CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Interactive effect of irrigation regimes and sowing dates on morphophysiological response, fodder yield and quality and antinutrient HCN of multi-cut sorghum in the semi-arid region
Full text linkA two-year field experiment (2016/2017) with three moisture regimes (60 CPE (cumulative pan evaporation), 120 CPE, and no irrigation) and six sowing dates in three replications was conducted to investigate the effect of different moisture regimes and sowing dates on multi-cut hybrid fodder sorghum in the semi-arid region. Early sowing and irrigation at 60 CPE had resulted in improved morpho-physiological responses with better fodder quality in terms of higher crude protein, invitro dry matter digestibility, and lower crude fiber in both seasons. Early sowing resulted in an increase of green fodder yield (GFY) from 638.7 to 805.4 q/ha in 2016 and from 643.7 to 780.9 q/ha in 2017. Irrigation at 60 CPE showed 46% and 41% increase in GFY over no irrigation. In all three cuts, HCN content was significantly higher in the crop with no irrigation and also in late sown crop (at 2nd and 3rd cuts).HCN decreased drastically by 41% (2016) and 36% (2017) in the crop irrigated at 60 CPE (at 1st cut). Findings suggest that late sowing of the sorghum affects the fodder yield and quality due to effect on growth parameters and therefore, the adverse effects of decreased precipitation as the result of a change in weather conditions can bediminished particularly by sowing early and irrigating at 60 CPE
Investigation of Forage Sorghum (Sorghum bicolor L.) Genotypes for Yield and Yield Components
Full text linkThe objective of this study was to evaluate the genetic variability of forage sorghum genotypes and to estimate genotypic, phenotypic, and environmental correlations with path and stability analysis. The experiments were conducted in Antalya and Konya locations of Turkey during 2014-2015 years by using 48 selected forage sorghum lines and 4 sorghum varieties. Experimental design was the randomized complete block, with three replications. Significant variations were recorded for all the characters among the genotypes. The highest plant height has been optained from 355.2 cm and 300.1 cm in Antalya and Konya location respectively. Days to 50% flowering ranged from 64.8-101.3 days in Antalya and 69.0-111.2 days in Konya. The highest forage yield was observed in Line-22 with 99.1 tha-1 in Antalya and in Line-41 with 75.5 tha-1 in Konya. Forage yield was significantly and highly positively correlated with hay yield (r = 0.9851**), plant leaf ratio (r=0.3478*) and stalk yield (r=0.9901**). Path analysis revealed the plant stalk ratio direct positive effect on forage yield. On the other hand, plant stalk yield had negative direct effect through forage yield. According to results of the stability analysis, Line-1, 3, 5, 13, 21,40, 42 and 44 were the most stable varieties
Combining ability analysis and heterotic grouping for grain yield among maize inbred lines selected for the mid-altitude and highland zones of Rwanda
Full text linkDevelopment and identification of maize parental lines that belong to different heterotic groups is a fundamental requirement for any hybrid production programme. The objective of this study was, therefore, to determine combining ability, heterosis and heterotic patterns for grain yield among ten selected local (unknown heterotic groups) and exotic (known heterotic groups) maize inbred lines and their progenies under mid-altitude and highland conditions of Rwanda. Forty-five single crosses from a 10 x 10 half-diallel mating design plus three checkswere tested in a 6 x 8 alpha-lattice design across twelve environments. General combining ability (GCA) and specific combining ability (SCA) effects were both highly significant (P<0.001-0.01), suggesting presence of both additive and non-additive gene effects. The percentage mid-parent heterosis (MPH) for grain yield ranged from36.4to 267.7% with a mean of 164%, while high-parent heterosis (HPH) varied from 33.2% to 236% with a mean of 130.4%. Based on MPH, the seven local maize inbred lines were discriminated and assigned into four different heterotic groups (S4, S7, S4/S6 and S6/S7). The highest heterotic patterns were realized between tester S4and tester S6 (hybrid S4/S6) and between group S7 and tester S4 (hybrid S2/S4). Identified patterns would be potentially useful for maize hybrid production in Rwanda. Similarly, the resulting hybrids could be recommended in sub-Saharan African regions with similar ecosystems. Significance of both additive and non-additive geneticeffects in the current germplasm suggests that the Rwandan breeding programme could use both hybridization and recurrent selection methods
Selection of sweet corn genotypes for resistance to Northern Leaf Blight using longitudinal analysis
