Soil Temperature Associated with Degradable, Non-Degradable Plastic and Organic Mulches and Their Effect on Biomass Production, Enzyme Activities and Seed Yield of Winter Rapeseed (Brassica napus L.)

ABSTRACT

There has been little information available on the effect of different degradable and non-degradable plastic mulches on soil temperature and their effect on biomass production, enzyme activities, growth, and yield of winter rapeseed. Hence, field experiments were conducted with different types of mulches mulch viz., black polyethylene, transparent polyethylene, herbicidal polyethylene film (herbicide coated), degradable polypropylene, straw mulch, and non-mulched control. The results indicated that, in general, the soil temperature got decreased with the advancement in each phenophases of rapeseed crop up to flowering stage. Thereafter, a gradual increase in the temperature up to harvest was observed, which was mainly due to the weather prevailed during that period. Among the different mulches evaluated, soil temperature was higher under transparent film mulch, followed by degradable, herbicidal film, and black polyethylene film mulches. Interestingly, the soil temperature under straw mulch was lower than non-mulched control in the early stages of the crop and at pod maturity stages. Irrespective of the types and colors, higher soil temperature under all the plastic mulches had significantly improved the growth including shoot length, root length, and root to shoot ratio and vigor index at 15 DAS. The highest total biomass was also produced with plastic mulches due to increased soil temperatures, which was apparent in the early stages of the crop. Higher soil temperature under plastic mulches markedly shortened the days to 50% flowering and maturity. The superoxide dismutase (SOD) and peroxidase POD activities were increased with enhanced soil temperatures, while malondialdehyde (MDA) was decreased with increasing soil temperature under all the plastic mulches. The increased number of pods per plant, number of seeds per pod, and seed yield observed with plastic mulches due to increased soil temperature indicates that modification of field soil temperature through management practices could improve rapeseed production by achieving an optimal balance between vegetative and reproductive growth.

KEYWORDS:

• Rapeseed
• degradable
• polyethylene films
• soil temperature
• enzyme