Tillage Effects on Crop Yield and Physicochemical Properties of Sodic Soils

Tillage modifies soil structure and has been suggested as a practice to improve physical, hydrological and chemical properties of compacted soils. But little is known about effect of long‐term tillage on physicochemical soil properties and crop yield on sodic soils in India. Our objective was to investigate the effect of different tillage regimes on crop yield (wheat and paddy rice) and physicochemical properties of sodic soils. Two sodic sites under conventional tillage for 5 (5‐YT; 5‐year tillage) and 9 (9‐YT; 9‐year tillage) years were selected for this study. Changes in crop yield and physicochemical soil properties were compared with a control, sodic land without any till history, that is, 0‐year tillage/untilled (0‐YT). Five replicated samples at 0‐ to 10‐cm and 10‐ to 20‐cm soils depths were analysed from each site. In the top, 0‐ to 10‐cm soil depth 5‐YT and 9‐YT sites had higher particle density (Pd), porosity, water holding capacity, hydraulic conductivity, organic carbon, total nitrogen (N_t), available nitrogen (N_avail), phosphorus (P_avail) and exchangeable calcium (Exch. Ca⁺⁺) than 0‐YT, whereas bulk density (Bd), C : N ratio and CaCO₃ were significantly lower. Bd, pH, EC and CaCO₃ increased significantly with depth in all the lands, whereas Pd, porosity, water holding capacity, hydraulic conductivity, organic carbon, N_t, N_avail, P_avail and Exch. Ca⁺⁺ decreased. We conclude that continuous tillage and cropping can be useful for physical and chemical restoration of sodic soils. Copyright © 2014 John Wiley & Sons, Ltd.     

The Influence of Plant Developmental Stage on Expression of Resistance to leaf Rust (Puccinia recondita) in Two Near Isogenic Lines of Wheat

Cultivar ‘Thatcher’, and ‘Thatcher’ lines with Lr 21 and Lr 22 were studied against a number of races of Puccinia recondita for seedling and adult plant reaction. The study has established that Lr 21 and Lr 22 are genes effective against P. recondita at adult plant stage. It has also shown that these genes confer resistance against all races when plants are inoculated at boot leaf stage.     

Fertility Improvement in Autotetraploids of Pea — Selection for Seed-Set and Disjunction Index

Four seed-set groups of plants, viz. unselected ‘general’ and selected ‘high’, ‘medium’ and ‘low’ were constituted in C₁ generation from randomly selected autotetraploids of two pea cultivars, T 163 and 5064-S. In C₂ generation, ten plants were selected at random in each of the four groups. Two seeds each from selected autotetraploids were drawn and bulked to make 20 seeds in each of the four groups to raise C₃ generation. Selection resulted in a gradual shift in seed-set, though the magnitude and nature varied with the group and generation. Improvement in the seed-set from C₁ to C₃ generation was associated with the increase in bivalents per cell, disjunction index and total chiasmata. Increase in total chiasmata was mostly due to an increase in proximal ones. Increase in seed-set was reflected in improvement of grain yield per plant.     

Callus Formation and Plant Regeneration from Protoplasts Derived from Suspension Culture of Rice (Oryza sativa L. cv. 'Taipei 177')

Protoplasts were isolated from young inflorescence-derived suspension cultures of a japonica rice cultivar ‘Taipei 177’. The isolated protoplasts which were cultured either in liquid, agar on Sea plaque agarose underwent sustained division. Maximum plating efficiency of 1.06% occurred in a medium containing macroelements of KM, microelements and vitamins of B5, 0.5 % Sea plaque agarose, 1.0 mg/l of 2,4-D, and glucose as an osmotic stabilizer. Green and albino plants were regenerated from the protocalli in MS semisolid medium containing 4 mg/l BAP, 0.5 mg/l NAA and 500 mg/l casein hydrolysate (MS_18–2).     

