Indole-3-acetic acid biosynthesis in <Emphasis Type="Italic">Aciculosporium take</Emphasis>, a causal agent of witches' broom of bamboo

 Aciculosporium take (Ascomycota; Clavicipitaceae) is a causal agent of witches' broom of bamboo plants. The symptoms of this disease are believed to be induced by plant hormones, particularly auxins. Indole-3-acetic acid (IAA) was identified in cultures of this fungus in an l-tryptophan-supplemented liquid medium. IAA production was confirmed on 30 isolates of A. take from various hosts and locations at levels up to 1 mg/l. The biosynthetic pathway of IAA in A. take culture was examined by analyzing intermediate products and by feeding experiments. The results showed that the indole-3-pyruvic acid pathway (l-tryptophan → indole-3-pyruvic acid → indole acetaldehyde → IAA) was the dominant pathway in A. take. Received: June 3, 2002 / Accepted: July 25, 2002     

Screening of <Emphasis Type="Italic">Botrytis cinerea</Emphasis> isolates from vineyards in Israel for resistance to fungicides

Plots in two vineyards in the Golan Heights, Israel were treated with six botryticides during three growing seasons with 3 applications per season. Applications of fenhexamid, pyrimethanil and cyprodinil + fludioxonil were effective, resulting in 52–65% and 53–63% mean reduction in grey mould incidence and severity, respectively. Carbendazim, fluazinam and iprodione were ineffective or slightly effective. Five hundred and sixteen B. cinerea isolates were collected from infected berries or trapped from the air in the vineyards, and profiles of sensitivity to benomyl, fenhexamid, fluazinam, fludioxonil, iprodione and pyrimethanil were established for each of the isolates based on a mycelial growth test. Seventy-four percent of the isolates were sensitive to the six tested fungicides, and the other 26% of the isolates were classified into 10 phenotypes characterized by resistance to one or more fungicides. Resistant isolates showed fitness parameters similar or reduced in comparison to sensitive isolates. Resistance to benzimidazoles and to dicarboximides was the most frequent (up to 25%) and apparently pre-existed in the populations tested. Increased frequency of benzimidazole resistance, but not dicarboximide resistance, was observed following the 3 years of applications of the fungicides. High level resistance to pyrimethanil was present at a frequency of about 2% in both vineyards in the first 2 years of the sampling survey and reached 10% in the third year at Site 2. A few isolates were resistant to fenhexamid or fludioxonil (0.8 or 0.2%, respectively). No strong resistance to fluazinam was detected, although numerous, less sensitive isolates, presumably possessing multi-drug resistance traits, were recovered at higher frequency from the plots treated with fluazinam than from the untreated plots.     

A variance-covariance structure to take into account repeated measurements and heteroscedasticity in growth modeling

This study proposes a within-subject variance-covariance (VC) structure to take into account repeated measurements and heteroscedasticity in a context of growth modeling. The VC structure integrates a variance function and a continuous autoregressive covariance structure. It was tested on a nonlinear growth model parameterized with data from permanent sample plots. Using a stand-level approach, basal area growth was independently modeled for red spruce (Picea rubens Sarg.) and balsam fir [Abies balsamea (L.) Mill.] in mixed stands. For both species, the implementation of the VC structure significantly improved the maximum likelihood of the model. In both cases, it efficiently accounted for heteroscedasticity and autocorrelation, since the normalized residuals no longer exhibited departures from the assumptions of independent error terms with homogeneous variances. Moreover, compared with traditional nonlinear least squares (NLS) models, models parameterized with this VC structure may generate more accurate predictions when prior information is available. This case study demonstrates that the implementation of a VC structure may provide parameter estimates that are consistent with asymptotically unbiased variances in a context of nonlinear growth modeling using a stand-level approach. Since the variances are no longer biased, the hypothesis tests performed on the estimates are valid when the number of observations is large.     

