Primary Spike Research Articles

Combining ability, heterosis and gene action for yield and its component traits incastor (Ricinus Communis L.)

An investigation on combining ability, heterosis and gene action for yield and its component traits in castor was carried out at AICRP Castor, UAS, Bangalore involving fifty hybrids developed from five pistillate lines as females and 10 testers as males. Analysis of variance revealed significant differences among parents and crosses for all yield attributing traits. The line YRCP-1 and tester RG-3160 showed significant positive effect for seed yield. The cross MCP-1×RG- 3160, expresses significant SCA effect for earliness, spike lengths, capsules on primary spike and seed yield/plant. Hybrids MCP-1 × RG-2787 (157.50 g) and DPC-22 × RG-2787 (186.77 g) involving poor performing parents produced high magnitude for seed yield/plant and yield attributing traits like 100 seed weight and oil percent (%).

Evaluation of castor landraces collected from N-W Rajasthan as noval geneticresources for breeding

An exploration was conducted in North-Western Rajasthan state and a total of 114 castor germplasm lines were collected from seven districts. Most of the accessions were tall in plant height. Variability for different traits viz., plant height (50-275 cm), node number (10-35), total length of primary spike (16-60 cm), length of primary spike covered by capsules (6-60 cm), 100 seed weight (7.1-53 g), total seed yield (23-416 g/plant)among the collections were very high. These 114 genotypes were grouped into 11 clusters using D2 analysis. Among the 11 clusters studied, plant height contributed highest towards genetic divergence (45.8%) followed by total seed yield/plant (36.4%). Principal component (PCA) analysis revealed that first three PC axes explained 64.7% of the total multivariate variation while the first five PC axes explaining 81.7%. Among these diverse germplasmcollections few promising accessions identified for node number RG-3840 (10), RG-3841 (11), 100-seed weight, RG-3832 (53.2g), RG-3839 (52.6 g), RG-3831(49.5 g), seed yield/plant, RG-3851-(416 g), RG-3860 (305 g) and RG-3895 (238 g). These landraces were found to be potential source of genetic diversity to castor repository.

Role of Genetic Variability and Their Associated Character on Yield Attributing Traits in Castor (Ricinus communis L.) Germplasm Lines

Castor (Ricinus communis L.) is an industrially important non-edible oil seed crop with limited genetic variation. It is consequently important to diversify the genetic base to utilize the diversity. The primary objective of this study was to assess the extent and significance of variability among castor genotypes concerning yield and its associated traits. A study with two hundred germplasm lines along with four checks on genotypes on variability, correlation, and path coefficient was carried out for nine traits. The genotypic coefficient of variation (GCV) and phenotypic coefficient of variation (PCV) values indicated the presence of broad variation for all characters except for days to 50 percent flowering, days to maturity, number of nodes, and oil content. However, high heritability coupled with high genetic advance as percent mean was observed for plant height, days to 50 percent flowering, days to maturity, number of nodes, total length of the primary spike, number of effective spikes, seed weight, and total yield. The character's plant height, number of nodes, total length of the primary spike, number of effective spikes, seed weight, and oil content show a positive significant correlation with the total yield. The path coefficient analysis indicates that the utmost positive direct effect on total yield was exerted by a number of effective spikes per plant. Hence it was concluded that selection for traits total length of the primary spike, number of effective spikes, and 100 seed weight beneficial in yield improvement programs of castor.

