Scope For Yield Improvement Research Articles

Exploitation of combining ability and heterosis potential for improvement in okra (Abelmoschus esculentus) genotypes

The present investigation was undertaken with the objective to carry out combining ability and heterosis for 13fruit yield and its attributing traits in 14 parents and their 24 crosses in okra (Abelmoschus esculentus (L.) Moench)at vegetable research farm, CCS Haryana Agricultural University, Hisar, Haryana during spring-summer season2019–20 and rainy (kharif) season 2020–21. Four crosses, viz. HB-20-3-4 × Hisar Naveen (HN), Hisar Mutant (HM)-1× Hisar Unnat (HU), HBMS-1 × Hisar Unnat (HU) and HB-76-2-4 × Hisar Naveen (HN) showed highly significantpositive economic heterosis for yield and its contributing traits.Parents HB-20-3-4 and HM-1 were found to be thebest general combiner for most of the economic traits. While, cross HB-60-1 × HN followed by HBMS-1 × HU, HB-20-3-4 × HN, HM-1 × HU and HB-96-2 × HU demonstrated strong SCA effects for yield and its attributes. The ratio of general combining ability (σ2GCA) and specific combining ability variances (σ2SCA) was less than one for all the quantitative traits indicating the non-additive gene effects predominated in determining the expression of allthese characters and demonstrates variability in genotypes, which provide ample scope for improvement of yield and its contributing traits in okra. Line HB-60-1 when crossed with Hisar Naveen, and HBMS-1 with Hisar Unnat gavesuperior hybrids as compared to other crosses. Hence, these parents can be exploited for further genetic improvement programmes and isolation of desirable segregants in okra.

Enhancement of mycelial biomass and lignocellulolytic enzymes of milky mushroom Calocybe indica through supplementation with organic amendments

Milky mushroom (Calocybe indica) also known as tropical mushroom or summer mushroom has significant attributes of milky white colour with high nutritive value and long shelf life. The yield performance of milky mushrooms again depends on the secretion of lignocellulolytic enzymes that further influence the colonization of mycelium on the substrates. In the present study, organic supplements viz. cakes of cotton, groundnut, sesamum, coconut cake, neem cake, powdered moth bean, red gram, horse gram, green gram, soya bean, lab-lab, maize, rice bran and wheat bran amended at 1% and 5% concentration induced profuse mycelial growth and enhanced ligninolytic enzyme secretion by Calocybe indica under in vitro conditions. The results revealed that wheat bran and red gram supplements at 5 % concentration in PDA medium were found to influence the mycelial growth on the 7th day (68.67 mm and 62.33 mm respectively). Similarly, both wheat bran and red gram supplements at 5 % in liquid medium supported increase in the biomass production of C. indica on the 15th day (1.83 and 1.40 g) followed by horse gram. The influence of organic supplements on the induction of lignocellulolytic activity showed that the maximum cellulase and xylanase activity (1.7 U/min/g and 0.835 U/min/g respectively) and laccase activity (1.6 U/min/g) were noticed in the substrate supplemented with wheat bran followed by horse gram (1.3 U/min/g) at 5% concentration under solid-state fermentation. However, the lignin peroxidase activity was maximum (0.59 U/min/g) in combination with wheat bran (2.5%) and red gram (2.5%) and manganese peroxidase activity was maximum in wheat bran supplement (0.3 U/min/g) at 5% concentration. It is inferred that amending organic supplements viz. wheat bran, horse gram and red gram to substrates enhance the mycelial growth, biomass production and lignocellulolytic enzyme secretion of C. indica and offers scope for yield improvement.

Genetic Diversity, Character association and Path-Coefficient study in QPM inbreds

