S. V. Sai Prasad

Traits and selection strategies to improve root systems and water uptake in water-limited wheat crops

Wheat yields globally will depend increasingly on good management to conserve rainfall and new varieties that use water efficiently for grain production. Here we propose an approach for developing new varieties to make better use of deep stored water. We focus on water-limited wheat production in the summer-dominant rainfall regions of India and Australia, but the approach is generally applicable to other environments and root-based constraints. Use of stored deep water is valuable because it is more predictable than variable in-season rainfall and can be measured prior to sowing. Further, this moisture is converted into grain with twice the efficiently of in-season rainfall since it is taken up later in crop growth during the grain-filling period when the roots reach deeper layers. We propose that wheat varieties with a deeper root system, a redistribution of branch root density from the surface to depth, and with greater radial hydraulic conductivity at depth would have higher yields in rainfed systems where crops rely on deep water for grain fill. Developing selection systems for mature root system traits is challenging as there are limited high-throughput phenotyping methods for roots in the field, and there is a risk that traits selected in the lab on young plants will not translate into mature root system traits in the field. We give an example of a breeding programme that combines laboratory and field phenotyping with proof of concept evaluation of the trait at the beginning of the selection programme. This would greatly enhance confidence in a high-throughput laboratory or field screen, and avoid investment in screens without yield value. This approach requires careful selection of field sites and years that allow expression of deep roots and increased yield. It also requires careful selection and crossing of germplasm to allow comparison of root expression among genotypes that are similar for other traits, especially flowering time and disease and toxicity resistances. Such a programme with field and laboratory evaluation at the outset will speed up delivery of varieties with improved root systems for higher yield.

Reclamation of alkali soils : Influence of amendments and leaching on transformation and availability of phosphorus

Abstract Phosphorus (P) availability to plants in reclaimed alkali soils was the main objective of this study, which was also focused on P transformations, decrease in Olsen‐P content, and magnitude of P lost in leachate in course of amendment application and leaching. Liquid sodium bicarbonate (NaHCO3) was added to nonalkali soils to set up four ESP (exchangeable sodium percentage) levels (viz., 2.9, 25.0, 50.0, and 75.0), but actual ESP levels obtained were 2.9, 24.6, 51.2, and 75.3. Amendments (viz., gypsum and pyrites) and P treatments (viz., 0 and 50 mg P Kg−1) were mixed with dry, sieved soil before filling into PVC (polyvinyl chloride) drainage columns, which were then compacted to uniform bulk density and leached with deionized water for 30 days. Results indicated that the pH and electrical conductivity (EC) of the soils increased with increase in ESP level of the soil but decreased with amendment application. Phosphorus addition to alkali soils decreased the pH on day 30, but it could not affect the EC of the soils. Successive increase in the ESP level of the soil increased the pH and EC off the leachate. Gypsum‐amended soils exhibited lower pH and EC values than pyrite‐amended soils. The EC of the leachate decreased sharply with time in amended soils, but the pH decreased slowly. Phosphorus addition affected the leachate pH earlier than the soil pH. Cumulative volume of leachate decreased with increasing ESP levels, but it increased with amendment and phosphorus application. Leaching of P increased with increase in ESP levels, and the maximum cumulative loss of P was 11.2 mg Kg−1 in the 75.3 ESP soil. Cumulative P lost in the pyrite‐amended soils was higher than the gypsum‐amended soils. Phosphorus leaching in the gypsum‐amended soils stopped at day 10 and beyond, but it continued until day 30 in the pyrite‐amended soils. Part of the applied P in alkali soils was also lost along with the native P, whereas it was protected in the nonalkali soils. OlsenP increased with increasing ESP levels, and alkali soils invariably contained higher Olsen P than nonalkali soils. At day 30, alkali soils contained much higher Olsen P (12.6 mg Kg−1) than nonalkali soils (5.9 mg Kg−1). In general, there was a decrease in the Olsen P with both of the amendments, but it decreased more with pyrites than with gypsum. Phosphorus added through monopotassium phosphate (KH2PO4) remained extractable by Olsens extractant up to day 30. Results also indicated that percent distribution of ammonium chloride (NH4Cl)‐P, calcium (Ca)‐P, and unknown P increased with rising ESP levels but iron (Fe)‐aluminum (Al)‐bound P and residual P decreased. Percent distribution of Ca‐P and unknown P exhibited an increase with time also. Unamended alkali soils contained more NH4Cl‐P than amended ones. Iron and Al‐ bound P and residual P increased more with pyrites, whereas formation of Ca‐P and unknown P was enhanced with gypsum. Applied P tended to convert more into NH4Cl‐P, Ca‐P, and residual P than to Fe‐Al‐bound P or unknown P fractions. Models developed to estimate Olsen P and P concentration in leachate, through pH or EC, have application value for P management in alkali soils that are leached after application of amendments.

