Interplanting Some Soybean Cultivars with Mandarin Trees in Sandy Soil

Two-year field experiments were carried out at El-Kassasen Horticultural Research Station, Agricultural Research Center (ARC), Ismailia government, Egypt, during 2018 and 2019 summer seasons to evaluate some soybean cultivars for interplanting with mandarin trees to achieve high productivity of both crops, land usage and profitability under sandy soil conditions. The treatments were the combinations of two cropping systems (interplanting and solid cultures) and five soybean cultivars (Giza 21, Giza 22, Giza 35, Giza 82 and Giza 111). A strip plot design with three replications was used. Interplanting soybean cultivar Giza 22 with mandarin trees gave a higher total count of rhizobia in rhizosphere of mandarin roots after 75 days from soybean sowing than the other treatments in both seasons. The highest fruit weight and volume, total soluble solids (T.S.S.), fruit yields per tree and per ha were obtained by growing soybean cultivar Giza 22 or Giza 111 with mandarin compared with the other treatments in both seasons. With respect to soybean crop, interplanting soybean with mandarin trees decreased percentages of light intensity at the middle and bottom of the plant, chlorophylls a and b, as well as, plant dry weight after 75 days from soybean sowing compared with those of solid culture in both seasons. Soybean cultivars Giza 22 and Giza 82 had higher light intensity at the middle and bottom of the plant, as well as chlorophyll a, meanwhile soybean cultivars Giza 22 and Giza 111 had higher plant dry weight than the other soybean cultivars after 75 days from soybean sowing in both seasons. Soybean cultivar Giza 22 and Giza 111 had higher plant dry weight than the other soybean cultivars under interplanting and solid plantings in both seasons. Interplanting soybean with mandarin trees decreased soybean seed yield and its attributes compared with soybean solid culture in both seasons. Soybean cultivars Giza 111 and Giza 22 gave a higher number of pods per plant, seed yields per plant and per ha than the other cultivars in both seasons. Soybean cultivars Giza 111 and Giza 22 followed by Giza 82 recorded a higher number of pods per plant, seed yields per plant and per ha under interplanting and solid cultures than the other treatments in both seasons. Interplanting soybean cultivar Giza 22 and Giza 111 with mandarin trees achieved higher LER, LEC, total return and MAI than solid culture of mandarin. Growing four ridges of soybean cultivars Giza 22 or Giza 111 between mandarin trees cultivar Fremont had higher productivity, land usage and profitability than mandarin solid culture under sandy soil conditions.