Initial screening of chili and sweet pepper germplasm for resistance to chili thrips, Scirtothrips dorsalis Hood

Summary A preliminary evaluation for resistance to chili thrips, Scirtothrips dorsalis Hood of 41 and 194 pepper (Capsicum annuum L.) germplasms during 1987 and 1988, respectively, indicated chili accessions may be a promising source of resistance. In contrast, all sweet pepper accessions tested were highly susceptible. A number of chili accessions produced a moderate yield, in spite of a high thrips infestation indicating tolerance to S. dorsalis. Rating for thrips damage was more reliable and efficient than estimating thrips numbers in screening pepper accessions for resistance to thrips. Highly significant, positive correlation between ratings at the seedling stage and final rating for thrips damage indicated the feasibility of screening pepper accessions at the seedling stage. Comparing the similarities in rating among accessions resulted in 40 distinct groups. The variance-covariance matrix of the data from these 40 groups was subjected to principal component analysis. This accounted for 56 and 18 per cent of the variation across the two principal axes, respectively. Projection of chili and sweet pepper accessions along these two axes revealed three distinct clusters. About 80 per cent of chili accessions formed the first cluster, 58 per cent of the sweet pepper accessions formed the second cluster and a third cluster exhibited intermediate ratings for thrips damage. The significance of these findings in relation to geographical divergence and resistance to thrips among pepper accessions is discussed.     

Aluminium tolerance in lentil (Lens culinaris Medik.) with monogenic inheritance pattern

The objectives of this study were to determine genetics of Al tolerance and whether the Al tolerance observed is governed by the same gene. The lines ‘L‐7903’ and ‘L‐4602’ have been developed through breeding programme as Al‐tolerant lines. These lines showed maximum root regrowth and minimum accumulation of Al and callose as compared to sensitive genotypes (‘BM‐4’ and ‘L‐4147’). Al tolerance in the parents, F₁, F₂ and backcross generations was estimated using the regrowth of the primary root after staining and scoring of fluorescent signals. The F₁ hybrids responded similarly to the tolerant parents, indicating dominance of Al tolerance over sensitivity. The segregation ratios obtained for Al tolerance and sensitivity in the F₂ and backcross generations were 3 : 1 and 1 : 1, respectively. Test of allelism confirmed the same gene was conferring Al tolerance in both genotypes (‘L‐7903’ and ‘L‐4602’) as the F₁ was also tolerant and no segregation of tolerant : sensitive was recorded. These results indicated that Al tolerance is a monogenic dominant trait that can be easily transferred to agronomic bases through backcross breeding technique.     

Identification of a diverse mini‐core panel of Indian rice germplasm based on genotyping using microsatellite markers

Identification of a small core germplasm set representing the available genetic diversity is essential for its proper evaluation and subsequent utilization in rice improvement programmes. For constituting a small diverse mini‐core panel of Indian rice germplasm, a representative set of 6912 accessions drawn based on their geographic origin from the whole rice germplasm collection available in the National Gene Bank was genotyped using 36 microsatellite markers. Automated fragment analysis of amplicons yielded a total of 435 alleles, with an average 12.4 and range of 3–29 alleles per locus. Polymorphism information content (PIC) ranged from 0.08 (RGNMS190) to 0.86 (RM552) with an average of 0.528. Based on genotyping data, a mini‐core consisting of 98 genotypes was identified. Ninety‐four per cent of the alleles present in the core set were present in the mini‐core. The identified small but diverse panel will be useful for further intensive trait‐specific evaluation and utilization in allele mining.     

Marker assisted accelerated introgression of null allele of kunitz trypsin inhibitor in soybean

Development of kunitz trypsin inhibitor (KTI)-free soybean is crucial for soy-food industry as the heat inactivation employed to inactivate the anti-nutritional factor in regular soybean incurs extra cost and affects protein solubility. In the presented work, a null allele of KTI from PI542044 was introgressed into cultivar ‘JS97-52’ (recurrent parent) through marker assisted backcrossing. Foreground selection in BC₁F₂, BC₂F₂ and BC₃F₂ was carried out using the null allele-specific marker in tandem with SSR marker Satt228, tightly linked with a trypsin inhibitor Ti locus. Background selection in null allele-carrying plants through 106 polymorphic SSR markers across the genome led to the identification of 9 KTI-free lines exhibiting 98.6% average recurrent parent genome content (RPGC) after three backcrosses, which otherwise had required 5–6 backcrosses through conventional method. Introgressed lines (ILs) were free from KTI and yielded at par with recurrent parent. Reduction of 68.8–83.5% in trypsin inhibitor content (TIC) in ILs compared to the recurrent parent (‘JS97-52’) was attributed to the elimination of KTI.