Wheats developed for high yield on stored soil moisture have deep vigorous root systems

Many rainfed wheat production systems are reliant on stored soil water for some or all of their water inputs. Selection and breeding for root traits could result in a yield benefit; however, breeding for root traits has traditionally been avoided due to the difficulty of phenotyping mature root systems, limited understanding of root system development and function, and the strong influence of environmental conditions on the phenotype of the mature root system. This paper outlines an international field selection program for beneficial root traits at maturity using soil coring in India and Australia. In the rainfed areas of India, wheat is sown at the end of the monsoon into hot soils with a quickly receding soil water profile; in season water inputs are minimal. We hypothesised that wheat selected and bred for high yield under these conditions would have deep, vigorous root systems, allowing them to access and utilise the stored soil water at depth around anthesis and grain-filling when surface layers were dry. The Indian trials resulted in 49 lines being sent to Australia for phenotyping. These lines were ranked against 41 high yielding Australian lines. Variation was observed for deep root traits e.g. in eastern Australia in 2012, maximum depth ranged from 118.8 to 146.3cm. There was significant variation for root traits between sites and years, however, several Indian genotypes were identified that consistently ranked highly across sites and years for deep rooting traits.

Evaluation of root characteristics, canopy temperature depression and stay green trait in relation to grain yield in wheat under early and late sown conditions

Forty wheat varieties was evaluated for grain yield in the field for two successive crop seasons (2009–10 and 2010–11), with 2 dates of sowing, viz., early (last week of October) and late (first week of December). Based on the yield potential, five high yielding and five low yielding varieties were selected to study the relationship between grain yield and root characteristics along with canopy temperature depression (CTD) and flag leaf drying under early and late sown conditions. It was observed that under early sown restricted irrigation conditions the high yielding varieties utilized energy in increasing the root length and root density to deeper soil depths instead of accumulating root weight, compared to low yielding varieties. In contrast, under late sown condition, the high yielding varieties had more root weight and density in their upper soil depths, compared to low yielding varieties. Hence, it can be suggested to select wheat varieties with high root density and more root length in the lower depths of the soil for rainfed/restricted irrigation conditions to mitigate the early heat effects, and varieties having high root density and more root length in the upper layers of the soil for late sown conditions to tolerate the late or terminal heat. Further, high CTD scores at 1st stage (vegetative) and high leaf score at fourth stage (post flowering) were found to be important selection parameters, which help in reducing the evapo-transpiration and increase 1000 grain weight under early sown limited irrigation condition, and thereby increase the grain yield; whereas, CTD at 3rd stage (flowering stage) contribute to maintain the stay green trait for longer period and reduce the loss due to evapo-transpiration and in-turn increase the grain yield under late sown conditions. These traits can be used as selection tools for physiological breeding programme to increase the production and productivity of wheat.

Genetic diversity for moisture deficit stress adaptive traits in bread wheat (Triticum aestivum L.)

A study was conducted to evaluate the genetic divergence for morphological and phenological traits under rainfed conditions in wheat. Seed material comprised of the 294 wheat genotypes used for this study and grouped into six clusters. Among the six clusters, cluster IV contained 86 and cluster I had 68 genotypes, followed by 12 genotypes in cluster V. Fifty one genotypes were grouped in cluster VI and 52 were included in cluster II, while cluster III was represented by 27 genotypes. Maximum cluster mean for the character grain yield per plot was observed for the cluster III (667.1) followed by cluster V (559.3). The minimum cluster mean under the rainfed conditions was observed for the cluster IV (269.3). Intra cluster distance was maximum for cluster III (3.125). The highest inter cluster distance was noted between cluster II and cluster IV (4.997). Parentage of 294 genotypes revealed that genotypes belonging to different eco-geographical areas were included in the same cluster. This indicated that there was no association between clustering pattern and eco-geographical distribution of genotypes.

Central Wheat Hs562'-A High Yielding Wheat Variety for Timely Sown Production Conditions of Northern Hill Zone

Dharam Pal1*, Madhu Patial1, KV Prabhu2, J Kumar1,7, Santosh Watpade1, RN Yadav3, Sanjay Kumar2, RK Sharma2, GP Singh2,8, Rajbir Yadav2, Vinod2, Anju M Singh2, SV Sai Prasad4, IS Solanki6,9, M Sivasamy5, JB Sharma2, PK Singh2, Neelu Jain2, Niharika Mallik2, Kiran Gaikwad2, Tapas Ranjan Das6, Vikas5, Jaya Prakash5, JB Singh2, Divya Ambati4, Vaibhav Singh2, AN Mishra4, Shivadhar2 and Ajay Arora2 1ICAR-IARI, Regional Station, Shimla, India 2ICAR-Indian Agricultural Research Institute, New Delhi, India 3ICAR-Indian Agricultural Research Institute, Regional Station, Karnal, India 4ICAR-Indian Agricultural Research Institute, Regional Station, Indore, India 5ICAR-Indian Agricultural Research Institute, Regional Station,Wellington, India 6ICAR-Indian Agricultural Research Institute, Regional Station,Pusa, India 7ICAR-NIBSM, Raipur, India 8ICAR-Indian Institute of Wheat and Barley Research, Karnal, India 9ICAR-Krishi Bhawan, New Delhi