Growth and yield performance of castor hybrids under different methods of planting and fertility levels in North Gujarat Agro-climatic region

A field experiment was conducted to evaluate the yield performance of castor hybrids under different methods of planting and fertility levels at Agronomy Instructional Farm, C P College of Agriculture, Sardarkrushinagar, Gujarat in loamy sand soil. The experiment consisted eight treatment combinations with two hybrids (GCH 7 and GCH 8), two planting methods (Direct seed sowing and Transplanting) and two fertility levels(75% RDF and 100% RDF) were undertaken in randomized block design with factorial concept and replicated four times. Significantly higher number of capsules (88.63) on primary spike, seed yield per plant (686.30 g), 100-seed weight (32.49 g), number of spikes (20.01) per plant, seed yield (3220 kg/ha) and stalk yield (5340 kg/ha) were recorded with GCH 8 hybrid. In plantingmethods, significantly higher number of capsules (89.09) on primary spike, seed yield per plant (688.65 g), number ofspikes (19.60) per plant, seed yield (3230 kg/ha), stalk yield (5361 kg/ha) and available P2O5 (48.7 kg/ha) and S (13.01 mg/kg) after harvest of crop were recorded under direct seed sown castor. 100% RDF registered significantly higher plant height (86.14 cm) at harvest, number of nodes (18.58) per plant, number of capsules (88.60) on primary spike, length of primary (74.57 cm) spikes, seed yield per plant (688.53 g), 100-seed weight (32.00 g), number ofspikes (19.66) per plant, seed yield (3190 kg/ha), stalk yield (5281 kg/ha) and available N, P2O5and S (156 kg/ha, 49.8 kg/ha and 13.35 mg/kg, respectively).

Genetic variability studies of major yield components in segregating population derived from pistillate lines of castor (Ricinus communis L.)

A segregating population was developed by crossing two pistillate (female) lines of castor viz., IPC-23 and IPC-21. Population behavior was studied to understand the variability for major yield and yield components. The distribution of node number, plant height and seed yield were deviated fromnormal distribution and it was positively skewed with significant leptokurtic curve indicating that the two parents with high seed yield were selected for population development. Positive skewness indicates that the plants with exceptionallyhigh seed yield were isolated from the population. Difference between phenotypic co-efficient of variation (PCV) and genotypic co-efficient of variation (GCV) was very low to moderate for major yield components viz., number of effective spikes per plant, number of nodes to primary spike, plant height, total spike length and effective spike length of primary indicating that phenotypic selection can be effectively used for yield improvement. High heritability and genetic advance over mean (GAM) indicated the role of additive gene action for plant height and total/effective primary spike length. Correlation of number of nodes up to the primary spike with plant height up to primary spike, and total/effective spike length was positive indicating the possibility of short-statured, early pistillate selections with long primary spikes in castor.

Spike S1 domain interactome in non-pulmonary systems: A role beyond the receptor recognition.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes Coronavirus Disease 2019 (COVID-19), which, since 2019 in China, has rapidly become a worldwide pandemic. The aggressiveness and global spread were enhanced by the many SARS-CoV-2 variants that have been isolated up to now. These mutations affect mostly the viral glycoprotein Spike (S), the capsid protein mainly involved in the early stages of viral entry processes, through the recognition of specific receptors on the host cell surface. In particular, the subunit S1 of the Spike glycoprotein contains the Receptor Binding Domain (RBD) and it is responsible for the interaction with the angiotensin-converting enzyme 2 (ACE2). Although ACE2 is the primary Spike host receptor currently studied, it has been demonstrated that SARS-CoV-2 is also able to infect cells expressing low levels of ACE2, indicating that the virus may have alternative receptors on the host cells. The identification of the alternative receptors can better elucidate the pathogenicity and the tropism of SARS-CoV-2. Therefore, we investigated the Spike S1 interactomes, starting from host membrane proteins of non-pulmonary cell lines, such as human kidney (HK-2), normal colon (NCM460D), and colorectal adenocarcinoma (Caco-2). We employed an affinity purification-mass spectrometry (AP-MS) to pull down, from the membrane protein extracts of all cell lines, the protein partners of the recombinant form of the Spike S1 domain. The purified interactors were identified by a shotgun proteomics approach. The lists of S1 potential interacting proteins were then clusterized according to cellular localization, biological processes, and pathways, highlighting new possible S1 intracellular functions, crucial not only for the entrance mechanisms but also for viral replication and propagation processes.

