Bread wheat cultivar PBW 343 carries residual additive resistance against virulent stripe rust pathotype

With continuous outbreaks of stripe rust (Puccinia striiformis f. sp. tritici) epidemics and rapid breakdown of deployed resistance in bread wheat (Triticum aestivum L.) cultivars in North West Plains Zone (NWPZ) in India warrant knowledge and deployment of new and durable sources of resistance to stripe rust. Bread wheat cultivar PBW 343, until recently the most widely cultivated wheat variety in India, is now highly susceptible to stripe rust (score 9 on a 1–9 scale), whereas PBW 621 (score 5.05–5.65) and HD 2967 (score 5.40–6.20) show low levels of resistance. We conducted an experiment, spanning three crop seasons (2013–2014 to 2015–2016), in which parental lines, F₁ and F₂ populations, F₃ and F₄ families from two bread wheat crosses, PBW 621/PBW 343 and HD 2967/PBW 343 were generated and evaluated for stripe rust resistance against a virulent pathotype. While the F₁ revealed partial dominance, the segregation pattern for stripe rust resistance in F₂ and F₃ showed transgressive segregation for resistance in both crosses. Chi-square analysis indicated that resistant segregants possessed two genes, one contributed by PBW 621 or HD 2967 (depending on the cross) and the other, unexpectedly but obviously, came from the most susceptible cultivar, PBW 343. Possible genetic mechanisms for this residual resistance and implications for breeding programs are discussed.     

Quantitative Estimation of Genetic Variability in Morphological Characteristics of Eastern Cottonwood (Populus deltoides Bartr.) Clones

The study was carried out to analyze the genetic variability for different growth parameters in poplar clones at the age of 2 and 3 yr in the nursery. Forty-nine exotic and indigenous clones of poplar were evaluated for eight morphological traits. Clones were planted in randomized block design (RBD) with three replications with four clones in a block in each treatment. Observations for different characters were recorded on six selected competitive clones per genotype. Results showed a high interclonal variability for most parameters. Statistically significant differences among clones indicated that the majority of study characters are controlled by genetic factors, specific to each clone. Highly significant genotypic difference supported by wide range of variation of mean and range values were observed for the characters under study. Significant and positive correlation was observed between diameter at breast height (DBH) and plant height. Leaf lamina length showed positive and significant correlation with petiole length, total leaf length, leaf width, and L/B ratio. Total leaf length showed positive and significant correlation with leaf width and L/B ratio. High estimates of heritability (in a broad sense) were observed for almost all characters in the study. High genetic advance expressed as percent of mean was recorded for petiole length (60.90), followed by plant height (60.78) and collar diameter (44.19) at 2 yr. At the age of 3 yr, genetic advance was found maximum for petiole length (60.05), followed by collar diameter (47.62) and plant height (45.29). The efforts for selecting new clones and their field-testing must continue under a long-term improvement plan so that the best clones can be recommended for plantations and hybridization programs.     

Seed Maturation Indicators in Pyracantha crenulata Roxb. in Kumaun Central Himalaya

Fruits of Pyracantha crenulata were collected from two locations varying by approximately 550 m in elevation from south aspect for assessing seed maturation indicators. The mean seed size (length×diameter) across the collection dates varied between 1.61 ± 0.7 and 4.93 ± 0.06 mm² across both the locations. The seed moisture content negatively correlated with germination. The change in fruit colour from dark green to light orange, the range of fruit moisture content (30.43% ± 0.06 to 36.10% ± 0.25) and the seed moisture content between 68.8% ± 0.68 and 71.6 ± 0.62 coincided with maximum germination and appear to be major indicators of seed maturation in Pyracantha crenulata.     

Comparing the model forms estimating generalised diameter-height relationships in Tecomella undulata plantations in hot arid region of India

Four generalised diameter-height equations were developed and compared for pure and even-aged stands of Tecomella undulata in hot arid region of Rajasthan State in India. The data used to fit the equations consisted of 1 540 diameter-height observations collected from the plots laid out in uniformly stocked stands of varying age and density. The performance of four equations was tested by non-linear least squares regression and evaluated using different statistical criteria. Finally, these equations, with the same values of coefficients ob- tained during the fitting phase, were validated by an independent data set consisting of 854 diameter-height observations. Overall, equation （4） （Hui and Gadow function） was found to perform best for both the fitting data set as well as validation data set.     

Carbon sequestration in Chir-Pine （Pinus roxburghii Sarg.） forests under various disturbance levels in Kumaun Central Himalaya

We studied variations in tree biomass and carbon sequestration rates of Chir Pine(Pinus roxburghii. Sarg.) forest in three categories of forest disturbance, protected, moderately disturbed, and highly disturbed. In the first year, total biomass was 14.7 t?ha-1 in highly disturbed site, 94.46 t?ha-1 in moderately disturbed forest, and 112.0 t?ha-1 in protected forest. The soil organic carbon in the top 20 cm of soil ranged from 0.63 to 1.2%. The total rate of carbon sequestration was 0.60(t/ha)·a-1on the highly disturbed site, 1.03(t/ha)·a-1 on the moderately disturbed site, and 4.3(t/ha)·a-1 on the protected site.