Modeling the distributions of species, especially of invasive species in non-native ranges, involves multiple challenges. Here, we developed some novel approaches to species distribution modeling aimed at reducing the influences of such challenges and improving the realism of projections. We estimated species-environment relationships for Parthenium hysterophorus L. (Asteraceae) with four modeling methods run with multiple scenarios of (i) sources of occurrences and geographically isolated background ranges for absences, (ii) approaches to drawing background (absence) points, and (iii) alternate sets of predictor variables. We further tested various quantitative metrics of model evaluation against biological insight. Model projections were very sensitive to the choice of training dataset. Model accuracy was much improved using a global dataset for model training, rather than restricting data input to the species' native range. AUC score was a poor metric for model evaluation and, if used alone, was not a useful criterion for assessing model performance. Projections away from the sampled space (i.e., into areas of potential future invasion) were very different depending on the modeling methods used, raising questions about the reliability of ensemble projections. Generalized linear models gave very unrealistic projections far away from the training region. Models that efficiently fit the dominant pattern, but exclude highly local patterns in the dataset and capture interactions as they appear in data (e.g., boosted regression trees), improved generalization of the models. Biological knowledge of the species and its distribution was important in refining choices about the best set of projections. A post hoc test conducted on a new Parthenium dataset from Nepal validated excellent predictive performance of our 'best' model. We showed that vast stretches of currently uninvaded geographic areas on multiple continents harbor highly suitable habitats for parthenium. However, discrepancies between model predictions and parthenium invasion in Australia indicate successful management for this globally significant weed.

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Studies were initiated for two consecutive years to find out the effect of time of transplanting and seedlings hill −1 on the productivity of rice in Dera Ismail Khan district of North West Frontier Province (NWFP), Pakistan. The experiment was laid out in a randomized complete block design with split plot arrangements. Main plots consisted of four transplanting dates viz. 20th and 27th of June and 4th and 11th of July while sub-plots contained 1, 2, 3 or 4 seedlings hill . It explains that the use of more seedlings hill −1 not only adds to cost but is also a mere wastage of natural resources. Based on research findings, we conclude that the use of 1 seedling hill −1 is most appropriate for timely sowing otherwise 4 seedlings hill -1 should be used to compensate for the yield gap in late transplanted rice.

The nature and magnitude of genetic effects on morpho-yield traits were studied in a 6 × 6 F 1 and F 2 diallel cross in upland cotton. An additive-dominance model was adequate for most of the traits except plant height and seed cotton yield, where the model was partially adequate. Genetic parameters were estimated following Hayman's and Mather's model. Additive effects controlled lint percentage and monopodia in both generations, and plant height and sympodia in F 2 . Non-additive inheritance with over-dominance controlled yield in both generations, and plant height and sympodia in F 1 . Most traits presented an unequal proportion of positive (U) and negative (V) alleles in the loci (H 2 < H 1 ) and an asymmetrical distribution of genes in the parents (H 2 /4H 1 < 0.25 and F different to zero). The value of H 2 /4H 1 was lower than maximum value (0.25) for all of traits, which arises when U = V = 0.5 over all loci. The proportion ͌ʳʲ 4DH1 ʲʲ + F ʲ/͌ʳʲ 4DH1 ʲʲ -F ʲ) confirmed by half of the traits that dominant alleles were in excess as compared to recessive alleles. Dominance effects (h 2 ) for most of the traits suggested that substantial contribution of dominance was not due to heterogeneity of loci in these parameters. Broad and narrow sense heritabilities were high for most of the traits. Correlation coefficient between the Wr + Vr and mid parental (y) indicated that dominant genes were responsible for increased sympodia, lint % and yield, and recessive genes increased monopodia and plant height. Genetic gain was encouraging for most traits. Cultivar CIM-1100 was identified by genetic advancement as a promising parental cultivar to cross combinations.Additional key words: additive-dominance model; additive and dominance effects; D, H 1 & H 2 genetic components of variance; seed cotton yield; upland cotton. ResumenEfectos genéticos en caracteres morfológicos y de rendimiento en algodón (Gossypium hirsutum L.)Se estudió la naturaleza y la magnitud de los efectos genéticos sobre los caracteres morfo-productivos en un cruce dialélico F 1 y F 2 de 6 × 6 en algodón tipo upland. Para la mayoría de los caracteres, excepto altura de planta y rendimiento de semilla, fue adecuado un modelo aditivo-dominante. Se estimaron los parámetros genéticos según Hayman y Mather. Los efectos aditivos controlaron el porcentaje de pelusa y los monopodios en ambas generaciones, y la altura de la planta y los simpodios en la F 2 . La herencia no aditiva con superdominancia controló el rendimiento en ambas generaciones y la altura de planta y los simpodios en la F 1 . La mayoría de los caracteres presentaron una proporción desigual de alelos positivos (U) y negativos (V) en los loci (H 2 < H 1 ) y una distribución asimétrica de los genes en los parentales (H 2 /4H 1 < 0,25 y F 0). El valor de H 2 /4H 1 estuvo por debajo del valor máximo (0,25) para todos los caracteres, lo que surge cuando U = V = 0,5 en todos los loci. La proporción ͌ʳʲ 4DH1 ʲʲ + F ʲ/͌ʳʲ 4DH1 ʲʲ -F ʲ) confirmó, para la mitad de los caracteres, que había un exc...

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Field studies were undertaken to explore the weed management strategies for transplanted and direct wet-seeded rice in the Dera Ismail Khan district of North-west Frontier Province, Pakistan. The experimental design was a randomized complete block with a split plot arrangement. The main plots consisted of two planting techniques (transplantation and direct seeding), while weed control practises assigned to the subplots included the use of the granular herbicide Sunstar 15WG (ethoxy sulfuron), Machete 60EC (butachlor), conventional hand weeding, and the weedy check (untreated control). Data were recorded on weed dynamics and the agronomic parameters of the rice crop. Economic analyses on the data were also run. The weed density and biomass were lower in the transplantation plots than the direct-seeding plots. The herbicides ethoxy sulfuron and butachlor reduced the density over the weedy check, with a density comparable to hand weeding in 2002, but slightly higher in 2003. As a result of weed management by hand weeding and herbicides, the paddy yield and its components were significantly higher for the transplanted method compared to the direct-seeded method. The comparable yield of herbicides with hand weeding offers an option for the use of herbicides as an alternative management tool. In light of our findings, it is concluded that for good economic returns, rice crops may be transplanted rather than direct-seeded. The herbicides ethoxy sulfuron and butachlor offer a weed control cover comparable with hand weeding under the transplantation method, while butachlor is good for controlling weeds even under the directseeded conditions in the agroclimatic conditions of the area.

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