The Effects of Brief Heat During Early Booting on Reproductive, Developmental, and Chlorophyll Physiological Performance in Common Wheat (Triticum aestivum L.).

Rising temperatures due to climate change threaten agricultural crop productivity. As a cool-season crop, wheat is heat-sensitive, but often exposed to high temperatures during the cultivation period. In the current study, a bread wheat panel of spring wheat genotypes, including putatively heat-tolerant Australian and CIMMYT genotypes, was exposed to a 5-day mild (34°C/28°C, day/night) or extreme (37°C/27°C) heat stress during the sensitive pollen developmental stage. Worsening effects on anther morphology were observed, as heat stress increased from mild to extreme. Even under mild heat, a significant decrease in pollen viability and number of grains per spike from primary spike was observed compared with the control (21°C/15°C), with Sunstar and two CIMMYT breeding lines performing well. A heat-specific positive correlation between the two traits indicates the important role of pollen fertility for grain setting. Interestingly, both mild and extreme heat induced development of new tillers after the heat stress, providing an alternative sink for accumulated photosynthates and significantly contributing to the final yield. Measurements of flag leaf maximum potential quantum efficiency of photosystem II (Fv/Fm) showed an initial inhibition after the heat treatment, followed by a full recovery within a few days. Despite this, model fitting using chlorophyll soil plant analysis development (SPAD) measurements showed an earlier onset or faster senescence rate under heat stress. The data presented here provide interesting entry points for further research into pollen fertility, tillering dynamics, and leaf senescence under heat. The identified heat-tolerant wheat genotypes can be used to dissect the underlying mechanisms and breed climate-resilient wheat.

Theoretical characteristics of mid-infrared gain switched pulsed iron-doped ZnSe laser

We report a four-level theoretical model revealing the laser kinetics of a gain-switched pulsed Fe2+:ZnSe laser that is established for the first time, to the best of our knowledge. The experimental results agree with the theoretical primary spike pulse and relaxation oscillation phenomenon of pulse. Furthermore, the effects of temperature, doping concentration, and the output coupler reflectivity on the performance of the pulsed Fe2+:ZnSe laser are simulated using the proposed model. The simulated results indicate that the laser efficiency is higher at low temperature and high Fe2+ concentrations, and the optimal output coupler reflectivity is ∼23% at 77 K.

Genetic parameters, diversity and character association studies in germplasm lines of castor (Ricinus communis L.)

Castor is an important non-edible oilseed crop having huge industrial and export potential. It is used as an efficient lubricant for high-speed engines and as an ingredient in several commodities. There is a critical need to identify or to improve the germplasm lines with desirable characters. In the present study, 82 germplasm lines were evaluated in augmented design to estimate the genetic parameters viz., PCV, GCV, heritability and genetic advance as per cent of mean, principal component analysis and correlation studies. Results showed that the difference between PCV and GCV was low indicating less impact of environment on trait expression. Heritability (broad sense) and genetic advance as per cent of mean values were high for all the traits thus role of additive gene action is found important in governing the traits. Cluster analysis studies revealed that all the genotypes were grouped into eight clusters and cluster VIII documented the highest mean values for hundred seed weight and plant yield. The entries PRC-2 and PCS-337 recorded higher hundred seed weights of 56.5 and 48.6 g, respectively and in turn higher yield. These lines can be utilized as parents in the hybrid development programme for yield improvement. Correlation studies revealed that plant yield showed a significant positive association with all the characters except for days to 50% flowering. Thus selection for these traits viz., primary spike length, effective primary spike length, the number of effective spikes per plant, the number of capsules per spike and hundred seed weight will be advantageous in attaining higher yields. Key words: Castor, cluster analysis, correlation, genetic variability, germplasm lines