Genetic Variability, Heritability and Diversity for Yield Contributing Traits in Reference Varieties of Wheat

Genetic variability study in 129 wheat varieties (80 bread and 49 durum wheat) revealed high magnitude of variability and high degree of heritability for majority of yield associated traits. Difference between the PCV and GCV was high for harvest index followed by number of grains per spike and grain yield/plant indicating the influence of environment on their expression. High magnitude of genotypic coefficient of variation (≥ 17.0%) was observed for spike length, plant height, grain yield/plant and flag leaf length, which indicates high degree of genetic variability and offers great scope for selection of these characters. High to moderate heritability coupled with high to moderate genetic advance as percentage of mean was exhibited for 7 traits viz., days to flowering, days to maturity, plant height, number of tillers/plant, biomass/plant, flag leaf length and 1000 grain weight, which indicated the predominance of additive gene action in the expression of these characters and very high possibility of improvement through selection for all these characters. Bread wheat varieties viz., CPAN 3004, GW 322, HI 617, HI 1500, DWR 39, DWR 195, GW 89, UP 2113, NP 700 and NP 771 and durum wheat varieties viz., A-28, HI 8381, MPO 215, HD 4530, HD 4672, NIDW 295, Raj 1555 and UAS 415 were found to be superior for grain yield and other traits along with being divergent from other lines, which can be utilized as donors for developing superior genotypes with high grain yield.

Near-isogenic lines in NP 4 background carrying the genes Lr13, Lr18, Lr19 and Lr26 as locally adapted differentials for Indian pathotypes of wheat leaf rust

A backcross programme was conducted to transfer 13 of the Lr genes present in the leaf rust differentials being currently used in India viz., Lr1, Lr2a, Lr2c, Lr3a, Lr9, Lr10, Lr13, Lr15, Lr17a, Lr18, Lr19, Lr20 and Lr26 in the background of wheat variety NP 4 having desired agronomic traits. Homozygous resistant lines carrying these genes singly have been developed through six backcrosses and subsequent selection. Nine of these lines have already been reported. Present communication reports the remaining four lines carrying the genes Lr13, Lr18, Lr19 and Lr26. These lines being locally adapted and early maturing are easy to maintain under Indian conditions, and can be widely used for virulence analysis and genetic studies.

Oral health status and awareness among tuberculosis patients in an Indian population

BACKGROUND Knowledge and awareness regarding oral health problems of tuberculosis patients are lacking among patients, physicians, as well as dental practitioners. AIM This study aimed to assess the oral health status and awareness among the tuberculosis patients in an Indian population. METHODS Study sample comprised of 210 tuberculosis patients and 210 nontuberculosis subjects. The tuberculosis patients were categorized into new patients (group A), previously treated (group B), and drug-resistant tuberculosis patients (group C). History of present problem and awareness about oral health was noted. Periodontal health status was ascertained using Community Periodontal Index (CPI). Other oral findings were also recorded. RESULTS The results were analyzed statistically. 62.9% of total tuberculosis patients had one or more oral problems. Most common problem was tooth pain (34%). CPI score was significantly higher (p<0.05) for tuberculosis patients (2.94) than in control group (1.34). Mean CPI score for groups A, B, and C patients was 2.83, 2.91, and 3.09, respectively. CONCLUSION This study suggests awareness of oral health status and oral manifestations of tuberculosis among physicians and dental professionals.

Near-isogenic lines in NP 4 background carrying the genes Lr1, Lr2a, Lr2c, Lr3a, Lr9, Lr10, Lr15, Lr17a and Lr20 as locally adapted differentials for Indian pathotypes of wheat leaf rust

Wheat leaf rust differentials being used in India include selected near-isogenic Lr lines in ‘Thatcher’ background (set A), some of the historical differentials like Malakoff, Webster, Loros etc. (set B) and IWP 94 (Lr23) out of a set of eight Indian wheat genotypes (set 0). The set A lines and most varieties in set B are late maturing as they require long photoperiod for flowering, which limits their utilization in virulence analysis and genetic studies under Indian conditions. A backcross programme was conducted to transfer those Lr genes which occur in these lines and varieties in the background of NP 4 having desired agronomic traits. Nine homozygous resistant lines carrying Lr1, Lr2a, Lr2c, Lr3a, Lr9, Lr10, Lr15, Lr17a, and Lr20 have been developed through six backcrosses and subsequent selection based on seedling tests with appropriate leaf rust pathotypes of selected BC6F3 lines having NP 4 plant type. These lines being locally adapted and early maturing are easy to maintain under Indian conditions, and can be widely used for virulence analysis and genetic studies.