Effects of Aluminium Toxicity on Root and Shoot Growth Of Rice and Chickpea Seedlings

Increasing concentrations of aluminium progressively declined primary root length and number of lateral roots in rice and chickpea seedlings grown in rhizobox. It also inhibited the root and shoot length, dry weight of root and shoot of rice and chickpea seedlings grown in solution culture. On the other hand, it enhanced shoot/root length ratio and dry weight ratio for both the genera. Bangladesh J. Bot. 50(4): 1195-1201, 2021 (December)

Identification and characterization of novel QTL conferring internal detoxification of aluminum in soybean

Aluminum (Al) toxicity inhibits soybean root growth, leading to insufficient water and nutrient uptake. In this research, two soybean lines (Magellan and PI 567731) were identified differing in Al tolerance as determined by primary root length ratio (PRL_Ratio), total root length ratio (TRL_Ratio), and root tip number ratio (RTN_Ratio) under Al stress compared to unstressed controlled conditions. Serious root necrosis was observed in PI 567731, but not in Magellan under Al stress. An F8 recombinant inbred line population derived from a cross between Magellan and PI 567731 was used to map the quantitative trait loci (QTL) for Al-tolerance. Three QTL on chromosomes 3, 13, and 20, with tolerant-alleles from Magellan, were identified. qAl_Gm13 and qAl_Gm20, explained large phenotypic variations (13-27%) and played roles in maintaining root elongation. qAl_Gm03 was involved in maintaining root initiation under Al stress. These results suggested the importance of using the parameters of root elongation and root initiation in Al tolerance studies. In addition, qAl_Gm13 and qAl_Gm20 were confirmed in near-isogenic backgrounds and were identified to epistatically regulate Al tolerance in internal detoxification instead of Al 3+ exclusion. The candidate genes for qAl_Gm13 and qAl_Gm20 were suggested by analyzing a previous RNA-seq study. Phylogenetic and pedigree analysis identified the tolerant alleles of both loci derived from the US ancestor line, A.K.[FC30761], originally from China. Our results provide novel genetic resources for breeding Al-tolerant soybeans and suggest that the internal detoxification contributes to soybean tolerance to excessive soil Al.

Allelopathic Effect of Powdered Russian Knapweed (Acroptilon repens L.) on the Growth Parameters of Redroot Amaranth (Amaranthus retroflexus L.)

To evaluate probable allelopathic effect of different parts of Russian knapweed (Acroptilon repens L.) on the growth of redroot amaranth (Amaranthus retroflexus L.) seedling, a factorial experiment was conducted based on randomized complete block design with three replications at the Faculty of Agriculture, Urmia University in 2012 (Iran). In this experiment, treatments were different parts of Russian knapweed (aerial part, flower and root) in different amounts (1, 2, 3 and 4 g/pot). Pots included 300 g of soil. Results showed the significant effect of Russian knapweed plant parts on the seedling emergence percent, root length, ratio of root/shoot length, seedling length, seedling fresh weight, and the significant effect of plant material amounts on the seedling emergence percent, seedling fresh weight and seedling dry weight. Interaction effect between plant material type and amount on the shoot length, root length, ratio of root/shoot length, seedling length was significant, too. The longest shoot (3.51 cm), root (1.75 cm), the highest ratio of root/shoot length (0.49) and seedling length (5.26 cm) belonged to control treatment. The highest seedling emergence percent of Amaranthus retroflexus (34.73%) and seedling fresh weight (0.176 g) were occurred at pots treated by Russian knapweed aerial part. The lowest seedling emergence percent (21.94 %) and seedling fresh weight (0.111 g) were obtained from application of Acroptilon repens powdered root. The maximum seedling dry (0.0126 g) and fresh (0.177 g) weight of Amaranthus retroflexus were obtained from control treatment.

Growth, gas exchange and competitive ability of Sorghum halepense populations under different soil water availability

Leguizamón, E. S., Yanniccari, M. E., Guiamet, J. J. and Acciaresi, H. A. 2011. Growth, gas exchange and competitive ability of Sorghum halepense populations under different soil water availability. Can. J. Plant Sci. 91: 1011–1025. Different studies have determined that environmental variation is a key factor determining the outcome of competition within plant communities. Considering the importance of the resource water in non-irrigated lands of Argentina, the aim was to determine the effects of water deficit on relative growth rate (RGR), root length ratio (RLR), gas exchange and competitive ability of Sorghum halepense populations collected in humid and subhumid regions of the Pampa plains. Under semi-controlled conditions, we compared plants of seven S. halepense populations subjected to three different levels of soil water availability during 3 wk: Field capacity (FC), 75% FC and drought (D). Moreover, total above-ground biomass of S. halepense and Zea mays plants growing together in competition was determined. It was found that those plants collected in humid or subhumid regions had greater RGR, gas exchange and RLR under FC and D, respectively. Zea mays achieved a higher competitive ability than S. halepense under FC, but plants collected in humid regions out-competed the crop when grown at 75% FC. Sorghum halepense plants collected in subhumid regions dominated under D. Root length ratio may have favored the maintenance of high levels of gas exchange and also high RGR, thus contributing to sustain a competitive hierarchy under soil water stress.