Effect of weather parameters on the seasonal dynamics of tobacco caterpillar, Spodoptera litura (Lepidoptera: Noctuidae) in castor in Telangana State

Field experiments were carried out for four years (2012-13 to 2015-16) to study the seasonal dynamics of tobacco caterpillar, Spodoptera litura in castor and its relationship with different weather parameters during kharif season in Telangana State. Moth catches of S. litura were observed throughout the crop season, wherein maximum catches (44.8 to 124 moths/trap/week) were observed during mid- August to late-October [33rd to 43rd Standard Meteorological Week (SMW)]. Peak oviposition (2.0 to 14.8egg-masses/5 plants) and larval incidence (14.4 to 48 larvae/5 plants) of S. liturawas recorded during mid-August to mid-November (33rd to 46th SMW) coinciding with the vegetative to primary spike development stage of the crop. The correlation analysis indicated that the moth catches and larval population of S. litura showed significant positive correlation with weather parameters viz., maximum temperature, minimum temperature, rainfall and rainy days, while egg-masses of S. litura showed significant negative correlation with morning relative humidity and minimum temperature.The stepwise regression analysis revealed that minimum temperature, rainy days, wind speed and evening relative humidity could explain 64 per cent variation in S. litura moth catches. Among all the variables morning relative humidity was found to contribute significantly and showed 59 per cent effect on the population fluctuation of eggmasses, while rainy days and maximum temperature could explain 51 per cent variation in larval population of S. litura in castor.The models were validated with independent data 2015-16. The overall results suggested that the models can be used for predicting the population of S. litura in castor for optimizing management strategies.

Relationship of node number with days to flowering and yield traits in castor (Ricinus communis L.) hybrids under rainfed and irrigated conditions

A set of 150 hybrids were evaluated in augmented design with three checks under rainfed and irrigated conditions at research farm of ICAR-Indian Institute of Oilseeds Research, Telangana and Anand Agricultural University, Anand, Gujarat to understand the environmental effect on node number and its influence on yield attributing traits. Results indicated that the number of nodes to the base of primary spike (NN) influenced not only days to 50% flowering (DFF) and yield traits but also plant canopy particularly under rainfed conditions. Under both rainfed and irrigated conditions, the genotypes with high node number, in general, recorded increased plant height, days to 50% flowering (DFF), primary spike length, and seed yield/plant. Under rainfed conditions, most of the early hybrids with NN <12 and DFF# 44 DAS recorded less seed yield, whereas, the yield potential was high in hybrids having NN 12 to 15 and DFF 45 to 50 DAS. However, no such pattern was noticed under irrigated conditions. Test weight and oil content were not influenced by node number or days for flowering.

The agro-morphological characterization of castor (Ricinus communis L.) inbred lines

Thirty six castor inbred lines were studied for agro-morphological characterization, the entire group of inbredlines showed wide range of genetic variation for qualitative traits like anthocyanin pigmentation on hypocotyl and younger leaves, bloom/waxiness, stem colour, types of internodes on main stem, leaf shape, petiole surface, types of flowers on primary spike, spike shape, spike compactness, spines on capsules, location of branches, branching pattern, seed shape, seed coat colour, seed mottling and seed caruncle and quantitative traits like days to 50% flowering, plant height, primary spike length, no. of nodes to primary raceme, 100 seed weight. The hypocotyl anthocyanin pigmentation showed close association with presence of anthocyanin pigmentation on young leaves. About 97% of inbred lines exhibited double bloom nature which is an important trait for drought tolerance in castor.