Full text linkNorthern Leaf Blight (NLB) of maize (Zea mays) is one of the most common maize diseases. The economic damage it causes is frequently linked to inadequate crop management and susceptible cultivars. To select sweet corn genotypes with a higher level of resistance to NLB, 18 single-cross hybrids, six populations, four interpopulation hybrids, and two controls were evaluated in two field trials. Genotypes were evaluated three times, and results were analyzed according to linear mixed models and repeated measures over time, using days to silk as a covariate. The entry effect was sliced into single-crosses, populations, controls and interclasses. Single-crosses were sliced in line, tester, and line by tester. Results indicate higher ear yield (EY) and greater severity in early genotypes, thereby validating the use of covariates. In all analyses, the selection accuracy was high, above 0.86. For NLB, population and simple hybrid means varied from one environment to another, while simple hybrids were always higher for yield.In the joint analysis of NLB, there was a significant difference between Entry and Entry x Location, Line x Location, Control x Location, and Interclass x Location interactions. For yield, only Entry, Single-Cross, Population, Interclass, Entry x Location, Single-Cross x Location, and Interclass x Locationeffects were significant. The P8HS population, and the interpopulation and simple hybrids from this population, showed less severity in the joint analysis. As a result, the breeding program should focus on lines derived from the P8HS population to select genotypes more resistant to NLB and with high EY
Heat stress in maize: characterization and phenotypic plasticity
Full text linkThe future challenge will be to produce more maize and other crops, in stressed environments. Two experimentswere carried out during the 2015-2016 season at INTA Leales field, Tucumán, Argentina. The treatments includeda factorial arrangement of two thermal environments (non-stress and heat stress) and 15 hybrids (Exp.1) and 6maize inbred lines (Exp.2). The hybrids and inbred lines showed phenotypic variability in most of the evaluatedtraits for heat stress during critical period for kernel set. The tropical genotypes (HS9, HS10 and L3) were identified as tolerant, while genotypes with a temperate x tropical and temperate genetic background (HS13, HS14 and L5) were identified as the most susceptible. There was a grain yield reduction of 82% and 78% in H13 and L5, respectively when comparing the non-heat stress environment with heat-stress environment. Range in phenotypic plasticity was similar for hybrids and inbred lines, being the largest for trait such as, grain yield, kernel number, anthesis-silking interval, harvest index, and the smallest for traits such as kernel weight, ear diameter, prolificacy, aboveground biomass at physiological maturity, cumulative thermal time to silking and leaf greenness post stress on ear leaf. The outcomes from this research are promising for future heat-stress screening, in order to increase the selection efficiency in a breeding program
Response of spiders (Araneae) to the introduction of an exotic pest (Diabrotica virgifera LeConte,1868 - Coleoptera, Chrysomelidae) in corn cultivations in Northern Italy
Full text linkThe response of spiders (Araneae) to the introduction of the corn rootworm (Diabrotica virgifera, Coleoptera Chrysomelidae, LeConte, 1868) was studied in 2010 and 2011 in two study areas in the Padana Plain (Northern Italy). The research was aimed at identifying the community of spiders which can prey on D. virgifera in corn fields,the rate of predation and the influence of landscape on the natural enemies’ response to the invader. The two study areas were different in terms of both land use and agricultural patterns. In the area south of the Po River corn is cultivated together with many other crops, according to a crop rotation pattern, while in the area north of the Po River (Po) the agricultural landscape is mostly dedicated to rice monoculture. Predation was observed only in the area south of the Po River, ranging from 9.9% to 40.3%, where Phylloneta impressa (Araneae Theridiidae, Koch,1881) was the most important predator of corn rootworm adults. In the area north of the Po River no predation was recorded. Those results are one more example of how the richness and abundance of potential natural enemies can be crucially affected by structure and composition of the landscape surrounding crop fields.Predation by spiders could potentially support an integrated pest management of D. virgifera in agricultural districts where the pest is limited by crop rotation. The rate of predation was inversely dependent on victims' density, therefore predation by spiders tended to be of minor importance when D. virgifera was at epidemic levels
Determination of the tolerance of maize cross-breeds and their parent material to bromoxynil – an inhibitor of photosystem II
Full text linkHerbicides can exert a phytotoxic effect on maize (Zea mays L.) plants. High maize cross-breeds tolerance to herbicides can be obtained by proper selection of parent material. Based on the knowledge of phenotypic signs of damage, it is possible to discard the parents that are the most susceptible to herbicides. The aim of the study wasto compare the response of maize cross-breeds Dumka and Rywal, their parental forms, and lines to bromoxynil – the herbicide belonging to PSII photosynthesis inhibitor group. Herbicide was used at the recommended (400 g ha-1) and double (800 g ha-1) rates. Bromoxynil phytotoxicity was reflected in changes in plant morphological traits,growth inhibition, and green matter reduction of the female parent of cross-breed Dumka and its component S64423- 2. This indication was confirmed in the study of photosynthesis parameters –chlorophyll content and chlorophyll fluorescence in leaves. The cross-breed Rywal and their male parent proved to be tolerant to the bromoxynil.