The thirty seven inbreds of quality protein maize of diverse origin, evaluated in RBD showed significant difference among the inbreds in respect of grain yield and its component traits. The characters like days to 50 % tasseling, days to 50 % silking and days to 75% dry husk were less influenced by the environmental factors because of lower differences in magnitudes between GCV and PCV. On the contrary, the characters like cob girth, number of kernels per row, number of kernel rows per cob and grain yield per plant were much influenced by the environmental factors as evidenced from higher differences in magnitude of PCV and GCV. High heritability with low genetic advances for characters like days to 50% tasseling, days to 50 % silking and days to 75 % dry husk indicated the predominance of non-additive gene action whereas high heritability with high genetic advance was reported for cob weight indicating the role of additive gene action. The characters viz., cob weight, 100- kernel weight, plant height, ear height, and no. of kernels per row were highly and positively correlated with grain yield per plant at genotypic and phenotypic levels. Ear height (0.837), days to 50 % silking (0.526) and number of kernels/rows per cob (0.455) in that order had large positive direct effect on grain yield per plant at genotypic level. Similar trend was also observed at phenotypic level. The indirect effects were generally small with only a few exceptions. A close examination of all the direct and indirect effects of the components traits on yield indicated the presence of enough scope for yield improvement through selection for no of leaves per plant, cob length, no. of kernels per row, cob weight and 100-kernel weight. Based on 14 quantitative characters, the 37 quality protein maize inbreds were grouped into13 clusters following D 2 analysis and Tocher™s method of grouping. Among the yield traits, days to 50 % silking, days to 50% tasseling, days to 75% dry husk, cob weight, 100 kernel weight and grain yield per plant were found to be the major contributor towards genetic divergence. The overall clustering pattern indicated that QPM 3-7, QPM 9-18, and QPM 1110-7-2 were much divergent from rest of the inbreds in the experiment. Similarly, the inbreds of cluster III and XI and inbreds of clusters IX, III and X were distantly and distinctly related to each other. The pattern of clustering as stated above further indicated that there was no strict association between inbreds developed from diverse base populations.

Evaluation of genetic diversity for yield and quality parameters of different potato (Solanum tuberosum L.) germplasm

An investigation was carried out at Vegetable Research Centre, G.B. Pant University of Agriculture and Technology, Pantnagar during spring-summer season 2011 and 2012 to study the genetic diversity using Mahalanobis’s D2 – technique among thirty five potato (Solanum tuberosum L.) germplasm for important yield attributing and quality traits. The D2 values were calculated and thirty five potato genotypes were grouped into nine clusters for growth characters and ten clusters for quality traits respectively. All the genotypes included in the present investigation, were indigenous, but their grouping in different clusters, suggested that genotypes did not follow the geographic distribution. The cluster I contained the maximum number of genotypes with respect to both yield attributing and quality traits. The inter cluster distance in most of the cases were higher than the intra-cluster distance indicating wider genetic diversity among the genotypes of different groups. Average tuber weight of potato plant contributed maximum (31.76%), followed by number of tuber per plant (27.56%), internodal length (14.45%) and plant dry matter content (13.61%) for growth characters. For quality characters, ascorbic acid content (24.70%), protein content of tuber (20.84%) and TSS of tuber (20.00%) contributed effectively towards genetic divergence. So, these traits will offer a good scope for improvement of yield and quality through rational selection of parental genotypes for future potato breeding. The findings indicated that use of parents selected from the same cross or from a cross involving a common parent should be avoided in hybridization. The results broadly showed there was no parallelism between geographical and genetic divergence.

Growth of sugarcane under high input conditions in tropical Australia. II. Sucrose accumulation and commercial yield

Information on the processes controlling the accumulation of sucrose over time can be used to assess the physiological basis of yield variation and consequently the scope for yield improvement in sugarcane. As commercial yield is commonly expressed on a fresh weight basis, and dry weight measures of sucrose accumulation aid biological interpretation, there is a need to study yield accumulation on both a fresh and dry weight basis. This study analysed the pattern of sucrose accumulation in the stalk in relation to crop biomass, and the concentration of sucrose in the stalk on a fresh and dry weight basis of two contrasting cultivars (Q117 and Q138) of sugarcane during the same season in tropical Australia, with irrigation and under plant and ratoon crop conditions. Over the 15 month season, 11 crop samplings were conducted. The key findings were that (1) greater than 95% of the aboveground sucrose accumulation is in the stalk; (2) a logistic relationship described the time trend in stalk sucrose accumulation, with maximum sucrose yield occurring 100 days before final harvest; (3) stalk biomass rather than stalk sucrose concentration was the major determinant of stalk sucrose accumulation; (4) maximum stalk sucrose concentration was stable across cultivars and crop classes at a value of 0.48 g g −1 stalk dry weight; (5) commercial yield expressed as the fresh millable stalk yield plateaued up to 230 days before final harvest and well before the attainment of maximum stalk biomass and sucrose yield due to increases in dry matter content during growth; (6) maximum stalk sucrose concentration on a fresh weight basis was obtained at a later crop age and was more variable across crops than maximum stalk sucrose concentration on a dry weight basis. The study highlighted the major influence that stalk dry matter content has on the relationship between sucrose yield and commercial yield, and that biological interpretation of crop response to climatic and management factors is difficult based on commonly available fresh weight measures of productivity. Optimising economic return from commercial sugarcane production requires further understanding on the factors controlling the dynamics of stalk dry matter content.

