Multivariate Analysis and Screening of Moth Bean Accessions for Biotic Stresses in the Arid Region of Western India

The present investigation assesses the genetic diversity and resilience of moth bean (Vigna aconitifolia) against the biotic stresses in the arid zones of India. This research was carried out at the ICAR-Indian Institute of Pulses Research, Regional Research Centre, Bikaner, and employed an augmented design to analyze 300 accessions for morphological and agronomic traits. The study integrated Pearson’s correlation, hierarchical clustering, and principal component analysis to understand trait interrelationships and genetic variance. The number of clusters per plant, number of pods per plant, plant height and test weight showed a highly significant and positive correlation, whereas days to 50% flowering and number of branches per plant showed a negative correlation with seed yield per plant. Hierarchical clustering subdivided accessions into fourteen clusters, and cluster1 best suited to arid conditions with 21 accessions. Principal component analysis with eigenvalues classified the accessions into eight principal components. PC1 contributed the maximum variation that is 32.21 percent, followed by other clusters. Cercospora leaf spot had the highest disease incidence among the three diseases (yellow mosaic virus, cercospora leaf spot and leaf curl virus diseases). The findings underscore the potential of exploiting genetic variability in moth beans for breeding programs aimed at enhancing yield and stress tolerance, crucial for sustainable production in resource-poor arid ecosystems.

Substrate, moisture, temperature and seed germination of the threatened endemic tree Eriotheca vargasii (Malvaceae) / Sustrato, humedad, temperatura y germinación de semillas del árbol endémico amenazado Eriotheca vargasii (Malvaceae)

Abstract We studied the germination of Eriotheca vargasii (Malvaceae), a poorly known endemic Peruvian Andean tree species characteristic of the dry forests of the Torobamba river valley, Peru. We determined seed characteristics, embryo morphology, viability, and assessed the influence of substrate (natural soil and commercially prepared media), temperature (controlled at 25 ºC and at ambient temperature between 18-22 ºC), and moisture (25 % and 50 % field capacity) on seed germination. Most seeds were ovoid in shape and although they contained well-developed embryos, only 46 % of them were viable. Substrate moisture levels had no influence on germination capacity or rate. In contrast, temperature and substrate type showed strong effects on germination. We observed the highest proportion of germinated seeds in prepared media at both temperatures tested (> 61 %). Furthermore, substrate types also influenced germination rates, with lower values in natural soil. The strongest effect on germination rates was by temperature, enhancing the difference in responses in substrate types (up to 90 % in commercially prepared media at 25 ºC). The low proportion of germinated seeds in soil (< 39 %), together with external local stress factors (e.g. grazing impact by herbivores), may be the critical factors contributing to the nearly total absence of seedlings and saplings of E. vargasiiin the study area despite abundant seed production. In order to ensure a supply of E. vargasii seedlings for reforestation efforts, we recommend producing E. vargasii plants in nurseries and conducting reforestation trials. We suggest that germination of seedlings is done following guidelines from this study. Rev. Biol. Trop. 66(3): 1162-1170. Epub 2018 September 01.

Resumen Estudiamos la germinación de Eriotheca vargasii (Malvaceae), un árbol endémico poco conocido de los andes peruanos y carácterístico de los bosques secos del valle del río Torobamba. Determinamos las características de la semilla, la morfología del embrión y la viabilidad; además evaluamos la influencia del sustrato (suelo y sustrato preparado comercialmente), temperatura (controlada a 25 ºC y sin control entre 18-22 ºC) y humedad (25 % y 50 % de capacidad de campo) sobre la germinación de las semillas. La mayoría de las semillas tuvo forma ovoide y aunque la mayoría contenía embriones bien desarrollados, sólo el 46 % de estas fue viable. Los niveles de humedad del sustrato no tuvieron influencia sobre la capacidad o tasa de germinación, mientras que la temperatura y el tipo de sustrato si tuvieron efectos visibles. Observamos las proporciones más altas de semillas germinadas en los sustratos preparados y en ambas temperaturas (> 61 %). Adicionalmente, el tipo de sustrato también influenció las tasas de germinación, con valores más bajos en el suelo natural. El efecto más fuerte sobre las tasas de germinación se dió por la temperatura, aumentando las diferencias de las respuestas de acuerdo al tipo de sustrato (hasta un 90 % de germinación en sustratos preparados comercialmente y a 25 ºC). La baja proporción de semillas germinadas en el suelo (< 39 %), junto con factores locales de estrés externos (como por ejemplo el impacto por herbivoría), pueden ser elementos clave que están contribuyendo a la casi ausencia total de plántulas de E. vargasii en el área de estudio, a pesar de una producción de semilla abundante. Para asegurar proveer plantones de E. Vargasii para esfuerzos de reforestación, recomendamos producir plantas de esta especie en viveros y realizar experimentos de reforestación. Sugerimos que la germinación de las plántulas se haga siguiendo las recomendaciones de este estudio.

Comparative study on growth, yield and carbon content in Pongamia pinnata under water stress and urea supplementation.

The growth, yield, and carbon content of eight-month old seedlings of Pongamia pinnata were compared under water and urea supplementation. One set of plants were subjected to water stress condition (WS), whereas the other supplied with 2 g of urea (WS+U) under WS. Both the experimental set ups were exposed to varying treatment levels which include full irrigation (100%, control) followed by 75 % (T1), 50 % (T2), 25 % (T3) and 12.5 % (T4). The growth, leaf area and relative water content were maximum under WS when compared to WS+U (p<0.001). The maximum biomass was produced in the seedlings under WS in control (1.68 g) followed by T1 (1.38 g), T2 (1.53 g), T3 (0.93 g) and T4 (0.73 g). A significant (p<0.001) reduction in biomass production was observed in WS+U in control (1.28 g), T1 (0.66 g), T2 (1.13 g) and T3 (0.44 g). T4 of WS+U showed similar biomass (0.73 g) as that of T4 of WS. Under WS, the highest biomass allocation was recorded in shoots followed by leaves and roots. Similar trend was observed in WS+U. However, the percentage of allocation was more in the roots of WS+U (27.2 %) when compared to WS (22.24 %). The highest amount of carbon content was observed in control plants treated under WS (9.59 g) followed by control plants of WS+U (7.31 g) (p<0.001). The results of the preliminary study clearly indicated that P. pinnata seedlings were able to cope-up with water stress conditions without urea application and can perform well in 50 % water availability and is best suited for the plantation programs in the semi-arid ecosystems.