Asif Saeed

Screening Pea Germplasm Against Erysiphe polygoni for Disease Severity and Latent Period

Powdery mildew disease caused by Erysiphe polygoni DC significantly reduces yield quantity and quality of edible seed in pea (Pisum sativum L.). Development of powdery mildew–resistant varieties is an economical and environmentally friendly approach to managing the disease. One hundred forty-six pea accessions, collected from different countries, were screened against powdery mildew. It was determined that accessions 9057, 9370, 9375, 10609, 10612, 18293, 18412, 19598, 19611, 19616, 19727, 19750, 19782, 20126, 20152, 20171, It-96, No. 267, and No. 380 were resistant; accessions It-96 and No. 267 were highly resistant. The correlation between disease score and latent period was negative, suggesting that these parameters should be used simultaneously for more precise screening against powdery mildew. The resistant accessions selected might be used as powdery mildew–resistant parent(s) in breeding programs depending upon the nature and number of gene(s) controlling for resistance.

Pathogenicity and Characterization of Geographically Distributed Isolates of Erysiphe polygoni

The incidence of powdery mildew disease on pea (Pisum sativum L.) is a major limiting factor to maximizing yields in different ecological and geographical zones due to environmental factors and the presence of pathogenic variation in Erysiphe polygoni DC. In order to develop a widely adopted powdery mildew–resistant cultivar it is necessary to challenge genotypes with all available pathogenic variants. In order to examine pathogenic variation, 23 naturally occurring single colony isolates of E. polygoni, collected from geographically diverse locations, were subjected to pathogenicity testing and characterization using a detached leaf assay. Isolates demonstrated small differences in pathogenicity against pea. Isolates MUZ-1 and MUZ-2 were the most virulent and produced disease symptoms even on the resistant cultivars. Isolates TTS-2 and TTS-6 were less virulent. Significant variation occurred among isolates for quantitative and qualitative parameters regardless of the degree of pathogenicity. There was variation for conidium length, conidium width, cleistothecia number, number of hyphae, ascus number, ascus length, ascospore number, and ascospore width. An unweighted pair group method with arithmetic mean phenogram, constructed on the basis of quantitative parameters, indicated that isolates were morphologically different but pathogenicity was not controlled by morphological features of the isolates, though morphological features can be used to distinguish between isolates.

Screening and evaluation of tomato germplasm for NaCl tolerance

Abstract The experiments were aimed at assessing the response of 72 tomato accessions to NaCl stress in the rooting media. The genotypic responses were compared using absolute values measuring shoot and root lengths, and fresh shoot and root weights. All the characters exhibited some reductions under increased salinity levels at seedling stage. Based upon absolute root length data, the accessions LA2661, CLN2498A, CLN1621L, BL1176, 6233, and 17870 were found to be more tolerant than the accessions 17902, LO2875, and LO4360. Assessment of Na+ and K+ ion content of nine accessions again substantiated the differing response of these accessions under 10 and 15 dS m−1 salinity levels. It was concluded that the potential of these genotypes to tolerate increased salt levels was found to be due to longer root, low accumulation of Na+, and greater K+/Na+ quotient.

Screening of tomato genotypes for salinity tolerance based on early growth attributes and leaf inorganic osmolytes

ABSTRACT The experiment containing three replicates of completely randomized factorial treatments was conducted in a glasshouse under controlled conditions with three simulated soil salinity levels (control, 10 and 15 dS m−1). Morpho-physiological traits (i.e. lengths, fresh weights and dry weights of root and shoot, number of leaves, root/shoot ratio, shoot Na+ accumulation, K+/Na+ ratio, Ca2+/Na+ ratio, membrane stability index, lycopene contents, chlorophyll-a and -b) were recorded to determine mechanism of salt tolerance of tomato at seedling stage. Principal component analysis (PCA) was used to express a three-way interaction of genotype × salinity level × traits that scattered the 25 tomato genotypes based on their morpho-physiological response to different NaCl levels. The negative association of Na+ with all other traits except root/shoot ratio and the morpho-physiological response trend of genotypes exposed that probable mechanism of salt tolerance was initially Na+ exclusion by abscising older leaves to have younger physiologically energetic, and lastly a higher activity of plants for root development to sustain them in saline soil. PCA three-way biplot efficiently recognized ANAHU, LA-2821, LO-2752, LO-2707, PB-017909, LO-2831-23 and 017860 as salt tolerant genotypes. On the other hand, ZARNITZA, GLACIER, LO-2692, LO-2576, BL-1079, 006233, 006232, 017856, NUTYT-701 and NAGINA were found to be salt susceptible.