Influence of environment on quality hybrid seed production in castor : A case study of participatory seed production

This paper highlights the observations made regarding the influence of environmental factors on genetic purity of hybrid seed produced during the participatory seed production oftwo castor hybrids viz., DCH 177 (DPC 9 x DCS 9) and DCH-519 (M 574 x DCS 78) in two villages of Mahabubnagar district, Telangana. Preliminary observations indicated that development of environmentally sensitive interspersed staminate flowers (ISF) on pistillate lines was influenced by their genetic nature, soil and agronomic management of crop as well as weather parameters. Higher incidence of ISF was observed in shallow and red soils irrigated by furrow method compared to medium/deep, clay loamy and black soils irrigated and fertigated by drip method, leading to higher number ofselfed female plants, low genetic purity of certified hybrid seed (<85%) and rejection of seed lots during certification. Abiotic stress factors like maximum temperature (>32°C temperature) increased the number of ISF in primary spike order itself and later decreased in subsequent spike orders owing to decreased temperatures. Incidence of whiteflies and Spodoptera wasparticularly high in intensively cultivated agro-ecosystems. Small and marginal farmers depending on family labour were better suited for hybrid seed production of castor. Selection of suitable agro-ecosystem, farmers and their training, and genetic nature of parents proved to be critical requirements for hybrid seed production in castor.

ICH-66, a new high yielding and biotic stress-resistant castor hybrid suitable for rainfed conditions of Peninsular India

ICH-66, a new castor hybrid has been developed at ICAR-Indian Institute of Oilseeds Research (ICAR-IIOR), Hyderabad, India and identified by Combined Varietal Identification Committee of Oilseed Crops during 2018 for release under rainfed areas of Peninsular India in kharif season. The hybrid was developed using the parents SKP-84 and ICS-164 and tested at station trials ofICAR-IIOR during 2013-14 and 2014-15. Considering its superiority over checks, it was evaluated in MLTs of AICRP (Castor) during 2015-16, 2016-17 and 2017-18 along with hybrid checks DCH-519 and DCH-177. ICH-66 recorded a mean seed yield of 1566 kg/ha which is 14.9 and 18.3 per cent higher than the checks DCH-519 (1324 kg/ha) and DCH-177 (1363 kg/ha) respectively. It also had a mean oil content of 48.6 per cent, which is 2.2 and 3.4 per cent higher than the check DCH-177 (47.0% oil content) and DCH-519 (47.6% oil content), respectively. The hybrid had a longer effective primary spike length (45 cm) and better 100-seed weight (29.0 g) under rainfed conditions compared with checks DCH-177 (39 cm and 27.3 g) and DCH-519 (44.8 cm and 26.4 g). The hybrid is medium in maturity duration (100-130 days for primary spike maturity), non-lodging and non-shattering type. The hybrid showed resistance against Fusarium wilt and Macrophomina root rot. It was also found resistant to leafhopper with hopper burn grade of 0 to 1 (on 0-4 scale) at multilocations in all the years of screening. Owing to its superiority for seed yield, oil content and biotic-stress resistance, it will be suitable for rainfed areas of Telangana, Andhra Pradesh, Karnataka, Tamil Nadu and Odishastates in India.

GNCH-1: a high yielding, wilt and leafhopper resistant castor hybrid suitable for Gujarat

GNCH-1 a high yielding, wilt and leafhopper resistant castor hybrid was developed by Pulses and Castor ResearchStation, Navsari Agricultural University,Navsari, Gujarat and released byCentral Sub-Committee onCrop Standards, Notification and Release (CVRC) of Variety for Agricultural Crops in 2017 for commercial cultivation under irrigated situation of Gujarat State, India. The hybrid GNCH-1 was developed by crossing a pistillate line SKP-84 with a male line DCS-94. On an average of 18 trials conducted for five years in south and middle Gujarat, the hybrid GNCH-1 recorded a seed yield of 2545 kg/ha which is 13.8, 35.9 and 31.0 per cent higher yield over the checks GCH-7, DCH-519 and DCH-177, respectively. The hybrid had long primary spike (64.8 cm), more numbers of capsules per primary spike (78.4), matures within 110-112 days and medium height (70-80 cm) which makes itsuitable for easy harvesting. The oil content of the hybrid GNCH-1 (47.0 to 48.0 %) revealed that it is at par with the checks. The hybrid screened for wilt at national wilt sick plots showed resistance reactions (< 20%) to wilt. GNCH-1 screened against leafhopper using infester row method during 2014-17 showed resistant reaction to leafhopper (hopper burn grade 0 to 1 on 0-4 scale). The hybrid demonstrated in the farmers fields for two years (2016-18) showed higher seed yield than the existing cultivars. Due to plasticity for sowing time, this new hybrid is a suitable choice for the farmers of south and middle Gujarat under irrigated condition during late kharif and rabi seasons and paddy based cropping system.

