Early Planting and Fertility Affect Root Production in Fresh Market Tomatoes

摘要

There is limited information on what is the optimal root system size in tomato (Lycopersicon esculentum Mill.) to produce high yield. Environmental and cultural factors can have significant impact on root development. The effect of early versus late spring establishment and different nutrient rates were evaluated for field-grown tomato on how they affected root systems and yield. Minirhizotron observation tubes were used to quantify root production and senescence in field-grown plants of tomato, cv.Mountain Spring. A low fertility regime of pre-plant fertilizer only was compared to a high fertility regime that combined pre-plant fertilizer with additional potassium and nitrogen fertigation during fruiting. Five harvests were conducted and yield ofUS No. 1 fruit was highest for early established plants treated with high fertility (34,140 kg-ha~(-1)), followed by late established plants receiving the low fertility treatment (32,252 kg-ha~(-1)), and late established plants receiving the high fertility treatment (28,085 kg-ha~(-1)). There was a marked effect of planting date on root growth initially; by mid-July early established plants had 140% more roots than late established plants. Over the growing season planting date and fertility had more limited impact on root systems, and in this study there was no apparent relationship between yield and white root counts (R~2 = 0.23). Root browning and senescence was clearly visible in the digital images obtained. Senescence in roots increased from about10% to 90% of the roots from fruit filling through harvest. By mid-September the low fertility-late established plants had slightly but significantly greater numbers of senescence roots (-15%) and fewer white roots (-25%) compared to the other plants.