Radiation interception and biomass accumulation in a sugarcane crop grown under irrigated tropical conditions

Little quantitative information relating yield accumulation in sugarcane to climatic factors is available to allow the maximum yield in different seasons and locations to be determined. By comparison of actual yield with the climatically determined maximum yield for a given crop, the extent of yield limitation due to management and soil and pest factors can be assessed. This paper analyses the relationship between radiation interception and biomass accumulation for an autumn-planted sugarcane crop grown under irrigated conditions at Ayr, Qld (lat. 19.5� S.). Crop samplings were conducted from 167 to 445 days after planting (DAP). Less than 60% of the seasonal incident solar radiation was intercepted by the crop. A radiation extinction coefficient of 0.38 was estimated from the relationship between green leaf area index and the fraction of the radiation intercepted (fi). A maximum crop radiation (SW, 0.35-2-5 8m) use efficiency (RUE) of 1.75 g MJ-1 was determined. The maximum crop growth rate over a 140 day period was 41.1 g m-2d-1. However, this value is dependent on fi and the incident radiation ( S ) , and accordingly would be expected to vary across locations. In contrast, the RUE value of 1.75 g MJ-1is independent of fi and S, and can be used as a baseline value to assess the extent of yield limitation and the scope for yield improvement at different locations. The maximum biomass production was 72 t ha-1and the maximum fresh cane yield was 201 t ha-1. However, these maximum yields were attained up to 4 months before the final sampling. Future research should examine the wider applicability of this early yield plateau, and focus on the factors responsible for the early cessation in yield accumulation.

Heterologous Protein Production by Filamentous Fungi

There are clearly many facets to successful production of heterologous proteins from filamentous fungi. The objectives are to exploit the natural ability of some species to secrete high levels of protein. The heterologous target proteins produced in a fungal host must be acceptable to the public and be economic to produce, i.e. the targets must be authentic (in structure and activity) and be produced in high yield to necessary levels of purity. The appearance of heterologous products from fungi on the market is testament to some success but, equally, there are considerable limitations in our ability to produce desired yields of many target proteins. We endorse the view of van den Hondel, Punt and van Gorcom (1991) that for the commercial production of heterologous proteins from filamentous fungi more information is required on transcriptional control, introns, mRNA stability and processing, translational efficiency, protein secretion, glycosylation and proteolysis. In addition, there is scope for yield improvement based on a better understanding of the physiology of growth/product secretion coupled to appropriate bioreactor operation. The authenticity of product is an aspect which will assume increasing importance, particularly for therapeutic proteins. The level at which the structures and functional activity of heterologous proteins are assessed will ultimately be determined by legislation. The analytical methods currently available are not always sufficient, for example, to reveal folded structures, and most proteins are not amenable to analysis by two-dimensional NMR. The authenticity of target heterologous proteins will also need to be assessed in relation to the glycosylation level and pattern. This is not easily done and explains the paucity of detailed information published to date on glycosylation of fungal proteins. Novel engineered proteins are already being produced from filamentous fungi where expression is an aid to investigation of structure-function relationships. Commercial production of such engineered proteins will require approval subject to a range of stringently applied tests and analyses. This imposes an even greater need to be able to specify and control, in a rational manner, the structures of recombinant proteins. The research needs for realization of improved yields are equally important in assuring authenticity of product. It is encouraging that progress is being made on all fronts, primarily with Aspergillus spp. and T. reesei, but also with other species, such as N. crassa.

Some effects of leaf area control on the yield of wheat

The effects on var. Olympic wheat of maintaining the leaf area index (LAI), once attained, at approximately 3 and 1, and of removing all leaves or half of each leaf at ear emergence, were assessed by comparison with an uncut crop (maximum LAI = 12). Leaf stripping at ear emergence had no significant effect on grain yield. Leaf area maintenance at LAI values of 3 and 1 greatly decreased grain yield by reducing both grain number per spikelet and mean grain weight by about 50%. These effects followed earlier reductions in the rate of development of the shoot apex. The results are discussed in relation to the yields obtained and conclusions reached by English workers, and to possible scope for yield improvement.