Relationship of round gourd (Praecitrullus fistulosus) fruit yield with soil temperature and nutrient uptake under different mulches and sowing times

Round gourd (Praecitrullus fistulosus), a shallow-rooted cucurbit-vegetable, is sensitive to temperature and needs nutrient-rich soil for its successful cultivation. A two-year study was conducted in the North-Indian plains to investigate the effects of mulching (M) [silver-black polyethylene (SBPM), black polyethylene (BPM), paddy straw (6 t ha−1) (PSM), and bare soil (BS)] at six sowing dates (DS) [1st week of March (DS1), April (DS2), May (DS3), June (DS4), July (DS5), and August (DS6)] on soil temperature, fruit yield, plant biomass, and nutrient (N, P, and K) uptake and concentrations in the fruit and plant. Since the interaction effects of year with DS and M were significant for most parameters, the data were analyzed separately by each year. The effects of DS, M, and interaction (DS × M) were significant for all the parameters; however, interaction effects were non-significant for fruit nutrient concentrations in both years of the study. All three mulches enhanced the nutrient concentrations in the fruit and plant compared to BS at all sowing times. However, these increments were not positively correlated with increases in total nutrient uptake, plant biomass, and fruit yield, as soil temperature played a more decisive role in improving fruit yield. The crop yield was significantly and positively correlated with N, P, and K uptake at all sowing times except for P uptake in DS4 and DS5. Therefore, in DS4 and DS5, additional application of P-fertilizers should be avoided, and efforts should be made to reduce the soil temperature using higher doses of PSM.