Combining ability of new pistillate lines for plant growth attributes, seed yield and its components in castor (Ricinus communis L.)

Combining ability of four newly developed pistillate lines were tested using Line x Tester analysis. Sixteen hybrids generated using four pistillate lines and four testers were studied along with parents and three checks to estimate combining ability for nine characters in castor. Non-additive gene action was preponderant in all the characters studied except for seed yield, which indicated a negative estimate. Among the female parents, IPC-15 (DPC-15) was a good general combiner for earliness and short plant height while IPC-19 (IPC-19) for late duration and tall plant height. Three pistillate lines, DPC-15 (IPC-15), DPC-19 (IPC-19) and DPC-21 (IPC-21) were identified as good general combiners for total and effective primary spike length. Among the eight parents studied, DCS-107 was a good general combiner for seed yield and other traits like total primary spike length, effective primary spike length and 100-seed weight. None of the hybrids were good specific combiners for seed yield and several other yield contributing characters while three hybrids viz., DPC-16 x DCS-107 (1800 kg/ha), DPC-15 x DCS-107 (1646 kg/ha) and DPC-21 x DCS-107 (1595 kg/ha) were identified as the top three performing hybrids. Among them, DPC-21 x DCS-107 (DCH-1720), has been tested in the All India Coordinated multi location trials for three years while DPC-15 x DCS-107 (PHT-12-2) wastested in three locations (2014-15) and found promising.

Selection of castor germplasm with important traits for drought tolerance under field conditions

India is the leading producer of castor with major area under rainfed cultivation. To improve the productivity in rainfed areas, varieties and hybrids with drought tolerance and water use efficiency (WUE) have to be developed. Hence, it is essential to select germplasm with important traits viz: for root growth, WUE, drought tolerance etc. Fourteen castor genotypes with more root volume (225–557 cm3), root dry weight (38–122 g/pl) and one poor root check (root volume of 94 cm3, root dry weight of 15.2 g/pl.) identified by screening in root structures were sown in field for 2 years. The experiment was conducted during 2010–2012 in late rabi (November first week) in split plot design with three replications and water stress was imposed from 30 to 90 DAS by withholding irrigation. Results revealed severe growth reduction in terms of reduced plant height, leaf number, stem girth, branches and total dry matter (56% reduction) with water stress. Seed yield of primary spike reduced significantly with water stress, but the reduction was less pronounced in secondaries and compensated in later order spikes. The reduction in total seed yield was 35%, total dry matter at harvest was 10% and harvest index was 14% with drought stress (pooled means). Among the Ricinus germplasm (RG) studied, RG 1494 and RG 2139 recorded <20% reduction in seed yield with low drought susceptibility index of <0.5. The root volume (310, 557 cm3), root dry weight (122, 93 g/pl.) of RG 1494 and RG 2139 recorded in root structures was also more. Chlorophyll content measured with SPAD chlorophyll meter reading and bloom content increased in water stressed plants as an adaptive feature. RG 1494, RG 2139 showed good performance during both years and also recorded better root and shoot growth characters, and can be used in drought breeding programs.

