The present study elucidated the role of triacontanol in regulating seed germination and seedling vigour of four cucumber cultivars under salt stress (50 mM NaCl). Seeds were soaked in aerated solution of triacontanol @ 25 μM, 50 μM for 12 h prior to sowing and untreated seeds were used as control. Priming enhanced the emergence rate, uniformity and early growth of cucumber seedlings under normal and saline conditions. Though, plants exposed to salt stress and seeds not treated with triacontanol showed poor performance in growth, physiology and biochemical attributes. However, priming with 25 and 50 μM triacontanol was very effective in decreasing time to start emergence, improved final emergence, shoot/root lengths, seedling dry weight, gas exchange attributes, chlorophyll and proline contents under saline conditions. Nonetheless, maximum relief from salt stress in all attributes was observed at 50 μM triacontanol. In conclusion, triacontanol can be successfully employed to improve the germination capacity and stand establishment of cucumber under saline conditions by reducing the deleterious effects of salinity.

To cite this paper: Mahboob, W., H.U. Rehman, S.M.A. Basra, I. Afzal, M.A. Abbas, M. Naeem, M. Abbas, 2015. Seed priming improves the performance of late sown spring maize (Zea mays) through better crop stand and physiological attributes. AbstractHigh soil temperature and low water potential is one of major impediment of reduced and delayed germination of spring maize under delayed planting. Seed priming helps to ameliorate the seedling establishment under both normal and less than optimal conditions but very few studies available highlight maize crop establishment improvement by seed priming on physiological basis under field conditions. The present field study evaluated the effects of various seed priming techniques on stand establishment, growth, yield and various physiological attributes of spring maize under normal and late sown conditions. The hybrid maize seed soaked with hydro-priming (water), osmopriming with CaCl 2 (Ψs= -1.25 MPa), moringa leaf extract (MLE; 1:30) and salicylic acid (SA; 50 mg L -1 ) were grown under two sowing dates (optimum and late conditions). Hydro-priming and dry seeds without priming were taken as controls. Among priming treatments, osmopriming with CaCl 2 reduced the time to 50% emergence (E 50 ), mean emergence time (MET), enhanced number of grains per cob, biological yield and improved relative water contents with reduced cell membrane permeability including grain protein contents. Osmopriming with moringa leaf extract (MLE) improved emergence time (EI), Chl a and b contents, grain yield and harvest index (HI) including hormonal priming with SA for maximum HI. Nevertheless, hydro-primed seeds exhibited the minimum days to maturity. The present study suggests that seed osmopriming with MLE and CaCl 2 are effective not only to improve seedling establishment but also yield performance of spring maize through physiological improvement under both optimal and late sown conditions.

Cucumber is an important vegetable but highly sensitive to salt stress. The present study was designed to investigate the comparative performance of cucumber genotypes under salt stress (50 mmol L−1) and stress alleviation through an optimized level of triacontanol @ 0.8 mg L−1. Four cucumber genotypes were subjected to foliar application of triacontanol under stress. Different physiological, biochemical, water relations and ionic traits were observed to determine the role of triacontanol in salt stress alleviation. Triacontanol ameliorated the lethal impact of salt stress in all genotypes, but Green long and Marketmore were more responsive than Summer green and 20252 in almost all the attributes that define the genetic potential of genotypes. Triacontanol performs as a good scavenger of ROS by accelerating the activity of antioxidant enzymes (SOD, POD, CAT) and compatible solutes (proline, glycinebetaine, phenolic contents), which lead to improved gas exchange attributes and water relations and in that way enhance the calcium and potassium contents or decline the sodium and chloride contents in cucumber leaves. Furthermore, triacontanol feeding also shows the answer to yield traits of cucumber. It was concluded from the results that the salinity tolerance efficacy of triacontanol is valid in enhancing the productivity of cucumber plants under salt stress. Triacontanol was more pronounced in green long and marketer green than in summer green and 20252. Hence, the findings of this study pave the way towards the usage of triacontanol @ 0.8 mg L−1, and green long and marketer genotypes may be recommended for saline soil.

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