Capturing genetic variability and selection of traits for heat tolerance in a chickpea recombinant inbred line (RIL) population under field conditions

Chickpea is the most important pulse crop globally after dry beans. Climate change and increased cropping intensity are forcing chickpea cultivation to relatively higher temperature environments. To assess the genetic variability and identify heat responsive traits, a set of 296 F_8–9 recombinant inbred lines (RILs) of the cross ICC 4567 (heat sensitive) × ICC 15614 (heat tolerant) was evaluated under field conditions at ICRISAT, Patancheru, India. The experiment was conducted in an alpha lattice design with three replications during the summer seasons of 2013 and 2014 (heat stress environments, average temperature 35 °C and above), and post-rainy season of 2013 (non-stress environment, max. temperature below 30 °C). A two-fold variation for number of filled pods (FPod), total number of seeds (TS), harvest index (HI), percent pod setting (%PodSet) and grain yield (GY) was observed in the RILs under stress environments compared to non-stress environment. A yield penalty ranging from 22.26% (summer 2013) to 33.30% (summer 2014) was recorded in stress environments. Seed mass measured as 100-seed weight (HSW) was the least affected (6 and 7% reduction) trait, while %PodSet was the most affected (45.86 and 44.31% reduction) trait by high temperatures. Mixed model analysis of variance revealed a high genotypic coefficient of variation (GCV) (23.29–30.22%), phenotypic coefficient of variation (PCV) (25.69–32.44%) along with high heritability (80.89–86.89%) for FPod, TS, %PodSet and GY across the heat stress environments. Correlation studies (r = 0.61–0.97) and principal component analysis (PCA) revealed a strong positive association among the traits GY, FPod, VS and %PodSet under stress environments. Path analysis results showed that TS was the major direct and FPod was the major indirect contributors to GY under heat stress environments. Therefore, the traits that are good indicators of high grain yield under heat stress can be used in indirect selection for developing heat tolerant chickpea cultivars. Moreover, the presence of large genetic variation for heat tolerance in the population may provide an opportunity to use the RILs in future-heat tolerance breeding programme in chickpea.     

Effects of silviculture treatments in a hurricane-damaged forest on carbon storage and emissions in central Hokkaido,Japan

Hurricanes cause abrupt carbon reduction in forests, but silviculture treatment can be an effective means of quickly regenerating and restoring hurricane-damaged sites. This study assessed how silviculture treatments affect carbon balance after hurricane damage in central Hokkaido, Japan. We examined carbon storage in trees and underground vegetation as well as carbon emissions from silviculture operations in 25-year-old stands, where scarification and plantation occurred just after hurricane damage. The amount of carbon stored varied according to silviculture treatment. Among three scarification treatments, a scarified depth of 0 cm (understory vegetation removal) led to the largest amount of carbon stored (64.7 t·ha-1 C). Among four plantation treatments, the largest amount of carbon was stored in a Larix hybrid (L. gmelinii var. japonica × L. kaempferi) plantation (80.3 t·ha-1 C). The plantation of Abies sachalinensis was not successful at accumulating carbon (40.5·ha-1 C). The amount of carbon emitted from silviculture operations was 0.05-0.14 t·ha-1 C, and it marginally affected the net carbon balance of the silviculture project. Results indicate that silviculture treatments should beperformed in an appropriate way to effectively recover the ability of carbon sequestration in hurricane-damaged forests.     

Greenhouse evaluation and inheritance analysis of transgenic cotton expressing <Emphasis Type="Italic">PTM3</Emphasis>, a MADS-box gene of Aspen

