About ten thousand wheat grain samples belonging to various trials like AVTs, NIVTs, IVTs, Special Trials and QCSN of AICW & BIP were analysed every year and based on detailed physic-chemical, electrophoretic, rheological parameters, HMWGS and baking evaluation, promising varieties were identified for different wheat products like chapati (C 306, PBW 175, HI 1563, K 8027, HD 2888, HD 2864, HI 1500, NIAW 1415, Lok 1, Raj 4120, K 9107, HI 1531, HD 2932), bread (HI 977, NI 5439, WH 1021, NW 2036, WH 1080, NIAW 34, HD 2932, NIAW 1415, K 9107, Lok 1, HD 2189, HD 2781), biscuit (UP 2425, Sonalika, HS 490) and pasta (PDW 233, WH 896, WHD 943, HI 8663, PDW 291, HI 8703).
Evaluation of genotypes for host resistance:
- The host resistance is the main thrust for the management of biotic stresses in a most economic and acceptable manner. The Crop Protection programme is actively involved in evaluation of resistance in pre yield trial material as well as in national and international nurseries, NIVT and AVT entries under artificially created epiphytotics of diseases, nematodes and insect pests at Karnal as well as at the coordinated centres in different agro-climatic zones.
- During the last five years, roughly 12,000 entries of wheat were evaluated in the form of various nurseries, like, Initial Plant Pathological Screening Nursery (IPPSN), Plant Pathological Screening Nursery (PPSN), Elite PPSN (EPPSN), Karnal bunt Screening Nursery (KBSN), Leaf Blight Screening Nursery (LBSN), Head scab Screening Nursery ( HSSN), Multiple Diseases/ Pests Screening Nursery (MDSN/MPSN), Loose Smut Screening Nursery (LSSN), Foliar aphids Screening Nursery (FASN),CCN Screening Nursery, etc.
- The materials flow through EPPSN, MDSN and the final product goes into NGSN where more than 180 entries were contributed in the last five years from this programme. These entries possessed resistance to rusts, leaf blight, Karnal bunt, powdery mildew, loose smut, flag smut, foot rot, root aphid, shoot fly, brown wheat mite, etc as well as multiple resistances to diseases and insect pests. These resistant lines were used as direct selection as well as hybridization and per cent utilization by different centres was up to 64 per cent.
Survey and Surveillance:
- Crop health monitoing is very important in wheat, hence realising its importance, survey and surveillance of crop health status was done during the crop season every year to monitor the disease/pest problems of the crop. In 2001, a new yellow rust pathotype 78S84 virulent on PBW 343 was detected in Punjab. Wheat Crop Health Newsletter was issued regularly on monthly basis every year during the crop season since 1995. Status of wheat rusts was also monitored in SAARC countries with the collabroation of CIMMYT. This has helped in strategy planning and for taking pre-emptive measures to avoid the epidemics of disease/pests. During the crop seasons 2009-10 and 2010-11, the major damage to crop due to yellow rust in North India was averted through timely action taken on the basis of survey and surveillance programme. Hence, no epidemic of yellow rusts could occur in India during any of the crop seasons.
Post harvest surveys and market pathology:
- The post-harvest grain sampling and analysis of grain samples was done for monitoring the status of Karnal bunt disease and to identify the disease free or low disease regions. Other seed-borne maladies like black point and discoloration (which may be confused by traders with KB), and ear cockle nematode were also monitored. Based on these analyses, the ‘low risk zone’, ‘high risk zone’ and ‘no risk zone’ have been identified for Karnal bunt.
Pathogenic and molecular variability in wheat pathogens, viz., Karnal bunt, head scab and leaf blight:
- Pathogenic and genetic variation in wheat pathogens, viz., Tilletia indica, Fusarium spp. and Biploaris sorokiniana was done on host differentials and through use of molecular markers.
- Analysis of 850 isolates of Tilletia indica collected from north-western plains zone (NWPZ) over a span of three crop seasons through PAGE technique and RAPD analysis revealed the presence of three protein variants and confirmed their distribution to three agro climatic zones within the NWPZ. Artificial infection assays using paired monosporidial lines (MLs) in form of sporulating mycelia raised from haploid allantoid sporidia isolated from teliospores collected from various places in the states of north west India revealed 8 mating types (self incompatibility alleles) in this heterothallic fungal pathogen of wheat.
Pathogenic and molecular variation among Fusarium spp. causing head scab of wheat in India:
- Six Fusarium spp. viz., F. graminearum, F. moniliforme, F. oxysporum, F. equiseti, F. semitectum and F. solani were isolated from diseased spikes sampled from Punjab, Tamil Nadu, and lower, mid and high Himalayas of Himachal Pradesh. Identification of Fusarium spp. was also done by using species specific primers. Thus aggressiveness of geographically distinct isolates varied with in species.
