3-4 μM) and BA 3 μM along with NAA (1 μM). Addition of 3-8% sucrose in the medium was found to be the best concentration for inducing 1-3 microtubers/culture.

Relative Effects of Uniconazole-p and other growth regulators on Micropropagation ratio of yam (Dioscorea spp.) plantlets at different growth phases

Abstract: Scarcity of seed, pest and diseases are major constraints to yam production. Tissue culture techniques of meristem culture combined with heat therapy have been used to produce high-yielding virus-tested plantlets of root crops, which are later multiplied through micropropagation. However, the micropropagation rate is low in yam. We investigated i n vitro , the rate of production of new nodes at some Plant growth regulator regimes applied at specific growth phases of yam. Three concentrations each of uniconazole-p (UP), gibberellic, jasmonic (JA) and naphthalene acetic (NAA) acids were applied at single node and primary nodal complex (PNC) formation phases in a split-plot design using two genotypes each of white and water yams. Number of nodes per plantlet was recorded after 16 weeks. The number of new nodes varied significantly with genotype by growth phase interaction and the main effect of PGRs. After 16 weeks, the control, 1.7µM UP and 0.03µM JA had highest means of 7, 9 and 8 nodes per plantlet compared to 2-3 nodes in the GA treatments. Thus, 4,900, 8,100 and 6,400 plantlets can be obtained in I year from a 100-node plant. In D. alata genotypes, addition of PGRs at PNC doubled the number of nodes per plantlet relative to addition at single node stage, while the effect of stage varied with genotype in D. rotundata . There is an important role for GA and its inhibitor-UP on the rate of yam micropropagation. Optimum multiplication rates can be achieved if the right PGR is applied at a standardized growth phase of a particular genotype. Earliness of genotypes seems to be a major factor that will determine the timing of application of PGRs.

In Vitro Propagation of Chinese Potato (Plectranthus rotundifolius (Poir.) J.K. Morton) Through Axillary Shoot Bud Culture

Abstract: An efficient and cost effective in vitro plant regeneration protocol through single nodal segment culture was achieved in the minor tropical tuber crop, Chinese potato (Plectranthus rotundifolius (Poir) JK Morton), through axillary shoot bud proliferation in Murashige and Skooge medium augmented with varying concentrations of 6-benzylaminopurine (BAP) and Kinetin (05–20 mg l-1) BAP at 1 mg l-1 was the most effective medium for multiple shoot induction, which gave an average of 38 shoots/ node, followed by Kinetin (05 mg l-1) inducing 22 shoots/node as compared to the other concentrations of hormones and MS basal medium alone, after 45 days of culture MS basal medium, though not promoting shoot multiplication, gave higher shoot length with elongated internodes In vitro multiplied shoots transferred to MS medium with 05 mg l-1 IBA was optimum for healthy rooting Rooting of the micro shoots also occurred in the Kinetin containing shoot multiplication medium itself from the base and nodes on ageing of the cultures after 85 days of culture The healthy and vigorous in vitro regenerated micro shoots were separated out and were hardened upon transfer to plastic cups with sterile soil and sand These were successfully acclimatized ex vitro in pots with potting mixture under green house conditions for four weeks The survival rate was 90% and the plants that established in the green house resembled the mother plants in habitat without any morphological variations This very simple and efficient protocol can be used to mass propagate elite stable clones of this very important aromatic tropical minor tuberous vegetable

Scientific rationality, adoption and perceived effectiveness of traditional agricultural practices of cassava (Manihot esculenta Crantz.) in Kolli Hills, India

Abstract: The tribes of the Kolli hills of Namakkal district in Tamil Nadu possessed rich tradition, heritage and experience in agriculture. Hence, an intensive study was found essential to identify, document, and analyze the Indigenous Tribal Agricultural Practices (ITAPs) of Kolli hills in Tamil Nadu. In this context a study was undertaken for collecting, classifying, documenting, analyzing the rationality, and studying the adoption of the selected ITAPs in tapioca. About 17 ITAPs on tapioca cultivation, in different clusters of villages of Kolli hills were documented. A questionnaire was prepared, with selected 17 ITAPs of tapioca for assessing the rationality of crop production and protection aspects of tapioca and was referred to 50 scientists, by rating them on a four point continuum ranging from 4 to 1.Having identified and selected the list of ITAPs with their rationality scores, further analysis was undertaken to test verify their extent of adoption and perceived effectiveness. The rational and effective ITAPs should be blended into the technology package for transfer of technology, so that the agricultural development will be sustainable.