The PTM3 (MADS-box) gene characterized from flower of Aspen was ectopically expressed in cotton and was found to result in desirable agronomic traits. Among several transgenic lines, the PTM3 cotton event-10 was found to flower significantly earlier than the control and yield better [Ramachandran et al. (2011)]. We report our findings on performance based on greenhouse evaluation and inheritance of PTM3 cotton event-10. The T₁ progeny of event-10 were grown in pots under RBD design. The progeny were confirmed by kanamycin imbibition test, PCR, and GUS assay which showed the segregation of transgene at about 3:1 ratio. GUS assay was performed with pollen from all transgenic plants; plants that expressed gus in all pollen versus those that showed segregation for expression were found to be at a ratio of 1:2. Similar to observations made in the T₀ generation of event-10, the agronomic evaluation of T₁ progeny exhibited, on an average, earliness of 13 days in flowering, 13.5 days in crop maturity, and 22% of yield enhancement. The T₂ progeny of homozygous lines were grown on field soil in the greenhouse under strip trial design to see the effect as observed from potted plants of T₁ progeny. Inheritance of transgene cassette to T₂ progeny was confirmed by the same tests used to analyze T₁ progeny. As exhibited by T₀ and T₁ progenies, the T₂ progeny also showed earliness of 8 days in flowering, 12 days in crop maturity, and 17% of yield enhancement. The data generated from the progeny over two generations confirms that the PTM3 cotton event-10 is superior in agronomic characters as compared to non-transgenic cotton and is of interest for breeding shorter duration varieties with improved yield.     

Woody species composition,diversity and structure of riparian forests of four watercourses types in Burkina Faso

Riparian forests are classified as endangered ecosystems in general,particularly in sahelian countries like Burkina Faso because of human-induced alterations and civil engineering works.The modification of this important habitat is continuing,with little attention being paid to the ecological or human consequences of these changes.The objective of this study is to describe the variation of woody species diversity and dynamic in riparian forests on different type of watercourse banks along phytogeographical gradient in Burkina Faso.All woody species were systematically measured in 90 sample plots with sides of 50 m × 20 m.Density,dominance,frequency and species and family importance values were computed to characterize the species composition.Different diver-sity indices were calculated to examine the heterogeneity of riparian forests.A total of 196 species representing 139 genera and 51 families were recorded in the overall riparian forests.The species richness of individuals with dbh ≥ 5cm increased significantly from the North to the South along the phytogeographical gradient and varied significantly between the different types of riparian forests.Similarity in tree species composition between riparian forests was low,which indicates high beta diversity and reflects differences in habitat conditions and topography.The structural characteristics varied significantly along the phyto-geographical gradient and between the different types of riparian forests.The diameter class distribution of trees in all riparian forests showed a reverse "J" shaped curve except riparian forest of stream indicating vegetation dominated by juvenile individuals.Considering the ecological importance of riparian forest,there is a need to delineate and classify them along watercourses throughout the country.     

Attributes of People’s Organisations and the institutional viability of selected Community-Based Forest Management projects in northern Luzon

An assessment was made of the attributes of People’s Organisations (POs) and of the institutional viability of Community-Based Forest Management (CBFM) programs in three project sites in the Philippines. In CBFM, the capacity of People’s Organisations, as de facto managers of forest resources, is being developed by non-government organisations under the guidance of local government units (LGUs) and the Department of Environment and Natural Resources (DENR). A survey was conducted of community members (case informants) and members of the various agencies (key informants) to ascertain the characteristics of successful POs and the relationship between these characteristics and the viability of CBFM. Although commendable contributions have been made to the forest management capability of POs, their standard of living and environmental conditions, there are also many instances in which institutional conflict among stakeholders is apparent. The great challenge for the various stakeholders is to orchestrate their differing interests so as to address successfully the critical issues of the low socioeconomic status of PO members, corruption, lack of transparency and accountability of the organisations involved, loss of interest of PO members in project activities, lack of technical assistance, loss of credibility of the DENR, and lack of equitable benefit sharing.     