- Cluster analysis of band sharing coefficients showed that there is a considerable genotypic variability among F. graminearum isolates obtained from infected wheat earheads from different geographic regions of India. Random Amplified Polymorphic DNA (RAPD) was also used to differentiate genetic variation in Fusarium spp. (31 isolates) pathogenic to wheat.
Pest situation in new RCTs:
- Pest system is highly influenced by the tillage practices. Role of tillage practices on pest situation was worked out which indicated higher incidence/damage of powdery mildew and termites under FIRBS wheras a reduced incidence/damage of powdery mildew, Karnal bunt and termites in zero tillage.
Evaluation and promotion of IPM modules at farmers fields:
- The IPM in wheat was introduced in late 90’s. it was later on validated and promoted on long scale at the farmers’ fields. Using farmers participatory approach in two districts of Haryana, viz., Karnal and Kaithal over a period of five years, an yield advantage of 9-15 per cent has been obtained consistently over the years which has encouraged the farmers to take up this technology on large scale. This technology has been transferred to the Extension Wing of the DWR Karnal. These IPM modules, with slight modifications, have been extended to the North Eastern Plain Zone and the Peninsular Zone through the involvement of the AICW&BIP centres. Encouraging results have been obtained and the studies are in progress through these cooperating centres.
Combating Leaf blight menace:
- Leaf blight is a major biotic factor responsible in lowering the wheat productivity in hot and humid environments of eastern India. Monitoring of leaf blight pathogens indicated that Bipolaris sorokiniana is the most predominant pathogen at national level. Based on cultural and morphological variations, 13 distinct isolates of B. sorokiniana and two of A. triticina, were categorized in different agroclimatic zones. The efforts for incorporating the resistance in wheat varieties against leaf blight were intensified during last five years have lead to improvement in the level of resistance against leaf blight in entries from various centers of eastern India.
Management of diseases and pests:
- Though wheat environment is relatively free from the use of pesticides, the judicious usage of chemical pesticides is recommended as a part of contingent plan to manage the diseases/pests as well as in cases where host resistance is not available. Hence, recommendation of newer fungicides like Raxil 2DS (tebuconazole), Thifluzamide, Tilt 25EC (propiconazole) for control of loose smut and Karnal bunt was made. Also Thiamethoxam 70WS and Fipronil as seed treatment for control of termites, Thiamethoxam 25 WG and Dantop 50 WG (clothianidin) were recommended as foliar sprays for the control of foliar aphids. The Confidor 200SL and Tilt 25EC were tested and found compatible for making combined sprays to control Karnal bunt and foliar aphids in wheat. Recommended Vitavax 200 WS for managing the loose smut and leaf blight in wheat. Recommended the use of Neem based pesticides and other botanicals for the control of leaf blight in wheat. As a part of biological control, Trichoderma viride was found effective for the control of loose smut smut and Karnal bunt diseases.
Rust pathotype monitoring and rust resistance gene postulation:
- The analysis of rust samples collected all over the wheat growing regions of the country on differential sets revealed the presence of different resistance genes. There have been differences in viluence pattern in case of brown and yellow rusts in different wheat growing zones. It may be mainly due to gene deployment and the varietal diversification characterized by cultivation of at least 55 different wheat varieties in India possessing different sets of genes for rust resistance. The strategic varietal diversification and their deployment over space and time has indeed helped in the yield stability and avoided rust epidemics over past four decades.
- The distribution pattern of rusts pathotypes varied with the type of cultivars grown over years. During the past few years, there is a quick appearance of new brown rust pathotypes overcoming the resistance imparted by Lr 26. This is in response to increased area under wheat possessing this gene. The pathogen evolution seems to be guided by the nature of wheat varieties under cultivation. A successful breeding programme has to remain one step ahead of the pathogen evo¬lution. Recently, the rust pathotypes like 78S84 (yellow rust) and Ug 99 (stem rust) have emerged which are posing real threat to present day varieties of wheat.
- The genetic stocks and genotypes have been identified and registered possessing resistance to the three wheat rusts and diseases such as foliar blight, loose smut, powdery mildew, flag smut and Karnal bunt. There is large number of material that possessed resistance to the foliar blight caused by Bipolaris sorokiniana.
- Brown rust race distribution frequency at national level shows that pathotypes of race groups 104 and 12 have reduced and that race 77 has increased steeply. The distribution pattern of the virulences gives the much needed indications for executing the resistant gene deployment.