Vinod Tiwari

Trait analysis, diversity, and genotype x environment interaction in some wheat landraces evaluated under drought and heat stress conditions

Both drought and heat stress are responsible for decline in wheat (Triticum aestivum L.) production in many regions of the world. Intergovernmental Panel on Climate Change (IPCC) has predicted increase in these areas. Development of heat and drought tolerant genotypes is on priority. Landraces are unexploited genetic resources for various agronomic traits contributing tolerance to abiotic stress. Twenty-five wheat genotypes were evaluated in irrigated timely, rainfed timely and irrigated late sown conditions for 2 yr using 10 agronomic traits for their response to drought and heat stress and four stress indices (stress susceptibility index, stress tolerance index, mean productivity, and stress tolerance) were calculated. Variability averaged over traits was highest under rainfed conditions. Grain yield, plant height, and productive tillers were more sensitive and test grain weight as tolerant under drought. Under heat stress grain yield, grain weight, test grain weight and phenological traits were more sensitive. Productive tillers and grain number per spike were identified as important selection parameters for drought and grain weight (per spike and test grain weight) as for heat tolerance. Genotypes IC 321987, IC 322005, IC 138852, IC 138870 adapted to stressed environments or genotypes CPAN 4079 and NEPAL 38 stable over all environments can be used for introgression of the stress tolerance in elite cultivars.

Dissecting the physiological and anatomical basis for high yield potential in HD 2967

The wheat genotype, HD 2967 is a popular wheat variety both in North West Plain Zone and North East Plain Zone due to its high yield potential, disease resistance and grain quality parameters. It has been proposed to study the yield attributing traits associated with this genotype. HD 2967 has 98 days of heading, 143 days of maturity, 102 cm plant height, 105 productive tillers per meter along with a 1000-grain weight of 36g. HD 2967 was found superior, for traits like stomatal conductance (gs) and water use efficiency (WUE). The Assimilation rate (A) was also significantly higher than other genotypes. Traits associated with sink strength, like number of tillers, grain filling percentage per spike (91.7%), grain number per spike (59) and grain weight per spike (2.22) were also found at par with other high yielding varieties.

Genetics of grain yield and its components in wheat under heat stress

Heat stress is a matter of a great concern for the wheat crop. Heat stress usually either hastens crop development or shortens the grain filling duration, which severely reduces grain yield. Being a complex trait, understanding the genetics and gene interactions of stress tolerance are the two primary requirements for improving yield levels. Genetic analysis through generation mean analysis helps to find out the nature of gene actions involved in a concerned trait by providing an estimate of main gene effects (additive and dominance) along with their digenic interactions (additive × additive, additive × dominance, and dominance × dominance). In the present investigation, we elucidated the inheritance pattern of different yield contributing traits under heat stress using different cross combinations which could be helpful for selecting a suitable breeding strategy. Thus six generations of five crosses were sown normal (non-stress, TS) and late (heat stress, LS) in a randomized block design with three replications during two crop seasons. The model was not adequate for late sown conditions indicating the expression of epistatic genes under stress conditions. The traits i.e. Days to heading (DH), Days to anthesis (DA), Days to maturity (DM), Grain filling duration (GFD), Grain yield (GY), Thousand grain weight (TGW), Grain weight per spike (GWS) and Heat susceptibility index (HSI) under heat stress conditions were found under the control of additive gene action with dominance × dominance interaction, additive gene action with additive × dominance epistatic effect, dominance gene action with additive × additive interaction effect, additive and dominance gene action with dominance × dominance interaction effect, additive gene action with additive × dominance epistatic effect, additive gene action with additive × additive interaction effect and dominance gene action with additive × additive interaction effect, respectively.

Development of an efficient and reproducible regeneration system in wheat (Triticum aestivum L.)

The availability of reproducible regeneration system through tissue culture is a major bottleneck in wheat improvement program. The present study has considered to develop an efficient callus induction and regeneration system using mature and immature embryos as explants in recently released agronomically superior spring wheat varieties. An efficient sterilization process was standardized using 0.1% HgCl2 and 70% ethanol for both seeds and embryos. The maximum possible combinations of plant growth regulators (PGRs) were evaluated for their effect on different wheat regeneration processes through tissue culture starting from callus to root induction. Picloram is found as an effective auxin with 87.63–98.67% callus induction efficiency in both explants. Supplementation of CuSO4 along with 2,4-D, zeatin in regeneration medium significantly enhanced the multiple shoot induction. The shoot development was achieved using full strength Murashige and Skoog’s (MS) medium and root induction using half MS medium without PGRs. The optimized medium and method has resulted up to 100% regeneration irrespective of the genotype used with high reproducibility. Thus, the standardized regeneration system can be used in the regeneration of healthy plants from embryos rescued from interspecies crosses, transgenic production, induced mutation breeding and recently developed genome editing techniques for the procreation of wheat plants having novel traits.

Identifying wheat landraces as genetic resources for drought and heat tolerance

IPCC has predicted increase in drought and heat affected areas under wheat. To combat this challenge, development of heat and drought tolerant wheat genotypes is on priority. Landraces are unexploited genetic resources for various agronomic traits contributing tolerance to abiotic stress. Twenty-one wheat genotypes were evaluated in irrigated timely, rainfed timely and irrigated late field conditions for two years for their response to drought and heat stress. Genotypes differed significantly in their response to 1000-grain weight under stress conditions. Stress susceptibility index (SSI) was used to identify drought and heat tolerant genotypes. Nine genotypes were tolerant to drought stress and 11 to heat stress. Six of these genotypes were tolerant to both the stresses. SSR and allele specific markers were used to validate the results. Allelic variation for heat tolerance was observed in two genotypes IC 36761A and IC 41504 with gwm 63. Similarly, SNP marker for distinguishing drought tolerance in bread wheat was used and bi-allelic variation with this primer was observed in genotypes IC 57586, IC 30276A, IC 36761A and IC 31405B. IC 36761A was tolerant to both the stresses and was differentiated using molecular markers also. This genotype can be used for breeding drought and heat tolerant cultivars.

An Operations Research Study for Implementation of Public Private Mix Partnership in Revised National Tuberculosis Control Programme (RNTCP) in the State of Rajasthan

A study sponsored by Central TB Division, MOHFW, Government of India, with the overall objective of enhancing of PPM under RNTCP in the state of Rajasthan was conducted by National Institute of Health and Family Welfare (NIHFW). After completing the diagnostic part of the study, a new approach of horizontal integration of PP and NGO schemes was suggested to overcome implementation constraints at government functionaries level, private providers level and community level. During the study it emerged that under RNTCP, PPs and NGOs are being involved but demand for services and supply of services is not properly matched. It was found that 59.2 per cent of eligible PPs were willing to be involved in various schemes under RNTCP. 51 per cent PPs informed that detection rate and cure rate can be increased if more PPs are involved in the programme. The findings of the study reveal that to fill the gap of demand and supply, NGOs should be given the responsibility of handling the paper work of PPs. Besides, they may be given the task of address verification of TB patients, default retrieval and awareness campaign under RNTCP.