Gas exchange responses of <Emphasis Type="Italic">Eucalyptus</Emphasis>, <Emphasis Type="Italic">C. africana</Emphasis> and <Emphasis Type="Italic">G. robusta</Emphasis> to varying soil moisture content in semi-arid (Thika) Kenya

A dramatic decline in forest cover in eastern Africa along with a growing population means that timber and poles for building and fuelwood are in short supply. To overcome this shortage, the region is increasingly turning to eucalyptus. But eucalyptus raises environmental concerns of its own. Fears that it will deplete water supply, affect wildlife and reduce associated crop yields have caused many countries in the region to discourage farmers from planting this exotic. This paper is part of a series of investigations on the growth and water use efficiency of faster growing eucalyptus hybrids, which was introduced from South Africa to Kenya. The hypothesis is that the new hybrids are more efficient in using water and more suitable for the semi-arid tropics than existing eucalyptus and two popular agroforestry species. Gas exchange characteristics of juvenile Eucalyptus grandis (W. Hill ex Maiden), two eucalyptus hybrids (E. grandis × Eucalyptus camaldulensis Dehnh.), Grevillea robusta (A. Cunn) and Cordia africana (Lam) was studied under field and pot conditions using an infrared gas analyzer was used to measure photosynthetic active radiation (PAR), net photosynthetic rate (A), stomatal conductance (g _s) and transpiration rate (E) at CO₂ concentrations of 360 μmol mol⁻¹ and ambient humidity and temperature. A, E and g _s varied between species, being highest in eucalyptus hybrid GC 15 (24.6 μmol m⁻² s⁻¹) compared to eucalyptus hybrid GC 584 (21.0 μmol m⁻² s⁻¹), E. grandis (19.2 μmol m⁻² s⁻¹), C. africana (17.7 μmol m⁻² s⁻¹) and G. robusta (11.1 μmol m⁻² s⁻¹). C. africana exhibited high E values (7.0 mmol m⁻² s⁻¹) at optimal soil moisture contents than G. robusta (3.9 mmol m⁻² s⁻¹) and eucalyptus (5.3 mmol m⁻² s⁻¹) in field experiment and G. robusta (3.2 mmol m⁻² s⁻¹) and eucalyptus (4.2 mmol m⁻² s⁻¹) in pot-grown trees. At very low soil moisture content, extremely small g _s values were recorded in GC 15 and E. grandis (8 mmol m⁻² s⁻¹) and G. robusta (14 mmol m⁻² s⁻¹) compared to GC 584 (46.9 mmol m⁻² s⁻¹) and C. africana (90.0 mmol m⁻² s⁻¹) indicating strong stomatal control by the species. Instantaneous water use efficiency ranged between 3 and 5 μmol mmol⁻¹ and generally decreased with decline in soil moisture in pot-grown trees but increased with declining soil moisture in field-grown trees.     

Identifying important biophysical and social determinants of on-farm tree growing in subsistence-based traditional agroforestry systems

Many expert-designed agroforestry projects enunciated in 1970s around the world, particularly in the developing countries, had uneven success due to inadequate adoption or abandonment after adoption. There are many empirical studies on factors affecting on-farm tree cultivation mainly where expert-designed agroforestry programmes were introduced but lacking in case of traditional agroforestry. Moreover, the concern to identify key factors influencing on-farm tree growing is gaining importance. The present study identifies key factors in on-farm tree growing based on investigation of traditional agroforestry using logistic regression approach. The study is based on household survey of 401 households located in Indian Western Himalaya. The factors affecting on-farm tree growing were grouped into: biophysical (included land use and infrastructural aspects) and social. Models predicting on-farm tree growing for each category were developed and key factors affecting on-farm tree growing in the respective category were identified. A composite model was also developed by combining biophysical and social factors. In the present study, farm size, agroclimatic zone, soil fertility, mobility and importance of tree for future generations respectively were the key factors which influenced tree growing. In contrast to many previous studies which considered either biophysical or social factors, the composite model in the present study reveals that both biophysical and social factors are simultaneously important in motivating the farmers to grow trees on their farms in traditional agroforestry. Moreover, the present study open vistas for using farmers’ experience and knowledge of adoption of agroforestry to stimulate on-farm tree growing. The wider implication of the study is that biophysical as well as social variables should be considered together in designing suitable agroforestry systems in various parts of the world.