Residual Effect of Pendimethalin and Other Herbicides Applied in Pigeonpea on Succeeding Crop of Greengram

Field experiment was conducted during 2012 and 2013 in the Research Area of College Farm, Navsari Agricultural University, Navsari to study the effect of residual behavior of pendimethalin applied in pigeonpea on succeeding greengram crop grown in rotation. Residual effect of pendimethalin was assessed by conducting bioassay studies on greengram in a randomized block design with three plant population levels 83, 333 plants/ha (P₁)’ 55, 555 plants/ha (P₂) and 41, 666 plants/ha (P₃) and eight weed management practices viz. (W₁) Unweeded control, (W₂) Weed free (HW at 20 and 40 DAS), (W₃) Pendimethalin @ 1 kg ha⁻¹ as pre-emergence (PE), (W₄) Imazethapyr @ 75 g ha⁻¹ (POE) at 20 DAS, (W₅) Quizalofop ethyl @ 40 g ha⁻¹ (POE) at 20 DAS, (W₆) Pendimethalin @ 1 kg ha⁻¹ (PE) + Imazethapyr @ 75 g ha⁻¹ (POE) at 40 DAS, (W₇) Pendimethalin @ 1 kg ha⁻¹ (PE) + Quizalofop ethyl @ 40 g ha⁻¹ (POE) at 40 DAS and (W₈) Pendimethalin @ 1 kg ha⁻¹ + hand weeding at 40 DAS were evaluated in factorial randomized block design with three replications. After harvest of pigeonpea, greengram crop was planted after slight disking without disturbing the original layout. pendimethalin applied in pigeonpea was found to persist even after 35 days after its application in pigeonpea and its residues in the soil medium donot caused phytotoxicity to succeeding crop of greengram. Plant population, plant height, number of branches per plant, dry matter weight and yield of greengram were non-significantly by pendimethalin. The residual effect of pendimethalin on greengram was not found to be significant. Neither the growth parameters nor the yield of greengram were not affected significantly by plant populations in wheat. Therefore, it can be inferred that increasing plant populations not helped in degradation of pendimethalin and greengram should be planted in rotation with pigeonpea where pendimethalin has been applied in pigeonpea.