Banik P, Pramanik P, Sarkar R R, Bhattacharya S, Chattopadhayay J
Agricultural and Ecological Research Unit, Indian Statistical Institute, 203 B.T. Road, Kolkata 700108, India.
Biosystems. 2007 Nov-Dec;90(3):818-29. doi: 10.1016/j.biosystems.2007.05.001. Epub 2007 May 10.
Many weeds interfere with the productivity of wheat and other winter annual crops; however, one common weed Medicago denticulata, appears to have a beneficial effect. An experiment was conducted at Agricultural Experimental Farm of the Indian Statistical Institute, Giridih, Jharkhand to observe the effect of M. denticulata (a legume) on different crops yield of barley (Hordeum vulgare Sensu lato), linseed (Linum usitatissimum L.), Indian mustard [Brassica juncea (L.) Czernj. & Cosson] and wheat (Triticum aestivum L.). The commensalisms interaction was studied, in which one species benefits, while the other is unaffected, between the crops, M. denticulata and other weeds, to observe the role of medicago as biological control agent of other weeds for enhancement of crop productivity. Further, a statistical test was performed to establish the effect of M. denticulata and weed infestations based on one-step Markov structure of the covariance matrix of the biomass. This permitted development of a mathematical model of a crop-M. denticulata-other weeds system and their interactions through direct and indirect competition for resources. Crops yield decreased considerably due to the presence of other weeds, while it increased due to introduction of medicago and hence medicago acted as a controlling agent in a crop-M. denticulata-other weeds system. Our mathematical analysis supported the experimental findings. The model parameters are estimated through a nonlinear least square and stochastic differential equations. Moreover, some thresholds for the growth of medicago population came out from our analysis that may be used as a biological control threshold for the enhancement of crop productivity.
许多杂草会影响小麦和其他冬季一年生作物的产量；然而，一种常见杂草——细齿苜蓿，似乎具有有益作用。在印度统计研究所位于贾坎德邦吉里迪的农业实验农场进行了一项实验，以观察细齿苜蓿（一种豆科植物）对大麦（广义大麦）、亚麻籽（亚麻）、印度芥菜[芥菜（L.）Czernj. & Cosson]和小麦（普通小麦）不同作物产量的影响。研究了共生相互作用，即作物、细齿苜蓿和其他杂草之间，一种物种受益而另一种不受影响的情况，以观察苜蓿作为其他杂草的生物防治剂对提高作物生产力的作用。此外，基于生物量协方差矩阵的单步马尔可夫结构进行了统计检验，以确定细齿苜蓿和杂草侵害的影响。这使得能够建立一个作物 - 细齿苜蓿 - 其他杂草系统及其通过对资源的直接和间接竞争进行相互作用的数学模型。由于其他杂草的存在，作物产量大幅下降，而由于引入苜蓿，产量增加，因此苜蓿在作物 - 细齿苜蓿 - 其他杂草系统中起到了控制剂的作用。我们的数学分析支持了实验结果。通过非线性最小二乘法和随机微分方程估计了模型参数。此外，我们的分析得出了一些苜蓿种群增长的阈值，可将其用作提高作物生产力的生物防治阈值。
