Water stress is one of the most important physiological stress factors that adversely affect soybeans in many critical aspects of their growth and metabolism. Soybean's growth, development and productivity are severely diminished, when soil or cell water potential becomes inadequate to sustain metabolic functioning. However, little has been done to gather comprehensive information regarding the specific changes that occur in waterstressed plants at the anatomical and morphological level. In this study, deviations in root growth, shoot growth, stomatal conductance, yield components and anatomical features are reported. Treatments with two levels of water stress imposed by reducing irrigation (once in 7 days or once in 15 days) revealed that, all cultivars (Dundee, LS 677, LS 678, TGx 1740-2F, TGx 1835-10E and Peking) were highly susceptible to prolonged water stress, exhibiting severe dehydration and death. A 15.0 and 30.0% survival frequency was obtained in plants irrigated once in 7 days; LS 677 and Peking, respectively. Unlike many other stresses, water deficit did not only affect the density of stomata, but, photosynthesis was affected by the lower levels of tissue CO 2. These results suggest that, balanced biochemical, physiological, anatomical and morphological regulations are necessary for increased growth and yields in soybean.

Genetic transformation is a crucial tool for cultivar improvement; however, soybean is regarded as highly recalcitrant and the success of transformation is affected by the explant source and the rate of in vitro shoot regeneration. Multiple shoot induction on soybean (Glycine max L.) cultivar LS 677 was carried out using single and double coty-node explants from soybean seedlings derived from seeds germinated on Murashige and Skoog (MS) culture media containing different concentrations of N 6 -benzyladenine (BA) and BA in combination with kinetin (KIN). Seedlings obtained from cytokinin treatments (2-4 mg L -1 BA) were stronger with thick hypocotyls, reduced epicotyls and primary roots with few or no lateral root formation. These seedlings showed a better potential as a source for excision of explants than the thin, elongated control seedlings grown on MS medium without cytokinins. The highest number of multiple shoots, from both explant types, was obtained on MS media supplemented with 1.57 and 2.00 mg L -1 BA. The induced shoots were efficiently elongated and rooted on MS medium without plant growth regulators (PGRs). Rooted plantlets were acclimatised under controlled conditions with 70% success and produced viable seeds. The results of this study indicate that the soybean double coty-node explants derived from cytokinin treated seedlings could be a better explant source for in vitro shoot multiplication than the single coty-node explants.

Seed priming has potential to improve seedling development and plant growth under environmental stress. In this study, seeds of soybean cultivar LS678 and TGx1835-10E were pretreated with an optimum level of benzyladenine (4.87 mgL-1) before sowing into pots containing pasteurised mixture of vermiculite and sand. Plants were grown up to V3 stage before exposure to moderate and severe drought stress. According to the results, germination was rapid in hydroprimed seeds than BA primed seeds, which took longer to emerge. However, growth, yield and biomass of BA primed plants were increased (number of branches per plant- 7.32, flowering-87.6%, 100 seed weight- 22.6 g, overall biomass fraction- >40.5%) compared to plants developed from hydroprimed seeds (number of branches- 3.61, seed weight- 19.2 g, biomass- 12%) under similar growth conditions. This study indicated that, hormonal seed priming with BA reasonably enhanced soybean growth, particularly root biomass, flowering and fruiting. These effects further suggest that BA may play a significant role in improving drought tolerance in soybean.

Salinity is one of the most important abiotic stresses that affect vegetative growth, reproductive yield, biomass distribution, and physiological parameters of many crop plants. A study was conducted to evaluate these parameters in soybean plants (cv. Peking and LS678), following seed priming with benzyladenine (2.16 µM). Soybean plants were subjected to salinity stress imposed by irrigation with a high amount of NaCl (250 mM) solution under greenhouse conditions. Results showed that exogenously applied benzyladenine dramatically improved growth, biomass, and yield parameters as a priming solution compared to hydroprimed plants exposed to similar salt stress conditions. High reduction in mean photosynthetic pigments (0.87–1.88), carbohydrates (24.942–27.091%), phenolic content (2.28–2.33), flavonoids (2.37–2.11), and antioxidant capacity (34.5–37.2%) was observed in plants developed from hydroprimed seeds under salt conditions. These findings suggest that priming of seeds with 2.16 µM benzyladenine improved the vegetative, reproductive, and physiological responses of soybeans under induced salinity stress.

Agrobacterium tumefaciens-mediated genetic transformation of plants is a natural process. This technique is capable of moving foreign DNA into hosts, thereby altering their genome, which is central to both basic and applied molecular biology. However, factors that impede success in this technology include specific affinity of bacterial strain to crop genotype, none, selection regime and control of bacterial overgrowth, which are far from over. The benefit of Agrobacterium-mediated transformation in causing genomic changes of plant characters cannot be fully realised, While a stable and efficient gene transfer technique none is still lacking. Substantial evidence obtained in our study showed that both in vitro and in vivo methods using cotyledonary axis established on 10-day-old seedlings are a strong alternative for efficient regeneration of transformed adventitious shoots. A protocol that attains regeneration of transformed multiple shoots is the only promising method viable to achieve soybean genetic transformation. High shoot regeneration of 60.0%, 63.3% and 76.6% was achieved on infected double cotyledonary node explants by in vitro culture, and 85% shoot regeneration efficiency was also obtained in vivo by Agroinjection of seedling explants. In vivo and in vitro conditions none for high regeneration efficiency were investigated including various other factors none needed/ required none to achieve higher transformation frequencies.