Assessment of maintenance breeding methods in maize (Zea mays L.)
Full text linkAn investigation was conducted at IASc. BHU, Varanasi (Rabi 2014-15 to Kharif 2017) with four maize inbreds using three maintenance methods (selfing, half-sibbing and full-sibbing) for four generations in which a significant amount of genetic correlation was found between the morphological and molecular analyses. The comparison offour inbreds revealed a deviation in the clustering pattern after the four generations of maintenance. A maximum similarity coefficient was recorded between HKI 193-1 FS and LM 10 FS lines; full-sibbing showed the highest similarity between the first and fourth generation. Most of the inbreds followed a similar clustering pattern in morphological as well as in molecular diversity analyses. HKI 1105 is considered as most stable inbred in terms of giving a wide range of partitioning the regression coefficient. The quadratic and cubic trend through the graphical method showed self-ingled to a negative [cb1] response as well as maximum changes whereas, the full-sibbingmethod recorded with the minimum changes over the generations. Comparison of the combining ability of the inbreds by three methods revealed that CML-161 followed by HKI 1105 recorded maximum and LM 10 recorded minimum significant GCA effects. Through all the experiments it was proved that selfing caused the highest lossof vigour whereas full-sibbing was most stable
Variability and stability evaluation in Indian Maize (Zea mays L.) landraces collected from North Eastern Himalayan region
Full text linkMaize landraces collected from Mizoram state of North Eastern India were evaluated for three years (2017, 2018 and 2019) to assess the amount of variability present among the genotypes, association of traits and stability(parametric and non-parametric). MZM-44 was found to be a superior line with respect to yield and yield related traits. Least difference between GCV and PCV in number of days to silking and tasseling suggested minimalinfluence of environment in three years which is contrasting as compared to yield per plant. Yield per plant was highly correlated with ear diameter and test weight. From path coefficient analysis it was observed that thousandseed weight has the highest direct effect on the yield predicting the possible influence of these characters on yield increase. The genotypes were grouped into seven distinct clusters. Stable line with respect to yield is MZM-40 according to four stability parameters and MZM-34 by five stability parameters. But there was no significant correlation between the yield and stability parameters noted which proves that no stability parameter can bedepicted as superior and all have their own shortfalls in explaining the stable genotype with respect to yield. Presence of diversity in germplasm for yield and yield related traits was observed and few stable genotypes fordifferent characters in three years were identified. This experiment paves the way for future yield and allied traits improvement programmes where the identified genotypes could play a pivotal role
The effect of water deficits around flowering on grain yield and plant morphology of maize in negative irrigation system
Full text linkFlowering is drought sensitive, which has been used as the critical phase for drought-tolerant evaluation or screening of maize varieties. It is hard to acquire parallel plants in imprecise irrigation regimes. Hence, a negative-pressure irrigation system was introduced for accurate water control in this study. A pot experiment was performed to explore the responses of three maize hybrids – Zhengdan 958, Danyu 39, and Danyu 405 – to water deficit around flowering. Five irrigation regimes, including well-irrigated treatment (CK), ten days of moderate water deficit since 13 - leaf stage (V13M) or tasseling (VTM), and ten days of severe water deficit since 13-leaf stage (V13S) or tasseling (VTS), were applied. The small values of coefficient of variance in most observed traits demonstrated the feasibility and stability in obtaining parallel plants in the negative-pressure irrigation system. Zhengdan 958 had the least grain yield reduction (4.32 – 23.0%) after water deficits, followed by Danyu 405 (13.5 – 27.0%), and Danyu 39 (13.8 – 34.2%). The less affected kernel number in Zhengdan 958 was mainly a result of slightly decreased ear length and small ear tip-barrenness in water deficit. On the other hand, Zhengdan 958 could maintain a more stable whole plant dry matter under water deficits, benefiting from the less influenced leaf area, plant height, and stem diameter. The reported results highlight that Zhengdan 958 showed a better drought tolerance than Danyu 39 and Danyu 405, which was mainly attributed to more stable kernel number and better morphological performances under water deficits