Productivity potential and monetary evaluation of Bt cotton hybrids under varied agronomic manipulations in semi-arid conditions.

Field experiments comprising three Btcotton hybrids in main, two plant geometries in sub and three nutrient levels in sub sub plots of Split Plot design replicated thrice were conducted at PAU, Regional Research Station, Faridkot during Kharif 2010 and 2011. MRC7361 recorded significantly the highest SCY (3121.6 kg ha(-1)) followed by Bioseed 6488 (2649.5 kg ha(-1)) and RCH134 (2107.4 kg ha(-1)). Statistically improved bolls per plant and boll weight primarily helped MRC7361 in achieving the highest yield. Owing to better fertilizer use efficiency (5.47) and water productivity (649.3 gm(-3)), highest net returns of < or = 101047 ha(-1) were observed with MRC7361 as compared to Bioseed 6488 (< or = 83343 ha(-1)) and RCH134 (< or = 63014 ha(-1)). Bolls per plant and benefit cost ratio was significantly enhanced under wider geometry of 67.5 x 90 cm. Application of 225 kg N, 45 kg P ha(-1) produced significantly higher SCY (2825.9 kg ha(-1)) owing to improved sympods and bolls per plant than 150 kg N, 30 kg P ha(-1) (2374.9 kg ha(-1)) and 187.5 kg N, 37.5 kg P ha(-1) (2677.6 kg ha(-1)). As a result of this, statistically highest net returns of < or = 89552 ha(-1) were obtained with application of 225 kg N, 45 kg Pha(-1). Water productivity improved significantly with each successive increase in the level of nutrients. Contrarily, fertilizer use efficiency exhibited reverse trend with statistically highest value (5.08) for the lowest level of nutrients.

Yield and fibre quality associated with cotton leaf curl disease of Bt-cotton in Punjab.

Cotton leaf curl disease (CLCuD), caused by Gemini virus and transmitted through whitefly (Bemisia tabaci) is a serious problem in Northern India, affecting the productivity to a great extent. Depending upon the severity of infection in susceptible varieties, the disease can cause upto 90.0 % yield losses besides this, it also causes deterioration in fibre quality. The objective of the present study was to determine the effect of cotton leaf curl disease on seed cotton yield and fibre characters of two popular Bt-cotton hybrids in Punjab. The disease caused 52.7% reduction in number of bolls and 54.2 % in boll weight in Bt cotton hybrid RCH 134. Similarly, it reduced the fibre length from 29.1 to 26.2 mm (9.9%); fibre uniformity from 68.9 to 68.1% (1.1%); fibre strength from 29.1 to 26.9 g per texture (7.5%) and miconaire value from 5.2 to 5.0 g inch(-1) (3.8%). Similar results were reported in Bt cotton hybrid MRC 6304, where the disease reduced the boll number and boll weight by 46.1 and 43.4%, respectively. However, to the fibre quality was not much affected by varying level of disease severity. The studies clearly reflect the adverse impact of CLCuD on yield and fibre quality especially 2.5% span length. Thus suggesting the management of disease using integrated disease management strategies to avoid quantitative and qualitative losses.

Prediction of testcross means and variances among F3 progenies of F1 crosses from testcross means and genetic distances of their parents in maize.

Prediction of the means and genetic variances in segregating generations could help to assess the breeding potential of base populations. In this study, we investigated whether the testcross (TC) means and variances of F3 progenies from F1 crosses in European maize can be predicted from the TC means of their parents and F1 crosses and four measures of parental genetic divergence: genetic distance (GD) determined by 194 RFLP or 691 AFLP(TM) (1) markers, mid-parent heterosis (MPH), and absolute difference between the TC means of parents (∣P1-P2∣). The experimental materials comprised six sets of crosses; each set consisted of four elite inbreds from the flint or dent germplasm and the six possible F1 crosses between them, which were evaluated for mid-parent heterosis. Testcross progenies of these materials and 20 random F3 plants per F1 cross were produced with a single-cross tester from the opposite heterotic group and evaluated in two environments. The characters studied were plant height, dry matter content and grain yield. The genetic distance between parent lines ranged between 0.17 and 0.70 for RFLPs and between 0.14 and 0.57 for AFLPs in the six sets. Testcross-means of parents, F1 crosses, and F3 populations averaged across the six crosses in a particular set generally agreed well for all three traits. Bartlett's test revealed heterogeneous TC variances among the six crosses in all sets for plant height, in four sets for grain yield and in five sets for dry matter content. Correlations among the TC means of the parents, F1 crosses, and F3 populations were highly significant and positive for all traits. Estimates of the TC variance among F3 progenies for the 36 crosses showed only low correlations with the four measures of parental genetic divergence for all traits. The results demonstrated that for our material, the TC means of the parents or the parental F1 cross can be used as predictors for the TC means of F3 populations. However, the prediction of the TC variance remains an unsolved problem.

Comparative efficiency of four selection methods for deriving high-yielding lines in mungbean [Vigna radiata (L.) Wilczek].

The comparative efficiency of four selection methods, viz., honeycomb (HC), pedigree selection (PS), single-seed descent (SSD) and the bulk method (BM), was assessed in three crosses of mungbean. The lines derived by each method, along with check varieties, were yield-tested in a compact family block design in F5 and F6 generations during summer and kharif of 1990. On the basis of the mean of the lines, the range, the number of superior lines over the best check, and the proportion of the top 10% lines in all the crosses and generations, the honeycomb method exhibited superiority over PS, SSD and BM for yield per plant and its component traits. PS, SSD and BM did not differ from each other. The honeycomb and SSD methods were found suitable for deriving superior lines for seed yield and pods per plant in mungbean.