Performance of Rabi Castor (Ricinus communis L.) under Zero-Tilled Conditions after Different Preceding Crops

A field experiment was conducted during kharif and rabi 2010–11 and 2011–12 at College Farm, College of Agriculture, Rajendranagar, ANGRAU. The experiment was laid out in split plot design, replicated thrice, with four preceding crops in main plots (green gram, groundnut, bajra and maize) and five nitrogen levels to rabi castor in sub plots (0, 40, 80, 120 & 160 kg N/ha). The results showed that among different preceding crops evaluated, green gram markedly increased growth parameters, yield attributes viz., length of primary spike, number of spikes/plant, number of capsules/primary spike and total number of capsules/plant of castor were also higher when castor followed green gram. The green gram-castor system recorded higher castor seed yield over bajra-castor, groundnut-castor and maize-castor systems. However, the seed yield of former two systems was found at a par during both the years. Stalk yield, harvest index followed the same trend. Among nitrogen levels, application of 160 kg N/ha and 120 kg N/ha, being at par, recorded better yield components like number of spikes/plant and more number of capsules/primary spike of castor over lower N levels. Similarly, the seed yield and stalk yield of castor at 160 kg N/ha was comparable to that of 120 kg N/ha and both were found superior to lower N levels during two years of study.

The Site of Spontaneous Ectopic Spike Initiation Facilitates Signal Integration in a Sensory Neuron.

Essential to understanding the process of neuronal signal integration is the knowledge of where within a neuron action potentials (APs) are generated. Recent studies support the idea that the precise location where APs are initiated and the properties of spike initiation zones define the cell's information processing capabilities. Notably, the location of spike initiation can be modified homeostatically within neurons to adjust neuronal activity. Here we show that this potential mechanism for neuronal plasticity can also be exploited in a rapid and dynamic fashion. We tested whether dislocation of the spike initiation zone affects signal integration by studying ectopic spike initiation in the anterior gastric receptor neuron (AGR) of the stomatogastric nervous system of Cancer borealis Like many other vertebrate and invertebrate neurons, AGR can generate ectopic APs in regions distinct from the axon initial segment. Using voltage-sensitive dyes and electrophysiology, we determined that AGR's ectopic spike activity was consistently initiated in the neuropil region of the stomatogastric ganglion motor circuits. At least one neurite branched off the AGR axon in this area; and indeed, we found that AGR's ectopic spike activity was influenced by local motor neurons. This sensorimotor interaction was state-dependent in that focal axon modulation with the biogenic amine octopamine, abolished signal integration at the primary spike initiation zone by dislocating spike initiation to a distant region of the axon. We demonstrate that the site of ectopic spike initiation is important for signal integration and that axonal neuromodulation allows for a dynamic adjustment of signal integration. Although it is known that action potentials are initiated at specific sites in the axon, it remains to be determined how the precise location of action potential initiation affects neuronal activity and signal integration. We addressed this issue by studying ectopic spiking in the axon of a single-cell sensory neuron in the stomatogastric nervous system. Action potentials were consistently initiated at a specific region of the axon trunk, near a motor neuropil. Spike frequency was regulated by motor neuron activity, but only if spike initiation occurred at this location. Neuromodulation of the axon dislocated the site of initiation, resulting in abolishment of signal integration from motor neurons. Thus, neuromodulation allows for a dynamic adjustment of axonal signal integration.

Character association and path analysis in castor (Ricinus communis L.)

Total seed yield g per plant exhibited significant positive correlation with seed yield at 120, 150, 180 days after sowing, total and effective length of primary spike, 100 capsule and seed weight, shelling per cent and oil content. Yield was significantly negatively correlated with number of nodes upto primary spike and seed specific gravity. Path analysis revealed that yield at 120 and 180 days after sowing, effective length of primary spike, and seed specific gravity exhibited significantly high direct effects in positive desirable direction. The number of nodes up to primary spike and total length of primary spike exhibited highly significant direct effects in negative direction for total seed yield. Their association with total seed yield was significant and positive indicating the factor that there exists a true and perfect association between these traits.