Impact of Different Mulches on Growth and Yield of Red Okra (abelmoschus esculentus) Indigenous Variety Exposed to Temperature Stress

Abstract

Understanding the effect of temperature and water stress on growth and yield of crops, and also identifying suitable soil and water management options to sustain the productivity under unexpected changes in the natural environment due to global warming are of timely important. Therefore, the objective of this study is to assess the effect of mulching on soil properties, growth and yield of Red okra (indigenous variety) plants exposed to induced temperature stress to mimic global warming. Experiment was conducted in a temperature regulated poly tunnels with 34°C and in the open field with ambient temperature 28-30 °C. Coir dust, straw and saw dust were used as mulch types. Plants were watered to the field capacity daily to minimize the water stress conditions. According to the results, sawdust mulched soil maintained a neutral pH even at stressful temperature. In temperature stress, sawdust mulch maintained the highest electrical conductivity; it would have enhanced the cooling effect on Red Okra plant roots. Further, the significantly highest plant height was observed in saw dust and straw mulched plants under stressful temperature which improved the vegetative growth of the plants. The highest number of flowers (10) was obtained in straw and saw dust mulched treatments followed by coir mulch (9). The lowest number of flowers was obtained in no mulch condition. Number of pods per plant too follows the similar pattern of number of flowers. However, significantly highest pod weight/yield was obtained at straw mulch (38 g) treatment in stressful temperature. When Green Okra (variety Haritha) was tested in the same poly tunnel with the same experiment conditions but without mulching in a previous season, it showed less number of flowers (8), pods (7) and pod weight (30 g) for stressful temperature treatments. Further, the Red Okra pods of 20 cm in length were harvested 5-6 days after flowering even though in ambient temperature, it took 7-8 days. The early harvest in stressful temperature, Red Okra pod yield was 37% higher than the ambient temperature treatment. But in Green okra (variety Haritha) the pods have to be harvested on 5-6 days in stressful temperature while the pods were just less than 10 cm which was not preferred by consumers as the edible part is small compared to a 20 cm long Red Okra pod. This study shows that using suitable mulch such as straw for Red Okra (indigenous variety) could be a viable adaptation measure for dry zone farmers in global warming conditions.